Changelog（更動日誌）

Python next

Release date: XXXX-XX-XX

Windows

Tests

  • gh-133744: Fix multiprocessing interrupt test. Add an event to synchronizethe parent process with the child process: wait until the child processstarts sleeping. Patch by Victor Stinner.

  • gh-133639: FixTestPyReplAutoindent.test_auto_indent_default() doesn'truninput_code.

  • gh-133131: The iOS testbed will now select the most recently released"SE-class" device for testing if a device isn't explicitly specified.

  • gh-109981: The test helper that counts the list of open file descriptorsnow uses the optimised/dev/fd approach on all Apple platforms, notjust macOS. This avoids crashes caused by guarded file descriptors.

Library

IDLE

  • gh-112936: fix IDLE: no Shell menu item in single-process mode.

Documentation

Core and Builtins

  • gh-134100: Fix a use-after-free bug that occurs when an imported moduleisn't insys.modules after its initial import. Patch byNico-Posada.

  • gh-133703: Fix hashtable in dict can be bigger than intended in somesituations.

  • gh-132869: Fix crash in thefree threading build when accessing anobject attribute that may be concurrently inserted or deleted.

  • gh-132762:fromkeys() no longer loops forever when adding asmall set of keys to a large base dict. Patch by Angela Liss.

  • gh-133543: Fix a possible memory leak that could occur when directlyaccessing instance dictionaries (__dict__) that later become part of areference cycle.

  • gh-133516: RaiseValueError when constantsTrue,False orNone are used as an identifier after NFKC normalization.

  • gh-133441: Fix crash upon setting an attribute with adictsubclass. Patch by Victor Stinner.

  • gh-132942: Fix two races in the type lookup cache. This affected thefree-threaded build and could cause crashes (apparently quite difficult totrigger).

  • gh-132713: Fixrepr(list) race condition: hold a strong reference tothe item while callingrepr(item). Patch by Victor Stinner.

  • gh-132747: Fix a crash when calling__get__() of amethod with aNone second argument.

  • gh-124476: Fix decoding from the locale encoding in the C.UTF-8 locale.

  • gh-131927: Compiler warnings originating from the same module and linenumber are now only emitted once, matching the behaviour of warningsemitted from user code. This can also be configured withwarningsfilters.

  • gh-127682: No longer call__iter__ twice when creating and executing agenerator expression. Creating a generator expression from a non-interablewill raise only when the generator expression is executed. This brings thebehavior of generator expressions in line with other generators.

  • gh-131878: Handle uncaught exceptions in the main input loop for the newREPL.

  • gh-131878: Fix support of unicode characters with two or more codepointson Windows in the new REPL.

  • gh-130804: Fix support of unicode characters on Windows in the new REPL.

  • gh-130070: Fixed an assertion error forexec() passed a stringsource and a non-Noneclosure. Patch by Bartosz Sławecki.

  • gh-129958: Fix a bug that was allowing newlines inconsitently in formatspecifiers for single-quoted f-strings. Patch by Pablo Galindo.

C API

Build

  • gh-133183: iOS compiler shims now includeIPHONEOS_DEPLOYMENT_TARGETin target triples, ensuring that SDK version minimums are honored.

  • gh-133167: Fix compilation process with--enable-optimizations and--without-docstrings.

  • gh-132649: ThePClayout script now allows passing--include-tcltk on Windows ARM64.

  • gh-117088: AIX linker don't support -h option, so avoid it throughplatform check

  • gh-132026: Fix use of undefined identifiers in platform triplet detectionon MIPS Linux platforms.

Python 3.13.3 final

Release date: 2025-04-08

macOS

  • gh-124111: Update macOS installer to use Tcl/Tk 8.6.16.

  • gh-131423: Update macOS installer to use OpenSSL 3.0.16. Patch by BénédiktTran.

  • gh-131025: Update macOS installer to ship with SQLite 3.49.1.

  • gh-91132: Update macOS installer to use ncurses 6.5.

Windows

  • gh-131423: Update bundled version of OpenSSL to 3.0.16. The new build alsodisables uplink support, which may be relevant to embedders but has noimpact on normal use.

  • gh-131025: Update Windows installer to ship with SQLite 3.49.1.

  • gh-131020:pylauncher correctly detects a BOMwhen searching for the shebang. Fix by Chris Eibl.

Tools/Demos

  • gh-131852:msgfmt no longer adds thePOT-Creation-Date togenerated.mo files for consistency with GNUmsgfmt.

  • gh-85012: Correctly resetmsgctxt when compiling messages inmsgfmt.

  • gh-130025: The iOS testbed now correctly handles symlinks used as Pythonframework references.

Tests

  • gh-131050:test_ssl.test_dh_params is skipped if the underlying TLSlibrary does not support finite-field ephemeral Diffie-Hellman.

  • gh-129200: Multiple iOS testbed runners can now be started at the sametime without introducing an ambiguity over simulator ownership.

  • gh-130292: The iOS testbed will now run successfully on a machine that hasnot previously run Xcode tests (such as CI configurations).

  • gh-130293: The tests of terminal colorization are no longer sensitive tothe value of theTERM variable in the testing environment.

  • gh-126332: Add unit tests for pyrepl.

Security

  • gh-131809: Update bundled libexpat to 2.7.1

  • gh-131261: Upgrade to libexpat 2.7.0

  • gh-127371: Avoid unbounded buffering fortempfile.SpooledTemporaryFile.writelines(). Previously, diskspillover was only checked after the lines iterator had been exhausted.This is now done after each line is written.

  • gh-121284: Fix bug in the folding of rfc2047 encoded-words when flatteningan email message using a modern email policy. Previously when anencoded-word was too long for a line, it would be decoded, split acrosslines, and re-encoded. But commas and other special characters in theoriginal text could be left unencoded and unquoted. This couldtheoretically be used to spoof header lines using a carefully constructedencoded-word if the resulting rendered email was transmitted or re-parsed.

Library

IDLE

  • gh-129873: Simplify displaying the IDLE doc by only copying the textsection of idle.html to idlelib/help.html. Patch by Stan Ulbrych.

Documentation

Core and Builtins

  • gh-132011: Fix crash when callinglist.append() as an unboundmethod.

  • gh-131998: Fix a crash when using an unbound methoddescriptorobject in a function where a bound method descriptor was used.

  • gh-131988: Fix a performance regression that caused scaling bottlenecks inthe free threaded build in 3.13.1 and 3.13.2.

  • gh-131719: Fix missing NULL check in_PyMem_FreeDelayed infree-threaded build.

  • gh-131670: Fixanext() failing on sync__anext__()raising an exception.

  • gh-131141: Fix data race insys.monitoring instrumentation whileregistering callback.

  • gh-130932: Fix incorrect exception handling in_PyModule_IsPossiblyShadowing

  • gh-130851: Fix a crash in thefree threading build whenconstructing acode object withco_conststhat contains instances of types that are not otherwise generated by thebytecode compiler.

  • gh-130794: Fix memory leak in thefree threadedbuild when resizing a shared list or dictionary from multiple short-livedthreads.

  • gh-130775: Do not crash on negativecolumn andend_column inast locations.

  • gh-130382: FixPyRefTracer_DESTROY not being sent fromPython/ceval.cPy_DECREF().

  • gh-130618: Fix a bug that was causingUnicodeDecodeError orSystemError to be raised when using f-strings withlambdaexpressions with non-ASCII characters. Patch by Pablo Galindo

  • gh-130163: Fix possible crashes related to concurrent change and use ofthesys module attributes.

  • gh-88887: Fixing multiprocessing Resource Tracker process leaking, usuallyobserved when running Python as PID 1.

  • gh-130115: Fix an issue with thread identifiers being sign-extended onsome platforms.

  • gh-128396: Fix a crash that occurs when callinglocals() inside aninline comprehension that uses the same local variable as the outer framescope where the variable is a free or cell var.

  • gh-116042: Fix location for SyntaxErrors of invalid escapes in thetokenizer. Patch by Pablo Galindo

  • gh-129983: Fix data race in compile_template insre.c.

  • gh-129967: Fix a race condition in thefree threading build whenrepr(set) is called concurrently withset.clear().

  • gh-129900: Fix return codes insideSystemExit not getting returnedby the REPL.

  • gh-129732: Fixed a race in_Py_qsbr_reserve in the free threadingbuild.

  • gh-129643: Fix thread safety ofPyList_Insert() in free-threadingbuilds.

  • gh-129668: Fix race condition when raisingMemoryError in the freethreaded build.

  • gh-129643: Fix thread safety ofPyList_SetItem() in free-threadingbuilds. Patch by Kumar Aditya.

  • gh-128714: Fix the potential races in get/set dunder methods__annotations__,__annotate__ and__type_params__ for functionobject, and add related tests.

  • gh-128632: Disallow__classdict__ as the name of a type parameter.Using this name would previously crash the interpreter in somecircumstances.

  • gh-127953: The time to handle aLINE event in sys.monitoring (andsys.settrace) is now independent of the number of lines in the codeobject.

  • gh-125331:from__future__importbarry_as_FLUFL now works in morecontexts, including when it is used in files, with the-c flag, and inthe REPL when there are multiple statements on the same line. Previously,it worked only on subsequent lines in the REPL, and when the appropriateflags were passed directly tocompile(). Patch by Pablo Galindo.

C API

Build

  • gh-131865: The DTrace build now properly passes theCC andCFLAGSvariables to thedtrace command when utilizing SystemTap on Linux.

  • gh-131675: Fix mimalloc library builds for 32-bit ARM targets.

  • gh-130673: Fix potentialKeyError when handling object sections duringJIT building process.

  • gh-130740: Ensure thatPython.h is included beforestdbool.hunlesspyconfig.h is included before or in some platform-specificcontexts.

  • gh-129838: Don't redefine_Py_NO_SANITIZE_UNDEFINED when compilingwith a recent GCC version and undefined sanitizer enabled.

  • gh-129660: Droptest_embed from PGO training, whose contribution inrecent versions is considered to be ignorable.

Python 3.13.2 final

Release date: 2025-02-04

macOS

  • gh-127592: Usage of the unified Apple System Log APIs was disabled whenthe minimum macOS version is earlier than 10.12.

Windows

  • gh-127353: Allow to force color output on Windows using environmentvariables. Patch by Andrey Efremov.

Tools/Demos

  • gh-129248: The iOS test runner now strips the log prefix from each lineoutput by the test suite.

  • gh-128152: Fix a bug where Argument Clinic's C pre-processor parser triedto parse pre-processor directives inside C comments. Patch by ErlendAasland.

Tests

  • gh-127906: Test the limited C API in test_cppext. Patch by Victor Stinner.

  • gh-127637: Add tests for thedis command-line interface. Patch byBénédikt Tran.

  • gh-126925: iOS test results are now streamed during test execution, andthe deprecated xcresulttool is no longer used.

Security

  • gh-105704: When usingurllib.parse.urlsplit() andurllib.parse.urlparse() host parsing would not reject domain namescontaining square brackets ([ and]). Square brackets are onlyvalid for IPv6 and IPvFuture hosts according toRFC 3986 Section 3.2.2.

  • gh-127655: Fixed theasyncio.selector_events._SelectorSocketTransport transport notpausing writes for the protocol when the buffer reaches the high watermark when usingasyncio.WriteTransport.writelines().

  • gh-126108: Fix a possibleNULL pointer dereference inPySys_AddWarnOptionUnicode().

  • gh-80222: Fix bug in the folding of quoted strings when flattening anemail message using a modern email policy. Previously when a quoted stringwas folded so that it spanned more than one line, the surrounding quotesand internal escapes would be omitted. This could theoretically be used tospoof header lines using a carefully constructed quoted string if theresulting rendered email was transmitted or re-parsed.

  • gh-119511: Fix a potential denial of service in theimaplib module.When connecting to a malicious server, it could cause an arbitrary amountof memory to be allocated. On many systems this is harmless as unusedvirtual memory is only a mapping, but if this hit a virtual address sizelimit it could lead to aMemoryError or other process crash. Onunusual systems or builds where all allocated memory is touched and backedby actual ram or storage it could've consumed resources doing so untilsimilarly crashing.

Library

  • gh-129502: Unlikely errors in preparing arguments forctypescallback are now handled in the same way as errors raised in the callbackof in converting the result of the callback -- usingsys.unraisablehook() instead ofsys.excepthook() and notsettingsys.last_exc and other variables.

  • gh-129403: CorrectedValueError message forasyncio.Barrier andthreading.Barrier.

  • gh-129409: Fix an integer overflow in thecsv module when writing adata field larger than 2GB.

  • gh-118761: Improve import time ofsubprocess by lazy importinglocale andsignal. Patch by Taneli Hukkinen.

  • gh-129346: Insqlite3, handle out-of-memory when creatinguser-defined SQL functions.

  • gh-129061: Fix FORCE_COLOR and NO_COLOR when empty strings. Patch by Hugovan Kemenade.

  • gh-128550: Removed an incorrect optimization relating to eager tasks inasyncio.TaskGroup that resulted in cancellations being missed.

  • gh-128991: Release the enter frame reference withinbdb callback

  • gh-128978: Fix aNameError insysconfig.expand_makefile_vars(). Patch by Bénédikt Tran.

  • gh-128961: Fix a crash when setting state on an exhaustedarray.array iterator.

  • gh-128894: Fixtraceback.TracebackException._format_syntax_error notto fail on exceptions with custom metadata.

  • gh-128916: Do not attempt to setSO_REUSEPORT on sockets of addressfamilies other thanAF_INET andAF_INET6, as it is meaninglesswith these address families, and the call with fail with Linux kernel6.12.9 and newer.

  • gh-128679: Fixtracemalloc.stop() race condition. Fixtracemalloc to support callingtracemalloc.stop() in onethread, while another thread is tracing memory allocations. Patch byVictor Stinner.

  • gh-128636: Fix PyREPL failure whenos.environ is overwritten withan invalid value.

  • gh-128562: Fix possible conflicts in generatedtkinter widget namesif the widget class name ends with a digit.

  • gh-128498: Default to stdout isatty for color detection instead of stderr.Patch by Hugo van Kemenade.

  • gh-128552: Fix cyclic garbage introduced byasyncio.loop.create_task() andasyncio.TaskGroup.create_task()holding a reference to the created task if it is eager.

  • gh-128479: Fixasyncio.staggered.staggered_race() leaking tasks andissuing an unhandled exception.

  • gh-128400: Fix crash when usingfaulthandler.dump_traceback() whileother threads are active on thefree threadedbuild.

  • gh-88834: Unify the instance check fortyping.Union andtypes.UnionType:Union now uses the instance checksagainst its parameters instead of the subclass checks.

  • gh-128302: Fixxml.dom.xmlbuilder.DOMEntityResolver.resolveEntity(), which wasbroken by the Python 3.0 transition.

  • gh-128302: Allowxml.dom.xmlbuilder.DOMParser.parse() to correctlyhandlexml.dom.xmlbuilder.DOMInputSource instances that onlyhave asystemId attribute set.

  • gh-112064: Fix incorrect handling of negative read sizes inHTTPResponse.read. Patch by YuryManushkin.

  • gh-58956: Fixed a frame reference leak inbdb.

  • gh-128131: Completely support random access of uncompressed unencryptedread-only zip files obtained byZipFile.open.

  • gh-112328:enum.EnumDict can now be used without resorting toprivate API.

  • gh-127975: Avoid reusing quote types inast.unparse() if not needed.

  • gh-128062: Revert the font ofturtledemo's menu bar to its defaultvalue and display the shortcut keys in the correct position.

  • gh-128014: Fix resetting the default window icon by passingdefault=''to thetkinter methodwm_iconbitmap().

  • gh-115514: Fix exceptions and incomplete writes afterasyncio._SelectorTransport is closed before writes arecompleted.

  • gh-41872: Fix quick extraction of module docstrings from a file inpydoc. It now supports docstrings with single quotes, escapesequences, raw string literals, and other Python syntax.

  • gh-127060: Set TERM environment variable to "dumb" to disable tracebackcolors in IDLE, since IDLE doesn't understand ANSI escape sequences. Patchby Victor Stinner.

  • gh-126742: Fix support of localized error messages reported bydlerror(3) andgdbm_strerror inctypes anddbm.gnu functions respectively. Patch by BénédiktTran.

  • gh-127873: When-E is set, only ignorePYTHON_COLORS and notFORCE_COLOR/NO_COLOR/TERM when colourising output. Patch byHugo van Kemenade.

  • gh-127870: Detect recursive calls in ctypes_as_parameter_ handling.Patch by Victor Stinner.

  • gh-127847: Fix the position when doing interleaved seeks and reads inuncompressed, unencrypted zip files returned byzipfile.ZipFile.open().

  • gh-127732: Theplatform module now correctly detects Windows Server2025.

  • gh-126821: macOS and iOS apps can now choose to redirect stdout and stderrto the system log during interpreter configuration.

  • gh-93312: Include<sys/pidfd.h> to getos.PIDFD_NONBLOCK constant.Patch by Victor Stinner.

  • gh-83662: Add missing__class_getitem__ method to the Pythonimplementation offunctools.partial(), to make it compatible withthe C version. This is mainly relevant for alternative Pythonimplementations like PyPy and GraalPy, because CPython will usually usethe C-implementation of that function.

  • gh-127586:multiprocessing.pool.Pool now properly restoresblocked signal handlers of the parent thread when creating processes viaeitherspawn orforkserver.

  • gh-98188: Fix an issue inemail.message.Message.get_payload() wheredata cannot be decoded if the Content Transfer Encoding mechanism containstrailing whitespaces or additional junk text. Patch by Hui Liu.

  • gh-127257: Inssl, system call failures that OpenSSL reports usingERR_LIB_SYS are now raised asOSError.

  • gh-127096: Do not recreate unnamed section on every read inconfigparser.ConfigParser. Patch by Andrey Efremov.

  • gh-127196: Fix crash when dict with keys in invalid encoding were passedto several functions in_interpreters module.

  • gh-126775: Makelinecache.checkcache() thread safe and GCre-entrancy safe.

  • gh-126332: Fix _pyrepl crash when entering a double CTRL-Z on anoverflowing line.

  • gh-126225:getopt andoptparse are no longer marked asdeprecated. There are legitimate reasons to use one of these modules inpreference toargparse, and none of these modules are at risk ofbeing removed from the standard library. Of the three,argparseremains the recommended default choice,unless one of the concerns notedat the top of theoptparse module documentation applies.

  • gh-125553: Fix round-trip invariance for backslash continuations intokenize.untokenize().

  • gh-123987: Fixed issue in NamespaceReader where a non-path item in anamespace path, such as a sentinel added by an editable installer, wouldbreak resource loading.

  • gh-123401: Thehttp.cookies module now supports parsing obsoleteRFC 850 date formats, in accordance withRFC 9110 requirements.Patch by Nano Zheng.

  • gh-122431:readline.append_history_file() now raises aValueError when given a negative value.

  • gh-119257: Show tab completions menu below the current line, which resultsin less janky behaviour, and fixes a cursor movement bug. Patch by DanielHollas

Documentation

Core and Builtins

  • gh-129345: Fix null pointer dereference insyslog.openlog() when anaudit hook raises an exception.

  • gh-129093: Fix f-strings such asf'{expr=}' sometimes not displayingthe full expression when the expression contains!=.

  • gh-124363: Treat debug expressions in f-string as raw strings. Patch byPablo Galindo

  • gh-128799: Add frame ofexcept* to traceback when it wraps a nakedexception.

  • gh-128078: Fix aSystemError when usinganext() with adefault tuple value. Patch by Bénédikt Tran.

  • gh-128717: Fix a crash when setting the recursion limit while otherthreads are active on thefree threaded build.

  • gh-128330: Restore terminal control characters on REPL exit.

  • gh-128079: Fix a bug whereexcept* does notproperly check the return value of anExceptionGroup'ssplit() function, leading to a crash in somecases. Now whensplit() returns an invalidobject,except* raises aTypeError withthe original raisedExceptionGroup object chained to it.

  • gh-128030: Avoid error from callingPyModule_GetFilenameObject on anon-module object when importing a non-existent symbol from a non-moduleobject.

  • gh-127903:Objects/unicodeobject.c: fix a crash on DEBUG builds in_copy_characters when there is nothing to copy.

  • gh-127599: Fix statistics for increments of object reference counts (inparticular, when a reference count was increased by more than 1 in asingle operation).

  • gh-127651: When raisingImportError for missing symbols infromimports, use__file__ in the error message if__spec__.origin isnot a location

  • gh-127582: Fix non-thread-safe object resurrection when calling finalizersand watcher callbacks in the free threading build.

  • gh-127434: The iOS compiler shims can now accept arguments with spaces.

  • gh-127536: Add missing locks around some list assignment operations in thefree threading build.

  • gh-126862: Fix a possible overflow when a class inherits from an absurdnumber of super-classes. Reported by Valery Fedorenko. Patch by BénédiktTran.

  • gh-127349: Fixed the error when resizing terminal in Python REPL. Patch bySemyon Moroz.

  • gh-126076: Relocated objects such astuple,bytes andstrobjects are properly tracked bytracemalloc and its associatedhooks. Patch by Pablo Galindo.

C API

Build

  • gh-129539: Don't redefineEX_OK when the system has thesysexits.hheader.

  • gh-128472: Skip BOLT optimization of functions using computed gotos,fixing errors on build with LLVM 19.

  • gh-123925: Fix building thecurses module on platforms withlibncurses but without libncursesw.

  • gh-128321: SetLIBS instead ofLDFLAGS when checking ifsqlite3 library functions are available. This fixes the ordering oflinked libraries during checks, which was incorrect when using astatically linkedlibsqlite3.

  • gh-127865: Fix build failure on systems without thread-locals support.

Python 3.13.1 final

Release date: 2024-12-03

macOS

  • gh-124448: Update bundled Tcl/Tk in macOS installer to 8.6.15.

Windows

  • gh-126911: Update credits command output.

  • gh-118973: Ensures the experimental free-threaded install includes the_tkinter module. The optional Tcl/Tk component must also be installedin order for the module to work.

  • gh-126497: Fixes venv failure due to missing redirector executables inexperimental free-threaded installs.

  • gh-126074: Removed unnecessary DLLs from Windows embeddable package

  • gh-125315: Avoid crashing inplatform due to slow WMI calls on someWindows machines.

  • gh-126084: Fix venvwlauncher to launch pythonw instead of python so noextra console window is created.

  • gh-125842: Fix aSystemError whensys.exit() is called with0xffffffff on Windows.

  • gh-125550: Enable thePython Launcher for Windows to detect Python 3.14 installs fromthe Windows Store.

  • gh-124448: Updated bundled Tcl/Tk to 8.6.15.

Tools/Demos

  • gh-126807: Fix extraction warnings inpygettext.py caused bymistaking function definitions for function calls.

  • gh-126167: The iOS testbed was modified so that it can be used bythird-party projects for testing purposes.

Tests

  • gh-126909: Fix test_os extended attribute tests to work on filesystemswith 1 KiB xattr size limit.

  • gh-125041: Re-enable skipped tests forzlib on the s390xarchitecture: only skip checks of the compressed bytes, which can bedifferent between zlib's software implementation and thehardware-accelerated implementation.

  • gh-124295: Add translation tests to theargparse module.

Security

  • gh-126623: Upgrade libexpat to 2.6.4

  • gh-125140: Remove the current directory fromsys.path when usingPyREPL.

  • gh-122792: Changed IPv4-mappedipaddress.IPv6Address to consistentlyuse the mapped IPv4 address value for deciding properties. Propertieswhich have their behavior fixed areis_multicast,is_reserved,is_link_local,is_global, andis_unspecified.

Library

IDLE

  • gh-122392: Increase currently inadequate vertical spacing for the IDLEbrowsers (path, module, and stack) on high-resolution monitors.

Documentation

  • gh-126622: Added stub pages for removed modules explaining their removal,where to find replacements, and linking to the last Python version thatsupported them. Contributed by Ned Batchelder.

  • gh-125277: Require Sphinx 7.2.6 or later to build the Pythondocumentation. Patch by Adam Turner.

  • gh-124872: Added definitions forcontext,current context,andcontext management protocol, updated related definitions to beconsistent, and expanded the documentation forcontextvars.Context.

  • gh-125018: Theimportlib.metadata documentation now includessemantic cross-reference targets for the significant documented APIs. Thismeans intersphinx references likeimportlib.metadata.version() willnow work as expected.

  • gh-70870: Clarified the dual usage of the term "free variable" (both theformal meaning of any reference to names defined outside the local scope,and the narrower pragmatic meaning of nonlocal variables named inco_freevars).

  • gh-121277: Writers of CPython's documentation can now usenext as theversion for theversionchanged,versionadded,deprecateddirectives.

  • gh-60712: Include theobject type in the lists of documentedtypes. Change by Furkan Onder and Martin Panter.

  • bpo-34008: ThePy_Main() documentation moved from the "Very HighLevel API" section to the "Initialization and Finalization" section.

    Also make it explicit that we expectPy_Main to typically be calledinstead ofPy_Initialize rather than after it (sincePy_Main makesits own call toPy_Initialize). Document that calling both issupported but is version dependent on which settings will be appliedcorrectly.

Core and Builtins

  • gh-113841: Fix possible undefined behavior division by zero incomplex's_Py_c_pow().

  • gh-127020: Fix a crash in the free threading build whenPyCode_GetCode(),PyCode_GetVarnames(),PyCode_GetCellvars(), orPyCode_GetFreevars() were calledfrom multiple threads at the same time.

  • gh-126980: Fix__buffer__() ofbytearray crashingwhenREAD orWRITE are passed as flags.

  • gh-126881: Fix crash in finalization of dtoa state. Patch by Kumar Aditya.

  • gh-126341: NowValueError is raised instead ofSystemErrorwhen trying to iterate over a releasedmemoryview object.

  • gh-126688: Fix a crash when callingos.fork() on some operatingsystems, including SerenityOS.

  • gh-126066: Fiximportlib to not write an incomplete .pyc files whena ulimit or some other operating system mechanism is preventing the writeto go through fully.

  • gh-126312: Fix crash during garbage collection on an object frozen bygc.freeze() on the free-threaded build.

  • gh-126139: Provide better error location when attempting to use afuture statement with an unknown future feature.

  • gh-126018: Fix a crash insys.audit() when passing a non-string asfirst argument and Python was compiled in debug mode.

  • gh-125942: On Android, theerrors setting ofsys.stdout waschanged fromsurrogateescape tobackslashreplace.

  • gh-125859: Fix a crash in the free threading build whengc.get_objects() orgc.get_referrers() is called during anin-progress garbage collection.

  • gh-125703: Correctly honourtracemalloc hooks in specializedPy_DECREF paths. Patch by Pablo Galindo

  • gh-125593: Use color to highlight error locations in traceback fromexception group

  • gh-125444: Fix illegal instruction for older Arm architectures. Patch byDiego Russo, testing by Ross Burton.

  • gh-124375: Fix a crash in the free threading build when the GC runsconcurrently with a new thread starting.

  • gh-125221: Fix possible race condition when calling__reduce_ex__() for the first time in the free threadingbuild.

  • gh-125038: Fix crash when iterating over a generator expression afterdirect changes ongi_frame.f_locals. Patch by Mikhail Efimov.

  • gh-123378: Fix a crash in the__str__() method ofUnicodeError objects when theUnicodeError.start andUnicodeError.end values are invalid or out-of-range. Patch byBénédikt Tran.

  • gh-116510: Fix a crash caused by immortal interned strings being sharedbetween sub-interpreters that use basic single-phase init. In that case,the string can be used by an interpreter that outlives the interpreterthat created and interned it. For interpreters that share obmalloc state,also share the interned dict with the main interpreter.

  • gh-122878: Use thepager binary, if available (e.g. on Debian andderivatives), to display REPLhelp().

  • gh-124188: Fix reading and decoding a line from the source file witnnon-UTF-8 encoding for syntax errors raised in the compiler.

  • gh-123930: Improve the error message when a script shadowing a module fromthe standard library causesImportError to be raised during a"from" import. Similarly, improve the error message when a scriptshadowing a third party module attempts to "from" import an attribute fromthat third party module while still initialising.

  • gh-122907: Building withHAVE_DYNAMIC_LOADING now works as well as itdid in 3.12. Existing deficiences will be addressed separately. (Seehttps://github.com/python/cpython/issues/122950.)

  • gh-118950: Fix bug where SSLProtocol.connection_lost wasn't getting calledwhen OSError was thrown on writing to socket.

  • gh-113570: Fixed a bug inreprlib.repr where it incorrectly called therepr method on shadowed Python built-in types.

  • gh-109746: If_thread.start_new_thread() fails to start a newthread, it deletes its state from interpreter and thus avoids its repeatedcleanup on finalization.

C API

  • gh-126554: Fix error handling inctypes.CDLL objects which couldresult in a crash in rare situations.

  • gh-125608: Fix a bug where dictionary watchers (e.g.,PyDict_Watch()) on an object's attribute dictionary(__dict__) were not triggered when the object's attributeswere modified.

  • bpo-34008: AddedPy_IsInitialized to the list of APIs that are safe tocall before the interpreter is initialized, and updated the embeddingtests to cover it.

Build

  • gh-123877: Setwasm32-wasip1 as the WASI target. The oldwasm32-wasi target is deprecated so it can be used for an eventualWASI 1.0.

  • gh-89640: Hard-code float word ordering as little endian on WASM.

  • gh-125940: The Android build now supports16 KB page sizes.

  • gh-89640: Improve detection of float word ordering on Linux when link-timeoptimizations are enabled.

  • gh-125269: Fix detection of whether-latomic is needed whencross-compiling CPython using the configure script.

  • gh-121634: Allow for specifying the target compile triple for WASI.

  • gh-122578: Use WASI SDK 24 for testing.

  • gh-115382: Fix cross compile failures when the host and target SOABIsmatch.

Python 3.13.0 final

Release date: 2024-10-07

Core and Builtins

  • gh-125008: Fixtokenize.untokenize() producing invalid syntax fordouble braces preceded by certain escape characters.

  • gh-124871: Fix compiler bug (in some versions of 3.13) where an assertionfails during reachability analysis.

Python 3.13.0 release candidate 3

Release date: 2024-10-01

macOS

  • gh-123797: Check for runtime availability ofptsname_r function onmacos.

Windows

  • gh-124609: Fix_Py_ThreadId for Windows builds using MinGW. Patch byTony Roberts.

  • gh-124254: Ensures experimental free-threaded binaries remain installedwhen updating.

  • gh-123915: Ensure thatTools\msi\buildrelease.bat uses differentdirectories for AMD64 and ARM64 builds.

Tests

  • gh-124378: Updatedtest_ttk to pass with Tcl/Tk 8.6.15.

Library

IDLE

  • gh-112938: Fix uninteruptable hang when Shell gets rapid continuousoutput.

  • gh-120104: Fix padding in config and search dialog windows in IDLE.

Documentation

  • gh-124720: Update "Using Python on a Mac" section of the "Python Setup andUsage" document and include information on installing free-threadingsupport.

  • gh-116622: Add an Android platform guide, and flag modules not availableon Android.

Core and Builtins

  • gh-124567: Revert the incremental GC (in 3.13), since it's not clear thebenefits outweigh the costs at this point.

  • gh-124642: Fixed scalability issue in free-threaded builds for lock-freereads from dictionaries in multi-threaded scenarios

  • gh-116510: Fix a bug that can cause a crash when sub-interpreters use"basic" single-phase extension modules. Shared objects could refer toPyGC_Head nodes that had been freed as part of interpreter cleanup.

  • gh-124547: When deallocating an object with inline values whose__dict__ is still live: if memory allocation for the inline valuesfails, clear the dictionary. Prevents an interpreter crash.

  • gh-124513: Fix a crash in FrameLocalsProxy constructor: check the numberof arguments. Patch by Victor Stinner.

  • gh-124442: Fix nondeterminism in compilation by sorting the value of__static_attributes__. Patch by kp2pml30.

  • gh-123856: Fix PyREPL failure when a keyboard interrupt is triggered afterusing a history search

  • gh-65961: Document the deprecation of setting and using__package__and__cached__.

  • gh-124027: Support<pageup>,<pagedown>, and<delete> keysin the Python REPL when$TERM is set tovt100.

  • gh-77894: Fix possible crash in the garbage collector when it tries tobreak a reference loop containing amemoryview object. Now amemoryview object can only be cleared if there are no buffersthat refer it.

  • gh-123339: Setting the__module__ attribute for a class nowremoves the__firstlineno__ item from the type's dict, so they will nolonger be inconsistent.

C API

  • gh-124160: Fix crash when importing modules containing state andsingle-phase initialization in a subinterpreter.

  • gh-123880: Fixed a bug that prevented circular imports of extensionmodules that use single-phase initialization.

Build

  • gh-124487: Windows builds now use Windows 8.1 as their API baseline(installation already required Windows 8.1).

  • gh-124043: Building using--with-trace-refs is (temporarily)disallowed when the GIL is disabled.

Python 3.13.0 release candidate 2

Release date: 2024-09-06

macOS

  • gh-123418: Updated macOS installer build to use OpenSSL 3.0.15.

Windows

  • gh-123418: Updated Windows build to use OpenSSL 3.0.15.

  • gh-122573: The Windows build of CPython now requires 3.10 or newer.

  • gh-100256:mimetypes no longer fails when it encounters aninaccessible registry key.

  • gh-79846: Makesssl.create_default_context() ignore invalidcertificates in the Windows certificate store

Tools/Demos

  • gh-123418: Update GitHub CI workflows to use OpenSSL 3.0.15 andmultissltests to use 3.0.15, 3.1.7, and 3.2.3.

Tests

  • gh-119727: Add--single-process command line option to Python testrunner (regrtest). Patch by Victor Stinner.

  • gh-101525: Skiptest_gdb if the binary is relocated by BOLT. Patch byDonghee Na.

Security

  • gh-123678: Upgrade libexpat to 2.6.3

  • gh-121285: Remove backtracking from tarfile header parsing forhdrcharset, PAX, and GNU sparse headers.

Library

IDLE

  • gh-120083: Add explicit black IDLE Hovertip foreground color needed forrecent macOS. Fixes Sonoma showing unreadable white on pale yellow. Patchby John Riggles.

Core and Builtins

  • gh-120221: asyncio REPL is now again properly recognizingKeyboardInterrupts. Display of exceptions raised in secondary threads isfixed.

  • gh-119310: Allow the new interactive shell to read history files writtenwith the editline library that use unicode-escaped entries. Patch byaorcajo and Łukasz Langa.

  • gh-123572: Fix key mappings for various F-keys in Windows for the newREPL. Patch by devdanzin

  • gh-119034: Change<pageup> and<pagedown> keys of the PythonREPL to history search forward/backward. Patch by Victor Stinner.

  • gh-123545: Fix a double decref in rare cases on experimental JIT builds.

  • gh-123484: Fix_Py_DebugOffsets for long objects to be relative to thestart of the object rather than the start of a subobject.

  • gh-123344: Add AST optimizations for type parameter defaults.

  • gh-123321: Prevent Parser/myreadline race condition from segfaulting onmulti-threaded use. Patch by Bar Harel and Amit Wienner.

  • gh-123177: Fix a bug causing stray prompts to appear in the middle ofwrapped lines in the new REPL.

  • gh-122982: Extend the deprecation period for bool inversion (~) by twoyears.

  • gh-123275: Support-Xgil=1 andPYTHON_GIL=1 on non-free-threaded builds.

  • gh-123177: Deactivate line wrap in the Apple Terminal via a ANSI escapecode. Patch by Pablo Galindo

  • gh-123229: Fix valgrind warning by initializing the f-string buffers to 0in the tokenizer. Patch by Pablo Galindo

  • gh-122298: Restore printout of GC stats whengc.set_debug(gc.DEBUG_STATS) is called. This featue was accidentallyremoved when implementing incremental GC.

  • gh-121804: Correctly show error locations when aSyntaxError israised in the basic REPL. Patch by Sergey B Kirpichev.

  • gh-123142: Fix too-wide source location in exception tracebacks comingfrom broken iterables in comprehensions.

  • gh-123048: Fix a bug where pattern matching code could emit aJUMP_FORWARD with no source location.

  • gh-123123: Fix displayingSyntaxError exceptions covering multiplelines. Patch by Pablo Galindo

  • gh-123083: Fix a potential use-after-free inSTORE_ATTR_WITH_HINT.

  • gh-123022: Fix crash in free-threaded build when callingPy_Initialize() from a non-main thread.

  • gh-122888: Fix crash on certain calls tostr() with positionalarguments of the wrong type. Patch by Jelle Zijlstra.

  • gh-116622: Fix Android stdout and stderr messages being truncated or lost.

  • gh-122527: Fix a crash that occurred when aPyStructSequence wasdeallocated after its type's dictionary was cleared by the GC. The type'stp_basicsize now accounts for non-sequencefields that aren't included in thePy_SIZE of the sequence.

  • gh-122445: Add only fields which are modified via self.* to__static_attributes__.

  • gh-98442: Fix too wide source locations of the cleanup instructions of awith statement.

  • gh-93691: Fix source locations of instructions generated for withstatements.

  • gh-120097:FrameLocalsProxy now subclassescollections.abc.Mappingand can be matched as a mapping inmatch statements

C API

Build

  • gh-123418: Updated Android build to use OpenSSL 3.0.15.

  • gh-123297: Propagate the value ofLDFLAGS toLDCXXSHARED insysconfig. Patch by Pablo Galindo

  • gh-116622: Rename build variableMODULE_LDFLAGS back toLIBPYTHON,as it's used by package build systems (e.g. Meson).

  • gh-118943: Fix an issue where the experimental JIT could be built severaltimes by themakeregen-all target, leading to possible raceconditions on heavily parallelized builds.

  • gh-118943: Fix a possible race condition affecting parallel buildsconfigured with--enable-experimental-jit, in whichFileNotFoundError could be caused by another process already movingjit_stencils.h.new tojit_stencils.h.

Python 3.13.0 release candidate 1

Release date: 2024-07-31

Tests

Security

  • gh-122133: Authenticate the socket connection for thesocket.socketpair() fallback on platforms whereAF_UNIX is notavailable like Windows.

    Patch by Gregory P. Smith <greg@krypto.org> and Seth Larson<seth@python.org>. Reported by Ellie <el@horse64.org>

  • gh-121957: Fixed missing audit events around interactive use of Python,now also properly firing forpython-i, as well as forpython-masyncio. The events in question arecpython.run_stdin andcpython.run_startup.

Library

IDLE

  • gh-122482: Change About IDLE to direct users to discuss.python.org insteadof the now unused idle-dev email and mailing list.

Core and Builtins

  • gh-116090: Fix an issue in JIT builds that prevented someforloops from correctly firingRAISE monitoring events.

  • gh-122208: Dictionary watchers now only deliver the PyDict_EVENT_ADDEDevent when the insertion is in a known good state to succeed.

  • gh-122300: Preserve AST nodes for f-string with single-element formatspecifiers. Patch by Pablo Galindo

  • gh-120906:frame.f_locals now supports arbitrary hashable objectsas keys.

  • gh-122029: Emitc_call events insys.setprofile() when aPyMethodObject pointing to aPyCFunction is called.

  • gh-122026: Fix a bug that caused the tokenizer to not correctly identifymismatched parentheses inside f-strings in some situations. Patch by PabloGalindo

  • gh-118934: MakePyEval_GetLocals return borrowed reference

C API

  • gh-116622: MakePyObject_Print work around a bug in Android andOpenBSD which prevented it from throwing an exception when trying to writeto a read-only stream.

  • gh-121489: Export private_PyBytes_Join() again.

Build

Python 3.13.0 beta 4

Release date: 2024-07-18

Tests

  • gh-121084: Fix test_typing random leaks. Clear typing ABC caches whenrunning tests for refleaks (-R option): call_abc_caches_clear()on typing abstract classes and their subclasses. Patch by Victor Stinner.

  • gh-121160: Add a test forreadline.set_history_length(). Note thatthis test may fail on readline libraries.

  • gh-121200: Fixtest_expanduser_pwd2() oftest_posixpath. Callgetpwnam() to getpw_dir, since it can be different thangetpwall()pw_dir. Patch by Victor Stinner.

  • gh-121188: When creating the JUnit XML file, regrtest now escapescharacters which are invalid in XML, such as the chr(27) control characterused in ANSI escape sequences. Patch by Victor Stinner.

Library

  • gh-57141: Theshallow argument tofilecmp.dircmp (new in Python3.13) is now keyword-only.

  • gh-121245: Simplify handling of the history file insite.register_readline() helper. TheCAN_USE_PYREPL variable nowwill be initialized, when imported. Patch by Sergey B Kirpichev.

  • gh-121332: Fix constructor ofast nodes with custom_attributes. Previously, passing custom attributes would raise aDeprecationWarning. Passing arguments to the constructor thatare not in_fields or_attributes remains deprecated. Patch byJelle Zijlstra.

  • gh-121279: AvoidNameError for thewarnings module whenaccessing the depracated atributes of theimportlib.abc module.

  • gh-121245: Fix a bug in the handling of the command history of the newREPL that caused the history file to be wiped at REPL exit.

  • gh-87744: Fix waitpid race while callingsend_signal() in asyncio. Patch by KumarAditya.

  • gh-121018: Fixed other issues whereargparse.ArgumentParser didnot honorexit_on_error=False.

  • gh-120678: Fix regression in the new REPL that meant that globals fromfiles passed using the-i argument would not be included in the REPL'sglobal namespace. Patch by Alex Waygood.

  • gh-120782: Fix wrong references of thedatetime types afterreloading the module.

  • gh-120713:datetime.datetime.strftime() now 0-pads years with lessthan four digits for the format specifiers%Y and%G on Linux.Patch by Ben Hsing

  • gh-117983: Defer thethreading import inimportlib.util until lazyloading is used.

  • gh-119189: When using the** operator orpow() withFraction as the base and an exponent that is notrational, a float, or a complex, the fraction is no longer converted to afloat.

  • gh-118714: Allowrestart in post-mortem debugging ofpdb.Removed restart message when the user quits pdb from post-mortem mode.

  • gh-105623: Fix performance degradation inlogging.handlers.RotatingFileHandler. Patch by Craig Robson.

IDLE

  • gh-78889: Stop Shell freezes by blocking user access to non-methodsys.stdout.shell attributes, which are all private.

Documentation

Core and Builtins

  • gh-121860: Fix crash when rematerializing a managed dictionary after itwas deleted.

  • gh-121814: Fixed the SegFault whenPyEval_SetTrace() is used withno Python frame on stack.

  • gh-121295: Fix PyREPL console getting into a blocked state afterinterrupting a long paste

  • gh-121794: Fix bug in free-threaded Python where a resurrected objectcould lead to a negative ref count assertion failure.

  • gh-121657: Improve theSyntaxError message if the user tries to useyieldfrom outside a function.

  • gh-121609: Fix pasting of characters containing unicode character joinersin the new REPL. Patch by Marta Gomez Macias

  • gh-117482: Unexpected slot wrappers are no longer created for builtinstatic types in subinterpreters.

  • gh-121499: Fix a bug affecting how multi-line history was being renderedin the new REPL after interacting with the new screen cache. Patch byPablo Galindo

  • gh-121497: Fix a bug that was preventing the REPL to correctly respect thehistory when an input hook was set. Patch by Pablo Galindo

  • gh-121012: Tier 2 execution now ensures that list iterators remainexhausted, once they become exhausted.

  • gh-121439: Allow tuples of length 20 in the freelist to be reused.

  • gh-121368: Fix race condition in_PyType_Lookup in the free-threadedbuild due to a missing memory fence. This could lead to_PyType_Lookup returning incorrect results on arm64.

  • gh-121130: Fix f-strings with debug expressions in format specifiers.Patch by Pablo Galindo

  • gh-121115:PyLong_AsNativeBytes() no longer uses__index__() methods by default. ThePy_ASNATIVEBYTES_ALLOW_INDEX flag has been added to allow it.

C API

Build

  • gh-120371: Support WASI SDK 22 by explicitly skipping functions that arejust stubs in wasi-libc.

  • gh-121731: Fix mimalloc compile error on GNU/Hurd

  • gh-121487: Fix deprecation warning for ATOMIC_VAR_INIT in mimalloc.

  • gh-121467: Fix a Makefile bug that prevented mimalloc header files frombeing installed.

  • gh-121103: On POSIX systems, excluding macOS framework installs, the libdirectory for the free-threaded build now includes a "t" suffix to avoidconflicts with a co-located default build installation.

  • gh-120831: The default minimum iOS version was increased to 13.0.

  • gh-113565: Improvecurses andcurses.panel dependency checksinconfigure.

Python 3.13.0 beta 3

Release date: 2024-06-27

Core and Builtins

  • gh-120838:Py_Finalize() andPy_FinalizeEx() nowalways run with the main interpreter active.

  • gh-113433: Subinterpreters now get cleaned up automatically during runtimefinalization.

  • gh-119462: Make sure that invariants of type versioning are maintained: *Superclasses always have their version number assigned before subclasses *The version tag is always zero if the tag is not valid. * The version tagis always non-zero if the tag is valid.

  • gh-120437: Fix_CHECK_STACK_SPACE optimization problems introduced ingh-118322.

  • gh-120722: Correctly set the bytecode position on return instructionswithin lambdas. Patch by Jelle Zijlstra.

  • gh-120367: Fix bug where compiler creates a redundant jump duringpseudo-op replacement. Can only happen with a synthetic AST that has a tryon the same line as the instruction following the exception handler.

  • gh-113993: Strings interned withsys.intern() are againgarbage-collected when no longer used, as per the documentation. Stringsinterned with the C functionPyUnicode_InternInPlace() are stillimmortal. Internals of the string interning mechanism have been changed.This may affect performance and identities ofstr objects.

  • gh-120384: Fix an array out of bounds crash inlist_ass_subscript,which could be invoked via some specificly tailored input: includingconcurrent modification of a list object, where one thread assigns a sliceand another clears it.

  • gh-120367: Fix crash in compiler on code with redundant NOPs and JUMPswhich show up after exception handlers are moved to the end of the code.

  • gh-120380: Fix Python implementation ofpickle.Pickler forbytes andbytearray objects when using protocol version5. Patch by Bénédikt Tran.

  • gh-120400: Support Linux perf profiler to see Python calls on RISC-Varchitecture.

  • gh-120221: Deliver real signals on Ctrl-C and Ctrl-Z in the new REPL.Patch by Pablo Galindo

  • gh-120346: RespectPYTHON_BASIC_REPL when running in interativeinspect mode (python-i). Patch by Pablo Galindo

  • gh-93691: Fix source locations of instructions generated for the iteratorof a for statement.

  • gh-120198: Fix a crash when multiple threads read and write to the same__class__ of an object concurrently.

  • gh-120298: Fix use-after free inlist_richcompare_impl which can beinvoked via some specificly tailored evil input.

  • gh-119666: Fix a compiler crash in the case where two comprehensions inclass scope both reference__class__.

  • gh-120225: Fix crash in compiler on empty block at end of exceptionhandler.

  • gh-119933: ImproveSyntaxError messages for invalid expressions ina type parameters bound, a type parameter constraint tuple or a defaulttype parameter. Patch by Bénédikt Tran.

  • bpo-24766: Fix handling ofdoc argument to subclasses ofproperty.

Library

Build

  • gh-120671: Fix failing configure tests due to a missing space whenappending to CFLAGS.

  • gh-120602: Correctly handle LLVM installs withLLVM_VERSION_SUFFIXwhen building with--enable-experimental-jit.

  • gh-120326: On Windows, fix build error when--disable-gil and--experimental-jit options are combined.

  • gh-120291: Make thepython-config shell script compatible withnon-bash shells.

C API

  • gh-120642: Remove the private_Py_CODEUNIT type from the public C API.The internalpycore_code.h header should now be used to get thisinternal type. Patch by Victor Stinner.

  • gh-120858:PyDict_Next() no longer locks the dictionary in thefree-threaded build. The locking needs to be done by the caller aroundthe entire iteration loop.

  • gh-120642: Remove the following unstable functions:

    • PyUnstable_Replace_Executor()

    • PyUnstable_SetOptimizer()

    • PyUnstable_GetOptimizer()

    • PyUnstable_GetExecutor()

    • PyUnstable_Optimizer_NewCounter()

    • PyUnstable_Optimizer_NewUOpOptimizer()

    Patch by Victor Stinner.

  • gh-119344: The critical section API is now public as part of thenon-limited C API.

  • gh-118789: AddPyUnstable_Object_ClearWeakRefsNoCallbacks(), whichclears weakrefs without calling their callbacks.

  • gh-117511: Make thePyMutex public in the non-limited C API.

Python 3.13.0 beta 2

Release date: 2024-06-05

Security

Core and Builtins

  • gh-119724: Reverted improvements to error messages forelif/elsestatements not matching any valid statements, which made in hard to locatethe syntax errors inside thoseelif/else blocks.

  • gh-119842: HonorPyOS_InputHook() in the new REPL. Patch by PabloGalindo

  • gh-119821: Fix execution ofannotation scopeswithin classes whenglobals is set to a non-dict. Patch by JelleZijlstra.

  • gh-119548: Add aclear command to the REPL. Patch by Pablo Galindo

  • gh-111999: Fix the signature ofstr.format_map().

  • gh-119560: An invalid assert in beta 1 has been removed. The assert wouldfail ifPyState_FindModule() was used in an extension module's initfunction before the module def had been initialized.

  • gh-119369: Fix deadlock during thread deletion in free-threaded build,which could occur when the GIL was enabled at runtime.

  • gh-119525: Fix deadlock involving_PyType_Lookup() cache in thefree-threaded build when the GIL is dynamically enabled at runtime.

  • gh-119311: Fix bug where names are unexpectedly mangled in the bases ofgeneric classes.

  • gh-119395: Fix bug where names appearing after a generic class are mangledas if they are in the generic class.

  • gh-119213: Non-builtin modules built with argument clinic were crashing ifused in a subinterpreter before the main interpreter. The objects thatwere causing the problem by leaking between interpreters carelessly havebeen fixed.

  • gh-119011: Fixestype.__type_params__ to return an empty tuple insteadof a descriptor.

  • gh-118692: Avoid creating unnecessaryStopIteration instances formonitoring.

  • gh-119049: Fix displaying the source line for warnings created by the CAPI if thewarnings module had not yet been imported.

  • gh-118844: Fix build failures when configuring with both--disable-giland--enable-experimental-jit.

  • gh-118921: Addcopy() method forFrameLocalsProxy which returns asnapshotdict for local variables.

  • gh-117657: Fix data races on the field that stores a pointer to theinterpreter's main thread that occur in free-threaded builds.

  • gh-118561: Fix race condition in free-threaded build wherelist.extend() could expose uninitialised memory to concurrentreaders.

  • gh-117195: Avoid assertion failure for debug builds when callingobject.__sizeof__(1)

Library

  • gh-119819: Fix regression to allow logging configuration withmultiprocessing queue types.

  • gh-117142: Thectypes module may now be imported in allsubinterpreters, including those that have their own GIL.

  • gh-118835: Fix _pyrepl crash when using custom prompt with ANSI escapecodes.

  • gh-117398: The_datetime module (C implementation fordatetime)now supports being imported in multiple interpreters.

  • gh-89727: Fix issue withshutil.rmtree() where aRecursionError is raised on deep directory trees.

  • gh-89727: Partially fix issue withshutil.rmtree() where aRecursionError is raised on deep directory trees. A recursion erroris no longer raised whenrmtree.avoids_symlink_attacks is false.

  • gh-119118: Fix performance regression in thetokenize module bycaching theline token attribute and calculating the column offsetmore efficiently.

  • gh-89727: Fix issue withos.fwalk() where aRecursionErrorwas raised on deep directory trees by adjusting the implementation to beiterative instead of recursive.

  • gh-119588:zipfile.Path.is_symlink now assesses if the given path is asymlink.

  • gh-119555: CatchSyntaxError fromcompile() in therunsource() method of the InteractiveColoredConsole. Patch by Sergey BKirpichev.

  • gh-113892: Now, the methodsock_connect ofasyncio.ProactorEventLoop raises aValueError if givensocket is not in non-blocking mode, as well as in other loopimplementations.

  • gh-119443: The interactive REPL no longer runs withfrom__future__importannotations enabled. Patch by Jelle Zijlstra.

  • gh-117398: Objects in the datetime C-API are now all statically allocated,which means better memory safety, especially when the module is reloaded.This should be transparent to users.

  • gh-118894:asyncio REPL now has the same capabilities as PyREPL.

  • gh-118911: In PyREPL, updatedmaybe-accept's logic so that if the userhitsEnter twice, they are able to terminate the block even ifthere's trailing whitespace. Also, now when the user hits arrow up, thecursor is on the last functional line. This matches IPython's behavior.Patch by Aya Elsayed.

  • gh-111201: Remove dependency toreadline from the new Python REPL.

  • gh-119174: Fix high DPI causes turtledemo(turtle-graphics examples)windows blurry Patch by Wulian233 and Terry Jan Reedy

  • gh-119121: Fix a NameError happening inasyncio.staggered.staggered_race. This function is now tested.

  • gh-119113: Fix issue wherepathlib.PurePath.with_suffix() didn'traiseTypeError when givenNone as a suffix.

  • gh-118643: Fix an AttributeError in theemail module when re-fold along address list. Also fix more cases of incorrect encoding of theaddress separator in the address list.

  • gh-58933: Makepdb return to caller frame correctly whenf_trace of the caller frame is not set

  • gh-118895: Setting attributes ontyping.NoDefault now raisesAttributeError instead ofTypeError.

  • gh-118868: Fixed issue where kwargs were no longer passed to the logginghandler QueueHandler

  • gh-118851:ctx arguments to the constructors ofast nodeclasses now default toast.Load(). Patch by JelleZijlstra.

  • gh-118760: Restore the default value oftkiter.wantobjects to1.

  • gh-118760: Fix errors in calling Tkinter bindings on Windows.

  • gh-118507: Fixos.path.isfile() on Windows for pipes. Speedupos.path.isjunction() andos.path.lexists() on Windows with anative implementation.

  • gh-118772: Allowtyping.TypeVar instances without a default tofollow instances without a default in some cases. Patch by Jelle Zijlstra.

  • gh-110863:os.path.realpath() now suppresses anyOSError fromos.readlink() whenstrict mode is disabled (the default).

  • gh-118263: Speed upos.path.splitroot() &os.path.normpath()with a direct C call.

  • gh-118033: Fixdataclasses.dataclass() not creating a__weakref__ slot when subclassingtyping.Generic.

  • gh-106531: Inimportlib.resources, sync withimportlib_resources6.3.2,including:MultiplexedPath now expectsTraversable paths,deprecating string arguments toMultiplexedPath; Enabled support forresources in namespace packages in zip files; FixedNotADirectoryErrorwhen calling files on a subdirectory of a namespace package.

  • gh-113978: Ignore warnings on text completion inside REPL.

  • gh-103956: Fix lack of newline characters intrace module outputwhen line tracing is enabled but source code line for current frame is notavailable.

  • gh-92081: Fix missing spaces in email headers when the spaces are mixedwith encoded 8-bit characters.

  • gh-103194: Prepare Tkinter for C API changes in Tcl 8.7/9.0 to avoid_tkinter.Tcl_Obj being unexpectedly returned instead ofbool,str,bytearray, orint.

  • gh-87106: Fixed handling ininspect.Signature.bind() of keywordarguments having the same name as positional-only arguments when avariadic keyword argument (e.g.**kwargs) is present.

  • bpo-45767: Fix integer conversion inos.major(),os.minor(),andos.makedev(). Support device numbers larger than2**63-1.Support non-existent device number (NODEV).

  • gh-67693: Fixurllib.parse.urlunparse() andurllib.parse.urlunsplit() for URIs with path starting with multipleslashes and no authority. Based on patch by Ashwin Ramaswami.

Tests

  • gh-119050: regrtest test runner: Add XML support to the refleak checker(-R option). Patch by Victor Stinner.

Build

  • gh-119729: On POSIX systems, the pkg-config (.pc) filenames nowinclude the ABI flags, which may include debug ("d") and free-threaded("t"). For example: *python-3.14.pc (default, non-debug build) *python-3.14d.pc (default, debug build) *python-3.14t.pc(free-threaded build)

  • gh-115119: Fall back to the bundled libmpdec if a system version cannot befound.

  • gh-119132: Updatesys.version to identify whether the build isdefault build or free-threading build. Patch By Donghee Na.

  • gh-118836: Fix anAssertionError when building with--enable-experimental-jit and the compiler emits aSHT_NOTEsection.

  • gh-118943: Fix a possible race condition affecting parallel buildsconfigured with--enable-experimental-jit, in which compilation errorscould be caused by an incompletely-generated header file.

Windows

  • gh-119679: Ensures correct import libraries are included in Windowsinstalls.

  • gh-119690: Adds Unicode support and fixes audit events for_winapi.CreateNamedPipe.

  • gh-111201: Add support for new pyrepl on Windows

  • gh-119070: Fixespy.exe handling of shebangs like/usr/bin/envpython3.12, which were previously interpreted aspython3.exe insteadofpython3.12.exe.

  • gh-117505: Fixes an issue with the Windows installer not running ensurepipin a fully isolated environment. This could cause unexpected interactionswith the user site-packages.

  • gh-118209: Avoid crashing inmmap on Windows when the mapped memoryis inaccessible due to file system errors or access violations.

  • gh-116145: Updated bundled Tcl/Tk to 8.6.14.

C API

  • gh-119585: Fix crash when a thread state that was created byPyGILState_Ensure() calls a destructor that duringPyThreadState_Clear() that calls back intoPyGILState_Ensure() andPyGILState_Release(). This mightoccur when in the free-threaded build or when using thread-local variableswhose destructors callPyGILState_Ensure().

  • gh-119336: Restore the removed_PyLong_NumBits() function. It is usedby the pywin32 project. Patch by Ethan Smith

  • gh-119247: AddedPy_BEGIN_CRITICAL_SECTION_SEQUENCE_FAST andPy_END_CRITICAL_SECTION_SEQUENCE_FAST macros to make it possible touse PySequence_Fast APIs safely when free-threaded, and update str.join towork without the GIL using them.

  • gh-111389: AddPyHASH_MULTIPLIER constant: prime multiplierused in string and various other hashes. Patch by Victor Stinner.

  • gh-116984: Make mimalloc includes relative to the current file to avoidembedders or extensions needing to includeInternal/mimalloc if theyare already including internal CPython headers.

  • gh-118789: Restore_PyWeakref_ClearRef that was previously removed inPython 3.13 alpha 1.

Python 3.13.0 beta 1

Release date: 2024-05-08

Security

  • gh-116741: Update bundled libexpat to 2.6.2

  • gh-117233: Detect BLAKE2, SHA3, Shake, & truncated SHA512 support in theOpenSSL-ish libcrypto library at build time. This allowshashlibto be used with libraries that do not to support every algorithm thatupstream OpenSSL does.

Core and Builtins

  • gh-118414: Add instrumented opcodes to YIELD_VALUE assertion for tracingcases.

  • gh-117953: When a builtin or extension module is imported for the firsttime, while a subinterpreter is active, the module's init function is nowrun by the main interpreter first before import continues in thesubinterpreter. Consequently, single-phase init modules now fail in anisolated subinterpreter without the init function running under thatinterpreter, whereas before it would run under the subinterpreterbeforefailing, potentially leaving behind global state and callbacks andotherwise leaving the module in an inconsistent state.

  • gh-117549: Don't use designated initializer syntax in inline functions ininternal headers. They cause problems for C++ or MSVC users who aren't yetusing the latest C++ standard (C++20). While internal, pycore_backoff.h,is included (indirectly, via pycore_code.h) by some key 3rd party softwarethat does so for speed.

  • gh-95382: Improve performance ofjson.dumps() andjson.dump()when using the argumentindent. Depending on the data the encoding usingjson.dumps() withindent can be up to 2 to 3 times faster.

  • gh-116322: In--disable-gil builds, the GIL will be enabled whileloading C extension modules. If the module indicates that it supportsrunning without the GIL, the GIL will be disabled once loading iscomplete. Otherwise, the GIL will remain enabled for the remainder of theinterpreter's lifetime. This behavior does not apply if the GIL has beenexplicitly enabled or disabled withPYTHON_GIL or-Xgil.

  • gh-118513: Fix incorrectUnboundLocalError when two comprehensionsin the same function both reference the same name, and in onecomprehension the name is bound while in the other it's an implicitglobal.

  • gh-118518: Allow the Linux perf support to work without frame pointersusing perf's advanced JIT support. The feature is activated when using thePYTHON_PERF_JIT_SUPPORT environment variable or when running Pythonwith-Xperf_jit. Patch by Pablo Galindo.

  • gh-117514: Addsys._is_gil_enabled() function that returns whether theGIL is currently enabled. In the default build it always returnsTruebecause the GIL is always enabled. In the free-threaded build, it mayreturnTrue orFalse.

  • gh-118164: Break a loop between the Python implementation of thedecimal module and the Python code for integer to stringconversion. Also optimize integer to string conversion for values in therange from 9_000 to 135_000 decimal digits.

  • gh-118473: Fixsys.set_asyncgen_hooks() not to be partially set whenraisingTypeError.

  • gh-118465: Compiler populates the new__firstlineno__ field on a classwith the line number of the first line of the class definition.

  • gh-118492: Fix an issue where the type cache can expose a previouslyaccessed attribute when a finalizer is run.

  • gh-117714: updateasync_generator.athrow().close() andasync_generator.asend().close() to close their section of theunderlying async generator

  • gh-111201: Theinteractive interpreter is now implemented inPython, which allows for a number of new features like colors, multilineinput, history viewing, and paste mode. Contributed by Pablo Galindo,Łukasz Langa and Lysandros Nikolaou based on code from the PyPy project.

  • gh-74929: Implement PEP 667: convertedFrameType.f_locals andPyFrame_GetLocals() to return awrite-through proxy object when the frame refers to a function orcomprehension.

  • gh-116767: Fix crash in compiler on 'async with' that has many contextmanagers.

  • gh-118335: Change how to use the tier 2 interpreter. Instead of runningPython with-Xuops or setting the environment variablePYTHON_UOPS=1, this choice is now made at build time by configuringwith--enable-experimental-jit=interpreter.

    Beware! This changes the environment variable to enable or disablemicro-ops toPYTHON_JIT. The oldPYTHON_UOPS is no longer used.

  • gh-118306: Update JIT compilation to use LLVM 18

  • gh-118160:Annotation scopes within classes cannow contain comprehensions. However, such comprehensions are not inlinedinto their parent scope at runtime. Patch by Jelle Zijlstra.

  • gh-118272: Fix bug wheregenerator.close does not free the generatorframe's locals.

  • gh-118216: Don't consider__future__ imports with dots before themodule name.

  • gh-118074: Make sure that the Executor objects in the COLD_EXITS arrayaren't assumed to be GC-able (which would access bytes outside theobject).

  • gh-107674: Lazy load frame line number to improve performance of tracing

  • gh-118082: ImproveSyntaxError message for imports without names,like infromximport andimport cases. It now points out to usersthatimport expects at least one name after it.

  • gh-118090: ImproveSyntaxError message for empty type parambrackets.

  • gh-117958: Added aget_jit_code() method to access JIT compiledmachine code from the UOp Executor when the experimental JIT is enabled.Patch by Anthony Shaw.

  • gh-117901: Add option for compiler's codegen to save nested instructionsequences for introspection.

  • gh-116622: Redirect stdout and stderr to system log when embedded in anAndroid app.

  • gh-109118:annotation scope within class scopescan now contain lambdas.

  • gh-117894: Preventagen.aclose() objects being re-used after.throw().

  • gh-117881: prevent concurrent access to an async generator viaathrow().throw() or asend().throw()

  • gh-117536: Fix aRuntimeWarning when callingagen.aclose().throw(Exception).

  • gh-117755: Fix mimalloc allocator for huge memory allocation (around8,589,934,592 GiB) on s390x. Patch by Victor Stinner.

  • gh-117750: Fix issue where an object's dict would get out of sync with theobject's internal values when being cleared.obj.__dict__.clear() nowclears the internal values, but leaves the dict attached to the object.

  • gh-117431: Improve the performance of the followingbytes andbytearray methods by adapting them to theMETH_FASTCALL calling convention:

    • count()

    • find()

    • index()

    • rfind()

    • rindex()

  • gh-117709: Speed up calls tostr() with positional-only argument, byusing thePEP 590vectorcall calling convention. Patch by ErlendAasland.

  • gh-117680: Give_PyInstructionSequence a Python interface and use itin tests.

  • gh-115776: Statically allocated objects are, by definition, immortal somust be marked as such regardless of whether they are in extension modulesor not.

  • gh-117385: Remove unhandledPY_MONITORING_EVENT_BRANCH andPY_MONITORING_EVENT_EXCEPTION_HANDLED events fromsys.settrace().

  • gh-116322: Extension modules may indicate to the runtime that they can runwithout the GIL. Multi-phase init modules do so by calling providingPy_MOD_GIL_NOT_USED for thePy_mod_gil slot, while single-phaseinit modules callPyUnstable_Module_SetGIL(mod,Py_MOD_GIL_NOT_USED)from their init function.

  • gh-116129: ImplementPEP 696, adding support for defaults on typeparameters. Patch by Jelle Zijlstra.

  • gh-93502: Add two new functions to the C-API,PyRefTracer_SetTracer() andPyRefTracer_GetTracer(), thatallows to track object creation and destruction the same way thetracemalloc module does. Patch by Pablo Galindo

  • gh-107674: Improved the performance ofsys.settrace() significantly

  • gh-95754: Improve the error message when a script shadowing a module fromthe standard library causesAttributeError to be raised. Similarly,improve the error message when a script shadowing a third party moduleattempts to access an attribute from that third party module while stillinitialising.

  • gh-99180: Elide uninformative traceback indicators inreturn andsimpleassignment statements. Patch by Pablo Galindo.

  • gh-105879: Allow theglobals andlocals arguments toexec() andeval() to be passed as keywords.

Library

  • gh-118418: ADeprecationWarning is now emitted if you fail to passa value to the newtype_params parameter oftyping._eval_type() ortyping.ForwardRef._evaluate(). (Using either of these private andundocumented functions is discouraged to begin with, but failing to pass avalue to thetype_params parameter may lead to incorrect behaviour onPython 3.12 or newer.)

  • gh-118660: Add an optional second type parameter totyping.ContextManager andtyping.AsyncContextManager,representing the return types of__exit__() and__aexit__() respectively. This parameter defaults tobool|None.

  • gh-118650: Theenum module allows method named_repr_* to bedefined onEnum types.

  • gh-118648: Add type parameter defaults totyping.Generator andtyping.AsyncGenerator.

  • gh-101137: Mime typetext/x-rst is now supported bymimetypes.

  • gh-118164: The Python implementation of thedecimal module couldappear to hang in relatively small power cases (like2**117) ifcontext precision was set to a very high value. A different method tocheck for exactly representable results is used now that doesn't rely oncomputing10**precision (which could be effectively too large tocompute).

  • gh-111744:breakpoint() andpdb.set_trace() now enter the debuggerimmediately after the call rather than before the next line is executed.

  • gh-118500: Addpdb support for zipapps

  • gh-118406: Add signature forsqlite3.Connection objects.

  • gh-101732: Use a Y2038 compatible openssl time function when available.

  • gh-118404: Fixinspect.signature() for non-comparable callables.

  • gh-118402: Fixinspect.signature() for the result of thefunctools.cmp_to_key() call.

  • gh-116622: On Android,sysconfig.get_platform now returns theformat specified byPEP 738.

  • gh-118285: Allow to specify the signature of custom callable instances ofextension type by the__text_signature__ attribute. Specify signaturesofoperator.attrgetter,operator.itemgetter, andoperator.methodcaller instances.

  • gh-118314: Fix an edge case inbinascii.a2b_base64() strict mode,where excessive padding is not detected when no padding is necessary.

  • gh-118271: Add thePhotoImage methodsread() to read animage from a file anddata() to get the image data. Addbackground andgrayscale parameters toPhotoImage methodwrite().

  • gh-118225: Add thePhotoImage methodcopy_replace() tocopy a region from one image to other image, possibly with pixel zoomingand/or subsampling. Addfrom_coords parameter toPhotoImagemethodscopy(),zoom() andsubsample(). Addzoomandsubsample parameters toPhotoImage methodcopy().

  • gh-118221: Fix a bug wheresqlite3.Connection.iterdump() could failif a customrowfactory was used.Patch by Erlend Aasland.

  • gh-118013: Fix regression introduced ingh-103193 that meant that callinginspect.getattr_static() on an instance would cause a strongreference to that instance's class to persist in an internal cache in theinspect module. This caused unexpected memory consumption if theclass was dynamically created, the class held strong references to otherobjects which took up a significant amount of memory, and the cachecontained the sole strong reference to the class. The fix for theregression leads to a slowdown ingetattr_static(), but thefunction should still be significantly faster than it was in Python 3.11.Patch by Alex Waygood.

  • gh-118218: Speed upitertools.pairwise() in the common case by up to1.8x.

  • gh-117486: Improve the behavior of user-defined subclasses ofast.AST. Such classes will now require no changes in the usualcase to conform with the behavior changes of theast module inPython 3.13. Patch by Jelle Zijlstra.

  • gh-90848: Fixedunittest.mock.create_autospec() to configure parentmock with keyword arguments.

  • gh-118168: Fix incorrect argument substitution whentyping.Unpackis used with the builtintuple.typing.Unpack now raisesTypeError when used with certain invalid types. Patch by JelleZijlstra.

  • gh-118131: Add command-line interface for therandom module. Patchby Hugo van Kemenade.

  • gh-118107: Fixzipimport reading of ZIP64 files with file entriesthat are too big or offset too far.

  • gh-102511: Fixos.path.normpath() for UNC paths on Windows. Speed upos.path.splitroot() with a native implementation.

  • gh-117535: Change the unknown filename ofwarnings fromsys to<sys> to clarify that it's not a real filename.

  • gh-114053: Fix erroneousNameError when callingtyping.get_type_hints() on a class that made use ofPEP 695 typeparameters in a module that hadfrom__future__importannotations atthe top of the file. Patch by Alex Waygood.

  • gh-116931: Add parameterfileobj check fortarfile.TarFile.addfile()

  • gh-117995: Don't raiseDeprecationWarning when asequenceof parameters is used to bind indexed, nameless placeholders. See alsogh-100668.

  • gh-80361: Fix TypeError inemail.message.Message.get_payload() whenthe charset isRFC 2231 encoded.

  • gh-86650: Fix IndexError when parse some emails with invalid Message-ID(including one-off addresses generated by Microsoft Outlook).

  • gh-117691: Improve the error messages emitted bytarfiledeprecation warnings relating to PEP 706. If afilter argument is notprovided toextract() orextractall, the deprecation warning nowpoints to the line in the user's code where the relevant function wascalled. Patch by Alex Waygood.

  • gh-115874: Fixed a possible segfault during garbage collection of_asyncio.FutureIter objects. Patch by Savannah Ostrowski.

  • gh-115060: Speed uppathlib.Path.glob() by omitting an initialis_dir() call. As a result of this change,glob() can no longer raiseOSError.

  • gh-77102:site module now parses.pth file with UTF-8 first,andlocale encoding ifUnicodeDecodeError happened. Itsupported only locale encoding before.

  • gh-76785: We've exposed the low-level_interpreters module for thesake of the PyPI implementation ofPEP 734. It was sometimes availableas the_xxsubinterpreters module and was formerly used only fortesting. For the most part, it should be considered an internal module,like_thread and_imp. Seehttps://discuss.python.org/t/pep-734-multiple-interpreters-in-the-stdlib/41147/26.

  • gh-115060: Speed uppathlib.Path.glob() by not scanning directoriesfor non-wildcard pattern segments.

  • gh-117727: Speed uppathlib.Path.iterdir() by usingos.scandir() internally.

  • gh-117586: Speed uppathlib.Path.walk() by working with stringsinternally.

  • gh-117722: Change the new multi-separator support inasyncio.StreamReader.readuntil() to only accept tuples of separatorsrather than arbitrary iterables.

  • gh-117692: Fixes a bug whendoctest.DocTestFinder was failing onwrappedbuiltin_function_or_method.

  • gh-117348: Largely restored import time performance of configparser byavoiding dataclasses.

  • gh-117641: Speedupos.path.commonpath() on Unix.

  • gh-117663: Fix_simple_enum to detect aliases when multiple argumentsare present but only one is the member value.

  • gh-117636: Speedupos.path.join().

  • gh-117618: Supportpackage.module asfilename forbreakcommand ofpdb

  • gh-102247: the status codes enum with constants in http.HTTPStatus areupdated to include the names from RFC9110. This RFC includes some HTTPstatuses previously only used for WEBDAV and assigns more generic names tothem.

    The old constants are preserved for backwards compatibility.

  • gh-117607: Speedupos.path.relpath().

  • gh-117586: Speed uppathlib.Path.glob() by working with stringsinternally.

  • gh-117225: Add colour to doctest output. Patch by Hugo van Kemenade.

  • gh-117566:ipaddress.IPv6Address.is_loopback() will now returnTrue for IPv4-mapped loopback addresses, i.e. addresses in the::ffff:127.0.0.0/104 address space.

  • gh-117546: Fix issue whereos.path.realpath() stopped resolvingsymlinks after encountering a symlink loop on POSIX.

  • gh-116720: Improved behavior ofasyncio.TaskGroup when anexternal cancellation collides with an internal cancellation. For example,when two task groups are nested and both experience an exception in achild task simultaneously, it was possible that the outer task group wouldmisbehave, because its internal cancellation was swallowed by the innertask group.

    In the case where a task group is cancelled externally and also must raiseanExceptionGroup, it will now call the parent task'scancel() method. This ensures that aasyncio.CancelledError will be raised at the nextawait,so the cancellation is not lost.

    An added benefit of these changes is that task groups now preserve thecancellation count (asyncio.Task.cancelling()).

    In order to handle some corner cases,asyncio.Task.uncancel() maynow reset the undocumented_must_cancel flag when the cancellationcount reaches zero.

  • gh-117516: Addtyping.TypeIs, implementingPEP 742. Patch byJelle Zijlstra.

  • gh-117503: Fix support of non-ASCII user names in bytes paths inos.path.expanduser() on Posix.

  • gh-117394:os.path.ismount() is now 2-3 times faster if the user haspermissions.

  • gh-117313: Only treat'\n','\r' and'\r\n' as line separatorsin re-folding theemail messages. Preserve control characters'\v','\f','\x1c','\x1d' and'\x1e' and Unicode lineseparators'\x85','\u2028' and'\u2029' as is.

  • gh-117142: Convert_ctypes to multi-phase initialisation(PEP 489).

  • gh-66543: Add themimetypes.guess_file_type() function which workswith file path. Passing file path instead of URL inguess_type() issoft deprecated.

  • gh-68583: webbrowser CLI: replace getopt with argparse, add long options.Patch by Hugo van Kemenade.

  • gh-116871: Name suggestions forAttributeError andImportError now only include underscored names if the original namewas underscored.

  • gh-116023: Don't show empty fields (valueNone or[]) inast.dump() by default. Addshow_empty=False parameter tooptionally show them.

  • gh-115961: Addedname andmode attributes for compressedand archived file-like objects in modulesbz2,lzma,tarfile andzipfile. The value of themodeattribute ofgzip.GzipFile was changed from integer (1 or2) to string ('rb' or'wb'). The value of themodeattribute of the readable file-like object returned byzipfile.ZipFile.open() was changed from'r' to'rb'.

  • gh-82062: Fixinspect.signature() to correctly handle parameterdefaults on methods in extension modules that use names defined in themodule namespace.

  • gh-83856: Honoratexit for allmultiprocessing start methods

  • gh-113081: Print colorized exception just like built-in traceback inpdb

  • gh-112855: Speed up pickling ofpathlib.PurePath objects. Patchby Barney Gale.

  • gh-111744: Support opcode events inbdb

  • gh-109617:ncurses: fixed a crash that could occur on macOS 13 orearlier when Python was built with Apple Xcode 15's SDK.

  • gh-83151: Enabled arbitrary statements and evaluations inpdb shellto access the local variables of the current frame, which made it possiblefor multi-scope code like generators or nested function to work.

  • gh-110209: Add__class_getitem__() totypes.GeneratorType andtypes.CoroutineType for typehinting purposes. Patch by James Hilton-Balfe.

  • gh-108191: Thetypes.SimpleNamespace now accepts an optionalpositional argument which specifies initial values of attributes as a dictor an iterable of key-value pairs.

  • gh-62090: Fix assertion errors caused by whitespace in metavars orSUPPRESS-ed groups inargparse by simplifying usage formatting.Patch by Ali Hamdan.

  • gh-102402: Adjustlogging.LogRecord to usetime.time_ns() and fixminor bug related to floating-point math.

  • gh-100242: Bring pure Python implementationfunctools.partial.__new__more in line with the C-implementation by not just always checking for thepresence of the attribute'func' on the first argument ofpartial.Instead, both the Python version and the C version perform anisinstance(func,partial) check on the first argument ofpartial.

  • gh-99730: HEAD requests are no longer upgraded to GET request duringredirects in urllib.

  • gh-66410: Setting thetkinter module globalwantobjectsto2 before creating theTk object or call thewantobjects() method of theTk object with argument2makes now arguments to callbacks registered in thetkinter moduleto be passed as various Python objects (int,float,bytes,tuple), depending on their internal representation in Tcl, instead ofalwaysstr.tkinter.wantobjects is now set to2 bydefault.

  • bpo-40943: Fix several IndexError when parse emails with truncatedMessage-ID, address, routes, etc, e.g.example@.

  • bpo-39324: Add mime type mapping for .md <-> text/markdown

  • bpo-18108:shutil.chown() now supportsdir_fd andfollow_symlinks keyword arguments.

  • bpo-30988: Fix parsing of emails with invalid address headers having aleading or trailing dot. Patch by tsufeki.

  • bpo-32839: Add theafter_info() method for Tkinter widgets.

Documentation

  • gh-117928: The minimum Sphinx version required for the documentation isnow 6.2.1.

Build

  • gh-118734: Fixes Windows build when invoked directly (not through thebuild.bat script) without specifying a value forUseTIER2.

  • gh-115119: Theconfigure option--with-system-libmpdecnow defaults toyes. The bundled copy oflibmpdecimal will beremoved in Python 3.15.

  • gh-117845: Fix building against recent libedit versions by detectingreadline hook signatures inconfigure.

  • gh-116622: A testbed project was added to run the test suite on Android.

  • gh-117645: Increase WASI stack size from 512 KiB to 8 MiB and the initialmemory from 10 MiB to 20 MiB. Patch by Victor Stinner.

  • gh-115119:configure now usespkg-config to detectdecimal dependencies if the--with-system-libmpdec optionis given.

Windows

  • gh-115119: Update Windows installer to use libmpdecimal 4.0.0.

  • gh-118486:os.mkdir() now acceptsmode of0o700 to restrictthe new directory to the current user.

  • gh-118347: Fixes launcher updates not being installed.

  • gh-118293: Themultiprocessing module now passes theSTARTF_FORCEOFFFEEDBACK flag when spawning processes to tell Windowsnot to change the mouse cursor.

  • gh-115009: Update Windows installer to use SQLite 3.45.3.

  • gh-90329: Suppress the warning displayed on virtual environment creationwhen the requested and created paths differ only by a short (8.3 style)name. Warnings will continue to be shown if a junction or symlink in thepath caused the venv to be created in a different location than originallyrequested.

  • gh-117786: Fixes virtual environments not correctly launching when createdfrom a Store install.

macOS

  • gh-115119: Update macOS installer to use libmpdecimal 4.0.0.

  • gh-114099: iOS preprocessor symbol usage was made compatible with oldermacOS SDKs.

  • gh-115009: Update macOS installer to use SQLite 3.45.3.

  • gh-91629: Use~/.config/fish/conf.d configs andfish_add_path to setPATH when installing for theFish shell.

IDLE

  • bpo-34774: Use user-selected color theme for Help => IDLE Doc.

C API

Python 3.13.0 alpha 6

Release date: 2024-04-09

Core and Builtins

  • gh-117494: Refactored the instruction sequence data structure out ofcompile.c into instruction_sequence.c.

  • gh-116968: Introduce a unified 16-bit backoff counter type(_Py_BackoffCounter), shared between the Tier 1 adaptive specializerand the Tier 2 optimizer. The API used for adaptive specializationcounters is changed but the behavior is (supposed to be) identical.

    The behavior of the Tier 2 counters is changed:

    • There are no longer dynamic thresholds (we never varied these).

    • All counters now use the same exponential backoff.

    • The counter forJUMP_BACKWARD starts counting down from 16.

    • Thetemperature in side exits starts counting down from 64.

  • gh-117431: Improve the performance of the followingbytes andbytearray methods by adapting them to theMETH_FASTCALL calling convention:

    • endswith()

    • startswith()

  • gh-117431: Improve the performance of the followingstr methodsby adapting them to theMETH_FASTCALL calling convention:

  • gh-117411: MovePyFutureFeatures to an internal header and make itprivate.

  • gh-109120: Added handle of incorrect star expressions, e.gf(3,*).Patch by Grigoryev Semyon

  • gh-117266: Fix crashes for certain user-created subclasses ofast.AST. Such classes are now expected to set the_field_types attribute.

  • gh-99108: Updated thehashlib built-inHACL* project C codefrom upstream that we use for many implementations when they are notpresent via OpenSSL in a given build. This also avoids the rare potentialfor a C symbol name one definition rule linking issue.

  • gh-117108: Change the old space bit of objects in the young generationfrom 0 to gcstate->visited, so that any objects created during GC willhave the old bit set correctly if they get moved into the old generation.

  • gh-117108: The cycle GC now chooses the size of increments based on thetotal heap size, instead of the rate of object creation. This ensures thatit can keep up with growing heaps.

  • gh-116735: ForINSTRUMENTED_CALL_FUNCTION_EX, setarg0 tosys.monitoring.MISSING instead ofNone forCALL event.

  • gh-113964: Starting new threads and process creation throughos.fork() are now only prevented once all non-daemon threads exit.

  • gh-116626: EnsureINSTRUMENTED_CALL_FUNCTION_EX always emitsCALL

  • gh-116554:list.sort() now exploits more cases of partial ordering,particularly those with long descending runs with sub-runs of equalvalues. Those are recognized as single runs now (previously, each block ofrepeated values caused a new run to be created).

  • gh-114099: Added a Loader that can discover extension modules in aniOS-style Frameworks folder.

  • gh-115775: Compiler populates the new__static_attributes__ field on aclass with the names of attributes of this class which are accessedthrough self.X from any function in its body.

  • gh-115776: The array of values, thePyDictValues struct is nowembedded in the object during allocation. This provides better performancein the common case, and does not degrade as much when the object's__dict__ is materialized.

  • gh-108362: Implement an incremental cyclic garbage collector. Bycollecting the old generation in increments, there is no need for a fullheap scan. This can hugely reduce maximum pause time for programs withlarge heaps.

    Reduce the number of generations from three to two. The old generation issplit into two spaces, "visited" and "pending".

    Collection happens in two steps:: * An increment is formed from the younggeneration and a small part of the pending space. * This increment isscanned and the survivors moved to the end of the visited space.

    When the collecting space becomes empty, the two spaces are swapped.

  • gh-109870: Dataclasses now callsexec() once per dataclass, insteadof once per method being added. This can speed up dataclass creation byup to 20%.

  • gh-97901: Mime typetext/rtf is now supported bymimetypes.

  • bpo-24612: Improve theSyntaxError that happens when 'not' appearsafter an operator. Patch by Pablo Galindo

Library

  • gh-117648: Improve performance ofos.path.join() andos.path.expanduser().

  • gh-117584: RaiseTypeError for non-paths inposixpath.relpath().

  • gh-117467: Preserve mailbox ownership when rewriting inmailbox.mbox.flush(). Patch by Tony Mountifield.

  • gh-114848: RaiseFileNotFoundError whengetcwd() returns'(unreachable)', which can happen on Linux >= 2.6.36 with glibc < 2.27.

  • gh-117459:asyncio.asyncio.run_coroutine_threadsafe() now keeps thetraceback ofCancelledError,TimeoutError andInvalidStateError which are raised in the coroutine.

  • gh-117381: Fix error message forntpath.commonpath().

  • gh-117337: Deprecate undocumentedglob.glob0() andglob.glob1() functions. Useglob.glob() and pass a directoryto itsroot_dir argument instead.

  • gh-117349: Optimise several functions inos.path.

  • gh-117348: Refactoredconfigparser.RawConfigParser._read() to reducecyclometric complexity and improve comprehensibility.

  • gh-117335: Raise TypeError for non-sequences forntpath.commonpath().

  • gh-66449:configparser.ConfigParser now accepts unnamed sectionsbefore named ones, if configured to do so.

  • gh-88014: In documentation ofgzip.GzipFile in module gzip,explain data type of optional constructor argumentmtime, and recommendmtime=0 for generating deterministic streams.

  • gh-117310: Fixed an unlikely early & extraPy_DECREF triggered crashinssl when creating a new_ssl._SSLContext if CPython wasbuilt implausibly such that the default cipher list is emptyor theSSL library it was linked against reports a failure from its CSSL_CTX_set_cipher_list() API.

  • gh-117294: ADocTestCase now reports as skipped if all examples in thedoctest are skipped.

  • gh-98966: Insubprocess, raise a more informative message whenstdout=STDOUT.

  • gh-117225: doctest: only print "and X failed" when non-zero, don'tpluralise "1 items". Patch by Hugo van Kemenade.

  • gh-117205: Speed upcompileall.compile_dir() by 20% when usingmultiprocessing by increasingchunksize.

  • gh-117178: Fix regression in lazy loading of self-referential modules,introduced ingh-114781.

  • gh-112383: Fixdis module's handling ofENTER_EXECUTORinstructions.

  • gh-117182: Lazy-loading of modules that modify their own__class__ nolonger reverts the__class__ totypes.ModuleType.

  • gh-117084: Fixzipfile extraction for directory entries with thename containing backslashes on Windows.

  • gh-117114: Makeos.path.isdevdrive() available on all platforms. Forthose that do not offer Dev Drives, it will always returnFalse.

  • gh-117110: Fix a bug that prevents subclasses oftyping.Any to beinstantiated with arguments. Patch by Chris Fu.

  • gh-109653: Deferred select imports in importlib.metadata andimportlib.resources for a 14% speedup.

  • gh-70647: Start the deprecation period for the current behavior ofdatetime.datetime.strptime() andtime.strptime() which alwaysfails to parse a date string with aValueError involving a day ofmonth such asstrptime("02-29","%m-%d") when a year isnotspecified and the date happen to be February 29th. This should help avoidusers finding new bugs every four years due to a natural mistakenassumption about the API when parsing partial date values.

  • gh-116987: Fixedinspect.findsource() for class code objects.

  • gh-114099: Modify standard library to allow for iOS platform differences.

  • gh-90872: On Windows,subprocess.Popen.wait() no longer callsWaitForSingleObject() with a negative timeout: pass0 ms if thetimeout is negative. Patch by Victor Stinner.

  • gh-116957: configparser: Don't leave ConfigParser values in an invalidstate (stored as a list instead of a str) after an earlier read raisedDuplicateSectionError or DuplicateOptionError.

  • gh-115538:_io.WindowsConsoleIO now emit a warning if a booleanvalue is passed as a filedescriptor argument.

  • gh-90095: Ignore empty lines and comments in.pdbrc

  • gh-106531: Refreshed zipfile._path fromzipp 3.18, providingbetter compatibility for PyPy, better glob performance for deeply nestedzipfiles, and providing internal access toCompleteDirs.inject for usein other tests (like importlib.resources).

  • gh-63207: On Windows,time.time() now uses theGetSystemTimePreciseAsFileTime() clock to have a resolution betterthan 1 us, instead of theGetSystemTimeAsFileTime() clock which has aresolution of 15.6 ms. Patch by Victor Stinner.

  • gh-116764: Restore support ofNone and other false values inurllib.parse functionsparse_qs() andparse_qsl(). Also, they now raise a TypeError fornon-zero integers and non-empty sequences.

  • gh-116811: InPathFinder.invalidate_caches, delegate toMetadataPathFinder.invalidate_caches.

  • gh-116647: Fix recursive child in dataclasses

  • gh-113171: Fixed various false positives and false negatives in

    Also in the correspondingipaddress.IPv4Network andipaddress.IPv6Network attributes.

  • gh-63283: Inencodings.idna, any capitalization of the ACE prefix(xn--) is now acceptable. Patch by Pepijn de Vos and Zackery Spytz.

  • gh-71042: Addplatform.android_ver(), which provides device and OSinformation on Android.

  • gh-73468: Added newmath.fma() function, wrapping C99'sfma()operation: fused multiply-add function. Patch by Mark Dickinson and VictorStinner.

  • gh-116608: Theimportlib.resources functionsis_resource(),open_binary(),open_text(),path(),read_binary(), andread_text() are un-deprecated, and supportsubdirectories via multiple positional arguments. Thecontents() function also allows subdirectories,but remains deprecated.

  • gh-116484: Change automatically generatedtkinter.Checkbuttonwidget names to avoid collisions with automatically generatedtkinter.ttk.Checkbutton widget names within the same parentwidget.

  • gh-114314: Inctypes, ctype data is now stored in type objectsdirectly rather than in a dict subclass. This is an internal change thatshould not affect usage.

  • gh-116401: Fix blockingos.fwalk() andshutil.rmtree() onopening named pipe.

  • gh-71052: Implementctypes.util.find_library() on Android.

  • gh-90535: Fix support ofinterval values > 1 inlogging.TimedRotatingFileHandler forwhen='MIDNIGHT' andwhen='Wx'.

  • gh-113308: Remove some internal protected parts fromuuid:_has_uuid_generate_time_safe,_netbios_getnode,_ipconfig_getnode, and_load_system_functions. They were unused.

  • gh-115627: Fix thessl module error handling of connectionterminate by peer. It now throws an OSError with the appropriate errorcode instead of an EOFError.

  • gh-114847: Speed upos.path.realpath() on non-Windows platforms.

  • gh-114271: Fix a race inthreading.Thread.join().

    threading._MainThread now always represents the main thread of themain interpreter.

    PyThreadState.on_delete andPyThreadState.on_delete_data have beenremoved.

  • gh-113538: Addasyncio.Server.close_clients() andasyncio.Server.abort_clients() methods which allow to moreforcefully close an asyncio server.

  • gh-85287: Changes Unicode codecs to return UnicodeEncodeError orUnicodeDecodeError, rather than just UnicodeError.

  • gh-113548:pdb now allows CLI arguments topdb-m.

  • gh-112948: Make completion ofpdb similar to Python REPL

  • gh-105866: Fixed_get_slots bug which caused error when definingdataclasses with slots and a weakref_slot.

  • gh-96471: Addasyncio.Queue termination withshutdown() method.

  • gh-89739: Thezipimport module can now read ZIP64 files.

  • bpo-33533:asyncio.as_completed() now returns an object that is bothan asynchronous iterator and plain iterator. The new asynchronousiteration pattern allows for easier correlation between prior tasks andtheir completed results. This is a closer match toconcurrent.futures.as_completed()'s iteration pattern. Patch byJustin Arthur.

  • bpo-27578:inspect.getsource() (and related functions) work withempty module files, returning'\n' (or reasonable equivalent) insteadof raisingOSError. Patch by Kernc.

  • bpo-37141: Accept an iterable of separators inasyncio.StreamReader.readuntil(), stopping when one of them isencountered.

  • gh-66543: Makemimetypes.guess_type() properly parsing of URLs withonly a host name, URLs containing fragment or query, and filenames withonly a UNC sharepoint on Windows. Based on patch by Dong-hee Na.

  • bpo-15010:unittest.TestLoader.discover() now saves the originalvalue ofunittest.TestLoader._top_level_dir and restores it at the endof the call.

Documentation

  • gh-115977: Remove compatibility references to Emscripten.

  • gh-114099: Add an iOS platform guide, and flag modules not available oniOS.

  • gh-91565: Changes to documentation files and config outputs to reflect thenew location for reporting bugs - i.e. GitHub rather than bugs.python.org.

Tests

  • gh-83434: Disable JUnit XML output (--junit-xml=FILE command lineoption) in regrtest when hunting for reference leaks (-R option).Patch by Victor Stinner.

  • gh-117187: Fix XML tests for vanilla Expat <2.6.0.

  • gh-116333: Tests of TLS related things (error codes, etc) were updated tobe more lenient about specific error message strings and behaviors as seenin the BoringSSL and AWS-LC forks of OpenSSL.

  • gh-117089: Consolidated tests for importlib.metadata in their ownmetadata package.

  • gh-115979: Update test_importlib so that it passes under WASI SDK 21.

  • gh-112536: Add --tsan to test.regrtest for running TSAN tests inreasonable execution times. Patch by Donghee Na.

  • gh-116307: Added import helperisolated_modules asCleanImportdoes not remove modules imported during the context. Use it inimportlib.resources tests to avoid leavingmod around to impedeimportlib.metadata tests.

Build

  • gh-114736: Have WASI builds use WASI SDK 21.

  • gh-115983: Skip building test modules that must be built as shared underWASI.

  • gh-71052: Add Android build script and instructions.

Windows

  • gh-117267: EnsureDirEntry.stat().st_ctime behaves consistently withos.stat() during the deprecation period ofst_ctime bycontaining the same value asst_birthtime. After the deprecationperiod,st_ctime will be the metadata change time (or unavailablethroughDirEntry), and onlyst_birthtime will contain the creationtime.

  • gh-116195: Improves performance ofos.getppid() by using analternate system API when available. Contributed by vxiiduu.

  • gh-88494: On Windows,time.monotonic() now uses theQueryPerformanceCounter() clock to have a resolution better than 1 us,instead of theGetTickCount64() clock which has a resolution of 15.6ms. Patch by Victor Stinner.

  • gh-116773: Fix instances of<_overlapped.Overlappedobjectat0xXXX>stillhaspendingoperationatdeallocation,theprocessmaycrash.

  • gh-91227: Fix the asyncio ProactorEventLoop implementation so that sendinga datagram to an address that is not listening does not prevent receivingany more datagrams.

  • gh-115119: Switched from vendoredlibmpdecimal code to aseparately-hosted external package in thecpython-source-depsrepository when building the_decimal module.

C API

  • gh-117642: FixPEP 737 implementation for%#T and%#N.

  • gh-87193:_PyBytes_Resize() can now be called for bytes objectswith reference count > 1, including 1-byte bytes objects. It creates a newbytes object and destroys the old one if it has reference count > 1.

  • gh-117021: Fix integer overflow inPyLong_AsPid() on non-Windows64-bit platforms.

  • gh-115756:PyCode_GetFirstFree() is an ustable API now and hasbeen renamed toPyUnstable_Code_GetFirstFree(). (Contributed byBogdan Romanyuk ingh-115781)

  • gh-116869: Addtest_cext test: build a C extension to check if thePython C API emits C compiler warnings. Patch by Victor Stinner.

  • gh-116869: Make the C API compatible with-Werror=declaration-after-statement compiler flag again. Patch byVictor Stinner.

  • gh-116936: AddPyType_GetModuleByDef() to the limited C API. Patchby Victor Stinner.

  • gh-116809: Restore removed private_PyErr_ChainExceptions1() function.Patch by Victor Stinner.

  • gh-115754: In the limited C API version 3.13, gettingPy_None,Py_False,Py_True,Py_Ellipsis andPy_NotImplementedsingletons is now implemented as function calls at the stable ABI level tohide implementation details. Getting these constants still return borrowedreferences. Patch by Victor Stinner.

  • gh-115754: AddPy_GetConstant() andPy_GetConstantBorrowed() functions to get constants. For example,Py_GetConstant(Py_CONSTANT_ZERO) returns astrong reference tothe constant zero. Patch by Victor Stinner.

  • gh-111696: Add support for%T,%T#,%N and%N# formats toPyUnicode_FromFormat(): format the fully qualified name of anobject type and of a type: callPyType_GetModuleName(). SeePEP 737 for more information. Patch by Victor Stinner.

  • gh-111696: AddPyType_GetModuleName() function to get the type'smodule name. Equivalent to getting thetype.__module__ attribute.Patch by Eric Snow and Victor Stinner.

  • gh-111696: AddPyType_GetFullyQualifiedName() function to get thetype's fully qualified name. Equivalent tof"{type.__module__}.{type.__qualname__}", ortype.__qualname__ iftype.__module__ is not a string or is equal to"builtins". Patchby Victor Stinner.

  • gh-85283: Thefcntl,grp,pwd,termios,_statisticsand_testconsole C extensions are now built with thelimited CAPI. Patch by Victor Stinner.

  • gh-111140: Add additional flags toPyLong_AsNativeBytes() andPyLong_FromNativeBytes() to allow the caller to determine how tohandle edge cases around values that fill the entire buffer.

  • gh-113024: AddPyObject_GenericHash() function.

Python 3.13.0 alpha 5

Release date: 2024-03-12

Security

Core and Builtins

  • gh-116604: Respect the status of the garbage collector when indirect callsare made viaPyErr_CheckSignals() and the evaluation breaker.Patch by Pablo Galindo

  • gh-112087:list is now compatible with the implementation ofPEP 703.

  • gh-116381: Add specialization forCONTAINS_OP.

  • gh-116296: Fix possible refleak inobject.__reduce__() internalerror handling.

  • gh-115823: Properly calculate error ranges in the parser when raisingSyntaxError exceptions caused by invalid byte sequences. Patch byPablo Galindo

  • gh-115778: AddtierN annotation for instruction definition ininterpreter DSL.

  • gh-115733: Fix crash when callingnext() on exhausted list iterators.

  • gh-115700: The regen-cases build stage now works on Windows.

  • gh-115347: Fix bug where docstring was replaced by a redundant NOP whenPython is run with-OO.

  • gh-115323: Make error message more meaningful for whenbytearray.extend() is called with astr object.

  • gh-112175: EveryPyThreadState now has its owneval_breaker,allowing specific threads to be interrupted.

  • gh-115154: Fix a bug that was causing thetokenize.untokenize()function to handle unicode named literals incorrectly. Patch by PabloGalindo

  • gh-112433: Add ability to force alignment ofctypes.Structure byway of the new_align_ attribute on the class.

  • gh-104090: The multiprocessing resource tracker now exits with non-zerostatus code if a resource leak was detected. It still exits with statuscode 0 otherwise.

  • gh-105858: Improve the constructors forast nodes. Arguments oflist types now default to an empty list if omitted, and optional fieldsdefault toNone. AST nodes now have an__annotations__ attributewith the expected types of their attributes. Passing unrecognized extraarguments to AST nodes is deprecated and will become an error in Python3.15. Omitting a required argument to an AST node is deprecated and willbecome an error in Python 3.15. Patch by Jelle Zijlstra.

  • gh-101860: Expose__name__ attribute on property.

  • gh-96497: Fix incorrect resolution of mangled class variables used inassignment expressions in comprehensions.

Library

  • gh-116600: Fixrepr() for globalFlag members.

  • gh-116349:platform.java_ver() is deprecated and will be removed in3.15. It was largely untested, had a confusing API, and was only usefulfor Jython support.

  • gh-116143: Fix a race in pydoc_start_server, eliminating a window inwhich_start_server can return a thread that is "serving" but withoutadocserver set.

  • gh-116127:typing: implementPEP 705 which addstyping.ReadOnly support totyping.TypedDict.

  • gh-116325:typing: raiseSyntaxError instead ofAttributeError on forward references as empty strings.

  • gh-115957: Whenasyncio.TaskGroup.create_task is called on an inactiveasyncio.TaskGroup, the given coroutine will be closed (which preventsaRuntimeWarning).

  • gh-115978: Disable preadv(), readv(), pwritev(), and writev() on WASI.

    Under wasmtime for WASI 0.2, these functions don't pass test_posix(https://github.com/bytecodealliance/wasmtime/issues/7830).

  • gh-88352: Fix the computation of the next rollover time in thelogging.TimedRotatingFileHandler handler.computeRollover() now always returns a timestamp larger than thespecified time and works correctly during the DST change.doRollover() no longer overwrite the already rolled over file,saving from data loss when run at midnight or during repeated time at theDST change.

  • gh-87115: Set__main__.__spec__ toNone when running a script withpdb

  • gh-76511: Fix UnicodeEncodeError inemail.Message.as_string() thatresults when a message that claims to be in the ascii character setactually has non-ascii characters. Non-ascii characters are now replacedwith the U+FFFD replacement character, like in thereplace errorhandler.

  • gh-89547: Add support for nested typing special forms likeFinal[ClassVar[int]].

  • gh-65824: Improve theless prompt inpydoc.

  • gh-116040: [Enum] fix by-value calls when second value is falsey; e.g.Cardinal(1, 0)

  • gh-115821: [Enum] Improve error message when calling super().__new__() incustom __new__.

  • gh-85644: Use theXDG_CURRENT_DESKTOP environment variable inwebbrowser to check desktop. Prefer it to the deprecatedGNOME_DESKTOP_SESSION_ID for GNOME detection.

  • gh-75988: Fixedunittest.mock.create_autospec() to pass the callthrough to the wrapped object to return the real result.

  • gh-115881: Fix issue whereast.parse() would incorrectly flagconditional context managers (such aswith(x()ifyelsez()):...)as invalid syntax iffeature_version=(3,8) was passed. This revertschanges to the grammar made as part ofgh-94949.

  • gh-115886: Fix silent truncation of the name with an embedded nullcharacter inmultiprocessing.shared_memory.SharedMemory.

  • gh-115532: Add kernel density estimation to the statistics module.

  • gh-115714: On WASI, thetime module no longer get process timeusingtimes() orCLOCK_PROCESS_CPUTIME_ID, system API is that isunreliable and is likely to be removed from WASI. The affected clockfunctions fall back to callingclock().

  • gh-115809: Improve algorithm for computing which rolled-over log files todelete inlogging.TimedRotatingFileHandler. It is now reliablefor handlers withoutnamer and with arbitrary deterministicnamerthat leaves the datetime part in the file name unmodified.

  • gh-74668:urllib.parse functionsparse_qs() andparse_qsl() now support bytes arguments containing rawand percent-encoded non-ASCII data.

  • gh-67044:csv.writer() now always quotes or escapes'\r' and'\n', regardless oflineterminator value.

  • gh-115712: Restore support of space delimiter withskipinitialspace=True incsv.csv.writer() now quotesempty fields if delimiter is a space and skipinitialspace is true andraises exception if quoting is not possible.

  • gh-112364: Fixedast.unparse() to handle format_spec with",' or\\. Patched by Frank Hoffmann.

  • gh-112997: Stop logging potentially sensitive callback arguments inasyncio unless debug mode is active.

  • gh-114914: Fix an issue where an abandonedStreamWriter would notbe garbage collected.

  • gh-111358: Fix a bug inasyncio.BaseEventLoop.shutdown_default_executor() to ensure thetimeout passed to the coroutine behaves as expected.

  • gh-115618: Fix improper decreasing the reference count forNoneargument inproperty methodsgetter(),setter() anddeleter().

  • gh-112720: Refactordis.ArgResolver to make it possible tosubclass and change the way jump args are interpreted.

  • gh-112006: Fixinspect.unwrap() for types with the__wrapper__data descriptor. Fixinspect.Signature.from_callable() for builtinsclassmethod() andstaticmethod().

  • gh-101293: Support callables with the__call__() method and types with__new__() and__init__() methods set to class methods, staticmethods, bound methods, partial functions, and other types of methods anddescriptors ininspect.Signature.from_callable().

  • gh-103092: Isolate_lsprof (applyPEP 687).

  • gh-113942:pydoc no longer skips global functions implemented asbuiltin methods, such asMethodDescriptorType andWrapperDescriptorType.

  • gh-115256: Added DeprecationWarning when accessing the tarfile attributeof TarInfo objects. The attribute is never used internally and is onlyattached to TarInfos when the tarfile is opened in write-mode, notread-mode. The attribute creates an unnecessary reference cycle which maycause corruption when not closing the handle after writing a tarfile.

  • gh-115197:urllib.request no longer resolves the hostname beforechecking it against the system's proxy bypass list on macOS and Windows.

  • gh-113812:DatagramTransport.sendto() will now send zero-lengthdatagrams if called with an empty bytes object. The transport flow controlalso now accounts for the datagram header when calculating the buffersize.

  • gh-114763: Protect modules loaded withimportlib.util.LazyLoaderfrom race conditions when multiple threads try to access attributes beforethe loading is complete.

  • gh-114709:posixpath.commonpath() now raises aValueErrorexception when passed an empty iterable. Previously,IndexError wasraised.

    posixpath.commonpath() now raises aTypeError exception whenpassedNone. Previously,ValueError was raised.

  • gh-114610: Fix bug wherepathlib.PurePath.with_stem() converted anon-empty path suffix to a stem when given an emptystem argument. Itnow raisesValueError, just likepathlib.PurePath.with_suffix() does when called on a path with anempty stem, given a non-emptysuffix argument.

  • gh-107361: Addssl.VERIFY_X509_PARTIAL_CHAIN andVERIFY_X509_STRICT to the default SSL context created withssl.create_default_context().

  • gh-112281: Allow creatingunion of types fortyping.Annotated with unhashable metadata.

  • gh-111775: Fiximportlib.resources.simple.ResourceHandle.open() fortext mode, added missedstream argument.

  • gh-90095: Make .pdbrc and -c work with any valid pdb commands.

  • gh-107625: Raiseconfigparser.ParsingError fromread() andread_file() methods ofconfigparser.ConfigParser if a key without a corresponding valueis continued (that is, followed by an indented line).

  • gh-107155: Fix incorrect output ofhelp(x) wherex is alambda function, which has an__annotations__ dictionaryattribute with a"return" key.

  • gh-57141: Add option fornon-shallow comparisons tofilecmp.dircmp likefilecmp.cmp(). Original patch by StevenWard. Enhanced by Tobias Rautenkranz

  • gh-69990:Profile.print_stats() has been improved to accept multiplesort arguments. Patched by Chiu-Hsiang Hsu and Furkan Onder.

  • gh-104061: Addsocket.SO_BINDTOIFINDEX constant.

  • gh-60346: Fix ArgumentParser inconsistent with parse_known_args.

  • gh-102389: Addwindows_31j to aliases forcp932 codec

  • gh-72249:functools.partial`sof:func:`repr() has been improved toinclude themodule name. Patched by Furkan Onder and AnilykaBarry.

  • gh-100985: Update HTTPSConnection to consistently wrap IPv6 Addresses whenusing a proxy.

  • gh-100884: email: fix misfolding of comma in address-lists over multiplelines in combination with unicode encoding.

  • gh-95782: Fixio.BufferedReader.tell(),io.BufferedReader.seek(),_pyio.BufferedReader.tell(),io.BufferedRandom.tell(),io.BufferedRandom.seek() and_pyio.BufferedRandom.tell() being able to return negative offsets.

  • gh-96310: Fix a traceback inargparse when all options in amutually exclusive group are suppressed.

  • gh-93205: Fixed a bug inlogging.handlers.TimedRotatingFileHandler where multiple rotatinghandler instances pointing to files with the same name but differentextensions would conflict and not delete the correct files.

  • bpo-31116: Add Z85 encoding tobase64.

  • bpo-44865: Add missing call to localization function inargparse.

  • bpo-43952: Fixmultiprocessing.connection.Listener.accept() toaccept empty bytes as authkey. Not accepting empty bytes as key causes itto hang indefinitely.

  • bpo-42125: linecache: get module name from__spec__ if available. Thisallows getting source code for the__main__ module when a customloader is used.

  • bpo-41122: Failing to pass arguments properly tofunctools.singledispatchmethod() now throws a TypeError instead ofhitting an index out of bounds internally.

  • bpo-40818: The asyncio REPL now runssys.__interactivehook__ onstartup. The default implementation ofsys.__interactivehook__provides auto-completion to the asyncio REPL. Patch contributed by RémiLapeyre.

  • bpo-33775: Add 'default' and 'version' help text for localization inargparse.

Documentation

Tests

  • gh-71052: Add test exclusions to support running the test suite onAndroid.

  • gh-71052: Enabletest_concurrent_futures on platforms that supportthreading but not multiprocessing.

  • gh-115796: Make '_testinternalcapi.assemble_code_object' construct theexception table for the code object.

  • gh-115720: Leak tests (-R,--huntrleaks) now show a summary of thenumber of leaks found in each iteration.

  • gh-115122: Add--bisect option to regrtest test runner: run failedtests withtest.bisect_cmd to identify failing tests. Patch by VictorStinner.

  • gh-115596: FixProgramPriorityTests intest_os permanentlychanging the process priority.

  • gh-115556: On Windows, commas passed in arguments toTools\buildbot\test.bat andPCbuild\\rt.bat are now properlyhandled.

  • gh-115420: Fix translation of exception handler targets by_testinternalcapi.optimize_cfg.

  • gh-115376: Fix segfault in_testinternalcapi.compiler_codegen on badinput.

Build

  • gh-116313: Get WASI builds to work under wasmtime 18 w/ WASI 0.2/preview2primitives.

  • gh-71052: Change Android'ssys.platform from"linux" to"android".

  • gh-116117: Backportlibb2's PR #42 to fix compiling CPython on 32-bitWindows withclang-cl.

  • gh-71052: Fix several Android build issues

  • gh-114099: A testbed project was added to run the test suite on iOS.

  • gh-115350: Fix building ctypes module with -DWIN32_LEAN_AND_MEAN defined

  • gh-111225: Link extension modules against libpython on Android.

  • gh-115737: The install name for libPython is now correctly set fornon-framework macOS builds.

  • gh-114099: Makefile targets were added to support compiling aniOS-compatible framework build.

Windows

  • gh-116012: Ensure the value ofGetLastError() is preserved across GILoperations.

  • gh-115582: Building extensions intended for free-threaded builds ofCPython now require compiling with/DPy_GIL_DISABLED manually whenusing a regular install. This is expected to change in future releases.

  • gh-115554: The installer now has more strict rules about updating thePython Launcher for Windows. In general, most users only have a single launcherinstalled and will see no difference. When multiple launchers have beeninstalled, the option to install the launcher is disabled until all butone have been removed. Downgrading the launcher (which was never allowed)is now more obviously blocked.

  • gh-115543:Python Launcher for Windows can now detect Python 3.13 when installed fromthe Microsoft Store, and will install Python 3.12 by default whenPYLAUNCHER_ALLOW_INSTALL is set.

macOS

  • gh-116145: Update macOS installer to Tcl/Tk 8.6.14.

IDLE

  • gh-88516: On macOS show a proxy icon in the title bar of editor windows tomatch platform behaviour.

Tools/Demos

  • gh-100176: Remove outdated Tools/{io,cc,string}bench

  • bpo-45101: Add consistency in usage message IO between 2 versions ofpython-config.

C API

  • gh-114626: Add again_PyCFunctionFastWithKeywords name, removed inPython 3.13 alpha 4 by mistake. Keep the old private_PyCFunctionFastWithKeywords name (Python 3.7) as an alias to the newpublic namePyCFunctionFastWithKeywords (Python 3.13a4). Patch byVictor Stinner.

  • gh-111418: AddPyHASH_MODULUS,PyHASH_BITS,PyHASH_INF andPyHASH_IMAG C macros. Patch bySergey B Kirpichev.

Python 3.13.0 alpha 4

Release date: 2024-02-15

Security

Core and Builtins

  • gh-112087: For an empty reverse iterator for list will be reduced toreversed(). Patch by Donghee Na

  • gh-114570: AddPythonFinalizationError exception. This exceptionderived fromRuntimeError is raised when an operation is blockedduring thePython finalization. Patch byVictor Stinner.

  • gh-114695: Addsys._clear_internal_caches(), which clears allinternal performance-related caches (and deprecate the less-generalsys._clear_type_cache() function).

  • gh-114828: Fix compilation crashes in uncommon code examples usingsuper() inside a comprehension in a class body.

  • gh-112069: Adaptset andfrozenset methods to ArgumentClinic.

  • gh-115011: Setters for members with an unsigned integer type now supportthe same range of valid values for objects that has a__index__() method as forint.

  • gh-114887: Changed socket type validation increate_datagram_endpoint() to accept all non-streamsockets. This fixes a regression in compatibility with raw sockets.

  • gh-114944: Fixes a race betweenPyParkingLot_Park and_PyParkingLot_UnparkAll.

  • gh-113462: Limit the number of versions that a single class can use.Prevents a few wayward classes using up all the version numbers.

  • gh-76763: Thechr() builtin function now always raisesValueError for values outside the valid range. Previously it raisedOverflowError for very large or small values.

  • gh-114806: No longer specialize calls to classes, if those classes havemetaclasses. Fixes bug where the__call__ method of the metaclass wasnot being called.

  • gh-107944: Improve error message for function calls with bad keywordarguments via getargs

  • gh-112529: The free-threaded build no longer allocates space for thePyGC_Head structure in objects that support cyclic garbage collection.A number of other fields and data structures are used as replacements,includingob_gc_bits,ob_tid, and mimalloc internal datastructures.

  • gh-114456: Lower the recursion limit under a debug build of WASI.

  • gh-114083: Compiler applies folding of LOAD_CONST with followinginstruction in a separate pass before other optimisations. This enablesjump threading in certain circumstances.

  • gh-114388: Fix aRuntimeWarning emitted when assign an integer-likevalue that is not an instance ofint to an attribute thatcorresponds to a C struct member oftype T_UINTand T_ULONG. Fix a doubleRuntimeWarning emitted when assign anegative integer value to an attribute that corresponds to a C structmember of type T_UINT.

  • gh-114265: Compiler propagates line numbers before optimization, leadingto more optimization opportunities and removing the need for theguarantee_lineno_for_exits hack.

  • gh-112529: The free-threaded build now has its own thread-safe GCimplementation that uses mimalloc to find GC tracked objects. It isnon-generational, unlike the existing GC implementation.

  • gh-114050: Fix segmentation fault caused by an incorrect format string inTypeError exception when more than two arguments are passed toint.

  • gh-112354: TheEND_FOR instruction now pops only one value. This is tobetter support side exits in loops.

  • gh-113884: Makequeue.SimpleQueue thread safe when the GIL isdisabled.

  • gh-114058: Implement the foundations of the Tier 2 redundancy eliminator.

  • gh-113939: frame.clear(): Clear frame.f_locals as well, and not only thefast locals. This is relevant once frame.f_locals was accessed, whichwould contain also references to all the locals.

  • gh-112050: Convertcollections.deque to use Argument Clinic.

  • gh-112050: Make methods oncollections.deque thread-safe when theGIL is disabled.

  • gh-113464: Add an option (--enable-experimental-jit forconfigure-based builds or--experimental-jit forPCbuild-basedones) to build anexperimental just-in-time compiler, based oncopy-and-patch

  • gh-113055: Make interp->obmalloc a pointer. For interpreters that sharestate with the main interpreter, this points to the same static memorystructure. For interpreters with their own obmalloc state, it is heapallocated. Add free_obmalloc_arenas() which will free the obmalloc arenasand radix tree structures for interpreters with their own obmalloc state.

  • gh-55664: Add warning when creatingtype using a namespacedictionary with non-string keys. Patched by Daniel Urban and Furkan Onder.

  • gh-104530: Use native Win32 condition variables.

Library

  • gh-115392: Fix a bug indoctest where incorrect line numbers wouldbe reported for decorated functions.

  • gh-114563: Fix severalformat() bugs when using the C implementationofDecimal: * memory leak in some rare cases when usingthez format option (coerce negative 0) * incorrect output whenapplying thez format option to typeF (fixed-point with capitalNAN /INF) * incorrect output when applying the# formatoption (alternate form)

  • gh-102840: Fix confused traceback when floordiv, mod, or divmod operationshappens between instances offractions.Fraction andcomplex.

  • gh-115165: Most exceptions are now ignored when attempting to set the__orig_class__ attribute on objects returned when callingtyping generic aliases (including generic aliases created usingtyping.Annotated). Previously onlyAttributeError wasignored. Patch by Dave Shawley.

  • gh-112903: Fix "issubclass() arg 1 must be a class" errors in certaincases of multiple inheritance with generic aliases (regression in early3.13 alpha releases).

  • gh-115133: Fix tests forXMLPullParserwith Expat 2.6.0.

  • gh-115059:io.BufferedRandom.read1() now flushes the underlyingwrite buffer.

  • gh-79382: Trailing** no longer allows to match files and non-existingpaths in recursiveglob().

  • gh-67837: Avoid race conditions in the creation of directories duringconcurrent extraction intarfile andzipfile.

  • gh-115060: Speed uppathlib.Path.glob() by removing redundant regexmatching.

  • gh-97928: Partially revert the behavior oftkinter.Text.count(). Bydefault it preserves the behavior of older Python versions, except thatsettingwantobjects to 0 no longer has effect. Add a new parameterreturn_ints: specifyingreturn_ints=True makesText.count()always returning the single count as an integer instead of a 1-tuple orNone.

  • gh-114628: When csv.Error is raised when handling TypeError, do not printthe TypeError traceback.

  • gh-85984: Added_POSIX_VDISABLE from C's<unistd.h> totermios.

  • gh-114965: Update bundled pip to 24.0

  • gh-114959:tarfile no longer ignores errors when trying to extracta directory on top of a file.

  • gh-114894: Addarray.array.clear().

  • gh-114071: Support tuple subclasses using auto() for enum member value.

  • gh-109475: Fix support of explicit option value "--" inargparse(e.g.--option=--).

  • gh-49766: Fixdate-datetimecomparison. Now the special comparison methods like__eq__ and__lt__ returnNotImplemented if one of comparands isdate and other isdatetime instead of ignoring thetime part and the time zone or forcefully return "not equal" or raiseTypeError. It makes comparison ofdate anddatetime subclasses more symmetric and allows to change thedefault behavior by overriding the special comparison methods insubclasses.

  • gh-110190: Fix ctypes structs with array on Windows ARM64 platform bysettingMAX_STRUCT_SIZE to 32 in stgdict. Patch by Diego Russo

  • gh-114678: Ensure that deprecation warning for 'N' specifier inDecimal format is not raised for cases where 'N' appearsin other places in the format specifier. Based on patch by Stefan Krah.

  • gh-70303: Return both files and directories frompathlib.Path.glob()if a pattern ends with "**". Previously only directories werereturned.

  • gh-109653: Improve import time ofimportlib.metadata andemail.utils.

  • gh-113280: Fix a leak of open socket in rare cases when error occurred inssl.SSLSocket creation.

  • gh-77749:email.policy.EmailPolicy.fold() now always encodesnon-ASCII characters in headers ifutf8is false.

  • gh-83383: Synchronization of thedbm.dumb database is now no-op ifthere was no modification since opening or last synchronization. Thedirectory file for a newly created emptydbm.dumb database is nowcreated immediately after opening instead of deferring this untilsynchronizing or closing.

  • gh-91602: Addfilter keyword-only parameter tosqlite3.Connection.iterdump() for filtering database objects todump. Patch by Mariusz Felisiak.

  • gh-112451: Prohibit subclassing pure-Pythondatetime.timezone.This is consistent with C-extension implementation. Patch by MariuszFelisiak.

  • gh-69893: Add theclose() method for the iterator returned byxml.etree.ElementTree.iterparse().

  • gh-109653: Reduce the import time ofthreading module by ~50%.Patch by Daniel Hollas.

  • gh-114492: Make the result oftermios.tcgetattr() reproducible onAlpine Linux. Previously it could leave a random garbage in some fields.

  • gh-114315: Makethreading.Lock a real class, not a factoryfunction. Add__new__ to_thread.lock type.

  • gh-100414: Adddbm.sqlite3 as a backend todbm, and make itthe new defaultdbm backend. Patch by Raymond Hettinger and ErlendE. Aasland.

  • gh-113267: Revert changes ingh-106584 which made calls ofTestResult methodsstartTest() andstopTest() unbalanced.

  • gh-75128: Ignore anOSError inasyncio.BaseEventLoop.create_server() when IPv6 is available but theinterface cannot actually support it.

  • gh-114423:_DummyThread entries inthreading._active are nowautomatically removed when the related thread dies.

  • gh-114257: Dismiss theFileNotFound error inctypes.util.find_library() and just returnNone on Linux.

  • gh-114321: Expose more platform specific constants in thefcntlmodule on Linux, macOS, FreeBSD and NetBSD.

  • gh-114328: Thetty.setcbreak() and newtty.cfmakecbreak() nolonger clears the terminal input ICRLF flag. This fixes a regressionintroduced in 3.12 that no longer matched how OSes define cbreak mode intheirstty(1) manual pages.

  • gh-114281: Remove type hints fromLib/asyncio/staggered.py. Theannotations in thetypeshedproject should be used instead.

  • gh-101438: Avoid reference cycle in ElementTree.iterparse. The iteratorreturned byElementTree.iterparse may hold on to a file descriptor.The reference cycle prevented prompt clean-up of the file descriptor ifthe returned iterator was not exhausted.

  • gh-114198: The signature for the__replace__ method ondataclasses now has the first argument namedself, rather thanobj.

  • gh-104522:OSError raised when run a subprocess now only hasfilename attribute set tocwd if the error was caused by a failedattempt to change the current directory.

  • gh-114149: Enum: correctly handle tuple subclasses in custom__new__.

  • gh-83648: Support deprecation of options, positional arguments andsubcommands inargparse.

  • gh-114087: Speed updataclasses.asdict up to 1.35x.

  • gh-109534: Fix a reference leak inasyncio.selector_events.BaseSelectorEventLoop when SSL handshakesfail. Patch contributed by Jamie Phan.

  • gh-79634: Acceptpath-like objects as patternsinpathlib.Path.glob() andrglob().

  • gh-112202: Ensure that aasyncio.Condition.notify() call does notget lost if the awakenedTask is simultaneously cancelled orencounters any other error.

  • gh-113951: Fix the behavior oftag_unbind() methods oftkinter.Text andtkinter.Canvas classes with threearguments. Previously,widget.tag_unbind(tag,sequence,funcid)destroyed the current binding forsequence, leavingsequence unbound,and deleted thefuncid command. Now it removes onlyfuncid from thebinding forsequence, keeping other commands, and deletes thefuncidcommand. It leavessequence unbound only iffuncid was the last boundcommand.

  • gh-97959: Fix rendering class methods, bound methods, method and functionaliases inpydoc. Class methods no longer have "method ofbuiltins.type instance" note. Corresponding notes are now added for classand unbound methods. Method and function aliases now have references tothe module or the class where the origin was defined if it differs fromthe current. Bound methods are now listed in the static methods section.Methods of builtin classes are now supported as well as methods of Pythonclasses.

  • gh-113796: Add more validation checks in thecsv.Dialectconstructor.ValueError is now raised if the same character is usedin different roles.

  • gh-113732: Fix support ofQUOTE_NOTNULL andQUOTE_STRINGS incsv.reader().

  • gh-113225: Speed uppathlib.Path.walk() by usingos.DirEntry.path where possible.

  • gh-89039: When replace() method is called on a subclass of datetime, dateor time, properly call derived constructor. Previously, only the baseclass's constructor was called.

    Also, make sure to pass non-zero fold values when creating subclasses invarious methods. Previously, fold was silently ignored.

  • gh-112919: Speed-updatetime.datetime.replace(),datetime.date.replace() anddatetime.time.replace().

  • gh-59013: Set breakpoint on the first executable line of the function,instead of the line of function definition when the user dobreakfuncusingpdb

  • gh-112343: Improve handling of pdb convenience variables to avoidreplacing string contents.

  • gh-112240: Add option to calendar module CLI to specify the weekday tostart each week. Patch by Steven Ward.

  • gh-111741: Recogniseimage/webp as a standard format in themimetypes module.

  • gh-43457: Fix thetkinter widget methodwm_attributes(). Itnow accepts the attribute name without the minus prefix to get windowattributes and allows to specify attributes and values to set as keywordarguments. Add new optional keyword argumentreturn_python_dict: callingw.wm_attributes(return_python_dict=True) returns the attributes as adict instead of a tuple. Callingw.wm_attributes() now returns a tupleinstead of string ifwantobjects was set to 0.

  • gh-82626: Many functions now emit a warning if a boolean value is passedas a file descriptor argument.

  • gh-111051: Added check for file modification during debugging withpdb

  • gh-110345: Show the Tcl/Tk patchlevel (rather than version) intkinter._test().

  • gh-38807: Fix race condition intrace. Instead of checking if adirectory exists and creating it, directly callos.makedirs() withthe kwargexist_ok=True.

  • gh-75705: Set unixfrom envelope inmailbox.mbox andmailbox.MMDF.

  • gh-106233: Fix stacklevel inInvalidTZPathWarning duringzoneinfo module import.

  • gh-105102: Allowctypes.Union to be nested inctypes.Structure when the system endianness is the opposite ofthe classes.

  • gh-104282: Fix null pointer dereference inlzma._decode_filter_properties() due to improper handling of BCJfilters with properties of zero length. Patch by Radislav Chugunov.

  • gh-96471: Addqueue.Queue termination withshutdown().

  • gh-101599: Changed argparse flag options formatting to remove redundancy.

  • gh-85984: Add POSIX pseudo-terminal functionsos.posix_openpt(),os.grantpt(),os.unlockpt(), andos.ptsname().

  • gh-102512: Whenos.fork() is called from a foreign thread (aka_DummyThread), the type of the thread in a child process is changed to_MainThread. Also changed its name and daemonic status, it can be nowjoined.

  • gh-88569: Addos.path.isreserved(), which identifies reservedpathnames such as "NUL", "AUX" and "CON". This function is only availableon Windows.

    Deprecatepathlib.PurePath.is_reserved().

  • bpo-38364: Theinspect functionsisgeneratorfunction,iscoroutinefunction,isasyncgenfunction now supportfunctools.partialmethod wrapped functions the same way they supportfunctools.partial.

Documentation

  • gh-115233: Fix an example forLoggerAdapter in theLogging Cookbook.

  • gh-114123: Move thecsv module docstring to thecsv moduleinstead of reexporting it from the internal_csv module, andremove__doc__ fromcsv.__all__.

    Movecsv.__version__ to thecsv module instead ofreexporting it from the internal_csv module, and remove__version__ fromcsv.__all__.

Tests

  • gh-114099: Added test exclusions required to run the test suite on iOS.

  • gh-105089: Fixtest.test_zipfile.test_core.TestWithDirectory.test_create_directory_with_writetest in AIX by doing a bitwise AND of 0xFFFF on mode , so that it will bein sync withzinfo.external_attr

Build

  • gh-115167: Avoid vendoringvcruntime140_threads.dll when building withVisual Studio 2022 version 17.8.

  • gh-113632: Promote WASI to a tier 2 platform and drop Emscripten from tier3 in configure.ac.

  • gh-114099: configure and Makefile were refactored to accommodate frameworkbuilds on Apple platforms other than macOS.

  • gh-114875: Addgetgrent() as a prerequisite for building thegrp module.

Windows

  • gh-115049: Fixespy.exe launcher failing when run as users withoutuser profiles.

  • gh-115009: Update Windows installer to use SQLite 3.45.1.

  • gh-109991: Update Windows build to use OpenSSL 3.0.13.

  • gh-111239: Update Windows builds to use zlib v1.3.1.

  • gh-100107: Thepy.exe launcher will no longer attempt to run theMicrosoft Store redirector when launching a script containing a/usr/bin/env shebang

  • gh-112984: Adds free-threaded binaries to Windows installer as an optionalcomponent.

  • gh-89240: Allowsmultiprocessing to create pools of greater than 62processes.

macOS

  • gh-115009: Update macOS installer to use SQLite 3.45.1.

  • gh-109991: Update macOS installer to use OpenSSL 3.0.13.

  • gh-114490: Add Mach-O linkage support forplatform.architecture().

  • gh-87804: On macOS the result ofos.statvfs andos.fstatvfs nowcorrectly report the size of very large disks, in previous versions thereported number of blocks was wrong for disks with at least 2**32 blocks.

IDLE

  • gh-96905: In idlelib code, stop redefining built-ins 'dict' and 'object'.

  • gh-103820: Revise IDLE bindings so that events from mouse button 4/5 onnon-X11 windowing systems (i.e. Win32 and Aqua) are not mistaken forscrolling.

Tools/Demos

  • gh-113516: Don't setLDSHARED when building for WASI.

  • gh-109991: Update GitHub CI workflows to use OpenSSL 3.0.13 andmultissltests to use 1.1.1w, 3.0.13, 3.1.5, and 3.2.1.

  • gh-115015: Fix a bug in Argument Clinic that generated incorrect code formethods with no parameters that use theMETH_METHOD | METH_FASTCALL| METH_KEYWORDS callingconvention. Only the positional parameter count was checked; any keywordargument passed would be silently accepted.

C API

Python 3.13.0 alpha 3

Release date: 2024-01-17

Security

  • gh-113659: Skip.pth files with names starting with a dot or hiddenfile attribute.

  • gh-112302: Created a Software Bill-of-Materials document and tooling fortracking dependencies.

Core and Builtins

  • gh-107901: Compiler duplicates basic blocks that have an eval breakercheck, no line number, and multiple predecessors.

  • gh-107901: A jump leaving an exception handler back to normal code nolonger checks the eval breaker.

  • gh-113655: Set the C recursion limit to 4000 on Windows, and 10000 onLinux/OSX. This seems to be near the sweet spot to maintain safety, butnot compromise backwards compatibility.

  • gh-113710: Add typed stack effects to the interpreter DSL, along withvarious instruction annotations.

  • gh-77046: On Windows, file descriptors wrapping Windows handles are nowcreated non inheritable by default (PEP 446). Patch by Zackery Spytzand Victor Stinner.

  • gh-113853: Guarantee that all executors make progress. This thenguarantees that tier 2 execution always makes progress.

  • gh-113753: Fix an issue where the finalizer ofPyAsyncGenASend objectsmight not be called if they were allocated from a free list.

  • gh-107901: Compiler changed so that synthetic jumps which are not at loopend no longer check the eval breaker.

  • gh-113703: Fix a regression in thecodeop module that was causingit to incorrectly identify incomplete f-strings. Patch by Pablo Galindo

  • gh-89811: Check for a validtp_version_tag before performing bytecodespecializations that rely on this value being usable.

  • gh-111488: Changed error message in case of no 'in' keyword after 'for' inlist comprehensions

  • gh-113657: Fix an issue that caused important instruction pointer updatesto be optimized out of tier two traces.

  • gh-113603: Fixed bug where a redundant NOP is not removed, causing anassertion to fail in the compiler in debug mode.

  • gh-113602: Fix an error that was causing the parser to try to overwriteexisting errors and crashing in the process. Patch by Pablo Galindo

  • gh-113486: No longer issue spuriousPY_UNWIND events for optimizedcalls to classes.

  • gh-113297: Fix segfault in the compiler on with statement with 19 contextmanagers.

  • gh-113212: Improvesuper error messages.

  • gh-111375: Only useNULL in the exception stack to indicate anexception was handled. Patch by Carey Metcalfe.

  • gh-112215: Increase the C recursion limit by a factor of 3 for non-debugbuilds, except for webassembly and s390 platforms which are unchanged.This mitigates some regressions in 3.12 with deep recursion mixing builtin(C) and Python code.

  • gh-113054: Fixed bug where a redundant NOP is not removed, causing anassertion to fail in the compiler in debug mode.

  • gh-106905: Use per AST-parser state rather than global state to trackrecursion depth within the AST parser to prevent potential race conditiondue to simultaneous parsing.

    The issue primarily showed up in 3.11 by multithreaded users ofast.parse(). In 3.12 a change to when garbage collection can betriggered prevented the race condition from occurring.

  • gh-108866: Change the API and contract of_PyExecutorObject to returnthe next_instr pointer, instead of the frame, and to always execute atleast one instruction.

  • gh-90350: Optimize builtin functionsmin() andmax().

  • gh-112943: Correctly compute end column offsets for multiline tokens inthetokenize module. Patch by Pablo Galindo

  • gh-112125: FixNone.__ne__(None) returningNotImplemented insteadofFalse.

  • gh-74616:input() now raises a ValueError when output on theterminal if the prompt contains embedded null characters instead ofsilently truncating it.

  • gh-112716: Fix SystemError in theimport statement and in__reduce__() methods of builtin types when__builtins__ is not adict.

  • gh-112730: Use color to highlight error locations in tracebacks. Patch byPablo Galindo

  • gh-112625: Fixes a bug where a bytearray object could be cleared whileiterating over an argument in thebytearray.join() method that couldresult in reading memory after it was freed.

  • gh-112660: Do not clear unexpected errors during formatting error messagesfor ImportError and AttributeError for modules.

  • gh-105967: Workaround a bug in Apple's macOS platform zlib library wherezlib.crc32() andbinascii.crc32() could produce incorrectresults on multi-gigabyte inputs. Including when usingzipfile onzips containing large data.

  • gh-95754: Provide a better error message when accessing invalid attributeson partially initialized modules. The origin of the module being accessedis now included in the message to help with the common issue of shadowingother modules.

  • gh-112217: Add check for the type of__cause__ returned from callingthe typeT inraisefromT.

  • gh-111058: Change coro.cr_frame/gen.gi_frame to returnNone after thecoroutine/generator has been closed. This fixes a bug wheregetcoroutinestate() andgetgeneratorstate()return the wrong state for a closed coroutine/generator.

  • gh-112388: Fix an error that was causing the parser to try to overwritetokenizer errors. Patch by pablo Galindo

  • gh-112387: Fix error positions for decoded strings with backwards tokenizeerrors. Patch by Pablo Galindo

  • gh-99606: Make code generated for an empty f-string identical to the codeof an empty normal string.

  • gh-112367: Avoid undefined behaviour when using the perf trampolines bynot freeing the code arenas until shutdown. Patch by Pablo Galindo

  • gh-112320: The Tier 2 translator now tracks the confidence level forstaying "on trace" (i.e. not exiting back to the Tier 1 interpreter) forbranch instructions based on the number of bits set in the branch"counter". Trace translation ends when the confidence drops below 1/3rd.

  • gh-109598:PyComplex_RealAsDouble()/PyComplex_ImagAsDouble() nowtries to convert an object to acomplex instance using its__complex__() method before falling back to the__float__()method. Patch by Sergey B Kirpichev.

  • gh-94606: Fix UnicodeEncodeError whenemail.message.get_payload()reads a message with a Unicode surrogate character and the message contentis not well-formed for surrogateescape encoding. Patch by SidneyMarkowitz.

  • bpo-21861: Use the object's actual class name in_io.FileIO.__repr__(),_io._WindowsConsoleIO() and_io.TextIOWrapper.__repr__(), to make these methods subclassfriendly.

  • bpo-45369: Remove LibreSSL workarounds as perPEP 644.

  • bpo-34392: Addedsys._is_interned().

Library

  • gh-114077: Fix possibleOverflowError insocket.socket.sendfile() when passcount larger than 2 GiB on32-bit platform.

  • gh-111803:plistlib now supports loading more deeply nested listsin binary format.

  • gh-114014: Fixed a bug infractions.Fraction where an invalidstring usingd in the decimals part creates a different error comparedto other invalid letters/characters. Patch by Jeremiah Gabriel Pascual.

  • gh-108364:sqlite3.Connection.iterdump() now ensures that foreignkey support is disabled before dumping the database schema, if there isany foreign key violation. Patch by Erlend E. Aasland and MariuszFelisiak.

  • gh-113971: Thezipfile.ZipInfo previously protected._compresslevel attribute has been made public as.compress_levelwith the old_compresslevel name remaining available as a property toretain compatibility.

  • gh-113877: Fixtkinter methodwinfo_pathname() on 64-bitWindows.

  • gh-113868: Addedmmap.MAP_NORESERVE,mmap.MAP_NOEXTEND,mmap.MAP_HASSEMAPHORE,mmap.MAP_NOCACHE,mmap.MAP_JIT,mmap.MAP_RESILIENT_CODESIGN,mmap.MAP_RESILIENT_MEDIA,mmap.MAP_32BIT,mmap.MAP_TRANSLATED_ALLOW_EXECUTE,mmap.MAP_UNIX03 andmmap.MAP_TPRO. All of them aremmap(2) flags on macOS.

  • gh-113848:asyncio.TaskGroup() andasyncio.timeout() contextmanagers now handleCancelledError subclasses as well asexactCancelledError.

  • gh-113661: unittest runner: Don't exit 5 if tests were skipped. Theintention of exiting 5 was to detect issues where the test suite wasn'tdiscovered at all. If we skipped tests, it was correctly discovered.

  • gh-96037: InsertTimeoutError in the context of the exception thatwas raised during exiting an expiredasyncio.timeout() block.

  • gh-113781: Silence unraisable AttributeError when warnings are emittedduring Python finalization.

  • gh-113238: AddAnchor toimportlib.resources (in order for thecode to comply with the documentation)

  • gh-111693:asyncio.Condition.wait() now re-raises the sameCancelledError instance that may have caused it to be interrupted.Fixed race condition inasyncio.Semaphore.acquire() when interruptedwith aCancelledError.

  • gh-113791: AddCLOCK_MONOTONIC_RAW_APPROX andCLOCK_UPTIME_RAW_APPROX totime on macOS. These are clocksavailable on macOS 10.12 or later.

  • gh-112932: Restore the ability forzipfile toextractall fromzip files with a "/" directory entry in them as is commonly added to zipsby some wiki or bug tracker data exporters.

  • gh-113568: Raise deprecation warnings frompathlib.PurePath andnot its private base classPurePathBase.

  • gh-113594: FixUnicodeEncodeError inemail when re-foldlines that contain unknown-8bit encoded part followed by non-unknown-8bitencoded part.

  • gh-113538: Inasyncio.StreamReaderProtocol.connection_made(), thereis callback that logs an error if the task wrapping the "connectedcallback" fails. This callback would itself fail if the task wascancelled. Prevent this by checking whether the task was cancelled first.If so, close the transport but don't log an error.

  • gh-113626: Add support for theallow_code argument in themarshalmodule. Passingallow_code=False prevents serialization andde-serialization of code objects which is incompatible between Pythonversions.

  • gh-85567: Fix resource warnings for unclosed files inpickle andpickletools command line interfaces.

  • gh-113537: Support loadsstr inplistlib.loads().

  • gh-89850: Add default implementations ofpickle.Pickler.persistent_id() andpickle.Unpickler.persistent_load() methods in the C implementation.Callingsuper().persistent_id() andsuper().persistent_load() insubclasses of the C implementation ofpickle.Pickler andpickle.Unpickler classes no longer causes infinite recursion.

  • gh-113569: Indicate if there were no actual calls in unittestassert_has_calls() failure.

  • gh-101225: Increase the backlog formultiprocessing.connection.Listener objects created bymultiprocessing.manager andmultiprocessing.resource_sharerto significantly reduce the risk of getting a connection refused errorwhen creating amultiprocessing.connection.Connection to them.

  • gh-113568: Raise audit events frompathlib.Path and not itsprivate base classPathBase.

  • gh-113543: Make sure thatwebbrowser.MacOSXOSAScript sendswebbrowser.open audit event.

  • gh-113028: When a second reference to a string appears in the input topickle, and the Python implementation is in use, we are guaranteedthat a single copy gets pickled and a single object is shared whenreloaded. Previously, in protocol 0, when a string contained certaincharacters (e.g. newline) it resulted in duplicate objects.

  • gh-113421: Fix multiprocessing logger for%(filename)s.

  • gh-111784: Fix segfaults in the_elementtree module. Fix firstsegfault during deallocation of_elementtree.XMLParser instances bykeeping strong reference topyexpat module in module state for capsulelifetime. Fix second segfault which happens in the same deallocationprocess by keeping strong reference to_elementtree module inXMLParser structure for_elementtree module lifetime.

  • gh-113407: Fix import ofunittest.mock when CPython is builtwithout docstrings.

  • gh-113320: Fix regression in Python 3.12 whereProtocolclasses that were not marked asruntime-checkable would be unnecessarily introspected,potentially causing exceptions to be raised if the protocol hadproblematic members. Patch by Alex Waygood.

  • gh-53502: Add a new optionaware_datetime inplistlib to loadsor dumps aware datetime.

  • gh-113358: Fix rendering tracebacks with exceptions with a broken__getattr__

  • gh-113214: Fix anAttributeError during asyncio SSL protocol aborts inSSL-over-SSL scenarios.

  • gh-113246: Update bundled pip to 23.3.2.

  • gh-87264: Fixed tarfile list() method to show file type.

  • gh-112182:asyncio.futures.Future.set_exception() now transformsStopIteration intoRuntimeError instead of hanging or othermisbehavior. Patch contributed by Jamie Phan.

  • gh-113225: Speed uppathlib.Path.glob() by usingos.DirEntry.path where possible.

  • gh-113149: Improve error message when a JSON array or object contains atrailing comma. Patch by Carson Radtke.

  • gh-113117: Thesubprocess module can now use theos.posix_spawn() function withclose_fds=True on platforms whereposix_spawn_file_actions_addclosefrom_np is available. Patch by JakubKulik.

  • gh-113199: Makehttp.client.HTTPResponse.read1 andhttp.client.HTTPResponse.readline close IO after reading all data whencontent length is known. Patch by Illia Volochii.

  • gh-113191: Add support ofos.fchmod() and a file descriptor inos.chmod() on Windows.

  • gh-113188: Fixshutil.copymode() andshutil.copystat() onWindows. Previously they worked differently ifdst is a symbolic link:they modified the permission bits ofdst itself rather than the file itpoints to iffollow_symlinks is true orsrc is not a symbolic link,and did not modify the permission bits iffollow_symlinks is false andsrc is a symbolic link.

  • gh-113119:os.posix_spawn() now acceptsenv=None, which makesthe newly spawned process use the current process environment. Patch byJakub Kulik.

  • gh-113202: Add astrict option tobatched() in theitertoolsmodule.

  • gh-61648: Detect line numbers of properties in doctests.

  • gh-113175: Sync with importlib_metadata 7.0, including improved typeannotations, fixed issue with symlinked packages inpackage_distributions, addedEntryPoints.__repr__, introduced thediagnose script, addedDistribution.origin property, and removeddeprecatedEntryPoint access by numeric index (tuple behavior).

  • gh-59616: Add support ofos.lchmod() and thefollow_symlinksargument inos.chmod() on Windows. Note that the default value offollow_symlinks inos.lchmod() isFalse on Windows.

  • gh-112559:signal.signal() andsignal.getsignal() no longercallrepr on callable handlers.asyncio.run() andasyncio.Runner.run() no longer callrepr on the task results.Patch by Yilei Yang.

  • gh-112962:dis module functions add cache information to theInstruction instance rather than creating fakeInstruction instances to represent the cache entries.

  • gh-112989: Reduce overhead to connect sockets withasyncioSelectorEventLoop.

  • gh-112970: Useclosefrom() on Linux where available (e.g.glibc-2.34), rather than only FreeBSD.

  • gh-110190: Fix ctypes structs with array on PPC64LE platform by settingMAX_STRUCT_SIZE to 64 in stgdict. Patch by Diego Russo.

  • gh-112540: The statistics.geometric_mean() function now returns zero fordatasets containing a zero. Formerly, it would raise an exception.

  • gh-87286: AddedLOG_FTP,LOG_NETINFO,LOG_REMOTEAUTH,LOG_INSTALL,LOG_RAS, andLOG_LAUNCHD tot thesyslog module, all of them constantson used on macOS.

  • gh-112800: FixasyncioSubprocessTransport.close() not to throwPermissionError when used with setuid executables.

  • gh-51944: Add the following constants to thetermios module. Thesevalues are present in macOS system headers:ALTWERASE,B14400,B28800,B7200,B76800,CCAR_OFLOW,CCTS_OFLOW,CDSR_OFLOW,CDTR_IFLOW,CIGNORE,CRTS_IFLOW,EXTPROC,IUTF8,MDMBUF,NL2,NL3,NOKERNINFO,ONOEOT,OXTABS,VDSUSP,VSTATUS.

  • gh-79325: Fix an infinite recursion error intempfile.TemporaryDirectory() cleanup on Windows.

  • gh-94692:shutil.rmtree() now only catches OSError exceptions.Previously a symlink attack resistant version ofshutil.rmtree() couldignore or pass to the error handler arbitrary exception when invalidarguments were provided.

  • gh-112736: The use of del-safe symbols insubprocess was refactored toallow for use in cross-platform build environments.

  • gh-112727: Speed uppathlib.Path.absolute(). Patch by Barney Gale.

  • gh-74690: Speedupissubclass() checks against simpleruntime-checkableprotocols by around6%. Patch by Alex Waygood.

  • gh-74690: Speedupisinstance() checks by roughly 20% forruntime-checkableprotocols that onlyhave one callable member. Speedupissubclass() checks for theseprotocols by roughly 10%. Patch by Alex Waygood.

  • gh-112645: Remove deprecation error on passingonerror toshutil.rmtree().

  • gh-112640: Addkwdefaults parameter totypes.FunctionType toset default keyword argument values.

  • gh-112622: Ensurename parameter is passed to event loop inasyncio.create_task().

  • gh-112618: Fix a caching bug relating totyping.Annotated.Annotated[str,True] is no longer identical toAnnotated[str,1].

  • gh-112334: Fixed a performance regression in 3.12'ssubprocess onLinux where it would no longer use the fast-pathvfork() system callwhen it could have due to a logic bug, instead falling back to the safebut slowerfork().

    Also fixed a second 3.12.0 potential security bug. If a value ofextra_groups=[] was passed tosubprocess.Popen or related APIs,the underlyingsetgroups(0,NULL) system call to clear the groups listwould not be made in the child process prior toexec().

    This was identified via code inspection in the process of fixing the firstbug.

  • gh-110190: Fix ctypes structs with array on Arm platform by settingMAX_STRUCT_SIZE to 32 in stgdict. Patch by Diego Russo.

  • gh-81194: Fix a crash insocket.if_indextoname() with specific value(UINT_MAX). Fix an integer overflow insocket.if_indextoname() on64-bit non-Windows platforms.

  • gh-112578: Fix a spuriousRuntimeWarning when executing thezipfile module.

  • gh-112516: Update the bundled copy of pip to version 23.3.1.

  • gh-112510: Addreadline.backend for the backend readline uses(editline orreadline)

  • gh-112328: [Enum] MakeEnumDict,EnumDict.member_names,EnumType._add_alias_ andEnumType._add_value_alias_ public.

  • gh-112509: Fix edge cases that could cause a key to be present in both the__required_keys__ and__optional_keys__ attributes of atyping.TypedDict. Patch by Jelle Zijlstra.

  • gh-101336: Addkeep_alive keyword parameter forAbstractEventLoop.create_server() andBaseEventLoop.create_server().

  • gh-63284: Added support for TLS-PSK (pre-shared key) mode to thessl module.

  • gh-112414: Fix regression in Python 3.12 where callingrepr() on amodule that had been imported using a customloader could failwithAttributeError. Patch by Alex Waygood.

  • gh-112358: Revert change tostruct.Struct initialization thatbroke some cases of subclassing.

  • gh-112405: Optimizepathlib.PurePath.relative_to(). Patch by AlexWaygood.

  • gh-94722: Fix bug where comparison between instances ofDocTest fails if one of them hasNone as its lineno.

  • gh-112361: Speed up a small handful ofpathlib methods by removingsome temporary objects.

  • gh-112345: Improve error message when trying to callissubclass()against atyping.Protocol that has non-method members. Patch byRandolf Scholz.

  • gh-112137: Changedis output to display no-lineno as "--" insteadof "None".

  • gh-112332: Deprecate theexc_type field oftraceback.TracebackException. Addexc_type_str to replace it.

  • gh-81620: Add extra tests forrandom.binomialvariate()

  • gh-112292: Fix a crash inreadline when imported from a subinterpreter. Patch by Anthony Shaw

  • gh-77621: Slightly improve the import time of thepathlib module bydeferring some imports. Patch by Barney Gale.

  • gh-112137: Changedis output to display logical labels for jumptargets instead of offsets.

  • gh-112139: AddSignature.format() to format signatures to stringwith extra options. And use it inpydoc to render more readablesignatures that have new lines between parameters.

  • gh-112105: Makereadline.set_completer_delims() work with libedit

  • gh-106922: Display multiple lines withtraceback when errors spanmultiple lines.

  • gh-111874: When creating atyping.NamedTuple class, ensure__set_name__() is called on all objects that define__set_name__ and exist in the values of theNamedTuple class'sclass dictionary. Patch by Alex Waygood.

  • gh-68166: Add support of the "vsapi" element type intkinter.ttk.Style.element_create().

  • gh-110275: Named tuple's methods_replace() and__replace__() nowraise TypeError instead of ValueError for invalid keyword arguments.

  • gh-99367: Do not manglesys.path[0] inpdb if safe_path is set

  • gh-111615: Fix a regression caused by a fix togh-93162 whereby youcouldn't configure aQueueHandler without specifying handlers.

  • gh-75666: Fix the behavior oftkinter widget'sunbind() methodwith two arguments. Previously,widget.unbind(sequence,funcid)destroyed the current binding forsequence, leavingsequence unbound,and deleted thefuncid command. Now it removes onlyfuncid from thebinding forsequence, keeping other commands, and deletes thefuncidcommand. It leavessequence unbound only iffuncid was the last boundcommand.

  • gh-67790: Implement basic formatting support (minimum width, alignment,fill) forfractions.Fraction.

  • gh-111049: Fix crash during garbage collection of theio.BytesIObuffer object.

  • gh-102980: Redirect the output ofinteract command ofpdb tothe same channel as the debugger. Add tests and improve docs.

  • gh-102988:email.utils.getaddresses() andemail.utils.parseaddr() now return('','') 2-tuples in moresituations where invalid email addresses are encountered instead ofpotentially inaccurate values. Add optionalstrict parameter to thesetwo functions: usestrict=False to get the old behavior, acceptmalformed inputs.getattr(email.utils,'supports_strict_parsing',False) can be use to check if thestrict parameter is available. Patchby Thomas Dwyer and Victor Stinner to improve theCVE 2023-27043 fix.

  • gh-52161:cmd.Cmd.do_help() now cleans docstrings withinspect.cleandoc() before writing them. Patch by Filip Łapkiewicz.

  • gh-82300: Addtrack parameter tomultiprocessing.shared_memory.SharedMemory that allows usingshared memory blocks without having to register with the POSIX resourcetracker that automatically releases them upon process exit.

  • gh-110109: Add privatepathlib._PurePathBase class: a base class forpathlib.PurePath that omits certain magic methods. It may be madepublic (along with_PathBase) in future.

  • gh-109858: Protectzipfile from "quoted-overlap" zipbomb. It nowraises BadZipFile when try to read an entry that overlaps with other entryor central directory.

  • gh-109786: Fix possible reference leaks and crash when re-enter the__next__() method ofitertools.pairwise.

  • gh-91539: Small (10 - 20%) and trivial performance improvement ofurllib.request.getproxies_environment(), typically useful when thereare many environment variables to go over.

  • gh-103363: Addfollow_symlinks keyword-only argument topathlib.Path.owner() andgroup(), defaulting toTrue.

  • gh-102130: Support tab completion incmd foreditline.

  • gh-99437:runpy.run_path() now decodes path-like objects, makingsure __file__ and sys.argv[0] of the module being run are always strings.

  • gh-104003: Addwarnings.deprecated(), a decorator to mark deprecatedfunctions to static type checkers and to warn on usage of deprecatedclasses and functions. SeePEP 702. Patch by Jelle Zijlstra.

  • gh-103708: Make hardcoded python name, a configurable parameter so thatdifferent implementations of python can override it instead of making hugediffs in sysconfig.py

  • gh-66515:mailbox.MH now supports folders that do not contain a.mh_sequences file (e.g. Claws Mail IMAP-cache folders). Patch bySerhiy Storchaka.

  • gh-83162: Renamedre.error toPatternError for clarity, andkeptre.error for backward compatibility. Patch by MatthiasBussonnier and Adam Chhina.

  • gh-91133: Fix a bug intempfile.TemporaryDirectory cleanup, whichnow no longer dereferences symlinks when working around file systempermission errors.

  • bpo-43153: On Windows,tempfile.TemporaryDirectory previously masked aPermissionError withNotADirectoryError during directory cleanup.It now correctly raisesPermissionError if errors are not ignored.Patch by Andrei Kulakov and Ken Jin.

  • bpo-32731:getpass.getuser() now raisesOSError for allfailures rather thanImportError on systems lacking thepwdmodule orKeyError if the password database is empty.

  • bpo-34321:mmap.mmap now has atrackfd parameter on Unix; if itisFalse, the file descriptor specified byfileno will not beduplicated.

  • bpo-35332: Theshutil.rmtree() function now ignores errors whencallingos.close() whenignore_errors isTrue, andos.close() no longer retried after error.

  • bpo-35928:io.TextIOWrapper now correctly handles the decodingbuffer afterread() andwrite().

  • bpo-26791:shutil.move() now moves a symlink into a directory whenthat directory is the target of the symlink. This provides the samebehavior as the mv shell command. The previous behavior raised anexception. Patch by Jeffrey Kintscher.

  • bpo-41422: Fixed memory leaks ofpickle.Pickler andpickle.Unpickler involving cyclic references via the internalmemo mapping.

  • bpo-19821: Thepydoc.ispackage() function has been deprecated.

  • bpo-40262: Thessl.SSLSocket.recv_into() method no longer requiresthebuffer argument to implement__len__ and supports buffers witharbitrary item size.

  • bpo-39912:warnings.filterwarnings() andwarnings.simplefilter() now raise appropriate exceptions instead ofAssertionError. Patch contributed by Rémi Lapeyre.

  • bpo-37260: Fixed a race condition inshutil.rmtree() in whichdirectory entries removed by another process or thread whileshutil.rmtree() is running can cause it to raise FileNotFoundError.Patch by Jeffrey Kintscher.

  • bpo-36959: Fix some error messages for invalid ISO format stringcombinations instrptime() that referred to directives not containedin the format string. Patch by Gordon P. Hemsley.

  • bpo-18060: Fixed a class inheritance issue that can cause segfaults whenderiving two or more levels of subclasses from a base class of Structureor Union.

  • bpo-29779: Add a newPYTHON_HISTORY environment variable to setthe location of a.python_history file.

  • bpo-21360:mailbox.Maildir now ignores files with a leading dot.

Documentation

  • gh-111699: Relocatesmtpd deprecation notice to its own section ratherthan underlocale in What's New in Python 3.12 document

  • gh-110746: Improved markup for valid options/values for methodsttk.treeview.column and ttk.treeview.heading, and for Layouts.

  • gh-95649: Document that theasyncio module contains code taken fromv0.16.0 of the uvloop project, as well as therequired MIT licensing information.

Tests

  • gh-111798: Disabletest_super_deep() fromtest_call under pydebugbuilds on WASI; the stack depth is too small to make the test useful.

  • gh-111801: Lower the recursion limit intest_isinstance fortest_infinitely_many_bases(). This prevents a stack overflow on apydebug build of WASI.

  • gh-111802: Specify a low recursion depth fortest_bad_getattr() intest.pickletester to avoid exhausting the stack under a pydebug buildfor WASI.

  • gh-44626: Fixos.path.isabs() incorrectly returningTrue whengiven a path that starts with exactly one (back)slash on Windows.

    Fixpathlib.PureWindowsPath.is_absolute() incorrectly returningFalse for some paths beginning with two (back)slashes.

  • gh-113633: Use module state for the _testcapi extension module.

  • gh-109980: Fixtest_tarfile_vs_tar intest_shutil for macOS, wheresystem tar can include more information in the archive thanshutil.make_archive.

  • gh-112769: The tests now correctly compare zlib version whenzlib.ZLIB_RUNTIME_VERSION contains non-integer suffixes. Forexample zlib-ng defines the version as1.3.0.zlib-ng.

  • gh-112334: Adds a regression test to verify thatvfork() is used whenexpected bysubprocess on vfork enabled POSIX systems (Linux).

  • gh-108927: Fixed order dependence in running tests in the same processwhen a test that has submodules (e.g. test_importlib) follows a test thatimports its submodule (e.g. test_importlib.util) and precedes a test (e.g.test_unittest or test_compileall) that uses that submodule.

  • bpo-40648: Test modes that file can get with chmod() on Windows.

Build

  • gh-114013: FixTools/wasm/wasi.py to not include the path topython.wasm as part ofHOSTRUNNER. The environment variable ismeant to specify how to run the WASI host only, havingpython.wasm andrelevant flags appended to theHOSTRUNNER. This fixesmaketestwork.

  • gh-113258: Changed the Windows build to write out generated frozen modulesinto the build tree instead of the source tree.

  • gh-112305: Fixed thecheck-clean-src step performed on out of treebuilds to detect errant$(srcdir)/Python/frozen_modules/*.h files andrecommend appropriate source tree cleanup steps to get a working buildagain.

  • gh-112536: Add support for thread sanitizer (TSAN)

  • gh-112867: Fix the build for the case that WITH_PYMALLOC_RADIX_TREE=0 set.

  • gh-103065: IntroduceTools/wasm/wasi.py to simplify doing a WASIbuild.

  • bpo-11102: Theos.major(),os.makedev(), andos.minor()functions are now available on HP-UX v3.

  • bpo-36351: Do not set ipv6type when cross-compiling.

Windows

  • gh-114096: Process privileges that are activated for creating directoryjunctions are now restored afterwards, avoiding behaviour changes in otherparts of the program.

  • gh-111877:os.stat() calls were returning incorrect time values forfiles that could not be accessed directly.

  • gh-111973: Update Windows installer to use SQLite 3.44.2.

  • gh-113009:multiprocessing: On Windows, fix a race condition inProcess.terminate(): no longer set thereturncode attribute toalways callWaitForSingleObject() inProcess.wait(). Previously,sometimes the process was still running afterTerminateProcess() evenifGetExitCodeProcess() is notSTILL_ACTIVE. Patch by VictorStinner.

  • gh-86179: Fixes path calculations when launching Python on Windows througha symlink.

  • gh-71383: Update Tcl/Tk in Windows installer to 8.6.13 with a patch tosuppress incorrect ThemeChanged warnings.

  • gh-111650: Ensures thePy_GIL_DISABLED preprocessor variable isdefined inpyconfig.h so that extension modules written in C areable to use it.

  • gh-112278: Reduce the time cost for some functions inplatform onWindows if current user has no permission to the WMI.

  • gh-73427: Deprecatesys._enablelegacywindowsfsencoding(). UsePYTHONLEGACYWINDOWSFSENCODING instead. Patch by Inada Naoki.

  • gh-87868: Correctly sort and remove duplicate environment variables in_winapi.CreateProcess().

  • bpo-37308: Fix mojibake inmmap.mmap when using a non-ASCIItagname argument on Windows.

macOS

  • gh-113666: Add the following constants to modulestat:UF_SETTABLE,UF_TRACKED,UF_DATAVAULT,SF_SUPPORTED,SF_SETTABLE,SF_SYNTHETIC,SF_RESTRICTED,SF_FIRMLINK andSF_DATALESS. The valuesUF_SETTABLE,SF_SUPPORTED,SF_SETTABLE andSF_SYNTHETIC are only available on macOS.

  • gh-113536:os.waitid() is now available on macOS

  • gh-110459: Runningconfigure...--with-openssl-rpath=X/Y/Z no longerfails to detect OpenSSL on macOS.

  • gh-74573: Document thatdbm.ndbm can silently corrupt DBM files onupdates when exceeding undocumented platform limits, and can crash(segmentation fault) when reading such a corrupted file. (FB8919203)

  • gh-65701: Thefreeze tool doesn't work with framework builds ofPython. Document this and bail out early when running the tool with such abuild.

  • gh-87277: webbrowser: Don't look for X11 browsers on macOS. Those aregenerally not used and probing for them can result in starting XQuartzeven if it isn't used otherwise.

  • gh-111973: Update macOS installer to use SQLite 3.44.2.

  • gh-108269: SetCFBundleAllowMixedLocalizations to true in theInfo.plist for the framework, embedded Python.app and IDLE.app withframework installs on macOS. This allows applications to pick up theuser's preferred locale when that's different from english.

  • gh-102362: Make sure the result ofsysconfig.get_plaform() includesat least a major and minor versions, even ifMACOSX_DEPLOYMENT_TARGETis set to only a major version during build to match the format expectedby pip.

  • gh-110017: Disable a signal handling stress test on macOS due to a bug inmacOS (FB13453490).

  • gh-110820: Make sure the preprocessor definitions forALIGNOF_MAX_ALIGN_T,SIZEOF_LONG_DOUBLE andHAVE_GCC_ASM_FOR_X64 are correct for Universal 2 builds on macOS.

  • gh-109981: Use/dev/fd on macOS to determine the number of open filesintest.support.os_helper.fd_count to avoid a crash with "guarded"file descriptors when probing for open files.

IDLE

  • gh-72284: Improve the lists of features, editor key bindings, and shellkey bingings in the IDLE doc.

  • gh-113903: Fix rare failure of test.test_idle, in test_configdialog.

  • gh-113729: Fix the "Help -> IDLE Doc" menu bug in 3.11.7 and 3.12.1.

  • gh-113269: Fix test_editor hang on macOS Catalina.

  • gh-112898: Fix processing unsaved files when quitting IDLE on macOS.

  • bpo-13586: Enter the selected text when opening the "Replace" dialog.

C API

Python 3.13.0 alpha 2

Release date: 2023-11-22

Core and Builtins

  • gh-112243: Don't include comments in f-string debug expressions. Patch byPablo Galindo

  • gh-112287: Slightly optimize the Tier 2 (uop) interpreter by only loadingoparg andoperand when needed. Also double the trace size limitagain, to 512 this time.

  • gh-112266: Change docstrings of__dict__ and__weakref__.

  • gh-111807: Lower the max parser stack depth to 1000 under WASI debugbuilds.

  • gh-111798: When Python is built in debug mode, set the C recursion limitto 500 instead of 1500. A debug build is likely built with lowoptimization level which implies higher stack memory usage than a releasebuild. Patch by Victor Stinner.

  • gh-106529: Enable translating unspecializedFOR_ITER to Tier 2.

  • gh-111916: Make hashlib related modules thread-safe without the GIL

  • gh-81137: Deprecate assignment to a function's__code__ field when thenew code object is of a mismatched type (e.g., from a generator to a plainfunction).

  • gh-79932: Raise exception ifframe.clear() is called on a suspendedframe.

  • gh-81925: Implement native thread ids for GNU KFreeBSD.

  • gh-111843: Use exponential backoff to reduce the number of failed tier 2optimization attempts by over 99%.

  • gh-110829: Joining a thread now ensures the underlying OS thread hasexited. This is required for safer fork() in multi-threaded processes.

  • gh-109369: Make sure that tier 2 traces are de-optimized if the code isinstrumented

  • gh-111772: Specialize slot loads and stores for _Py_T_OBJECT as well asPy_T_OBJECT_EX

  • gh-111666: Speed upBaseExceptionGroup.derive(),BaseExceptionGroup.subgroup(), andBaseExceptionGroup.split()by changing how they parse passed arguments.

  • gh-111654: Fix runtime crash when some error happens in opcodeLOAD_FROM_DICT_OR_DEREF.

  • gh-111623: Add support for sharing tuples between interpreters using thecross-interpreter API. Patch by Anthony Shaw.

  • gh-111354: The oparg ofYIELD_VALUE is now1 if theinstruction is part of a yield-from or await, and0 otherwise.

    The SUSPENDED frame state is now split intoSUSPENDED andSUSPENDED_YIELD_FROM. This simplifies the code in_PyGen_yf.

  • gh-111520: Merge the Tier 1 (bytecode) and Tier 2 (micro-ops) interpreterstogether, moving the Tier 2 interpreter loop and switch into_PyEval_EvalFrameDefault() inPython/ceval.c. ThePython/executor.c file is gone. Also theTIER_ONE andTIER_TWOmacros are now handled by the code generator.

    Beware! This changes the environment variables to enable micro-ops andtheir debugging toPYTHON_UOPS andPYTHON_LLTRACE.

  • gh-109181: Speed upTraceback object creation by lazily computethe line number. Patch by Pablo Galindo

  • gh-111420: Allow type comments in parenthesizedwith statements

  • gh-111438: Add support for sharing floats between interpreters using thecross-interpreter API. Patch by Anthony Shaw.

  • gh-111435: Add support for sharing ofTrue andFalse betweeninterpreters using the cross-interpreter API. Patch by Anthony Shaw.

  • gh-102388: Fix a bug whereiso2022_jp_3 andiso2022_jp_2004 codecsread out of bounds

  • gh-111366: Fix an issue in thecodeop that was causingSyntaxError exceptions raised in the presence of invalid syntax tonot contain precise error messages. Patch by Pablo Galindo

  • gh-111380: Fix a bug that was causingSyntaxWarning to appear twicewhen parsing if invalid syntax is encountered later. Patch by Pablogalindo

  • gh-111374: Added a new environment variablePYTHON_FROZEN_MODULES. It determines whether or not frozenmodules are ignored by the import machinery, equivalent of the-Xfrozen_modules command-line option.

  • gh-111354: Removeoparg fromYIELD_VALUE. ChangeopargofRESUME to include information about the except-depth. Thesechanges make it possible to simplify the code in generator close.

  • gh-94438: Fix a regression that prevented jumping acrossisNone andisnotNone when debugging. Patch by Savannah Ostrowski.

  • gh-67224: Show source lines in tracebacks when using the-c optionwhen running Python. Patch by Pablo Galindo

  • gh-111123: Fix a bug where aglobal declaration in anexcept block is rejected when the global is used in theelse block.

  • gh-110938: Fix error messages for indented blocks with functions andclasses with generic type parameters. Patch by Pablo Galindo

  • gh-109214: Remove unnecessary instruction pointer updates before returningfrom frames.

  • gh-110912: Correctly display the traceback forMemoryErrorexceptions using thetraceback module. Patch by Pablo Galindo

  • gh-109894: Fixed crash due to improperly initialized staticMemoryError in subinterpreter.

  • gh-110892: ReturnNULL forPyTrace_RETURN events caused by anexception

  • gh-110864: Fix argument parsing by_PyArg_UnpackKeywordsWithVararg forfunctions defining pos-or-keyword, vararg, and kw-only parameters.

  • gh-109094: Replaceprev_instr on the interpreter frame byinstr_ptr which points to the beginning of the instruction that iscurrently executing (or will execute once the frame resumes).

  • gh-110805: Allow the repl to show source code and complete tracebacks.Patch by Pablo Galindo

  • gh-110722: AddPYTHON_PRESITE=package.module to import a moduleearly in the interpreter lifecycle beforesite.py is executed. Pythonneeds to bebuilt in debug mode for this option toexist.

  • gh-110481: Implement biased reference counting in--disable-gilbuilds.

  • gh-110543: Fix regression in Python 3.12 wheretypes.CodeType.replace() would produce a broken code object ifcalled on a module or class code object that contains a comprehension.Patch by Jelle Zijlstra.

  • gh-89519: Removed chainedclassmethod descriptors (introduced inbpo-19072). This can no longer be used to wrap other descriptorssuch asproperty. The core design of this feature was flawed andcaused a number of downstream problems. To "pass-through" aclassmethod, consider using the__wrapped__ attributethat was added in Python 3.10.

  • gh-103615: Use local events for opcode tracing

  • bpo-46657: Add mimalloc memory allocator support.

  • gh-106718: When PyConfig.stdlib_dir is explicitly set, it's now respectedand won't be overridden by PyConfig.home.

  • gh-106905: Fix incorrect SystemError about AST constructor recursion depthmismatch.

  • gh-100445: Improve error message for unterminated strings with escapes.

  • bpo-45759: Improved error messages forelif/else statements notmatching any valid statements. Patch by Jeremiah Vivian.

Library

Tests

  • gh-111808: Make the default value oftest.support.infinite_recursion()to be conditional based on whether optimizations were used when compilingthe interpreter. This helps with platforms like WASI whose stack size isgreatly restricted in debug builds.

  • gh-110722: Gathering line coverage of standard libraries within theregression test suite is now precise, as well as much faster. Patch byŁukasz Langa.

  • gh-110367: Make regrtest--verbose3 option compatible with--huntrleaks-jN options. The./python-mtest-j1-R3:3--verbose3 command now works as expected. Patch by Victor Stinner.

  • gh-111165: Remove no longer used functionsrun_unittest() andrun_doctest() from thetest.support module.

  • gh-110932: Fix regrtest if theSOURCE_DATE_EPOCH environment variableis defined: use the variable value as the random seed. Patch by VictorStinner.

  • gh-110995: test_gdb: Fix detection of gdb built without Python scriptingsupport. Patch by Victor Stinner.

  • gh-110918: Test case matching patterns specified by options--match,--ignore,--matchfile and--ignorefile are now tested in theorder of specification, and the last match determines whether the testcase be run or ignored.

  • gh-108747: Add unit test forusercustomize andsitecustomize hooksfromsite.

Build

  • gh-96954: Makemakeregen-unicodedata work for out-of-tree builds ofCPython.

  • gh-112088: AddTools/build/regen-configure.sh script to regenerate theconfigure with an Ubuntu container image. Thequay.io/tiran/cpython_autoconf:271 container image(tiran/cpython_autoconf) isno longer used. Patch by Victor Stinner.

  • gh-111046: For wasi-threads, memory is now exported to fix compatibilityissues with some wasm runtimes.

  • gh-110828: AIX 32bit needs-latomic to build the_testcapiextension module.

  • gh-85283: Theerrno,md5,resource,winsound,_ctypes_test,_multiprocessing.posixshmem,_scproxy,_stat,_testimportmultiple and_uuid C extensions are nowbuilt with thelimited C API. Patch by VictorStinner.

Windows

  • gh-111856: Fixesfstat() on file systems that do not supportfile ID requests. This includes FAT32 and exFAT.

  • gh-111293: Fixos.DirEntry.inode dropping higher 64 bits of a fileid on some filesystems on Windows.

  • gh-110913: WindowsConsoleIO now correctly chunks large buffers withoutsplitting up UTF-8 sequences.

macOS

  • gh-59703: For macOS framework builds, ingetpath.c use the systemdladdr function to find the path to the shared library rather thandepending on deprecated macOS APIs.

  • gh-110950: Update macOS installer to include an upstream Tcl/Tk fix fortheSecurecodingisnotenabledforrestorablestate! warningencountered in Tkinter on macOS 14 Sonoma.

  • gh-111015: Ensure that IDLE.app and Python Launcher.app are installed withappropriate permissions on macOS builds.

  • gh-71383: Update macOS installer to include an upstream Tcl/Tk fix for thettk::ThemeChanged error encountered in Tkinter.

  • gh-92603: Update macOS installer to include a fix accepted by upstreamTcl/Tk for a crash encountered after the firsttkinter.Tk() instanceis destroyed.

IDLE

  • bpo-35668: Add docstrings to the IDLE debugger module. Fix two bugs:initializeIdb.botframe (should be in Bdb); inIdb.in_rpc_code,check whetherprev_frame isNone before trying to use it. Greatlyexpand test_debugger.

Tools/Demos

  • gh-111903: Argument Clinic now supports the@critical_sectiondirective that instructs Argument Clinic to generate a critical sectionaround the function call, which locks theself object in--disable-gil builds. Patch by Sam Gross.

C API

  • gh-112026: Add again the private_PyThreadState_UncheckedGet()function as an alias to the new publicPyThreadState_GetUnchecked() function. Patch by Victor Stinner.

  • gh-112026: Restore the removed_PyDict_GetItemStringWithError()function. It is used by numpy. Patch by Victor Stinner.

  • gh-112026: Restore removed private C API functions, macros and structureswhich have no simple replacement for now:

    • _PyDict_GetItem_KnownHash()

    • _PyDict_NewPresized()

    • _PyHASH_BITS

    • _PyHASH_IMAG

    • _PyHASH_INF

    • _PyHASH_MODULUS

    • _PyHASH_MULTIPLIER

    • _PyLong_Copy()

    • _PyLong_FromDigits()

    • _PyLong_New()

    • _PyLong_Sign()

    • _PyObject_CallMethodId()

    • _PyObject_CallMethodNoArgs()

    • _PyObject_CallMethodOneArg()

    • _PyObject_CallOneArg()

    • _PyObject_EXTRA_INIT

    • _PyObject_FastCallDict()

    • _PyObject_GetAttrId()

    • _PyObject_Vectorcall()

    • _PyObject_VectorcallMethod()

    • _PyStack_AsDict()

    • _PyThread_CurrentFrames()

    • _PyUnicodeWriter structure

    • _PyUnicodeWriter_Dealloc()

    • _PyUnicodeWriter_Finish()

    • _PyUnicodeWriter_Init()

    • _PyUnicodeWriter_Prepare()

    • _PyUnicodeWriter_PrepareKind()

    • _PyUnicodeWriter_WriteASCIIString()

    • _PyUnicodeWriter_WriteChar()

    • _PyUnicodeWriter_WriteLatin1String()

    • _PyUnicodeWriter_WriteStr()

    • _PyUnicodeWriter_WriteSubstring()

    • _PyUnicode_AsString()

    • _PyUnicode_FromId()

    • _PyVectorcall_Function()

    • _Py_IDENTIFIER()

    • _Py_c_abs()

    • _Py_c_diff()

    • _Py_c_neg()

    • _Py_c_pow()

    • _Py_c_prod()

    • _Py_c_quot()

    • _Py_c_sum()

    • _Py_static_string()

    • _Py_static_string_init()

    Patch by Victor Stinner.

  • gh-112026: Add again<ctype.h> and<unistd.h> includes inPython.h, but don't include them in the limited C API version 3.13 andnewer. Patch by Victor Stinner.

  • gh-111956: Add internal-only one-time initialization API:_PyOnceFlagand_PyOnceFlag_CallOnce.

  • gh-111262: AddPyDict_Pop() andPyDict_PopString()functions: remove a key from a dictionary and optionally return theremoved value. This is similar todict.pop(), but without thedefault value and not raisingKeyError if the key missing. Patch byStefan Behnel and Victor Stinner.

  • gh-111863: RenamePy_NOGIL toPy_GIL_DISABLED. Patch by Hugo vanKemenade.

  • gh-111138: AddPyList_Extend() andPyList_Clear()functions: similar to Pythonlist.extend() andlist.clear()methods. Patch by Victor Stinner.

  • gh-108765: On Windows,Python.h no longer includes the<stddef.h>standard header file. If needed, it should now be included explicitly.Patch by Victor Stinner.

  • gh-111569: Implement "Python Critical Sections" fromPEP 703. These aremacros to help replace the GIL with per-object locks in the--disable-gil build of CPython. The macros are no-ops in the defaultbuild.

  • gh-111506: In the limited C API version 3.13,Py_SET_REFCNT()function is now implemented as an opaque function call. Patch by VictorStinner.

  • gh-108082: AddPyErr_FormatUnraisable() function.

  • gh-110964: Move the undocumented private _PyArg functions and_PyArg_Parser structure to internal C API (pycore_modsupport.h). Patchby Victor Stinner.

  • gh-110815: Support non-ASCII keyword names inPyArg_ParseTupleAndKeywords().

  • gh-109587: IntroducedPyUnstable_PerfTrampoline_CompileCode(),PyUnstable_PerfTrampoline_SetPersistAfterFork() andPyUnstable_CopyPerfMapFile(). These functions allow extensionmodules to initialize trampolines eagerly, after the application is"warmed up". This makes it possible to have perf-trampolines running in analways-enabled fashion.

  • gh-85283: Add thePySys_Audit() function to the limited C API.Patch by Victor Stinner.

  • gh-85283: AddPyMem_RawMalloc(),PyMem_RawCalloc(),PyMem_RawRealloc() andPyMem_RawFree() to the limited CAPI. Patch by Victor Stinner.

  • gh-106672: FunctionsPyDict_GetItem(),PyDict_GetItemString(),PyMapping_HasKey(),PyMapping_HasKeyString(),PyObject_HasAttr(),PyObject_HasAttrString(), andPySys_GetObject(), whichclear all errors occurred during calling the function, report now themusingsys.unraisablehook().

  • gh-67565: Remove redundant C-contiguity check ingetargs.c,binascii,ssl and Argument Clinic. Patched by Stefan Krahand Furkan Onder

Python 3.13.0 alpha 1

Release date: 2023-10-13

Security

  • gh-108310: Fixed an issue where instances ofssl.SSLSocket werevulnerable to a bypass of the TLS handshake and included protections (likecertificate verification) and treating sent unencrypted data as if it werepost-handshake TLS encrypted data. Security issue reported asCVE 2023-40217 by Aapo Oksman. Patch by Gregory P. Smith.

  • gh-107774: PEP 669 specifies thatsys.monitoring.register_callbackwill generate an audit event. Pre-releases of Python 3.12 did not generatethe audit event. This is now fixed.

  • gh-102988: Reverted theemail.utils security improvement changereleased in 3.12beta4 that unintentionally causedemail.utils.getaddresses to fail to parse email addresses with acomma in the quoted name field. Seegh-106669.

  • gh-99108: Refresh our new HACL* built-inhashlib code fromupstream. Built-in SHA2 should be faster and an issue with SHA3 on 32-bitplatforms is fixed.

  • gh-102509: Start initializingob_digit during creation ofPyLongObject objects. Patch by Illia Volochii.

Core and Builtins

  • gh-110782: Fix crash whentyping.TypeVar is constructed with akeyword argument. Patch by Jelle Zijlstra.

  • gh-110752: Resetceval.eval_breaker ininterpreter_clear()

  • gh-110721: Use thetraceback implementation for the defaultPyErr_Display() functionality. Patch by Pablo Galindo

  • gh-110696: Fix incorrect error message for invalid argument unpacking.Patch by Pablo Galindo

  • gh-104169: Split the tokenizer into two separate directories: - One partincludes the actual lexeme producing logic and lives inParser/lexer.- The second part wraps the lexer according to the different tokenizationmodes we have (string, utf-8, file, interactive, readline) and lives inParser/tokenizer.

  • gh-110688: Remove undocumentedtest_c_api method fromset,which was only defined for testing purposes underPy_DEBUG. Now wehave proper CAPI tests.

  • gh-104584: Fix a reference leak when running withPYTHONUOPS or-Xuops enabled.

  • gh-110514: AddPY_THROW tosys.setprofile() events

  • gh-110489: Optimisemath.ceil() when the input is exactly a float,resulting in about a 10% improvement.

  • gh-110455: Guardassert(tstate->thread_id>0) with#ifndefHAVE_PTHREAD_STUBS. This allows for for pydebug builds to work underWASI which (currently) lacks thread support.

  • gh-110309: Remove unnecessary empty constant nodes in the ast of f-stringspecs.

  • gh-110259: Correctly identify the format spec in f-strings (with single ortriple quotes) that have multiple lines in the expression part and includea formatting spec. Patch by Pablo Galindo

  • gh-110237: Fix missing error checks for calls toPyList_Append in_PyEval_MatchClass.

  • gh-110164: regrtest: If theSOURCE_DATE_EPOCH environment variable isdefined, regrtest now disables tests randomization. Patch by VictorStinner.

  • gh-109889: Fix the compiler's redundant NOP detection algorithm to skipover NOPs with no line number when looking for the next instruction'slineno.

  • gh-109853:sys.path[0] is now set correctly for subinterpreters.

  • gh-109923: Set line number on thePOP_TOP that follows aRETURN_GENERATOR.

  • gh-105716: Subinterpreters now correctly handle the case where they havethreads running in the background. Before, such threads would interferewith cleaning up and destroying them, as well as prevent running anotherscript.

  • gh-109369: The internal eval_breaker and supporting flags, plus themonitoring version have been merged into a single atomic integer to speedup checks.

  • gh-109823: Fix bug where compiler does not adjust labels when removing anempty basic block which is a jump target.

  • gh-109793: The main thread no longer exits prematurely when asubinterpreter is cleaned up during runtime finalization. The bug was aproblem particularly because, when triggered, the Python process wouldalways return with a 0 exitcode, even if it failed.

  • gh-109719: Fix missing jump target labels when compiler reorders cold/warmblocks.

  • gh-109595: Add-Xcpu_count command line option tooverride return results ofos.cpu_count() andos.process_cpu_count(). This option is useful for users who need tolimit CPU resources of a container system without having to modify thecontainer (application code). Patch by Donghee Na.

  • gh-109627: Fix bug where the compiler does not assign a new jump targetlabel to a duplicated small exit block.

  • gh-109596: Fix some tokens in the grammar that were incorrectly marked assoft keywords. Also fix some repeated rule names and ensure that repeatedrules are not allowed. Patch by Pablo Galindo

  • gh-109496: On a Python built in debug mode,Py_DECREF() nowcalls_Py_NegativeRefcount() if the object is a dangling pointer todeallocated memory: memory filled with0xDD "dead byte" by the debughook on memory allocators. The fix is to check the reference countbefore checking for_Py_IsImmortal(). Patch by Victor Stinner.

  • gh-107265: Deopt opcodes hidden by the executor when base opcode is needed

  • gh-109371: Deopted instructions correctly for tool initialization andmodified the incorrect assertion in instrumentation, when a previous toolalready sets INSTRUCTION events

  • gh-105658: Fix bug where the line trace of an except block ending with aconditional includes an excess event with the line of the conditionalexpression.

  • gh-109219: Fix compiling type param scopes that use a name which is alsofree in an inner scope.

  • gh-109351: Fix crash when compiling an invalid AST involving a named(walrus) expression.

  • gh-109341: Fix crash when compiling an invalid AST involving aast.TypeAlias.

  • gh-109195: Fix source location for theLOAD_* instruction preceding aLOAD_SUPER_ATTR to load thesuper global (or shadowing variable)so that it encompasses only the namesuper and not the followingparentheses.

  • gh-109256: Opcode IDs for specialized opcodes are allocated in their ownrange to improve stability of the IDs for the 'real' opcodes.

  • gh-109216: Fix possible memory leak inBUILD_MAP.

  • gh-109207: Fix a SystemError in__repr__ of symtable entry object.

  • gh-109179: Fix bug where the C traceback display drops notes fromSyntaxError.

  • gh-109118: Disallow nested scopes (lambdas, generator expressions, andcomprehensions) within PEP 695 annotation scopes that are nested withinclasses.

  • gh-109156: Add tests for de-instrumenting instructions while keeping theinstrumentation for lines

  • gh-109114: Relax the detection of the error message for invalid lambdasinside f-strings to not search for arbitrary replacement fields to avoidfalse positives. Patch by Pablo Galindo

  • gh-105848: Add a newCALL_KW opcode, used for calls containingkeyword arguments. Also, fix a possible crash when jumping over methodcalls in a debugger.

  • gh-109052: Use the base opcode when comparing code objects to avoidinterference from instrumentation

  • gh-109118: Fix interpreter crash when a NameError is raised inside thetype parameters of a generic class.

  • gh-88943: Improve syntax error for non-ASCII character that follows anumerical literal. It now points on the invalid non-ASCII character, noton the valid numerical literal.

  • gh-108976: Fix crash that occurs after de-instrumenting a code object in amonitoring callback.

  • gh-108732: Make iteration variables of module- and class-scopedcomprehensions visible to pdb and other tools that useframe.f_localsagain.

  • gh-108959: Fix caret placement for error locations for subscript andbinary operations that involve non-semantic parentheses and spaces. Patchby Pablo Galindo

  • gh-104584: Fix a crash when running withPYTHONUOPS or-Xuops enabled and an error occurs during optimization.

  • gh-108727: Definetp_dealloc forCounterOptimizer_Type. This fixesa segfault on deallocation.

  • gh-108520: Fixmultiprocessing.synchronize.SemLock.__setstate__() toproperly initializemultiprocessing.synchronize.SemLock._is_fork_ctx. This fixes aregression when passing a SemLock across nested processes.

    Renamemultiprocessing.synchronize.SemLock.is_fork_ctx tomultiprocessing.synchronize.SemLock._is_fork_ctx to avoid exposingit as public API.

  • gh-108654: Restore locals shadowed by an inlined comprehension if thecomprehension raises an exception.

  • gh-108488: Change the initialization of inline cache entries so that thecache entry forJUMP_BACKWARD is initialized to zero, instead of theadaptive_counter_warmup() value used for all other instructions. Thiscounter, unique among instructions, counts up from zero.

  • gh-108716: Turn off deep-freezing of code objects. Modules are stillfrozen, so that a file system search is not needed for common modules.

  • gh-108614: Add RESUME_CHECK instruction, to avoid having to handleinstrumentation, signals, and contexts switches in the tier 2 executionengine.

  • gh-108487: Move an assert that would cause a spurious crash in a deviouscase that should only trigger deoptimization.

  • gh-106176: Use aWeakValueDictionary to track the lists containing themodules each thread is currently importing. This helps avoid a referenceleak from keeping the list around longer than necessary. Weakrefs are usedas GC can't interrupt the cleanup.

  • gh-105481: The regen-opcode build stage was removed and its work is nowdone in regen-cases.

  • gh-107901: Fix missing line number onJUMP_BACKWARD at the endof a for loop.

  • gh-108113: Thecompile() built-in can now accept a new flag,ast.PyCF_OPTIMIZED_AST, which is similar toast.PyCF_ONLY_ASTexcept that the returnedAST is optimized according to the value oftheoptimize argument.

    ast.parse() now accepts an optional argumentoptimize which ispassed on to thecompile() built-in. This makes it possible toobtain an optimizedAST.

  • gh-107971: Opcode IDs are generated from bytecodes.c instead of being hardcoded in opcode.py.

  • gh-107944: Improve error message for function calls with bad keywordarguments. Patch by Pablo Galindo

  • gh-108390: Raise an exception when setting a non-local event (RAISE,EXCEPTION_HANDLED, etc.) insys.monitoring.set_local_events.

    Fixes crash when tracing in recursive calls to Python classes.

  • gh-108035: Remove the_PyCFrame struct, moving the pointer to thecurrent interpreter frame back to the threadstate, as it was for 3.10 andearlier. The_PyCFrame existed as a performance optimization fortracing. Since PEP 669 has been implemented, this optimization no longerapplies.

  • gh-91051: Fix abort / segfault when using all eight type watcher slots, onplatforms wherechar is signed by default.

  • gh-106581: Fix possible assertion failures and missing instrumentationevents whenPYTHONUOPS or-Xuops is enabled.

  • gh-107526: Revert convertingvars,dir,next,getattr, anditer to argument clinic.

  • gh-84805: Autogenerate signature forMETH_NOARGS andMETH_O extension functions.

  • gh-107758: Make thedump_stack() routine used by thelltracefeature (low-level interpreter debugging) robust against recursion byensuring that it never calls a__repr__ method implemented in Python.Also make the similar output for Tier-2 uops appear onstdout (insteadofstderr), to match thelltrace code in ceval.c.

  • gh-107659: Add docstrings forctypes.pointer() andctypes.POINTER().

  • gh-105848: Modify the bytecode so that the actual callable for aCALL is at a consistent position on the stack (regardless ofwhether or not bound-method-calling optimizations are active).

  • gh-107674: Fixed performance regression insys.settrace.

  • gh-107724: In pre-release versions of 3.12, up to rc1, the sys.monitoringcallback function for thePY_THROW event was missing the third,exception argument. That is now fixed.

  • gh-84436: Skip reference count modifications for many known immortalobjects.

  • gh-107596: Specialize subscriptingstr objects byintindexes.

  • gh-107080: Trace refs builds (--with-trace-refs) were crashing whenused with isolated subinterpreters. The problematic global state has beenisolated to each interpreter. Other fixing the crashes, this change doesnot affect users.

  • gh-107557: Generate the cases needed for the barebones tier 2 abstractinterpreter for optimization passes in CPython.

  • gh-106608: Make_PyUOpExecutorObject variable length.

  • gh-100964: Clear generators' exception state afterreturn to breakreference cycles.

  • gh-107455: Improve error messages when converting an incompatible type toctypes.c_char_p,ctypes.c_wchar_p andctypes.c_void_p.

  • gh-107263: Increase C recursion limit for functions other than the maininterpreter from 800 to 1500. This should allow functions likelist.__repr__ andjson.dumps to handle all the inputs that theycould prior to 3.12

  • gh-104584: Fix an issue which caused incorrect inline caches to be readwhen running withPYTHONUOPS or-Xuops enabled.

  • gh-104432: Fix potential unaligned memory access on C APIs involvingreturned sequences ofchar* pointers within thegrp andsocket modules. These were revealed using a-fsaniziter=alignment build on ARM macOS. Patch by Christopher Chavez.

  • gh-106078: Isolate_decimal (applyPEP 687). Patch by CharlieZhao.

  • gh-106898: Add the exception as the third argument toPY_UNINDcallbacks insys.monitoring. This makes thePY_UNWIND callbackconsistent with the other exception handling callbacks.

  • gh-106895: Raise aValueError when a monitoring callback functionreturnsDISABLE for events that cannot be disabled locally.

  • gh-106897: Add aRERAISE event tosys.monitoring, which occurswhen an exception is reraise, either explicitly by a plainraisestatement, or implicitly in anexcept orfinally block.

  • gh-77377: Ensure that multiprocessing synchronization objects created in afork context are not sent to a different process created in a spawncontext. This changes a segfault into an actionable RuntimeError in theparent process.

  • gh-106931: Statically allocated string objects are now interned globallyinstead of per-interpreter. This fixes a situation where such a stringwould only be interned in a single interpreter. Normal string objects areunaffected.

  • gh-104621: Unsupported modules now always fail to be imported.

  • gh-107122: Adddbm.ndbm.ndbm.clear() todbm.ndbm. Patch ByDonghee Na.

  • gh-107122: Adddbm.gnu.gdbm.clear() todbm.gnu. Patch ByDonghee Na.

  • gh-107015: The ASYNC and AWAIT tokens are removed from the Grammar, whichremoves the possibility of makingasync andawait soft keywordswhen usingfeature_version<7 inast.parse().

  • gh-106917: Fix classmethod-stylesuper() method calls (i.e., wherethe second argument tosuper(), or the implied second argument drawnfromself/cls in the case of zero-arg super, is a type) when thetarget of the call is not a classmethod.

  • gh-105699: Python no longer crashes due an infrequent race wheninitializing per-interpreter interned strings. The crash would manifestwhen the interpreter was finalized.

  • gh-105699: Python no longer crashes due to an infrequent race in settingPy_FileSystemDefaultEncoding andPy_FileSystemDefaultEncodeErrors(both deprecated), when simultaneously initializing two isolatedsubinterpreters. Now they are only set during runtime initialization.

  • gh-106908: Fix various hangs, reference leaks, test failures, andtracing/introspection bugs when running withPYTHONUOPS or-Xuops enabled.

  • gh-106092: Fix a segmentation fault caused by a use-after-free bug inframe_dealloc when the trashcan delays the deallocation of aPyFrameObject.

  • gh-106485: Reduce the number of materialized instances dictionaries bydematerializing them when possible.

  • gh-106719: No longer suppress arbitrary errors in the__annotations__getter and setter in the type and module types.

  • gh-106723: Propagatefrozen_modules to multiprocessing spawned processinterpreters.

  • gh-104909: SplitLOAD_ATTR_INSTANCE_VALUE into micro-ops.

  • gh-104909: SplitLOAD_GLOBAL specializations into micro-ops.

  • gh-106597: A new debug structure of offsets has been added to the_PyRuntimeState that will help out-of-process debuggers and profilersto obtain the offsets to relevant interpreter structures in a way that isagnostic of how Python was compiled and that doesn't require copying theheaders. Patch by Pablo Galindo

  • gh-106487: Allow thecount argument ofstr.replace() to be akeyword. Patch by Hugo van Kemenade.

  • gh-96844: Improve error message oflist.remove(). Patch by DongheeNa.

  • gh-81283: Compiler now strips indents from docstrings. It reducespycfile size 5% when the module is heavily documented. This change affects to__doc__ so tools like doctest will be affected.

  • gh-106396: When the format specification of an f-string expression isempty, the parser now generates an emptyast.JoinedStr node forit instead of an one-elementast.JoinedStr with an empty stringast.Constant.

  • gh-100288: SpecializeLOAD_ATTR for non-descriptors on theclass. AddsLOAD_ATTR_NONDESCRIPTOR_WITH_VALUES andLOAD_ATTR_NONDESCRIPTOR_NO_DICT.

  • gh-106008: Fix possible reference leaks when failing to optimizecomparisons withNone in the bytecode compiler.

  • gh-106145: Makeend_lineno andend_col_offset required ontype_param ast nodes.

  • gh-106213: Changed the way that Emscripten call trampolines work forcompatibility with Wasm/JS Promise integration.

  • gh-106182:sys.getfilesystemencoding() andsys.getfilesystemencodeerrors now return interned Unicode object.

  • gh-106210: Removed Emscripten import trampoline as it was no longernecessary for Pyodide.

  • gh-104584: Added a new, experimental, tracing optimizer and interpreter(a.k.a. "tier 2"). This currently pessimizes, so don't use yet -- this isinfrastructure so we can experiment with optimizing passes. To enable it,pass-Xuops or setPYTHONUOPS=1. To get debug output, setPYTHONUOPSDEBUG=N whereN is a debug level (0-4, where 0 is nodebug output and 4 is excessively verbose).

  • gh-105775:LOAD_CLOSURE is now a pseudo-op.

  • gh-105730: Allow any callable other than type objects as the conditionpredicate inBaseExceptionGroup.split() andBaseExceptionGroup.subgroup().

  • gh-105979: Fix crash in_imp.get_frozen_object() due to improperexception handling.

  • gh-106003: Add a newTO_BOOL instruction, which performs booleanconversions forPOP_JUMP_IF_TRUE,POP_JUMP_IF_FALSE,andUNARY_NOT (which all expect exactbool values now).Also, modify the oparg ofCOMPARE_OP to include an optional"boolean conversion" flag.

  • gh-98931: Ensure customSyntaxError error messages are raised forinvalid imports with multiple targets. Patch by Pablo Galindo

  • gh-105724: Improveassert error messages by providing exact errorrange.

  • gh-105908: Fixed bug wheregh-99111 breaks future importbarry_as_FLUFL in the Python REPL.

  • gh-105840: Fix possible crashes when specializing function calls with toomany__defaults__.

  • gh-105831: Fix an f-string bug, where using a debug expression (the=sign) that appears in the last line of a file results to the debug bufferthat holds the expression text being one character too small.

  • gh-105800: Correctly issueSyntaxWarning in f-strings if invalidsequences are used. Patch by Pablo Galindo

  • gh-105340: Include the comprehension iteration variable inlocals()inside a module- or class-scope comprehension.

  • gh-105331: RaiseValueError if thedelay argument toasyncio.sleep() is a NaN (matchingtime.sleep()).

  • gh-105587: The runtime can't guarantee that immortal objects will not bemutated by Extensions. Thus, this modifies _PyStaticObject_CheckRefcnt towarn instead of asserting.

  • gh-105564: Don't include artificil newlines in theline attribute oftokens in the APIs of thetokenize module. Patch by Pablo Galindo

  • gh-105549: Tokenize separatelyNUMBER andNAME tokens that are notambiguous. Patch by Pablo Galindo.

  • gh-105588: Fix an issue that could result in crashes when compilingmalformedast nodes.

  • gh-100987: Allow objects other than code objects as the "executable" ininternal frames. In the long term, this can help tools like Cython andPySpy interact more efficiently. In the shorter term, it allows us toperform some optimizations more simply.

  • gh-105375: Fix bugs in thebuiltins module where exceptions couldend up being overwritten.

  • gh-105375: Fix bug in the compiler where an exception could end up beingoverwritten.

  • gh-105375: Improve error handling inPyUnicode_BuildEncodingMap()where an exception could end up being overwritten.

  • gh-105486: Change the repr ofParamSpec list of args intypes.GenericAlias.

  • gh-105678: Break theMAKE_FUNCTION instruction into two parts,MAKE_FUNCTION which makes the function andSET_FUNCTION_ATTRIBUTEwhich sets the attributes on the function. This makes the stack effect ofMAKE_FUNCTION regular to ease optimization and code generation.

  • gh-105435: Fix spurious newline character if file ends on a commentwithout a newline. Patch by Pablo Galindo

  • gh-105390: Correctly raisetokenize.TokenError exceptions insteadofSyntaxError for tokenize errors such as incomplete input. Patchby Pablo Galindo

  • gh-105259: Don't include newline character for trailingNEWLINE tokensemitted in thetokenize module. Patch by Pablo Galindo

  • gh-104635: Eliminate redundantSTORE_FAST instructions in thecompiler. Patch by Donghee Na and Carl Meyer.

  • gh-105324: Fix the main function of thetokenize module whenreading fromsys.stdin. Patch by Pablo Galindo

  • gh-33092: Simplify and speed up interpreter for f-strings. RemovesFORMAT_VALUE opcode. AddCONVERT_VALUE,FORMAT_SIMPLE andFORMAT_WITH_SPEC opcode. Compiler emits more efficient sequence foreach format expression.

  • gh-105229: Remove remaining two-codeunit superinstructions. All remainingsuperinstructions only take a single codeunit, simplifying instrumentationand quickening.

  • gh-105235: Prevent out-of-bounds memory access duringmmap.find()calls.

  • gh-98963: Restore the ability for a subclass ofproperty todefine__slots__ or otherwise be dict-less by ignoring failures to seta docstring on such a class. This behavior had regressed in 3.12beta1.AnAttributeError where there had not previously been one wasdisruptive to existing code.

  • gh-104812: The "pending call" machinery now works for all interpreters,not just the main interpreter, and runs in all threads, not just the mainthread. Some calls are still only done in the main thread, ergo in themain interpreter. This change does not affect signal handling nor theexisting public C-API (Py_AddPendingCall()), which both still onlytarget the main thread. The new functionality is meant strictly forinternal use for now, since consequences of its use are not wellunderstood yet outside some very restricted cases. This change brings thecapability in line with the intention when the state was madeper-interpreter several years ago.

  • gh-105194: Do not escape with backslashes f-string format specifiers.Patch by Pablo Galindo

  • gh-105229: Replace some dynamic superinstructions with single instructionequivalents.

  • gh-105162: Fixed bug in generator.close()/throw() where an inner iteratorwould be ignored when the outer iterator was instrumented.

  • gh-105164: Ensure annotations are set up correctly if the only annotationin a block is within amatch block. Patch by Jelle Zijlstra.

  • gh-105148: Make_PyASTOptimizeState internal to ast_opt.c. Make_PyAST_Optimize take two integers instead of a pointer to this struct.This avoids the need to include pycore_compile.h in ast_opt.c.

  • gh-104799: Attributes ofast nodes that are lists now default tothe empty list if omitted. This means that some code that previouslyraisedTypeError when the AST node was used will now proceed withthe empty list instead. Patch by Jelle Zijlstra.

  • gh-105111: Remove the old trashcan macrosPy_TRASHCAN_SAFE_BEGIN andPy_TRASHCAN_SAFE_END. They should be replaced by the new macrosPy_TRASHCAN_BEGIN andPy_TRASHCAN_END.

  • gh-105035: Fixsuper() calls on types with customtp_getattro implementation (e.g. meta-types.)

  • gh-105017: Show CRLF lines in the tokenize string attribute in both NL andNEWLINE tokens. Patch by Marta Gómez.

  • gh-105013: Fix handling of multiline parenthesized lambdas ininspect.getsource(). Patch by Pablo Galindo

  • gh-105017: Do not include an additional finalNL token when parsingfiles having CRLF lines. Patch by Marta Gómez.

  • gh-104976: Ensure that trailingDEDENTtokenize.TokenInfoobjects emitted by thetokenize module are reported as in Python3.11. Patch by Pablo Galindo

  • gh-104972: Ensure that theline attribute intokenize.TokenInfo objects in thetokenize module arealways correct. Patch by Pablo Galindo

  • gh-104955: Fix signature for the new__release_buffer__()slot. Patch by Jelle Zijlstra.

  • gh-104690: Starting new threads and process creation throughos.fork() during interpreter shutdown (such as fromatexithandlers) is no longer supported. It can lead to race condition betweenthe main Python runtime thread freeing thread states while internalthreading routines are trying to allocate and use the state of justcreated threads. Or forked children trying to use the mid-shutdown runtimeand thread state in the child process.

  • gh-104879: Fix crash when accessing the__module__ attribute of typealiases defined outside a module. Patch by Jelle Zijlstra.

  • gh-104825: Tokens emitted by thetokenize module do not include animplicit\n character in theline attribute anymore. Patch byPablo Galindo

  • gh-104770: If a generator returns a value upon being closed, the value isnow returned bygenerator.close().

  • gh-89091: RaiseRuntimeWarning for unawaited async generatormethods likeasend(),athrow() andaclose(). Patch by Kumar Aditya.

  • gh-96663: Add a better, more introspect-able error message when settingattributes on classes without a__dict__ and no slot member for theattribute.

  • gh-93627: Update the Python pickle module implementation to match the Cimplementation of the pickle module. For objects setting reduction methodslike__reduce_ex__() or__reduce__() toNone, pickling will result in aTypeError.

  • gh-101006: Improve error handling when readmarshal data.

  • gh-91095: Specializes calls to most Python classes. Specifically, anyclass that inherits fromobject, or another Python class, and does notoverride__new__.

    The specialized instruction does the following:

    1. Creates the object (by callingobject.__new__)

    2. Pushes a shim frame to the frame stack (to cleanup after__init__)

    3. Pushes the frame for__init__ to the frame stack

    Speeds up the instantiation of most Python classes.

Library

  • gh-110786:sysconfig's CLI now ignoresBrokenPipeError,making it exit normally if its output is being piped and the pipe closes.

  • gh-103480: Thesysconfig module is now a package, instead of asingle-file module.

  • gh-110733: Micro-optimization: Avoid callingmin(),max() inBaseEventLoop._run_once().

  • gh-94597: Addedasyncio.EventLoop for use with theasyncio.run()loop_factory kwarg to avoid calling the asynciopolicy system.

  • gh-110682:runtime-checkableprotocolsused to consider__match_args__ a protocol member in__instancecheck__ if it was present on the protocol. Now, thisattribute is ignored if it is present.

  • gh-110488: Fix a couple of issues inpathlib.PurePath.with_name(): asingle dot was incorrectly considered a valid name, and inPureWindowsPath, a name with an NTFS alternate data stream, likea:b, was incorrectly considered invalid.

  • gh-110590: Fix a bug in_sre.compile() whereTypeError wouldbe overwritten byOverflowError when thecode argument was a listof non-ints.

  • gh-65052: Preventpdb from crashing when trying to displayundisplayable objects

  • gh-110519: Deprecation warning about non-integer number ingettextnow always refers to the line in the user code where gettext function ormethod is used. Previously it could refer to a line ingettext code.

  • gh-89902: Deprecate non-standard format specifier "N" fordecimal.Decimal. It was not documented and only supported in theC implementation.

  • gh-110378:contextmanager() andasynccontextmanager() context managers now close aninvalid underlying generator object that yields more then one value.

  • gh-106670: Inpdb, set convenience variable$_exception forpost mortem debugging.

  • gh-110365: Fixtermios.tcsetattr() bug that was overwriting existingerrors during parsing integers fromterm list.

  • gh-109653: Slightly improve the import time of several standard-librarymodules by deferring imports ofwarnings within those modules.Patch by Alex Waygood.

  • gh-110273:dataclasses.replace() now raises TypeError instead ofValueError if specify keyword argument for a field declared withinit=False or miss keyword argument for required InitVar field.

  • gh-110249: Add--inline-caches flag todis command line.

  • gh-109653: Fix a Python 3.12 regression in the import time ofrandom. Patch by Alex Waygood.

  • gh-110222: Add support of struct sequence objects incopy.replace().Patched by Xuehai Pan.

  • gh-109649:multiprocessing,concurrent.futures,compileall: Replaceos.cpu_count() withos.process_cpu_count() to select the default number of workerthreads and processes. Get the CPU affinity if supported. Patch by VictorStinner.

  • gh-110150: Fix base case handling in statistics.quantiles. Now allows asingle data point.

  • gh-110036: On Windows, multiprocessingPopen.terminate() now catchesPermissionError and get the process exit code. If the process isstill running, raise again thePermissionError. Otherwise, theprocess terminated as expected: store its exit code. Patch by VictorStinner.

  • gh-110038: Fixed an issue that causedKqueueSelector.select() to notreturn all the ready events in some cases when a file descriptor isregistered for both read and write.

  • gh-110045: Update thesymtable module to support the new scopesintroduced byPEP 695.

  • gh-88402: Add new variables tosysconfig.get_config_vars() onWindows:LIBRARY,LDLIBRARY,LIBDIR,SOABI, andPy_NOGIL.

  • gh-109631:re functions such asre.findall(),re.split(),re.search() andre.sub() which perform shortrepeated matches can now be interrupted by user.

  • gh-109653: Reduce the import time ofemail.utils by around 43%.This results in the import time ofemail.message falling by around18%, which in turn reduces the import time ofimportlib.metadata byaround 6%. Patch by Alex Waygood.

  • gh-109818: Fixreprlib.recursive_repr() not copying__type_params__ from decorated function.

  • gh-109047:concurrent.futures: Theexecutor manager thread nowcatches exceptions when adding an item to thecall queue. During Pythonfinalization, creating a new thread can now raiseRuntimeError.Catch the exception and callterminate_broken() in this case. Patch byVictor Stinner.

  • gh-109782: Ensure the signature ofos.path.isdir() is identical onall platforms. Patch by Amin Alaee.

  • gh-109653: Improve import time offunctools by around 13%. Patch byAlex Waygood.

  • gh-109590:shutil.which() will prefer files with an extension inPATHEXT if the given mode includesos.X_OK on win32. If noPATHEXT match is found, a file without an extension inPATHEXT canbe returned. This change will haveshutil.which() act more similarlyto previous behavior in Python 3.11.

  • gh-109653: Reduce the import time ofenum by over 50%. Patch byAlex Waygood.

  • gh-109593: Avoid deadlocking on a reentrant call to the multiprocessingresource tracker. Such a reentrant call, though unlikely, can happen if aGC pass invokes the finalizer for a multiprocessing object such asSemLock.

  • gh-109653: Reduce the import time oftyping by around a third.Patch by Alex Waygood.

  • gh-109649: Addos.process_cpu_count() function to get the number oflogical CPUs usable by the calling thread of the current process. Patch byVictor Stinner.

  • gh-74481: Addset_error_mode related constants inmsvcrt module inPython debug build.

  • gh-109613: Fixos.stat() andos.DirEntry.stat(): check forexceptions. Previously, on Python built in debug mode, these functionscould trigger a fatal Python error (and abort the process) when a functionsucceeded with an exception set. Patch by Victor Stinner.

  • gh-109599: Expose the type of PyCapsule objects astypes.CapsuleType.

  • gh-109109: You can now get the raw TLS certificate chains from TLSconnections viassl.SSLSocket.get_verified_chain() andssl.SSLSocket.get_unverified_chain() methods.

    Contributed by Mateusz Nowak.

  • gh-109559: Updateunicodedata database to Unicode 15.1.0.

  • gh-109543: Remove unnecessaryhasattr() check duringtyping.TypedDict creation.

  • gh-109495: Remove unnecessary extra__slots__ indatetime's pure python implementation to reduce memorysize, as they are defined in the superclass. Patch by James Hilton-Balfe

  • gh-109461:logging: Use a context manager for lock acquisition.

  • gh-109096:http.server.CGIHTTPRequestHandler has been deprecatedfor removal in 3.15. Its design is old and the web world has long sincemoved beyond CGI.

  • gh-109409: Fix error when it was possible to inherit a frozen dataclassfrom multiple parents some of which were possibly not frozen.

  • gh-109375: Thepdbalias command now prevents registeringaliases without arguments.

  • gh-109319: Deprecate thedis.HAVE_ARGUMENT field in favour ofdis.hasarg.

  • gh-107219: Fix a race condition inconcurrent.futures. When a processin the process pool was terminated abruptly (while the future was runningor pending), close the connection write end. If the call queue is blockedon sending bytes to a worker process, closing the connection write endinterrupts the send, so the queue can be closed. Patch by Victor Stinner.

  • gh-66143: Thecodecs.CodecInfo object has been made copyable andpickleable. Patched by Robert Lehmann and Furkan Onder.

  • gh-109187:pathlib.Path.resolve() now treats symlink loops likeother errors: in strict mode,OSError is raised, and in non-strictmode, no exception is raised.

  • gh-50644: Attempts to pickle or create a shallow or deep copy ofcodecs streams now raise a TypeError. Previously, copying failedwith a RecursionError, while pickling produced wrong results thateventually caused unpickling to fail with a RecursionError.

  • gh-109174: Add support oftypes.SimpleNamespace incopy.replace().

  • gh-109164:pdb: Replacegetopt withargparse forparsing command line arguments.

  • gh-109151: Enablereadline editing features in thesqlite3command-line interface (python-msqlite3).

  • gh-108987: Fix_thread.start_new_thread() race condition. If athread is created during Python finalization, the newly spawned thread nowexits immediately instead of trying to access freed memory and lead to acrash. Patch by Victor Stinner.

  • gh-108682: Enum: requirenames=() ortype=... to create an emptyenum using the functional syntax.

  • gh-109033: Exceptions raised by os.utime builtin function now include therelated filename

  • gh-108843: Fix an issue inast.unparse() when unparsing f-stringscontaining many quote types.

  • gh-108469:ast.unparse() now supports newf-string syntaxintroduced in Python 3.12. Note that thef-string quotes arereselected for simplicity under the new syntax. (Patch by Steven Sun)

  • gh-108751: Addcopy.replace() function which allows to create amodified copy of an object. It supports named tuples, dataclasses, andmany other objects.

  • gh-108682: Enum: raiseTypeError ifsuper().__new__() is calledfrom a custom__new__.

  • gh-108278: Deprecate passing the callback callable by keyword for thefollowingsqlite3.Connection APIs:

    The affected parameters will become positional-only in Python 3.15.

    Patch by Erlend E. Aasland.

  • gh-105829: Fix concurrent.futures.ProcessPoolExecutor deadlock

  • gh-108295: Fix crashes related to use of weakrefs ontyping.TypeVar.

  • gh-108463: Make expressions/statements work as expected in pdb

  • gh-108277: Addos.timerfd_create(),os.timerfd_settime(),os.timerfd_gettime(),os.timerfd_settime_ns(), andos.timerfd_gettime_ns() to provide a low level interface for Linux'stimer notification file descriptor.

  • gh-107811:tarfile: extraction of members with overly large UID orGID (e.g. on an OS with 32-bitid_t) now fails in the same wayas failing to set the ID.

  • gh-64662: Fix support for virtual tables insqlite3.Connection.iterdump(). Patch by Aviv Palivoda.

  • gh-108111: Fix a regression introduced ingh-101251 for 3.12, resulting inan incorrect offset calculation ingzip.GzipFile.seek().

  • gh-108294:time.sleep() now raises an auditing event.

  • gh-108278: Deprecate passing name, number of arguments, and the callableas keyword arguments, for the followingsqlite3.Connection APIs:

    The affected parameters will become positional-only in Python 3.15.

    Patch by Erlend E. Aasland.

  • gh-108322: Speed-up NormalDist.samples() by using the inverse CDF methodinstead of calling random.gauss().

  • gh-83417: Add the ability for venv to create a.gitignore file whichcauses the created environment to be ignored by Git. It is on by defaultwhen venv is called via its CLI.

  • gh-105736: Harmonized the pure Python version ofOrderedDict with the C version. Now, both versionsset up their internal state in__new__. Formerly, the pure Pythonversion did the set up in__init__.

  • gh-108083: Fix bugs in the constructor ofsqlite3.Connection andsqlite3.Connection.close() where exceptions could be leaked. Patchby Erlend E. Aasland.

  • gh-107932: Fixdis module to properly report and display bytecode thatdo not have source lines.

  • gh-105539:sqlite3 now emits anResourceWarning if asqlite3.Connection object is notclosed explicitly. Patch by Erlend E. Aasland.

  • gh-107995: The__module__ attribute on instances offunctools.cached_property is now set to the name of the module inwhich the cached_property is defined, rather than "functools". This meansthat doctests incached_property docstrings are now properly collectedby thedoctest module. Patch by Tyler Smart.

  • gh-107963: Fixmultiprocessing.set_forkserver_preload() to check thegiven list of modules names. Patch by Donghee Na.

  • gh-106242: Fixesos.path.normpath() to handle embedded nullcharacters without truncating the path.

  • gh-81555:xml.dom.minidom now only quotes" in attributes.

  • gh-50002:xml.dom.minidom now preserves whitespaces in attributes.

  • gh-93057: Passing more than one positional argument tosqlite3.connect() and thesqlite3.Connection constructor isdeprecated. The remaining parameters will become keyword-only in Python3.15. Patch by Erlend E. Aasland.

  • gh-76913: Addmerge_extra parameter/feature tologging.LoggerAdapter

  • gh-107913: Fix possible losses oferrno andwinerror values inOSError exceptions if they were cleared or modified by the cleanupcode before creating the exception object.

  • gh-107845:tarfile.data_filter() now takes the location of symlinksinto account when determining their target, so it will no longer rejectsome valid tarballs withLinkOutsideDestinationError.

  • gh-107812: Extend socket's netlink support to the FreeBSD platform.

  • gh-107805: Fix signatures of module-level generated functions inturtle.

  • gh-107782:pydoc is now able to show signatures which are notrepresentable in Python, e.g. forgetattr anddict.pop.

  • gh-56166: Deprecate passing optional argumentsmaxsplit,count andflags in module-level functionsre.split(),re.sub() andre.subn() as positional. They should only be passed by keyword.

  • gh-107710: Speed uplogging.getHandlerNames().

  • gh-107715: Fixdoctest.DocTestFinder.find() in presence of classnames with special characters. Patch by Gertjan van Zwieten.

  • gh-100814: Passing a callable object as an option value to a Tkinter imagenow raises the expected TclError instead of an AttributeError.

  • gh-72684: Addtkinter widget methods:tk_busy_hold(),tk_busy_configure(),tk_busy_cget(),tk_busy_forget(),tk_busy_current(), andtk_busy_status().

  • gh-106684: RaiseResourceWarning whenasyncio.StreamWriteris not closed leading to memory leaks. Patch by Kumar Aditya.

  • gh-107465: Addpathlib.Path.from_uri() classmethod.

  • gh-107077: Seems that in some conditions, OpenSSL will returnSSL_ERROR_SYSCALL instead ofSSL_ERROR_SSL when a certificationverification has failed, but the error parameters will still containERR_LIB_SSL andSSL_R_CERTIFICATE_VERIFY_FAILED. We are nowdetecting this situation and raising the appropriatessl.SSLCertVerificationError. Patch by Pablo Galindo

  • gh-107576: Fixtypes.get_original_bases() to only return__orig_bases__ if it is present oncls directly. Patch byJames Hilton-Balfe.

  • gh-105481: Removeopcode.is_pseudo,opcode.MIN_PSEUDO_OPCODE andopcode.MAX_PSEUDO_OPCODE, which were added in 3.12, were neverdocumented and were not intended to be used externally.

  • gh-105481:opcode.ENABLE_SPECIALIZATION (which was added in 3.12but never documented or intended for external usage) is moved to_opcode.ENABLE_SPECIALIZATION where tests can access it.

  • gh-107396: tarfiles; Fixed use before assignment of self.exception forgzip decompression

  • gh-107409: Set__wrapped__ attribute inreprlib.recursive_repr().

  • gh-107406: Implement new__repr__() method forstruct.Struct. Now it returnsStruct(<formatrepr>).

  • gh-107369: Optimizetextwrap.indent(). It is ~30% faster for largeinput. Patch by Inada Naoki.

  • gh-78722: Fix issue wherepathlib.Path.iterdir() did not raiseOSError until iterated.

  • gh-105578: Deprecatetyping.AnyStr in favor of the new TypeParameter syntax. See PEP 695.

  • gh-62519: Makegettext.pgettext() search plural definitions whentranslation is not found.

  • gh-107089: Shelves opened withshelve.open() have a much fasterclear() method. Patch by James Cave.

  • gh-82500: Fix overflow on 32-bit systems withasyncioos.sendfile() implementation.

  • gh-83006: Document behavior ofshutil.disk_usage() for non-mountedfilesystems on Unix.

  • gh-65495: Use lowercasemailfrom andrcptto insmptlib.SMTP.

  • gh-106186: Do not reportMultipartInvariantViolationDefect defect whentheemail.parser.Parser class is used to parse emails withheadersonly=True.

  • gh-105002: Fix invalid result fromPurePath.relative_to() methodwhen attempting to walk a ".." segment inother withwalk_upenabled. AValueError exception is now raised in this case.

  • gh-106739: Add thertype_cache to the warning message (as an additionto the type of leaked objects and the number of leaked objects alreadyincluded in the message) to make debugging leaked objects easier when themultiprocessing resource tracker process finds leaked objects at shutdown.This helps more quickly identify what was leaked and/or why the leakedobject was not properly cleaned up.

  • gh-106751: OptimizeSelectSelector.select() for many iteration case.Patch By Donghee Na.

  • gh-106751: Optimize_PollLikeSelector.select() for many iterationcase.

  • gh-106751: OptimizeKqueueSelector.select() for many iteration case.Patch By Donghee Na.

  • gh-106831: Fix potential missingNULL check ofd2i_SSL_SESSIONresult in_ssl.c.

  • gh-105481: The various opcode lists in thedis module are nowgenerated from bytecodes.c instead of explicitly constructed in opcode.py.

  • gh-106727: Makeinspect.getsource() smarter for class for same namedefinitions

  • gh-106789: Remove import ofpprint fromsysconfig.

  • gh-105726: Added__slots__ tocontextlib.AbstractContextManager andcontextlib.AbstractAsyncContextManager so that child classes canuse__slots__.

  • gh-106774: Update the bundled copy of pip to version 23.2.1.

  • gh-106751:selectors: OptimizeEpollSelector.select() code bymoving some code outside of the loop.

  • gh-106752: Fixed several bugs in zipfile.Path, including: inzipfile.Path.match(), Windows separators are no longer honored (andnever were meant to be); Fixedname/suffix/suffixes/stemoperations when no filename is present and the Path is not at the root ofthe zipfile; Reworked glob for performance and more correct matchingbehavior.

  • gh-105293: Remove call toSSL_CTX_set_session_id_context during clientside context creation in thessl module.

  • gh-106734: Disable tab completion in multiline mode ofpdb

  • gh-105481: Expose opcode metadata through_opcode.

  • gh-106670: Add the newexceptions command to the Pdb debugger. Itmakes it possible to move between chained exceptions when using postmortem debugging.

  • gh-106602: Add __copy__ and __deepcopy__ inenum

  • gh-106664:selectors: Add_SelectorMapping.get() method andoptimize_SelectorMapping.__getitem__().

  • gh-106628: Speed up parsing of emails by about 20% by not compiling a newregular expression for every single email.

  • gh-89427: Set the environment variableVIRTUAL_ENV_PROMPT atvenv activation, even whenVIRTUAL_ENV_DISABLE_PROMPT is set.

  • gh-106530: Revert a change tocolorsys.rgb_to_hls() that causeddivision by zero for certain almost-white inputs. Patch by Terry JanReedy.

  • gh-106584: Fix exit code forunittest if all tests are skipped. Patchby Egor Eliseev.

  • gh-106566: Optimize(?!) (pattern which always fails) in regularexpressions.

  • gh-106554:selectors: Reduce Selector overhead by using adict.get() to lookup file descriptors.

  • gh-106558: Remove ref cycle in callers ofconvert_to_error() by deletingresultfrom scope in afinally block.

  • gh-100502: Addpathlib.PurePath.pathmod class attribute thatstores the implementation ofos.path used for low-level pathoperations: eitherposixpath orntpath.

  • gh-106527: Reduce overhead to add and removeasyncio readers andwriters.

  • gh-106524: Fix crash in_sre.template() with templates containinginvalid group indices.

  • gh-106531: Removed_legacy and the names it provided fromimportlib.resources:Resource,contents,is_resource,open_binary,open_text,path,read_binary, andread_text.

  • gh-106052:re module: fix the matching of possessive quantifiers inthe case of a subpattern containing backtracking.

  • gh-106510: Improve debug output for atomic groups in regular expressions.

  • gh-106503: Fix ref cycle inasyncio._SelectorSocketTransport byremoving_write_ready inclose.

  • gh-105497: Fix flag mask inversion when unnamed flags exist.

  • gh-90876: Preventmultiprocessing.spawn from failing toimport inenvironments wheresys.executable isNone. This regressed in 3.11with the addition of support for path-like objects in multiprocessing.

  • gh-106403: Instances oftyping.TypeVar,typing.ParamSpec,typing.ParamSpecArgs,typing.ParamSpecKwargs, andtyping.TypeVarTuple onceagain support weak references, fixing a regression introduced in Python3.12.0 beta 1. Patch by Jelle Zijlstra.

  • gh-89812: Add privatepathlib._PathBase class, which providesexperimental support for virtual filesystems, and may be made public in afuture version of Python.

  • gh-106292: Check for an instance-dict cached value in the__get__()method offunctools.cached_property(). This better matches thepre-3.12 behavior and improves compatibility for users subclassingfunctools.cached_property() and adding a__set__() method.

  • gh-106350: Detect possible memory allocation failure in the libtommathfunctionmp_init() used by the_tkinter module.

  • gh-106330: Fix incorrect matching of empty paths inpathlib.PurePath.match(). This bug was introduced in Python 3.12.0beta 1.

  • gh-106309: Deprecatetyping.no_type_check_decorator(). No major typechecker ever added support for this decorator. Patch by Alex Waygood.

  • gh-102541: Makepydoc.doc() catch bad moduleImportError whenoutput stream is notNone.

  • gh-106263: Fix crash when callingrepr with a manually constructedSignalDict object. Patch by Charlie Zhao.

  • gh-106236: Replaceassert statements withraiseRuntimeError inthreading, so that_DummyThread cannot be joined even with-OO.

  • gh-106238: Fix rare concurrency bug in lock acquisition by the loggingpackage.

  • gh-106152: Added PY_THROW event hook forcProfile for generators

  • gh-106075: Addedasyncio.taskgroups.__all__ toasyncio.__all__ forexport in star imports.

  • gh-104527: Zipapp will now skip over appending an archive to itself.

  • gh-106046: Improve the error message fromos.fspath() if called onan object where__fspath__ is set toNone. Patch by Alex Waygood.

  • gh-105987: Fix crash due to improper reference counting inasyncioeager task factory internal routines.

  • gh-105974: Fix bug where atyping.Protocol class that had one ormore non-callable members would raiseTypeError whenissubclass() was called against it, even if it defined a custom__subclasshook__ method. The behaviour in Python 3.11 and lower --which has now been restored -- was not to raiseTypeError in thesesituations if a custom__subclasshook__ method was defined. Patch byAlex Waygood.

  • gh-96145: Reverted addition ofjson.AttrDict.

  • gh-89812: Addpathlib.UnsupportedOperation, which is raised insteadofNotImplementedError when a path operation isn't supported.

  • gh-105808: Fix a regression introduced ingh-101251 for 3.12, causinggzip.GzipFile.flush() to not flush the compressor (nor pass alongthezip_mode argument).

  • gh-105481:stack_effect() no longer raises an exception if anoparg is provided for anopcode that doesn't use its arg, or whenit is not provided for anopcode that does use it. In the latter case,the stack effect is returned foroparg=0.

  • gh-104799: Enableast.unparse() to unparse function and classdefinitions created without the newtype_params field fromPEP 695.Patch by Jelle Zijlstra.

  • gh-105793: Addfollow_symlinks keyword-only argument topathlib.Path.is_dir() andis_file(), defaultingtoTrue.

  • gh-105570: Deprecate two methods of creatingtyping.TypedDictclasses with 0 fields using the functional syntax:TD=TypedDict("TD") andTD=TypedDict("TD",None). Both will bedisallowed in Python 3.15. To create aTypedDict class with 0 fields,either useclassTD(TypedDict):pass orTD=TypedDict("TD",{}).

  • gh-105745: Fixwebbrowser.Konqueror.open method.

  • gh-105733:ctypes: Deprecate undocumentedctypes.SetPointerType() andctypes.ARRAY() functions. Patchby Victor Stinner.

  • gh-105687: Remove deprecatedre.template,re.T,re.TEMPLATE,sre_constans.SRE_FLAG_TEMPLATE.

  • gh-105684: Supportingasyncio.Task.set_name() is now mandatory forthird party task implementations. The undocumented_set_task_name()function (deprecated since 3.8) has been removed. Patch by Kumar Aditya.

  • gh-105375: Fix a bug in_Unpickler_SetInputStream() where anexception could end up being overwritten in case of failure.

  • gh-105626: Change the default return value ofhttp.client.HTTPConnection.get_proxy_response_headers() to beNone and not{}.

  • gh-105375: Fix bugs insys where exceptions could end up beingoverwritten because of deferred error handling.

  • gh-105605: Hardenpyexpat error handling during moduleinitialisation to prevent exceptions from possibly being overwritten, andobjects from being dereferenced twice.

  • gh-105375: Fix bug indecimal where an exception could end up beingoverwritten.

  • gh-105375: Fix bugs in_datetime where exceptions could beoverwritten in case of module initialisation failure.

  • gh-105375: Fix bugs in_ssl initialisation which could lead toleaked references and overwritten exceptions.

  • gh-105375: Fix a bug inarray.array where an exception could endup being overwritten.

  • gh-105375: Fix bugs in_ctypes where exceptions could end up beingoverwritten.

  • gh-105375: Fix a bug in theposix module where an exception couldbe overwritten.

  • gh-105375: Fix bugs in_elementtree where exceptions could beoverwritten.

  • gh-105375: Fix bugs inzoneinfo where exceptions could beoverwritten.

  • gh-105375: Fix bugs inerrno where exceptions could be overwritten.

  • gh-105566: Deprecate creating atyping.NamedTuple class usingkeyword arguments to denote the fields (NT=NamedTuple("NT",x=int,y=str)). This will be disallowed in Python 3.15. Use the class-basedsyntax or the functional syntax instead.

    Two methods of creatingNamedTuple classes with 0 fields using thefunctional syntax are also deprecated, and will be disallowed in Python3.15:NT=NamedTuple("NT") andNT=NamedTuple("NT",None). Tocreate aNamedTuple class with 0 fields, either useclassNT(NamedTuple):pass orNT=NamedTuple("NT",[]).

  • gh-105545: Remove deprecated in 3.11webbrowser.MacOSXOSAScript._nameattribute.

  • gh-105497: Fix flag inversion when alias/mask members exist.

  • gh-105509:typing.Annotated is now implemented as an instance oftyping._SpecialForm rather than a class. This should have nouser-facing impact for users of thetyping module public API.

  • gh-105375: Fix bugs inpickle where exceptions could beoverwritten.

  • gh-70303: EmitFutureWarning frompathlib.Path.glob() andrglob() if the given pattern ends with "**". In afuture Python release, patterns with this ending will match both files anddirectories. Add a trailing slash to only match directories.

  • gh-105375: Fix a bug insqlite3 where an exception could beoverwritten in thecollationcallback.

  • gh-105382: Removecafile,capath andcadefault parameters of theurllib.request.urlopen() function, deprecated in Python 3.6. Patchby Victor Stinner.

  • gh-105376:logging: Remove undocumented and untestedLogger.warn() andLoggerAdapter.warn() methods andlogging.warn() function. Deprecated since Python 3.3, they werealiases to thelogging.Logger.warning() method,logging.LoggerAdapter.warning() method andlogging.warning()function. Patch by Victor Stinner.

  • gh-105332: Revert pickling method from by-name back to by-value.

  • gh-104554: Add RTSPS scheme support in urllib.parse

  • gh-105292: Add option totraceback.format_exception_only() torecurse into the nested exception of aBaseExceptionGroup.

  • gh-105280: Fix bug whereisinstance([],collections.abc.Mapping) couldevaluate toTrue if garbage collection happened at the wrong time. Thebug was caused by changes to the implementation oftyping.Protocol in Python 3.12.

  • gh-80480:array: Add'w' typecode that representsPy_UCS4.

  • gh-105239: Fix longstanding bug whereissubclass(object,typing.Protocol) would evaluate toTrue in some edge cases. Patch byAlex Waygood.

  • gh-104310: In the beta 1 release we added a utility function for extensionmodule authors, to use when testing their module for support in multipleinterpreters or under a per-interpreter GIL. The name of that functionhas changed fromallowing_all_extensions to_incompatible_extension_module_restrictions. The default for the"disable_check" argument has change fromTrue toFalse, to bettermatch the new function name.

  • gh-105080: Fixed inconsistent signature on derived classes forinspect.signature()

  • gh-105144: Fix a recent regression in thetyping module. Theregression meant that doingclassFoo(X,typing.Protocol), whereXwas a class that hadabc.ABCMeta as its metaclass, would thencause subsequentisinstance(1,X) calls to erroneously raiseTypeError. Patch by Alex Waygood.

  • gh-62948: Theio.IOBase finalizer now logs theclose() methoderrors withsys.unraisablehook. Previously, errors were ignoredsilently by default, and only logged inPython Development Mode or onPython built on debug mode. Patchby Victor Stinner.

  • gh-105096:wave: Deprecate thegetmark(),setmark() andgetmarkers() methods of thewave.Wave_read andwave.Wave_write classes. They will be removed in Python 3.15.Patch by Victor Stinner.

  • gh-104992: Remove the untested and undocumentedunittest.TestProgram.usageExit() method, deprecated in Python 3.11.Patch by Hugo van Kemenade.

  • gh-104996: Improve performance ofpathlib.PurePath initialisationby deferring joining of paths when multiple arguments are given.

  • gh-101588: Deprecate undocumented copy/deepcopy/pickle support foritertools.

  • gh-103631: Fixpathlib.PurePosixPath(pathlib.PureWindowsPath(...)) notconverting path separators to restore 3.11 compatible behavior.

  • gh-104947: Make comparisons betweenpathlib.PureWindowsPathobjects consistent across Windows and Posix to match 3.11 behavior.

  • gh-104773:PEP 594: Remove theaudioop module, deprecated inPython 3.11. Patch by Victor Stinner.

  • gh-104773:PEP 594: Remove theaifc module, deprecated inPython 3.11. Patch by Victor Stinner.

  • gh-104773:PEP 594: Remove theuu module, deprecated in Python3.11. Patch by Victor Stinner.

  • gh-104935: Fix bugs with the interaction betweentyping.runtime_checkable() andtyping.Generic that wereintroduced by thePEP 695 implementation. Patch by Jelle Zijlstra.

  • gh-104773:PEP 594: Remove thecrypt module and its private_crypt extension, deprecated in Python 3.11. Patch by VictorStinner.

  • gh-104773:PEP 594: Remove thenis module, deprecated in Python3.11. Patch by Victor Stinner.

  • gh-104898: Add missing__slots__ toos.PathLike.

  • gh-104773:PEP 594: Remove thexdrlib module, deprecated inPython 3.11. Patch by Victor Stinner.

  • gh-104773:PEP 594: Remove thenntplib module, deprecated inPython 3.11. Patch by Victor Stinner.

  • gh-104886: Remove the undocumentedconfigparser.LegacyInterpolation class, deprecated in thedocstring since Python 3.2, and with a deprecation warning since Python3.11. Patch by Hugo van Kemenade.

  • gh-104786: Remove kwargs-basedtyping.TypedDict creation

  • gh-104876: Remove theturtle.RawTurtle.settiltangle() method,deprecated in docs since Python 3.1 and with a deprecation warning sincePython 3.11. Patch by Hugo van Kemenade.

  • gh-104773:PEP 594: Removed themsilib package, deprecated inPython 3.11.

  • gh-104773:PEP 594: Remove thespwd module, deprecated inPython 3.11: thepython-pam project can be used instead. Patch byVictor Stinner.

  • gh-75552: Removed thetkinter.tix module, deprecated since Python 3.6.

  • gh-104773:PEP 594: Remove thechunk module, deprecated inPython 3.11. Patch by Victor Stinner.

  • gh-104773:PEP 594: Remove themailcap module, deprecated inPython 3.11. Patch by Victor Stinner.

  • gh-104773:PEP 594: Remove thesunau module, deprecated inPython 3.11. Patch by Victor Stinner.

  • gh-104780:PEP 594: Remove theossaudiodev module, deprecatedin Python 3.11. Patch Victor Stinner.

  • gh-104773:PEP 594: Remove thepipes module, deprecated inPython 3.11. Patch by Victor Stinner.

  • gh-104873: Addtyping.get_protocol_members() to return the set ofmembers defining atyping.Protocol. Addtyping.is_protocol() to check whether a class is atyping.Protocol. Patch by Jelle Zijlstra.

  • gh-104874: Document the__name__ and__supertype__ attributes oftyping.NewType. Patch by Jelle Zijlstra.

  • gh-104835: Removed the followingunittest functions, deprecated inPython 3.11:

    • unittest.findTestCases()

    • unittest.makeSuite()

    • unittest.getTestCaseNames()

    UseTestLoader methods instead:

    Patch by Hugo van Kemenade.

  • gh-104804: Remove the untested and undocumentedwebbrowserMacOSX class, deprecated in Python 3.11. Patch by Hugo vanKemenade.

  • gh-83863: Support for usingpathlib.Path objects as contextmanagers has been removed. Before Python 3.9, exiting the context managermarked a path as "closed", which caused some (but not all!) methods toraise when called. Since Python 3.9, using a path as a context managerdoes nothing.

  • gh-104799: Adjust the location of the (seePEP 695)type_paramsfield onast.ClassDef,ast.AsyncFunctionDef, andast.FunctionDef to better preserve backward compatibility. Patchby Jelle Zijlstra

  • gh-104797: Allowtyping.Protocol classes to inherit fromcollections.abc.Buffer. Patch by Jelle Zijlstra.

  • gh-104783: Removelocale.resetlocale() function deprecated in Python3.11. Patch by Victor Stinner.

  • gh-104780: Remove the2to3 program and thelib2to3 module,deprecated in Python 3.11. Patch by Victor Stinner.

  • gh-104773:PEP 594: Remove thetelnetlib module, deprecated inPython 3.11. Patch by Victor Stinner.

  • gh-104773:PEP 594: Remove theimghdr module, deprecated inPython 3.11. Patch by Victor Stinner.

  • gh-104773:PEP 594: Remove thecgi andcgitb modules,deprecated in Python 3.11. Patch by Victor Stinner.

  • gh-104773:PEP 594: Remove thesndhdr module, deprecated inPython 3.11. Patch by Victor Stinner.

  • gh-104372: On Linux wheresubprocess can use thevfork()syscall for faster spawning, prevent the parent process from blockingother threads by dropping the GIL while it waits for the vfork'ed childprocessexec() outcome. This prevents spawning a binary from a slowfilesystem from blocking the rest of the application.

  • gh-99108: We now release the GIL around built-inhashlibcomputations of reasonable size for the SHA families and MD5 hashfunctions, matching what our OpenSSL backed hash computations alreadydoes.

  • gh-102613: Improve performance ofpathlib.Path.glob() when expandinga pattern with a non-terminal "**" component by filtering walked pathsthrough a regular expression, rather than callingos.scandir() morethan once on each directory.

  • gh-104399: Prepare the_tkinter module for building with Tcl 9.0 andfuture libtommath by replacing usage of deprecated functionsmp_to_unsigned_bin_n() andmp_unsigned_bin_size() whennecessary.

  • gh-102676: Add fieldsstart_offset,cache_offset,end_offset,baseopname,baseopcode,jump_target andoparg todis.Instruction.

  • gh-103558: Fixedparent argument validation mechanism ofargparse. Improved test coverage.

  • gh-103464: Provide helpful usage messages when parsing incorrectpdb commands.

  • gh-103384: Generalize the regex patternBaseConfigurator.INDEX_PATTERNto allow spaces and non-alphanumeric characters in keys.

  • gh-103124: Added multiline statement support forpdb

  • gh-101162: Forbid usingbuiltins.issubclass() withtypes.GenericAlias as the first argument.

  • gh-103200: Fix cache repopulation semantics ofzipimport.invalidate_caches(). The cache is now repopulated uponretrieving files with an invalid cache, not when the cache is invalidated.

  • gh-100061: Fix a bug that causes wrong matches for regular expressionswith possessive qualifier.

  • gh-77609: Addfollow_symlinks argument topathlib.Path.glob() andrglob(), defaulting to false.

  • gh-102541: Hide traceback inhelp() prompt, when import failed.

  • gh-102120: Added a stream mode totarfile that allows for readingarchives without caching info about the inner files.

  • gh-102029: Deprecate passing any arguments tothreading.RLock().

  • gh-88233: Refactoredzipfile._strip_extra to use higher levelabstractions for extras instead of a heavy-state loop.

  • gh-102024: Reduce calls of_idle_semaphore.release() inconcurrent.futures.thread._worker().

  • gh-73435: Add support for recursive wildcards inpathlib.PurePath.match().

  • gh-84867:unittest.TestLoader no longer loads test cases fromexactunittest.TestCase andunittest.FunctionTestCaseclasses.

  • gh-99203: Restore following CPython <= 3.10.5 behavior ofshutil.make_archive(): do not create an empty archive ifroot_dir is not a directory, and, in that case, raiseFileNotFoundError orNotADirectoryError regardless offormat choice. Beyond the brought-back behavior, the function may nowalso raise these exceptions indry_run mode.

  • gh-80480: EmitDeprecationWarning forarray's'u' typecode, deprecated in docs since Python 3.3.

  • gh-94924:unittest.mock.create_autospec() now properly returnscoroutine functions compatible withinspect.iscoroutinefunction()

  • gh-94777: Fix hangingmultiprocessingProcessPoolExecutor whena child process crashes while data is being written in the call queue.

  • gh-92871: Remove thetyping.io andtyping.re namespaces,deprecated since Python 3.8. All items are still available from the maintyping module.

  • bpo-43633: Improve the textual representation of IPv4-mapped IPv6addresses (RFC 4291 Sections 2.2, 2.5.5.2) inipaddress. Patchby Oleksandr Pavliuk.

  • bpo-44850: Improve performance ofoperator.methodcaller() using thePEP 590vectorcall convention. Patch by Anthony Lee and PieterEendebak.

  • bpo-44185:unittest.mock.mock_open() will call theclose()method of the file handle mock when it is exiting from the contextmanager. Patch by Samet Yaslan.

  • bpo-40988: Improve performance offunctools.singledispatchmethodby caching the generated dispatch wrapper. Optimization suggested byfrederico. Patch by @mental32, Alex Waygood and Pieter Eendebak.

  • bpo-41768:unittest.mock speccing no longer calls class properties.Patch by Melanie Witt.

  • bpo-18319: Ensuregettext(msg) retrieve translations even if a pluralform exists. In other words:gettext(msg)==ngettext(msg,'',1).

  • bpo-17013: AddThreadingMock tounittest.mock that can be usedto create Mock objects that can wait until they are called. Patch byKarthikeyan Singaravelan and Mario Corchero.

Documentation

Tests

  • gh-110647: Fix test_stress_modifying_handlers() of test_signal. Patch byVictor Stinner.

  • gh-103053: Fix test_tools.test_freeze on FreeBSD: run "make distclean"instead of "make clean" in the copied source directory to remove also the"python" program. Patch by Victor Stinner.

  • gh-110167: Fix a deadlock in test_socket when server fails with a timeoutbut the client is still running in its thread. Don't hold a lock to callcleanup functions in doCleanups(). One of the cleanup function waits untilthe client completes, whereas the client could deadlock if it calledaddCleanup() in such situation. Patch by Victor Stinner.

  • gh-110388: Add tests fortty.

  • gh-81002: Add tests fortermios.

  • gh-110367: regrtest: When using worker processes (-jN) with --verbose3option, regrtest can now display the worker output even if a workerprocess does crash. Previously, sys.stdout and sys.stderr were replacedand so the worker output was lost on a crash. Patch by Victor Stinner.

  • gh-110267: Add tests for pickling and copying PyStructSequence objects.Patched by Xuehai Pan.

  • gh-110171:libregrtest now always sets and showsrandom.seed, sotests are more reproducible. Use--randseed flag to pass the explicitrandom seed for tests.

  • gh-110152: RemoveTools/scripts/run_tests.py andmakehostrunnertest. Just run./python-mtest--slow-ci,makebuildbottest ormaketest instead. Python test runner (regrtest) nowhandles cross-compilation and HOSTRUNNER. It also adds options to Pythonsuch fast-u-E-Wdefault-bb when--fast-ci or--slow-cioption is used. Patch by Victor Stinner.

  • gh-110031: Skip test_threading tests using thread+fork if Python is builtwith Address Sanitizer (ASAN). Patch by Victor Stinner.

  • gh-110088: Fix test_asyncio timeouts: don't measure the maximum duration,a test should not measure a CI performance. Only measure the minimumduration when a task has a timeout or delay. AddCLOCK_RES totest_asyncio.utils. Patch by Victor Stinner.

  • gh-109974: Fix race conditions in test_threading lock tests. Wait until acondition is met rather than usingtime.sleep() with a hardcodednumber of seconds. Patch by Victor Stinner.

  • gh-110033: Fixtest_interprocess_signal() oftest_signal. Makesure that thesubprocess.Popen object is deleted before the testraising an exception in a signal handler. Otherwise,Popen.__del__()can get the exception which is logged asExceptionignoredin:... andthe test fails. Patch by Victor Stinner.

  • gh-109594: Fix test_timeout() of test_concurrent_futures.test_wait. Removethe future which may or may not complete depending if it takes longer thanthe timeout or not. Keep the second future which does not complete beforewait() timeout. Patch by Victor Stinner.

  • gh-109972: Split test_gdb.py file into a test_gdb package made of multipletests, so tests can now be run in parallel. Patch by Victor Stinner.

  • gh-109566: regrtest: When--fast-ci or--slow-ci option is used,regrtest now replaces the current process with a new process to add-u-Wdefault-bb-E options to Python. Patch by Victor Stinner.

  • gh-109748: Fixtest_zippath_from_non_installed_posix() of test_venv:don't copy__pycache__/ sub-directories, because they can be modifiedby other Python tests running in parallel. Patch by Victor Stinner.

  • gh-109739: regrtest: Fix reference leak check on Windows. Disable the loadtracker on Windows in the reference leak check mode (-R option). Patch byVictor Stinner.

  • gh-109276: regrtest: When a test fails with "env changed" and the --rerunoption is used, the test is now re-run in verbose mode in a fresh process.Patch by Victor Stinner.

  • gh-103053: Skip test_freeze_simple_script() of test_tools.test_freeze ifPython is built with./configure--enable-optimizations, which meanswith Profile Guided Optimization (PGO): it just makes the test too slow.The freeze tool is tested by many other CIs with other (faster) compilerflags. Patch by Victor Stinner.

  • gh-109580: Skiptest_perf_profiler if Python is built with ASAN, MSANor UBSAN sanitizer. Python does crash randomly in this test on such build.Patch by Victor Stinner.

  • gh-109566: regrtest: Add--fast-ci and--slow-ci options.--fast-ci uses a default timeout of 10 minutes and-uall,-cpu(skip slowest tests).--slow-ci uses a default timeout of 20 minutesand-uall (run all tests). Patch by Victor Stinner.

  • gh-109425: libregrtest now decodes stdout of test worker processes withthe "backslashreplace" error handler to log corrupted stdout, instead offailing with an error and not logging the stdout. Patch by Victor Stinner.

  • gh-109396: Fixtest_socket.test_hmac_sha1() in FIPS mode. Use a longerkey: FIPS mode requires at least of at least 112 bits. The previous keywas only 32 bits. Patch by Victor Stinner.

  • gh-104736: Fix test_gdb on Python built with LLVM clang 16 on Linuxppc64le (ex: Fedora 38). Search patterns in gdb "bt" command output todetect when gdb fails to retrieve the traceback. For example, skip a testifBacktracestopped:framedidnotsavethePC is found. Patch byVictor Stinner.

  • gh-109276: libregrtest now callsrandom.seed() before running eachtest file when-r/--randomize command line option is used. Moreover,it's also called in worker processes. It should help to make tests moredeterministic. Previously, it was only called once in the main processbefore running all test files and it was not called in worker processes.Patch by Victor Stinner.

  • gh-109276: libregrtest now uses a separated file descriptor to write testresult as JSON. Previously, if a test wrote debug messages late around theJSON, the main test process failed to parse JSON. Patch by Victor Stinner.

  • gh-108996: Fix and enabletest_msvcrt.

  • gh-109237: Fixtest_site.test_underpth_basic() when the workingdirectory contains at least one non-ASCII character: encode the._pthfile to UTF-8 and enable the UTF-8 Mode to use UTF-8 for the child processstdout. Patch by Victor Stinner.

  • gh-109230: Fixtest_pyexpat.test_exception(): it can now be run from adirectory different than Python source code directory. Before, the testfailed in this case. Skip the test if Modules/pyexpat.c source is notavailable. Skip also the test on Python implementations other thanCPython. Patch by Victor Stinner.

  • gh-108996: Add tests formsvcrt.

  • gh-109015: Fix test_asyncio, test_imaplib and test_socket tests on FreeBSDif the TCP blackhole is enabled (sysctlnet.inet.tcp.blackhole). Skipthe few tests which failed withETIMEDOUT which such non standardconfiguration. Currently, theFreeBSD GCP image enables TCP and UDPblackhole (sysctlnet.inet.tcp.blackhole=2 andsysctlnet.inet.udp.blackhole=1).Patch by Victor Stinner.

  • gh-91960: Skiptest_gdb if gdb is unable to retrieve Python frameobjects: if a frame is<optimizedout>. When Python is built with"clang -Og", gdb can fail to retrieve theframe parameter of_PyEval_EvalFrameDefault(). In this case, tests likepy_bt() arelikely to fail. Without getting access to Python frames,python-gdb.pyis mostly clueless on retrieving the Python traceback. Moreover,test_gdb is no longer skipped on macOS if Python is built with Clang.Patch by Victor Stinner.

  • gh-108962: Skiptest_tempfile.test_flags() ifchflags() fails with"OSError: [Errno 45] Operation not supported" (ex: on FreeBSD 13). Patchby Victor Stinner.

  • gh-91960: FreeBSD 13.2 CI coverage for pull requests is now provided byCirrus-CI (a hosted CI service that supports Linux, macOS, Windows, andFreeBSD).

  • gh-89392: Removed support oftest_main() function in tests. They nowalways use normal unittest test runner.

  • gh-108851: Fixtest_tomllib recursion tests for WASI buildbots: reducethe recursion limit and compute the maximum nested array/dict depending onthe current available recursion limit. Patch by Victor Stinner.

  • gh-108851: Addget_recursion_available() andget_recursion_depth()functions to thetest.support module. Patch by Victor Stinner.

  • gh-108834: Add--fail-rerunoption option to regrtest: if a testfailed when then passed when rerun in verbose mode, exit the process withexit code 2 (error), instead of exit code 0 (success). Patch by VictorStinner.

  • gh-108834: Rename regrtest--verbose2 option (-w) to--rerun.Keep--verbose2 as a deprecated alias. Patch by Victor Stinner.

  • gh-108834: When regrtest reruns failed tests in verbose mode (./python-mtest--rerun), tests are now rerun in fresh worker processes ratherthan being executed in the main process. If a test does crash or is killedby a timeout, the main process can detect and handle the killed workerprocess. Tests are rerun in parallel if the-jN option is used to runtests in parallel. Patch by Victor Stinner.

  • gh-108822:regrtest now computes statistics on all tests: successes,failures and skipped.test_netrc,test_pep646_syntax andtest_xml_etree now return results in theirtest_main() function.Patch by Victor Stinner and Alex Waygood.

  • gh-108794: Thedoctest.DocTestRunner.run() method now counts thenumber of skipped tests. Adddoctest.DocTestRunner.skips anddoctest.TestResults.skipped attributes. Patch by Victor Stinner.

  • gh-108388: Convert test_concurrent_futures to a package of 7 sub-tests.Patch by Victor Stinner.

  • gh-108388: Split test_multiprocessing_fork,test_multiprocessing_forkserver and test_multiprocessing_spawn into testpackages. Each package is made of 4 sub-tests: processes, threads, managerand misc. It allows running more tests in parallel and so reduce the totaltest duration. Patch by Victor Stinner.

  • gh-105776: Fix test_cppext when the C compiler command-std=c11option: remove-std= options from the compiler command. Patch byVictor Stinner.

  • gh-107652: Set up CIFuzz to run fuzz targets in GitHub Actions. Patch byIllia Volochii.

  • gh-107237:test_logging: Fixtest_udp_reconnection() by increasingthe timeout from 100 ms to 5 minutes (LONG_TIMEOUT). Patch by VictorStinner.

  • gh-107178: Add the C API test for functions in the Mapping Protocol, theSequence Protocol and some functions in the Object Protocol.

  • gh-106714: test_capi: Fix test_no_FatalError_infinite_loop() to no longerwrite a coredump, by using test.support.SuppressCrashReport. Patch byVictor Stinner.

  • gh-104090: Avoid creating a reference to the test object incollectedDurations().

  • gh-106752: Moved tests forzipfile.Path intoLib/test/test_zipfile/_path. Madezipfile._path a package.

  • gh-106690: Add .coveragerc to cpython repository for use with coveragepackage.

  • gh-101634: When running the Python test suite with-jN option, if aworker stdout cannot be decoded from the locale encoding report a failedtestn so the exitcode is non-zero. Patch by Victor Stinner.

  • gh-105084: When the Python build is configured--with-wheel-pkg-dir,tests requiring thesetuptools andwheel wheels will search forthe wheels inWHEEL_PKG_DIR.

  • gh-81005: String tests are modified to reflect thatstr andunicode are merged in Python 3. Patch by Daniel Fortunov.

  • gh-103186: Suppress and assert expected RuntimeWarnings intest_sys_settrace.py

  • gh-69714: Add additional tests tocalendar to achieve full testcoverage.

Build

  • gh-103053: "make check-clean-src" now also checks if the "python" programis found in the source directory: fail with an error if it does exist.Patch by Victor Stinner.

  • gh-109191: Fix compile error when building with recent versions oflibedit.

  • gh-110276: No longer ignorePROFILE_TASK failure silently:command used by Profile Guided Optimization (PGO). Patch by VictorStinner.

  • gh-109566: Removemaketestall target: usemakebuildbottestinstead. Patch by Victor Stinner.

  • gh-109740: The experimental--disable-gil configure flag now includes"t" (for "threaded") in extension ABI tags.

  • gh-109054: Fix building the_testcapi extension on Linux AArch64 whichrequires linking to libatomic when<cpython/pyatomic.h> is used: the_Py_atomic_or_uint64() function requires libatomic__atomic_fetch_or_8() on this platform. The configure script nowchecks if linking to libatomic is needed and generates a new LIBATOMICvariable used to build the _testcapi extension. Patch by Victor Stinner.

  • gh-63760: Fix Solaris build: no longer redefine thegethostname()function. Solaris defines the function since 2005. Patch by VictorStinner, original patch by Jakub Kulík.

  • gh-108740: Fix a race condition inmakeregen-all. Thedeepfreeze.c source and files generated by Argument Clinic are nowgenerated or updated before generating "global objects". Previously, someidentifiers may miss depending on the order in which these files weregenerated. Patch by Victor Stinner.

  • gh-108634: Python built withconfigure--with-trace-refs(tracing references) is now ABI compatible with Python release build anddebug build. Patch by Victor Stinner.

  • gh-85283: The_stat C extension is now built with thelimited CAPI. Patch by Victor Stinner.

  • gh-108447: Fix x86_64 GNU/Hurd build

  • gh-107814: When callingfind_python.bat with-q it did notproperly silence the output of nuget. That is now fixed.

  • gh-105481: Remove the make targetregen-opcode-targets, merge its workintoregen-opcode which repeats most of the calculation. Thissimplifies the code for the build and reduces code duplication.

  • gh-106881: Check forlinux/limits.h before including it inModules/posixmodule.c.

  • gh-95855: Refactor platform triplet detection code and add detection forMIPS soft float and musl libc.

  • gh-106962: Detect MPI compilers inconfigure.

  • gh-106118: Fix compilation for platforms withoutO_CLOEXEC. Theissue was introduced with Python 3.12b1 ingh-103295. Patch by ErlendAasland.

  • gh-105875: SQLite 3.15.2 or newer is required to build thesqlite3extension module. Patch by Erlend Aasland.

  • gh-90005: Fix a regression inconfigure where we could end upunintentionally linking withlibbsd.

  • gh-102404: Document how to perform a WASI build on Linux. Also addTools/wasm/build_wasi.sh as a reference implementation of the docs.

  • gh-89886: Autoconf 2.71 and aclocal 1.16.4 is now required to regenerate!configure.

  • gh-104692: Includecommoninstall as a prerequisite forbininstall

    This ensures thatcommoninstall is completed beforebininstall isstarted when parallel builds are used (make-jinstall), and so thepython3 symlink is only installed after all standard library modulesare installed.

  • gh-101538: Add experimental wasi-threads support. Patch by TakashiYamamoto.

Windows

  • gh-110437: Allows overriding the source of VC redistributables so thatreleases can be guaranteed to never downgrade between updates.

  • gh-109286: Update Windows installer to use SQLite 3.43.1.

  • gh-82367:os.path.realpath() now resolves MS-DOS style file nameseven if the file is not accessible. Patch by Moonsik Park.

  • gh-109991: Update Windows build to use OpenSSL 3.0.11.

  • gh-106242: Fixesrealpath() to behave consistently whenpassed a path containing an embedded null character on Windows. In strictmode, it now raisesOSError instead of the unexpectedValueError, and in non-strict mode will make the path absolute.

  • gh-83180: Changes thePython Launcher for Windows to prefer an active virtualenvironment when the launched script has a shebang line using a Unix-likevirtual command, even if the command requests a specific version ofPython.

  • gh-106844: Fix integer overflow and truncating by the null character in_winapi.LCMapStringEx() which affectsntpath.normcase().

  • gh-105436: Ensure that an empty environment block is terminated by twonull characters, as is required by Windows.

  • gh-105146: Updated the links at the end of the installer to point toDiscourse rather than the mailing lists.

  • gh-103646: When installed from the Microsoft Store,pip no longerdefaults to per-user installs. However, as the install directory isunwritable, it should automatically decide to do a per-user installanyway. This should resolve issues whenpip is passed an option thatconflicts with--user.

  • gh-88745: Improve performance ofshutil.copy2() by using theoperating system'sCopyFile2 function. This may result in subtlechanges to metadata copied along with some files, bringing them in linewith normal OS behavior.

  • gh-104820: Fixesstat() and related functions on file systemsthat do not support file ID requests. This includes FAT32 and exFAT.

  • gh-104803: Addos.path.isdevdrive() to detect whether a path is on aWindows Dev Drive. ReturnsFalse on platforms that do not support DevDrive, and is absent on non-Windows platforms.

macOS

  • gh-109286: Update macOS installer to use SQLite 3.43.1.

  • gh-109991: Update macOS installer to use OpenSSL 3.0.11.

  • gh-99079: Update macOS installer to use OpenSSL 3.0.9.

IDLE

  • gh-104719: Remove IDLE's modification of tokenize.tabsize and test otheruses of tokenize data and methods.

Tools/Demos

  • gh-109991: Update GitHub CI workflows to use OpenSSL 3.0.11 andmultissltests to use 1.1.1w, 3.0.11, and 3.1.3.

  • gh-108494:Argument Clinic now has apartial support of theLimited API: seedocumentation in the Python Developer's GuidePatch by Victor Stinner.

  • gh-107704: It is now possible to deprecate passing keyword arguments forkeyword-or-positional parameters with Argument Clinic, using the new/[fromX.Y] syntax. (To be read as"positional-only from Python versionX.Y".) Seedocumentation in the Python Developer's Guidefor more information.

  • gh-107880: Argument Clinic can now clone__init__() and__new__() methods.

  • gh-104683: Add--exclude option to Argument Clinic CLI.

  • gh-95065: Argument Clinic now supports overriding automatically generatedsignature by using directive@text_signature. Seedocumentation inthe Python Developer's Guide

  • gh-107609: Fix duplicate module check in Argument Clinic. Previously, aduplicate definition would incorrectly be silently accepted. Patch byErlend E. Aasland.

  • gh-107467: The Argument Clinic command-line tool now prints to stderrinstead of stdout on failure.

  • gh-106970: Fix bugs in the Argument Clinicdestination<name>clearcommand; the destination buffers would never be cleared, and thedestination directive parser would simply continue to the faulthandler after processing the command. Patch by Erlend E. Aasland.

  • gh-106706: Change bytecode syntax for families to remove redundant namematching pseudo syntax.

  • gh-106359: Argument Clinic now explicitly forbids "kwarg splats" infunction calls used as annotations.

  • gh-103186:freeze now fetchesCONFIG_ARGS from the originalCPython instance the Makefile uses to call utility scripts. Patch byIjtaba Hussain.

  • gh-95065: It is now possible to deprecate passing parameters positionallywith Argument Clinic, using the new*[fromX.Y] syntax. (To be readas"keyword-only from Python version X.Y".) Seedocumentation in thePython Developer's Guidefor more information. Patch by Erlend E. Aasland with help from AlexWaygood, Nikita Sobolev, and Serhiy Storchaka.

C API

Python 3.12.0 beta 1

Release date: 2023-05-22

Security

  • gh-99889: Fixed a security in flaw inuu.decode() that could allowfor directory traversal based on the input if noout_file wasspecified.

  • gh-104049: Do not expose the local on-disk location in directory indexesproduced byhttp.client.SimpleHTTPRequestHandler.

  • gh-99108: Upgrade built-inhashlib SHA3 implementation to averified implementation from theHACL* project. Used when OpenSSL isnot present or lacks SHA3.

  • gh-102153:urllib.parse.urlsplit() now strips leading C0 control andspace characters following the specification for URLs defined by WHATWG inresponse toCVE 2023-24329. Patch by Illia Volochii.

Core and Builtins

  • gh-102856: Implement PEP 701 changes in thetokenize module. Patchby Marta Gómez Macías and Pablo Galindo Salgado

  • gh-104615: Fix wrong ordering of assignments in code likea,a=x,y.Contributed by Carl Meyer.

  • gh-104572: Improve syntax error message for invalid constructs inPEP 695 contexts and in annotations whenfrom__future__importannotations is active.

  • gh-104482: Fix three error handling bugs in ast.c's validation of patternmatching statements.

  • gh-102818: Do not add a frame to the traceback in thesys.setprofileandsys.settrace trampoline functions. This ensures that frames arenot duplicated if an exception is raised in the callback function, andensures that frames are not omitted if a C callback is used and that doesnot add the frame.

  • gh-104405: Fix an issue where somebytecode instructions couldignorePEP 523 when "inlining" calls.

  • gh-103082: Change behavior ofsys.monitoring.events.LINE events insys.monitoring: Line events now occur when a new line is reacheddynamically, instead of using a static approximation, as before. Thismakes the behavior very similar to that of "line" events insys.settrace. This should ease porting of tools from 3.11 to 3.12.

  • gh-104263: Fixfloat("nan") to produce a quiet NaN on platforms (likeMIPS) where the meaning of the signalling / quiet bit is inverted from itsusual meaning. Also introduce a new macroPy_INFINITY matching C99'sINFINITY, and refactor internals to rely on C99'sNAN andINFINITY macros instead of hard-coding bit patterns for infinities andNaNs. Thanks Sebastian Berg.

  • gh-99113: Multi-phase init extension modules may now indicate that theysupport running in subinterpreters that have their own GIL. This is doneby usingPy_MOD_PER_INTERPRETER_GIL_SUPPORTED as the value for thePy_mod_multiple_interpreters module def slot. Otherwise the module,by default, cannot be imported in such subinterpreters. (This does notaffect the main interpreter or subinterpreters that do not have their ownGIL.) In addition to the isolation that multi-phase init already normallyrequires, support for per-interpreter GIL involves one additionalconstraint: thread-safety. If the module has external (linked)dependencies and those libraries have any state that isn't thread-safethen the module must do the additional work to add thread-safety. Thisshould be an uncommon case.

  • gh-99113: The GIL is now (optionally) per-interpreter. This is thefundamental change for PEP 684. This is all made possible by virtue ofthe isolated state of each interpreter in the process. The behavior ofthe main interpreter remains unchanged. Likewise, interpreters createdusingPy_NewInterpreter() are not affected. To get an interpreterwith its own GIL, callPy_NewInterpreterFromConfig().

  • gh-104108: Multi-phase init extension modules may now indicate whether ornot they actually support multiple interpreters. By default such modulesare expected to support use in multiple interpreters. In the uncommoncase that one does not, it may use the newPy_mod_multiple_interpreters module def slot. A value of0 meansthe module does not support them.1 means it does. The default is1.

  • gh-104142: Fix an issue wherelist ortuple repetitioncould fail to respectPEP 683.

  • gh-104078: Improve the performance ofPyObject_HasAttrString()

  • gh-104066: Improve the performance ofhasattr() for module objectswith a missing attribute.

  • gh-104028: Reduce object creation while calling callback function from gc.Patch by Donghee Na.

  • gh-104018: Disallow the "z" format specifier in %-format of bytes objects.

  • gh-102213: Fix performance loss when accessing an object's attributes with__getattr__ defined.

  • gh-103895: Improve handling of edge cases in showingException.__notes__. Ensures that the messages always end with anewline and that string/bytes are not exploded over multiple lines. Patchby Carey Metcalfe.

  • gh-103907: Don't modify the refcounts of known immortal objects(True,False, andNone) in the main interpreterloop.

  • gh-103899: Provide a helpful hint in theTypeError message whenaccidentally calling amodule object that has a callable attributeof the same name (such asdis.dis() ordatetime.datetime).

  • gh-103845: Remove both line and instruction instrumentation before addingnew ones for monitoring, to avoid newly added instrumentation beingremoved immediately.

  • gh-103763: ImplementPEP 695, adding syntactic support for genericclasses, generic functions, and type aliases.

    A newtypeX=... syntax is added for type aliases, which resolves atruntime to an instance of the new classtyping.TypeAliasType. Thevalue is lazily evaluated and is accessible through the.__value__attribute. This is implemented as a new AST nodeast.TypeAlias.

    New syntax (classX[T]:...,deffunc[T]():...) is added fordefining generic functions and classes. This is implemented as a newtype_params attribute on the AST nodes for classes and functions. Thisnode holds instances of the new AST classesast.TypeVar,ast.ParamSpec, andast.TypeVarTuple.

    typing.TypeVar,typing.ParamSpec,typing.ParamSpecArgs,typing.ParamSpecKwargs,typing.TypeVarTuple, andtyping.Generic are now implemented in C rather than Python.

    There are new bytecode instructionsLOAD_LOCALS,LOAD_CLASSDICT_OR_GLOBAL, andLOAD_CLASSDICT_OR_DEREF to supportcorrect resolution of names in class namespaces.

    Patch by Eric Traut, Larry Hastings, and Jelle Zijlstra.

  • gh-103801: Adds three minor linting fixes to the wasm module caught thatwere caught by ruff.

  • gh-103793: Optimized asyncio Task creation by deferring expensive stringformatting (task name generation) from Task creation to the first timeget_name is called. This makes asyncio benchmarks up to 5% faster.

  • gh-102310: Change the error range for invalid bytes literals.

  • gh-103590: Do not wrap a single exception raised from atry-except*construct in anExceptionGroup.

  • gh-103650: Change the perf map format to remove the '0x' prefix from theaddresses

  • gh-102856: Implement the required C tokenizer changes for PEP 701. Patchby Pablo Galindo Salgado, Lysandros Nikolaou, Batuhan Taskaya, Marta GómezMacías and sunmy2019.

  • gh-100530: Clarify the error message raised when the called part of aclass pattern isn't actually a class.

  • gh-101517: Fix bug in line numbers of instructions emitted forexcept*.

  • gh-103492: ClarifySyntaxWarning with literalis comparison byspecifying which literal is problematic, since comparisons usingiswith e.g.None and bool literals are idiomatic.

  • gh-87729: AddLOAD_SUPER_ATTR (and a specialization forsuper().method()) to speed upsuper().method() andsuper().attr. This makessuper().method() roughly 2.3x faster andbrings it within 20% of the performance of a simple method call. Patch byVladimir Matveev and Carl Meyer.

  • gh-103488: Change the internal offset distinguishing yield and returntarget addresses, so that the instruction pointer is correct for exceptionhandling and other stack unwinding.

  • gh-82012: The bitwise inversion operator (~) on bool is deprecated. Itreturns the bitwise inversion of the underlyingint representationsuch thatbool(~True)==True, which can be confusing. Usenot forlogical negation of bools. In the rare case that you really need thebitwise inversion of the underlyingint, convert to int explicitly~int(x).

  • gh-77757: Exceptions raised in a typeobject's__set_name__ method areno longer wrapped by aRuntimeError. Context information is addedto the exception as aPEP 678 note.

  • gh-103333:AttributeError now retains thename attribute whenpickled and unpickled.

  • gh-103242: Migrateset_ecdh_curve() method not touse deprecated OpenSSL APIs. Patch by Donghee Na.

  • gh-103323: We've replaced our use of_PyRuntime.tstate_current with athread-local variable. This is a fairly low-level implementation detail,and there should be no change in behavior.

  • gh-84436: The implementation of PEP-683 which adds Immortal Objects byusing a fixed reference count that skips reference counting to makeobjects truly immutable.

  • gh-102700: Allow built-in modules to be submodules. This allows submodulesto be statically linked into a CPython binary.

  • gh-103082: ImplementPEP 669 Low Impact Monitoring for CPython.

  • gh-88691: Reduce the number of inlineCACHE entries forCALL.

  • gh-102500: Make the buffer protocol accessible in Python code using thenew__buffer__ and__release_buffer__ magic methods. SeePEP 688 for details. Patch by Jelle Zijlstra.

  • gh-97933:PEP 709: inline list, dict and set comprehensions to improveperformance and reduce bytecode size.

  • gh-99184: Bypass instance attribute access of__name__ inrepr ofweakref.ref.

  • gh-98003: Complex function calls are now faster and consume no C stackspace.

  • bpo-39610:len() for 0-dimensionalmemoryview objects (suchasmemoryview(ctypes.c_uint8(42))) now raises aTypeError.Previously this returned1, which was not consistent withmem_0d[0] raising anIndexError.

  • bpo-31821: Fixpause_reading() to work when called fromconnection_made() inasyncio.

Library

  • gh-104600:functools.update_wrapper() now sets the__type_params__ attribute (added byPEP 695).

  • gh-104340: When anasyncio pipe protocol loses its connection due toan error, and the caller doesn't awaitwait_closed() on thecorrespondingStreamWriter, don't log a warning about an exceptionthat was never retrieved. After all, according to theStreamWriter.close() docs, thewait_closed() call is optional("not mandatory").

  • gh-104555: Fix issue where anissubclass() check comparing a classX against aruntime-checkableprotocolY with non-callable members would notcauseTypeError to be raised if anisinstance() call hadpreviously been made comparing an instance ofX toY. This issuewas present in edge cases on Python 3.11, but became more prominent in3.12 due to some unrelated changes that were made to runtime-checkableprotocols. Patch by Alex Waygood.

  • gh-104372: Refactored the_posixsubprocess internals to avoid Python CAPI usage between fork and exec when markingpass_fds= filedescriptors inheritable.

  • gh-104484: Addedcase_sensitive argument topathlib.PurePath.match()

  • gh-75367: Fix data descriptor detection ininspect.getattr_static().

  • gh-104536: Fix a race condition in the internalmultiprocessing.process cleanup logic that could manifest as anunintendedAttributeError when callingprocess.close().

  • gh-103857: Update datetime deprecations' stracktrace to point to thecalling line

  • gh-101520: Move the core functionality of thetracemalloc module inthePython/ folder, leaving just the module wrapper inModules/.

  • gh-104392: Remove undocumented and unused_paramspec_tvars attributefrom some classes intyping.

  • gh-102613: Fix issue wherepathlib.Path.glob() raisedRecursionError when walking deep directory trees.

  • gh-103000: Improve performance ofdataclasses.asdict() for thecommon case wheredict_factory isdict. Patch by David C Ellis.

  • gh-104301: Allow leading whitespace in disambiguated statements inpdb.

  • gh-104139: Teachurllib.parse.unsplit() to retain the"//" whenassemblingitms-services://?action=generate-bugs styleApple PlatformDeploymentURLs.

  • gh-104307:socket.getnameinfo() now releases the GIL whilecontacting the DNS server

  • gh-104310: Users may now useimportlib.util.allowing_all_extensions()(a context manager) to temporarily disable the strict compatibility checksfor importing extension modules in subinterpreters.

  • gh-87695: Fix issue wherepathlib.Path.glob() raisedOSErrorwhen it encountered a symlink to an overly long path.

  • gh-104265: Prevent possible crash by disallowing instantiation of the_csv.Reader and_csv.Writer types. The regression wasintroduced in 3.10.0a4 with PR 23224 (bpo-14935). Patch by RadislavChugunov.

  • gh-102613: Improve performance ofpathlib.Path.glob() when expandingrecursive wildcards ("**") by merging adjacent wildcards andde-duplicating results only when necessary.

  • gh-65772: Remove unneeded comments and code in turtle.py.

  • gh-90208: Fixed issue wherepathlib.Path.glob() returned incompleteresults when it encountered aPermissionError. This method nowsuppresses allOSError exceptions, except those raised from callingis_dir() on the top-level path.

  • gh-104144: Optimizeasyncio.TaskGroup when usingasyncio.eager_task_factory(). Skip scheduling a done callback if aTaskGroup task completes eagerly.

  • gh-104144: Optimizeasyncio.gather() when usingasyncio.eager_task_factory() to complete eagerly if all fututrescompleted eagerly. Avoid scheduling done callbacks for futures thatcomplete eagerly.

  • gh-104114: Fix issue wherepathlib.Path.glob() returns paths usingthe case of non-wildcard segments for corresponding path segments, ratherthan the real filesystem case.

  • gh-104104: Improve performance ofpathlib.Path.glob() by usingre.IGNORECASE to implement case-insensitive matching.

  • gh-104102: Improve performance ofpathlib.Path.glob() whenevaluating patterns that contain'../' segments.

  • gh-103822: Update the return type ofweekday to the newly added Dayattribute

  • gh-103629: Update therepr oftyping.Unpack according toPEP 692.

  • gh-103963: Makedis display the names of the args forCALL_INTRINSIC_*.

  • gh-104035: Do not ignore user-defined__getstate__ and__setstate__ methods for slotted frozen dataclasses.

  • gh-103987: Inmmap, fix several bugs that could lead to access tomemory-mapped files after they have been invalidated.

  • gh-103977: Improve import time ofplatform module.

  • gh-88773: Addedturtle.teleport() to theturtle module tomove a turtle to a new point without tracing a line, visible or invisible.Patch by Liam Gersten.

  • gh-103935: Useio.open_code() for files to be executed instead ofrawopen()

  • gh-68968: Fixed garbled output ofassertEqual()when an input lacks final newline.

  • gh-100370: Fix potentialOverflowError insqlite3.Connection.blobopen() for 32-bit builds. Patch by Erlend E.Aasland.

  • gh-102628: Substitute CTRL-D with CTRL-Z insqlite3 CLI banner whenrunning on Windows.

  • gh-103636: Module-level attributesJanuary andFebruary aredeprecated fromcalendar.

  • gh-103583: Isolate_multibytecodec and codecs extension modules.Patches by Erlend E. Aasland.

  • gh-103848: Add checks to ensure that[ bracketed] hosts found byurllib.parse.urlsplit() are of IPv6 or IPvFuture format.

  • gh-103872: Update the bundled copy of pip to version 23.1.2.

  • gh-99944: Makedis display the value of oparg ofKW_NAMES.

  • gh-74940: The C.UTF-8 locale is no longer converted to en_US.UTF-8,enabling the use of UTF-8 encoding on systems which have no localesinstalled.

  • gh-103861: Fixzipfile.Zipfile creating invalid zip files whenforce_zip64 was used to add files to them. Patch by Carey Metcalfe.

  • gh-103857: Deprecateddatetime.datetime.utcnow() anddatetime.datetime.utcfromtimestamp(). (Patch by Paul Ganssle)

  • gh-103839: Avoid compilation error due to tommath.h not being found whenbuilding Tkinter against Tcl 8.7 built with bundled libtommath.

  • gh-103791:contextlib.suppress now supports suppressingexceptions raised as part of anExceptionGroup. If other exceptionsexist on the group, they are re-raised in a group that does not containthe suppressed exceptions.

  • gh-90750: Usedatetime.datetime.fromisocalendar() in theimplementation ofdatetime.datetime.strptime(), which should nowaccept only valid ISO dates. (Patch by Paul Ganssle)

  • gh-103685: Preparetkinter.Menu.index() for Tk 8.7 so that it doesnot raiseTclError:expectedintegerbutgot"" when it should returnNone.

  • gh-81403:urllib.request.CacheFTPHandler no longer raisesURLError if a cached FTP instance is reused. ftplib's endtransfermethod calls voidresp to drain the connection to handle FTP instance reuseproperly.

  • gh-103699: Add__orig_bases__ to non-generic TypedDicts, call-basedTypedDicts, and call-based NamedTuples. Other TypedDicts and NamedTuplesalready had the attribute.

  • gh-103693: Add convenience variable feature topdb

  • gh-92248: Deprecatetype,choices, andmetavar parameters ofargparse.BooleanOptionalAction.

  • gh-89415: Addsocket constants for source-specific multicast. Patchby Reese Hyde.

  • gh-103673:socketserver gainsForkingUnixStreamServer andForkingUnixDatagramServer classes. Patch by Jay Berry.

  • gh-103636: Added Enum for months and days in the calendar module.

  • gh-84976: Create a newLib/_pydatetime.py file that defines the Pythonversion of thedatetime module, and makedatetime import thecontents of the new library only if the C implementation is missing.Currently, the full Python implementation is defined and then deleted ifthe C implementation is not available, slowing downimportdatetimeunnecessarily.

  • gh-103596: Attributes/methods are no longer shadowed by same-named enummembers, although they may be shadowed by enum.property's.

  • gh-103584: Updatedimportlib.metadata with changes fromimportlib_metadata 5.2 through 6.5.0, including: Supportinstalled-files.txt forDistribution.files when present.PackageMetadata now stipulates an additionalget method allowingfor easy querying of metadata keys that may not be present.packages_distributions now honors packages and modules with Pythonmodules that not.py sources (e.g..pyc,.so). Expand protocolforPackageMetadata.get_all to match the upstream implementation ofemail.message.Message.get_all in python/typeshed#9620. Deprecated useofDistribution without defining abstract methods. Deprecatedexpectation thatPackageMetadata.__getitem__ will returnNone formissing keys. In the future, it will raise aKeyError.

  • gh-103578: Fixed a bug wherepdb crashes when reading source filewith different encoding by replacingio.open() withio.open_code(). The new method would also call into the hook set byPyFile_SetOpenCodeHook().

  • gh-103556: Now creatinginspect.Signature objects withpositional-only parameter with a default followed by apositional-or-keyword parameter without one is impossible.

  • gh-103559: Update the bundled copy of pip to version 23.1.1.

  • gh-103548: Improve performance ofpathlib.Path.absolute() andcwd() by joining paths only when necessary. Alsoimprove performance ofpathlib.PurePath.is_absolute() on Posix byskipping path parsing and normalization.

  • gh-103538: Remove_tkinter module code guarded by definition of theTK_AQUA macro which was only needed for Tk 8.4.7 or earlier and wasnever actually defined by any build system or documented for manual use.

  • gh-103533: UpdatecProfile to use PEP 669 API

  • gh-103525: Fix misleading exception message when mixedstr andbytes arguments are supplied topathlib.PurePath andPath.

  • gh-103489: Addgetconfig() andsetconfig() toConnection tomake configuration changes to a database connection. Patch by Erlend E.Aasland.

  • gh-103365: Set default Flag boundary toSTRICT and fix bitwiseoperations.

  • gh-103472: Avoid a potentialResourceWarning inhttp.client.HTTPConnection by closing the proxy / tunnel'sCONNECT response explicitly.

  • gh-103462: Fixed an issue with usingwritelines() inasyncio to send verylarge payloads that exceed the amount of data that can be written in onecall tosocket.socket.send() orsocket.socket.sendmsg(),resulting in the remaining buffer being left unwritten.

  • gh-103449: Fix a bug in doc string generation indataclasses.dataclass().

  • gh-103092: Isolate_collections (applyPEP 687). Patch byErlend E. Aasland.

  • gh-103357: Added support forlogging.Formatterdefaultsparameter tologging.config.dictConfig() andlogging.config.fileConfig(). Patch by Bar Harel.

  • gh-103092: Adapt thewinreg extension module toPEP 687.

  • gh-74690: The performance ofisinstance() checks againstruntime-checkableprotocols has beenconsiderably improved for protocols that only have a few members. Toachieve this improvement, several internal implementation details of thetyping module have been refactored, includingtyping._ProtocolMeta.__instancecheck__,typing._is_callable_members_only, andtyping._get_protocol_attrs.Patches by Alex Waygood.

  • gh-74690: The members of a runtime-checkable protocol are now considered"frozen" at runtime as soon as the class has been created. See"What's new in Python 3.12" for moredetails.

  • gh-103256: Fixed a bug that causedhmac to raise an exception whenthe requested hash algorithm was not available in OpenSSL despite beingavailable separately as part ofhashlib itself. It now falls backproperly to the built-in. This could happen when, for example, yourOpenSSL does not include SHA3 support and you want to computehmac.digest(b'K',b'M','sha3_256').

  • gh-102778: Supportsys.last_exc inidlelib.

  • gh-103285: Improve performance ofast.get_source_segment().

  • gh-103225: Fix a bug inpdb when displaying line numbers ofmodule-level source code.

  • gh-103092: Adapt themsvcrt extension module toPEP 687.

  • gh-103092: Adapt thewinsound extension module toPEP 687.

  • gh-93910: Remove deprecation of enummember.member access.

  • gh-102978: Fixesunittest.mock.patch() not enforcing functionsignatures for methods decorated with@classmethod or@staticmethod when patch is called withautospec=True.

  • gh-103092: Isolate_socket (applyPEP 687). Patch by Erlend E.Aasland.

  • gh-100479: Addpathlib.PurePath.with_segments(), which creates apath object from arguments. This method is called whenever a derivativepath is created, such as frompathlib.PurePath.parent. Subclassesmay override this method to share information between path objects.

  • gh-103220: Fix issue whereos.path.join() added a slash when joiningonto an incomplete UNC drive with a trailing slash on Windows.

  • gh-103204: Fixeshttp.server accepting HTTP requests with HTTPversion numbers preceded by '+', or '-', or with digit-separating '_'characters. The length of the version numbers is also constrained.

  • gh-75586: Fix various Windows-specific issues withshutil.which.

  • gh-103193: Improve performance ofinspect.getattr_static(). Patch byAlex Waygood.

  • gh-103176:sys._current_exceptions() now returns a mapping fromthread-id to an exception instance, rather than to a(typ,exc,tb)tuple.

  • gh-103143: Polish the help messages and docstrings ofpdb.

  • gh-103015: Addentrypoint keyword-only parameter tosqlite3.Connection.load_extension(), for overriding the SQLiteextension entry point. Patch by Erlend E. Aasland.

  • gh-103000: Improve performance ofdataclasses.astuple() anddataclasses.asdict() in cases where the contents are common Pythontypes.

  • gh-102953: The extraction methods intarfile, andshutil.unpack_archive(), have a new afilter argument that allowslimiting tar features than may be surprising or dangerous, such ascreating files outside the destination directory. SeeExtraction filters for details.

  • gh-97696: Implemented an eager task factory in asyncio. When used as atask factory on an event loop, it performs eager execution of coroutines.Coroutines that are able to complete synchronously (e.g. return or raisewithout blocking) are returned immediately as a finished task, and thetask is never scheduled to the event loop. If the coroutine blocks, the(pending) task is scheduled and returned.

  • gh-81079: Addcase_sensitive keyword-only argument topathlib.Path.glob() andrglob().

  • gh-101819: Isolate theio extension module by applyingPEP 687.Patch by Kumar Aditya, Victor Stinner, and Erlend E. Aasland.

  • gh-91896: Deprecatecollections.abc.ByteString

  • gh-101362: Speed uppathlib.Path construction by omitting thepath anchor from the internal list of path parts.

  • gh-102114: Functions in thedis module that accept a source codestring as argument now print a more concise traceback when the stringcontains a syntax or indentation error.

  • gh-62432: Theunittest runner will now exit with status code 5 ifno tests were run. It is common for test runner misconfiguration to failto find any tests, this should be an error.

  • gh-78079: Fix incorrect normalization of UNC device path roots, andpartial UNC share path roots, inpathlib.PurePath. Pathlib nolonger appends a trailing slash to such paths.

  • gh-85984: Addtty.cfmakeraw() andtty.cfmakecbreak() totty and modernize, the behavior oftty.setraw() andtty.setcbreak() to use POSIX.1-2017 Chapter 11 "General TerminalInterface" flag masks by default.

  • gh-101688: Implementtypes.get_original_bases() to provide furtherintrospection for types.

  • gh-101640:argparse.ArgumentParser now catches errors whenwriting messages, such as whensys.stderr isNone. Patch byOleg Iarygin.

  • gh-83861: Fix datetime.astimezone method return value when invoked on anaive datetime instance that represents local time falling in a timezonetransition gap. PEP 495 requires that instances with fold=1 produceearlier times than those with fold=0 in this case.

  • gh-89550: Decrease execution time of somegzip file writes by 15%by adding more appropriate buffering.

  • gh-95299: Remove the bundled setuptools wheel fromensurepip, and stopinstalling setuptools in environments created byvenv.

  • gh-99353: Respect thehttp.client.HTTPConnection.debuglevelflag inurllib.request.AbstractHTTPHandler when its constructorparameterdebuglevel is not set. And do the same for*HTTPS*.

  • gh-98040: Remove the long-deprecatedimp module.

  • gh-97850: Deprecatepkgutil.find_loader() andpkgutil.get_loader() in favor ofimportlib.util.find_spec().

  • gh-94473: Flatten arguments intkinter.Canvas.coords(). It nowaccepts not onlyx1,y1,x2,y2,... and[x1,y1,x2,y2,...],but also(x1,y1),(x2,y2),... and[(x1,y1),(x2,y2),...].

  • gh-98040: Remove more deprecated importlib APIs:find_loader(),find_module(),importlib.abc.Finder,pkgutil.ImpImporter,pkgutil.ImpLoader.

  • gh-96522: Fix potential deadlock in pty.spawn()

  • gh-96534: Support divert(4) added in FreeBSD 14.

  • gh-87474: Fix potential file descriptor leaks insubprocess.Popen.

  • gh-94906: Support multiple steps inmath.nextafter(). Patch byShantanu Jain and Matthias Gorgens.

  • gh-51574: Maketempfile.mkdtemp() return absolute paths when itsdir parameter is relative.

  • gh-94518: Convert private_posixsubprocess.fork_exec() to useArgument Clinic.

  • gh-92184: When creating zip files usingzipfile,os.altsep, ifnotNone, will always be treated as a path separator even when it isnot/. Patch by Carey Metcalfe.

  • bpo-46797: Deprecation warnings are now emitted forast.Num,ast.Bytes,ast.Str,ast.NameConstant andast.Ellipsis. These have been documented as deprecated sincePython 3.8, and will be removed in Python 3.14.

  • bpo-44844: Enableswebbrowser to detect and launch Microsoft Edgebrowser.

  • bpo-45606: Fixed the bug inpathlib.Path.glob() -- previously adangling symlink would not be found by this method when the pattern is anexact match, but would be found when the pattern contains a wildcard orthe recursive wildcard (**). With this change, a dangling symlink willbe found in both cases.

  • bpo-23041: AddQUOTE_STRINGS andQUOTE_NOTNULLto the suite ofcsv module quoting styles.

  • bpo-24964: Addedhttp.client.HTTPConnection.get_proxy_response_headers() thatprovides access to the HTTP headers on a proxy server response to theCONNECT request.

  • bpo-17258:multiprocessing now supports stronger HMAC algorithmsfor inter-process connection authentication rather than only HMAC-MD5.

  • bpo-39744: Makeasyncio.subprocess.Process.communicate() close thesubprocess's stdin even when called withinput=None.

  • bpo-22708: http.client CONNECT method tunnel improvements: Use HTTP 1.1protocol; send a matching Host: header with CONNECT, if one is notprovided; convert IDN domain names to Punycode. Patch by Michael Handler.

Documentation

  • gh-67056: Document that the effect of registering or unregistering anatexit cleanup function from within a registered cleanup functionis undefined.

  • gh-103629: Mention the new way of typing**kwargs withUnpack andTypedDict introduced inPEP 692.

  • gh-48241: Clarifying documentation about the url parameter tourllib.request.urlopen and urllib.request.Request needing to be encodedproperly.

  • gh-86094: Add support for Unicode Path Extra Field in ZipFile. Patch byYeojin Kim and Andrea Giudiceandrea

  • gh-99202: Fix extension type from documentation for compiling in C++20mode

Tests

  • gh-104494: Updatetest_pack_configure_in andtest_place_configure_in for changes to error message formatting in Tk8.7.

  • gh-104461: Run test_configure_screen on X11 only, since theDISPLAYenvironment variable and-screen option for toplevels are not usefulon Tk for Win32 or Aqua.

  • gh-86275: Added property-based tests to thezoneinfo tests, alongwith stubs for thehypothesis interface. (Patch by Paul Ganssle)

  • gh-103329: Regression tests for the behaviour ofunittest.mock.PropertyMock were added.

  • gh-102795: fix use of poll in test_epoll's test_control_and_wait

  • gh-75729: Fix theos.spawn* tests failing on Windowswhen the working directory or interpreter path contains spaces.

Build

  • gh-101282: BOLT optimization is now applied to the libpython sharedlibrary if building a shared library. BOLT instrumentation and applicationsettings can now be influenced via theBOLT_INSTRUMENT_FLAGS andBOLT_APPLY_FLAGS configure variables.

  • gh-99017:PYTHON_FOR_REGEN now require Python 3.10 or newer.

  • gh-104490: Define.PHONY / virtual make targets consistently andproperly.

  • gh-104106: Add gcc fallback of mkfifoat/mknodat for macOS. Patch byDonghee Na.

  • gh-103532: TheTKINTER_PROTECT_LOADTK macro is no longer defined orused in the_tkinter module. It was previously only defined whenbuilding against Tk 8.4.13 and older, but Tk older than 8.5.12 has beenunsupported sincegh-91152.

  • gh-99069: Extended workaround definingstatic_assert when missing fromthe libc headers to all clang and gcc builds. In particular, this fixesbuilding on macOS <= 10.10.

  • gh-100220: Changed the default value of theSHELL Makefile variablefrom/bin/sh to/bin/sh-e to ensure that complex recipescorrectly fail after an error. Previously,makeinstall could fail toinstall some files and yet return a successful result.

  • gh-90656: Add platform triplets for 64-bit LoongArch:

    • loongarch64-linux-gnusf

    • loongarch64-linux-gnuf32

    • loongarch64-linux-gnu

    Patch by Zhang Na.

Windows

  • gh-104623: Update Windows installer to use SQLite 3.42.0.

  • gh-82814: Fix a potential[Errno13]Permissiondenied when usingshutil.copystat() within Windows Subsystem for Linux (WSL) on amounted filesystem by addingerrno.EACCES to the list of ignorederrors within the internal implementation.

  • gh-103088: Fix virtual environmentactivate script havingincorrect line endings for Cygwin.

  • gh-103088: Fixes venvs not working in bash on Windows across differentdisks

  • gh-102997: Update Windows installer to use SQLite 3.41.2.

  • gh-88013: Fixed a bug whereTypeError was raised when callingntpath.realpath() with a bytes parameter in some cases.

macOS

  • gh-99834: Update macOS installer to Tcl/Tk 8.6.13.

  • gh-104623: Update macOS installer to SQLite 3.42.0.

  • gh-103545: Addos.PRIO_DARWIN_THREAD,os.PRIO_DARWIN_PROCESS,os.PRIO_DARWIN_BG andos.PRIO_DARWIN_NONUI. These can be used withos.setpriority to run the process at a lower priority and make use ofthe efficiency cores on Apple Silicon systems.

  • gh-104180: Support reading SOCKS proxy configuration from macOS SystemConfiguration. Patch by Sam Schott.

  • gh-60436: update curses textbox to additionally handle backspace using thecurses.ascii.DEL key press.

  • gh-102997: Update macOS installer to SQLite 3.41.2.

IDLE

  • gh-104499: Fix completions for Tk Aqua 8.7 (currently blank).

  • gh-104496: About prints both tcl and tk versions if different (expectedsomeday).

  • gh-88496: Fix IDLE test hang on macOS.

Tools/Demos

  • gh-104389: Argument Clinic C converters now accept theunused keyword,for wrapping a parameter withPy_UNUSED. Patch by Erlend E.Aasland.

C API

Python 3.12.0 alpha 7

Release date: 2023-04-04

Core and Builtins

  • gh-102192: Deprecated_PyErr_ChainExceptions in favour of_PyErr_ChainExceptions1.

  • gh-89987: Reduce the number of inlineCACHE entries forBINARY_SUBSCR.

  • gh-102859: RemovedJUMP_IF_FALSE_OR_POP andJUMP_IF_TRUE_OR_POP instructions.

  • gh-101975: Fixedstacktop value on tracing entries to avoid corruptionon garbage collection.

  • gh-102778: Addsys.last_exc and deprecatesys.last_type,sys.last_value andsys.last_traceback, which hold the sameinformation in its legacy form.

  • gh-100982: Replace all occurrences ofCOMPARE_AND_BRANCH withCOMPARE_OP.

  • gh-102701: Fix overflow when creating very large dict.

  • gh-102755: AddPyErr_DisplayException() which takes just anexception instance, to replace the legacyPyErr_Display() whichtakes the(typ,exc,tb) triplet.

  • gh-102594: Add note to exception raised inPyErr_SetObject whennormalization fails.

  • gh-90997: Shrink the number of inlineCACHE entries used byLOAD_GLOBAL.

  • gh-102491: Improve import time ofplatform by removing IronPythonversion parsing. The IronPython version parsing was not functional (seehttps://github.com/IronLanguages/ironpython3/issues/1667).

  • gh-101291: Rearrage bits in first field (after header) of PyLongObject. *Bits 0 and 1: 1 - sign. I.e. 0 for positive numbers, 1 for zero and 2 fornegative numbers. * Bit 2 reserved (probably for the immortal bit) * Bits3+ the unsigned size.

    This makes a few operations slightly more efficient, and will enable amore compact and faster 2s-complement representation of most ints infuture.

  • gh-102397: Fix segfault from race condition in signal handling duringgarbage collection. Patch by Kumar Aditya.

  • gh-102406:codecs encoding/decoding errors now get the contextinformation (which operation and which codecs) attached asPEP 678notes instead of through chaining a new instance of the exception.

  • gh-102281: Fix potential nullptr dereference and use of uninitializedmemory in fileutils. Patch by Max Bachmann.

  • gh-102300: Reuse operands with refcount of 1 in float specializations ofBINARY_OP.

  • gh-102213: Fix performance loss when accessing an object's attributes with__getattr__ defined.

  • gh-102255: Improve build support for the Xbox. Patch by Max Bachmann.

  • gh-102027: Fix SSE2 and SSE3 detection in_blake2 internal module.Patch by Max Bachmann.

  • gh-101865: Deprecateco_lnotab in code objects, schedule it forremoval in Python 3.14

  • bpo-1635741: Adapt_pickle toPEP 687. Patch by Mohamed Koubaaand Erlend Aasland.

Library

Documentation

Tests

  • gh-102980: Improve test coverage onpdb.

  • gh-102537: Adjust the error handling strategy intest_zoneinfo.TzPathTest.python_tzpath_context. Patch by Paul Ganssle.

  • gh-101377: Improved test_locale_calendar_formatweekday of calendar.

Build

  • gh-102973: Add a dev container (along with accompanying Dockerfile) fordevelopment purposes.

  • gh-102711: Fix-Wstrict-prototypes compiler warnings.

Windows

  • gh-102690: Updatewebbrowser to fall back to Microsoft Edge insteadof Internet Explorer.

  • gh-99726: Improves correctness of stat results for Windows, and usesfaster API when available

Tools/Demos

C API

  • gh-102013: Add a new (unstable) C-API function for iterating over GC'ableobjects using a callback:PyUnstable_VisitObjects.

Python 3.12.0 alpha 6

Release date: 2023-03-07

Security

  • gh-99108: Replace builtin hashlib implementations of MD5 and SHA1 withverified ones from the HACL* project.

  • gh-101727: Updated the OpenSSL version used in Windows and macOS binaryrelease builds to 1.1.1t to addressCVE 2023-0286,CVE 2022-4303,andCVE 2022-4303 perthe OpenSSL 2023-02-07 security advisory.

  • gh-99108: Replace the builtinhashlib implementations of SHA2-384and SHA2-512 originally from LibTomCrypt with formally verified,side-channel resistant code from theHACL* project. The builtins remain afallback only used when OpenSSL does not provide them.

  • gh-101283:subprocess.Popen now uses a safer approach to findcmd.exe when launching withshell=True. Patch by Eryk Sun, basedon a patch by Oleg Iarygin.

Core and Builtins

  • gh-102493: Fix regression in semantics of normalisation inPyErr_SetObject.

  • gh-102416: Do not memoize incorrectly automatically generated loop rulesin the parser. Patch by Pablo Galindo.

  • gh-102356: Fix a bug that caused a crash when deallocating deeply nestedfilter objects. Patch by Marta Gómez Macías.

  • gh-102336: Cleanup Windows 7 specific special handling. Patch by MaxBachmann.

  • gh-102250: Fixed a segfault occurring when the interpreter calls a__bool__ method that raises.

  • gh-102126: Fix deadlock at shutdown when clearing thread states if anyfinalizer tries to acquire the runtime head lock. Patch by Kumar Aditya.

  • gh-102027: UseGetCurrentProcessId on Windows whengetpid isunavailable. Patch by Max Bachmann.

  • gh-102056: Fix error handling bugs in interpreter's exception printingcode, which could cause a crash on infinite recursion.

  • gh-100982: Restrict the scope of theFOR_ITER_RANGE instructionto the scope of the originalFOR_ITER instruction, to allowinstrumentation.

  • gh-101967: Fix possible segfault inpositional_only_passed_as_keywordfunction, when new list created.

  • gh-101952: Fix possible segfault inBUILD_SET opcode, when new setcreated.

  • gh-74895:socket.getaddrinfo no longer raisesOverflowError forintport values outside of the Clong range. Out of range values are left up to the underlying string basedC library API to report. Asocket.gaierrorSAI_SERVICE mayoccur instead, or no error at all as not all platform C libraries generatean error.

  • gh-101799: AddCALL_INTRINSIC_2 and use it instead ofPREP_RERAISE_STAR.

  • gh-101857: Fix xattr support detection on Linux systems by widening thecheck to linux, not just glibc. This fixes support for musl.

  • gh-84783: Make the slice object hashable. Patch by Will Bradshaw andFurkan Onder.

  • gh-87849: Change theSEND instruction to leave the receiver on thestack. This allows the specialized form ofSEND to skip the chain of Ccalls and jump directly to theRESUME in the generator or coroutine.

  • gh-101765: Fix SystemError / segmentation fault in iter__reduce__when internal access ofbuiltins.__dict__ keys mutates the iterobject.

  • gh-101430: Updatetracemalloc to handle presize of object properly.Patch by Donghee Na.

  • gh-101696: Invalidate type version tag in_PyStaticType_Dealloc forstatic types, avoiding bug where a false cache hit could crash theinterpreter. Patch by Kumar Aditya.

  • gh-101632: Adds a newRETURN_CONST instruction.

  • gh-100719: Remove gi_code field from generator (and coroutine and asyncgenerator) objects as it is redundant. The frame already includes areference to the code object.

  • gh-98627: When an interpreter is configured to check (and only then),importing an extension module will now fail when the extension does notsupport multiple interpreters (i.e. doesn't implement PEP 489 multi-phaseinit). This does not apply to the main interpreter, nor to subinterpreterscreated withPy_NewInterpreter().

Library

Documentation

Tests

  • gh-102019: Fix deadlock on shutdown iftest_current_{exception,frames}fails. Patch by Jacob Bower.

  • gh-85984: Utilize new "winsize" functions from termios in pty tests.

  • gh-89792:test_tools now copies up to 10x less source data to atemporary directory during thefreeze test by ignoring git metadataand other artifacts. It also limits its python build parallelism based onos.cpu_count instead of hard coding it as 8 cores.

Build

  • gh-99942: On Android, in a static build, python-config in embed mode nolonger incorrectly reports a library to link to.

  • gh-99942: On Android, python.pc now correctly reports the library to linkto, the same as python-config.sh.

  • gh-100221: Fix creating install directories inmakesharedinstall ifthey exist outsideDESTDIR already.

  • gh-96821: Explicitly mark C extension modules that need defined signedinteger overflow, and add a configure option--with-strict-overflow. Patch by Matthias Görgens and ShantanuJain.

Windows

  • gh-102344: Implementwinreg.QueryValue usingQueryValueEx andwinreg.SetValue usingSetValueEx. Patch by Max Bachmann.

  • gh-101881: Handle read and write operations on non-blocking pipes properlyon Windows.

  • gh-101881: Add support for the os.get_blocking() and os.set_blocking()functions on Windows.

  • gh-101849: Ensures installer will correctly upgrade existingpy.exelauncher installs.

  • gh-101763: Updates copy of libffi bundled with Windows installs to 3.4.4.

  • gh-101759: Update Windows installer to SQLite 3.40.1.

  • gh-101614: Correctly handle extensions built against debug binaries thatreferencepython3_d.dll.

  • gh-101196: The functionsos.path.isdir,os.path.isfile,os.path.islink andos.path.exists are now 13% to 28% faster onWindows, by making fewer Win32 API calls.

macOS

  • gh-101759: Update macOS installer to SQLite 3.40.1.

C API

Python 3.12.0 alpha 5

Release date: 2023-02-07

Security

  • gh-99108: Replace the builtinhashlib implementations of SHA2-224and SHA2-256 originally from LibTomCrypt with formally verified,side-channel resistant code from theHACL* project. The builtins remain afallback only used when OpenSSL does not provide them.

Core and Builtins

  • gh-92173: Fix thedefs andkwdefs arguments toPyEval_EvalCodeEx() and a reference leak in that function.

  • gh-59956: The GILState API is now partially compatible withsubinterpreters. Previously,PyThreadState_GET() andPyGILState_GetThisThreadState() would get out of sync, causinginconsistent behavior and crashes.

  • gh-101400: Fix wrong lineno in exception message oncontinue orbreak which are not in a loop. Patch by Donghee Na.

  • gh-101372: Fixis_normalized() to properly handle theUCD 3.2.0 cases. Patch by Donghee Na.

  • gh-101266: Fixsys.getsizeof() reporting forintsubclasses.

  • gh-101291: Refactor thePyLongObject struct into a normal Pythonobject header and aPyLongValue struct.

  • gh-101046: Fix a possible memory leak in the parser when raisingMemoryError. Patch by Pablo Galindo

  • gh-101037: Fix potential memory underallocation issue for instances ofint subclasses with value zero.

  • gh-100762: Record the (virtual) exception block depth in the oparg ofYIELD_VALUE. Use this to avoid the expensivethrow() whenclosing generators (and coroutines) that can be closed trivially.

  • gh-100982: Adds a newCOMPARE_AND_BRANCH instruction. This is abit more efficient when performing a comparison immediately followed by abranch, and restores the design intent of PEP 659 that specializations arelocal to a single instruction.

  • gh-100942: Fixed segfault in property.getter/setter/deleter that occurredwhen a property subclass overrode the__new__ method to return anon-property instance.

  • gh-100923: Remove themask cache entry for theCOMPARE_OPinstruction and embed the mask into the oparg.

  • gh-100892: Fix race while iterating over thread states in clearingthreading.local. Patch by Kumar Aditya.

  • gh-91351: Fix a case where re-entrant imports could corrupt the importdeadlock detection code and cause aKeyError to be raised out ofimportlib/_bootstrap. In addition to the straightforward cases,this could also happen when garbage collection leads to a warning beingemitted -- as happens when it collects an open socket or file)

  • gh-100726: Optimize construction ofrange object for medium sizeintegers.

  • gh-100712: Added option to build cpython with specialization disabled, bysettingENABLE_SPECIALIZATION=False inopcode, followed bymakeregen-all.

  • bpo-32780: Inter-field padding is now inserted into the PEP3118 formatstrings obtained fromctypes.Structure objects, reflecting theirtrue representation in memory.

Library

  • gh-101541: [Enum] - fix psuedo-flag creation

  • gh-101570: Upgrade pip wheel bundled with ensurepip (pip 23.0)

  • gh-101323: Fix a bug where errors where not thrown byzlib._ZlibDecompressor if encountered during decompressing.

  • gh-101317: Addssl_shutdown_timeout parameter forasyncio.StreamWriter.start_tls().

  • gh-101326: Fix regression when passingNone as second or thirdargument toFutureIter.throw.

  • gh-92123: Adapt the_elementtree extension module to multi-phase init(PEP 489). Patches by Erlend E. Aasland.

  • gh-100795: Avoid potential unexpectedfreeaddrinfo call (double free)insocket when when a libcgetaddrinfo() implementation leavesgarbage in an output pointer when returning an error. Original patch bySergey G. Brester.

  • gh-101143: Remove unused references toTimerHandle inasyncio.base_events.BaseEventLoop._add_callback.

  • gh-101144: Makezipfile.Path.open() andzipfile.Path.read_text() also acceptencoding as a positionalargument. This was the behavior in Python 3.9 and earlier. 3.10introduced a regression where supplying it as a positional argument wouldlead to aTypeError.

  • gh-94518: Group-related variables of_posixsubprocess module arerenamed to stress that supplementary group affinity is added to a fork,not replace the inherited ones. Patch by Oleg Iarygin.

  • gh-101015: Fixtyping.get_type_hints() on'*tuple[...]' and*tuple[...]. It must not drop theUnpack part.

  • gh-101000: Addos.path.splitroot(), which splits a path into a3-item tuple(drive,root,tail). This new function is used bypathlib to improve the performance of path construction by up to athird.

  • gh-100573: Fix a Windowsasyncio bug with named pipes where aclient doingos.stat() on the pipe would cause an error in the serverthat disabled serving future requests.

  • gh-39615:warnings.warn() now has the ability to skip stack framesbased on code filename prefix rather than only a numericstacklevelvia the newskip_file_prefixes keyword argument.

  • gh-100750: pass encoding kwarg to subprocess in platform

  • gh-100160: Emit a deprecation warning inasyncio.DefaultEventLoopPolicy.get_event_loop() if there is nocurrent event loop set and it decides to create one.

  • gh-96290: Fix handling of partial and invalid UNC drives inntpath.splitdrive(), and inntpath.normpath() on non-Windowssystems. Paths such as '\server' and '\' are now considered bysplitdrive() to contain only a drive, and consequently are notmodified bynormpath() on non-Windows systems. The behaviour ofnormpath() on Windows systems is unaffected, as native OS APIs areused. Patch by Eryk Sun, with contributions by Barney Gale.

  • gh-99952: Fix a reference undercounting issue inctypes.Structurewithfrom_param() results larger than a C pointer.

  • gh-67790: Add float-style formatting support forfractions.Fraction instances.

  • gh-99266: Preserve more detailed error messages inctypes.

  • gh-86682: Ensure runtime-created collections have the correct module nameusing the newly added (internal)sys._getframemodulename().

  • gh-88597:uuid now has a command line interface. Trypython-muuid-h.

  • gh-60580:ctypes.wintypes.BYTE definition changed fromc_byte toc_ubyte to match Windows SDK.Patch by Anatoly Techtonik and Oleg Iarygin.

  • gh-94518:_posixsubprocess now initializes all UID and GID variablesusing a reserved-1 value instead of a separate flag. Patch by OlegIarygin.

  • bpo-38941: Thexml.etree.ElementTree module now emitsDeprecationWarning when testing the truth value of anxml.etree.ElementTree.Element. Before, the Python implementationemittedFutureWarning, and the C implementation emitted nothing.

  • bpo-40077: Convertelementtree types to heap types. Patch by ErlendE. Aasland.

  • bpo-29847: Fix a bug wherepathlib.Path accepted and ignoredkeyword arguments. Patch provided by Yurii Karabas.

  • gh-77772:ctypes.CDLL,ctypes.OleDLL,ctypes.WinDLL, andctypes.PyDLL now acceptpath-like objects as theirname argument.Patch by Robert Hoelzl.

Documentation

  • gh-88324: Rewordsubprocess to emphasize default behavior ofstdin,stdout, andstderr arguments. Remove inaccurate statementabout child file handle inheritance.

Tests

  • gh-101334:test_tarfile has been updated to pass when run as a highUID.

Build

  • gh-101282: Update BOLT configuration not to use deprecated usage of--splitfunctions. Patch by Donghee Na.

  • gh-101522: Allow overriding Windows dependencies versions and paths usingMSBuild properties.

  • gh-77532: Minor fixes to allow building withPlatformToolset=ClangCLon Windows.

  • gh-101152: In accordance withPEP 699, thema_version_tag field inPyDictObject is deprecated for extension modules. Accessing thisfield will generate a compiler warning at compile time. This field will beremoved in Python 3.14.

  • gh-100340: Allows -Wno-int-conversion for wasm-sdk 17 and onwards, thusenables building WASI builds once against the latest sdk.

  • gh-101060: Conditionally add-fno-reorder-blocks-and-partition inconfigure. Effectively fixes--enable-bolt when using Clang, as thisappears to be a GCC-only flag.

  • gh-98705:__bool__ is defined in AIX system header files which breaksthe build in AIX, so undefine it.

  • gh-98636: Fix a regression in detectinggdbm_compat library for the_gdbm module build.

  • gh-96305:_aix_support now uses a simple code to get platform detailsrather than the now non-existent_bootsubprocess during bootstrap.

Windows

  • gh-101543: Ensure the install path in the registry is only used when thestandard library hasn't been located in any other way.

  • gh-101467: Thepy.exe launcher now correctly filters when only asingle runtime is installed. It also correctly handles prefix matches ontags so that-3.1 does not match3.11, but would still match3.1-32.

  • gh-99834: Updates bundled copy of Tcl/Tk to 8.6.13.0

  • gh-101135: Restore ability to launch older 32-bit versions from thepy.exe launcher when both 32-bit and 64-bit installs of the sameversion are available.

  • gh-82052: Fixed an issue where writing more than 32K of Unicode output tothe console screen in one go can result in mojibake.

  • gh-100320: Ensures thePythonPath registry key from an install is usedwhen launching from a different copy of Python that relies on an existinginstall to provide a copy of its modules and standard library.

  • gh-100247: Restores support for thepy.exe launcher findingshebang commands in its configuration file using the full command name.

Python 3.12.0 alpha 4

Release date: 2023-01-10

Core and Builtins

  • gh-100776: Fix misleading default value ininput()'s__text_signature__.

  • gh-99005: RemoveUNARY_POSITIVE,ASYNC_GEN_WRAP andLIST_TO_TUPLE, replacing them with intrinsics.

  • gh-99005: Add newCALL_INTRINSIC_1 instruction. RemoveIMPORT_STAR,PRINT_EXPR andSTOPITERATION_ERROR, replacing them with theCALL_INTRINSIC_1 instruction.

  • gh-100288: Remove the LOAD_ATTR_METHOD_WITH_DICT specialized instruction.Stats show it is not useful.

  • gh-100720: Added_PyFrame_NumSlotsForCodeObject, which returns thenumber of slots needed in a frame for a given code object.

  • gh-100719: Removed the co_nplaincellvars field from the code object, as itis redundant.

  • gh-100637: Fixint.__sizeof__() calculation to include the 1-elementob_digit array for0 andFalse.

  • gh-100649: Update the native_thread_id field of PyThreadState after fork.

  • gh-100126: Fix an issue where "incomplete" frames could be briefly visibleto C code while other frames are being torn down, possibly resulting incorruption or hard crashes of the interpreter while running finalizers.

  • gh-87447: FixSyntaxError on comprehension rebind checking withnames that are not actually redefined.

    Now reassigningb in[(b:=1)fora,b.propinsome_iter] isallowed. Reassigninga is still disallowed as perPEP 572.

  • gh-100268: Addint.is_integer() to improve duck type compatibilitybetweenint andfloat.

  • gh-100425: Improve the accuracy ofsum() with compensated summation.

  • gh-100374: Fix incorrect result and delay insocket.getfqdn(). Patchby Dominic Socular.

  • gh-100357: Convertvars,dir,next,getattr, anditerto argument clinic.

  • gh-100117: Improve the output ofcodeobject.co_lines() by emittingonly one entry for each line range.

  • gh-90043: Handle NaNs when specializingCOMPARE_OP forfloat values.

  • gh-100222: Redefine the_Py_CODEUNIT typedef as a union to describeits layout to the C compiler, avoiding type punning and improving clarity.

  • gh-99955: Internal compiler functions (in compile.c) now consistentlyreturn -1 on error and 0 on success.

  • gh-100188: TheBINARY_SUBSCR_LIST_INT andBINARY_SUBSCR_TUPLE_INTinstructions are no longer used for negative integers because thoseinstructions always miss when encountering negative integers.

  • gh-99110: Initialize frame->previous in frameobject.c to fix asegmentation fault when accessing frames created byPyFrame_New().

  • gh-94155: Improved the hashing algorithm for code objects, mitigating somehash collisions.

  • gh-99540:None now hashes to a constant value. This is not arequirements change.

  • gh-100143: When built with--enable-pystats, stats collection is nowoff by default. To enable it early at startup, pass the-Xpystatsflag. Stats are now always dumped, even if switched off.

  • gh-100146: ImproveBUILD_LIST opcode so that it works similarly to theBUILD_TUPLE opcode, by stealing references from the stack rather thanrepeatedly using stack operations to set list elements. Implementationdetails are in a new private API_PyList_FromArraySteal().

  • gh-100110: SpecializeFOR_ITER for tuples.

  • gh-100050: Honor existing errors obtained when searching for mismatchingparentheses in the tokenizer. Patch by Pablo Galindo

  • gh-92216: Improve the performance ofhasattr() for type objects witha missing attribute.

  • gh-99582: Freezezipimport module into_bootstrap_python.

  • gh-99554: Pack debugging location tables more efficiently during bytecodecompilation.

  • gh-98522: Add an internal version number to code objects, to give betterversioning of inner functions and comprehensions, and thus betterspecialization of those functions. This change is invisible to both Pythonand C extensions.

  • gh-94603: Improve performance oflist.pop for small lists.

  • gh-89051: Addssl.OP_LEGACY_SERVER_CONNECT

  • bpo-32782:ctypes arrays of length 0 now report a correct itemsizewhen amemoryview is constructed from them, rather than always givinga value of 0.

Library

Documentation

Tests

  • gh-100454: Start running SSL tests with OpenSSL 3.1.0-beta1.

  • gh-100086: The Python test runner (libregrtest) now logs Python buildinformation like "debug" vs "release" build, or LTO and PGO optimizations.Patch by Victor Stinner.

  • gh-93018: Make two tests forgiving towards host system libexpat withbackported security fixes applied.

Build

  • gh-100540: Removed the--with-system-fficonfigure option;libffi must now always be supplied by the system on all non-Windowsplatforms. The option has had no effect on non-Darwin platforms forseveral releases, and in 3.11 only had the non-obvious effect of invokingpkg-config to findlibffi and never setting-DUSING_APPLE_OS_LIBFFI. Now on Darwin platformsconfigure willfirst check for the OSlibffi and then fall back to the sameprocessing as other platforms if it is not found.

  • gh-88267: Avoid exporting Python symbols in linked Windows applicationswhen the core is built as static.

  • bpo-41916: Allow override of ac_cv_cxx_thread so that cross compiledpython can set -pthread for CXX.

Windows

  • gh-100180: Update Windows installer to OpenSSL 1.1.1s

  • gh-99191: Use_MSVC_LANG>=202002L instead of less-precise_MSC_VER>=1929 to more accurately test for C++20 support inPC/_wmimodule.cpp.

  • gh-79218: DefineMS_WIN64 for Mingw-w64 64bit, fix cython compilationfailure.

  • gh-99941: Ensure thatasyncio.Protocol.data_received() receives animmutablebytes object (as documented), instead ofbytearray.

  • bpo-43984:winreg.SetValueEx() now leaves the target value untouchedin the case of conversion errors. Previously,-1 would be written incase of such errors.

  • bpo-34816:hasattr(ctypes.windll,'nonexistant') now returnsFalseinstead of raisingOSError.

macOS

  • gh-100180: Update macOS installer to OpenSSL 1.1.1s

  • gh-100540: Removed obsoletedlfcn.h shim from the_ctypesextension module, which has not been necessary since Mac OS X 10.2.

Tools/Demos

  • bpo-45256: Fix a bug that caused anAttributeError to be raised inpython-gdb.py whenpy-locals is used without a frame.

  • gh-100342: Add missingNULL check for possible allocation failure in*args parsing in Argument Clinic.

C API

  • gh-99947: Raising SystemError on import will now have its cause be set tothe original unexpected exception.

  • gh-99240: In argument parsing, after deallocating newly allocated memory,reset its pointer to NULL.

  • gh-98724: ThePy_CLEAR,Py_SETREF andPy_XSETREF macros now only evaluate their arguments once. If anargument has side effects, these side effects are no longer duplicated.Patch by Victor Stinner.

Python 3.12.0 alpha 3

Release date: 2022-12-06

Security

  • gh-100001:python-mhttp.server no longer allows terminal controlcharacters sent within a garbage request to be printed to the stderrserver log.

    This is done by changing thehttp.serverBaseHTTPRequestHandler.log_message method to replace controlcharacters with a\xHH hex escape before printing.

  • gh-87604: Avoid publishing list of active per-interpreter audit hooks viathegc module

Core and Builtins

  • gh-99891: Fix a bug in the tokenizer that could cause infinite recursionwhen showing syntax warnings that happen in the first line of the source.Patch by Pablo Galindo

  • gh-91054: AddPyCode_AddWatcher() andPyCode_ClearWatcher() APIs to register callbacks to receivenotification on creation and destruction of code objects.

  • gh-99729: Fix an issue that could cause frames to be visible to Pythoncode as they are being torn down, possibly leading to memory corruption orhard crashes of the interpreter.

  • gh-99708: Fix bug where compiler crashes on an if expression with an emptybody block.

  • gh-99578: Fix a reference bug in_imp.create_builtin() after thecreation of the first sub-interpreter for modulesbuiltins andsys. Patch by Victor Stinner.

  • gh-99581: Fixed a bug that was causing a buffer overflow if the tokenizercopies a line missing the newline character from a file that is as long asthe available tokenizer buffer. Patch by Pablo galindo

  • gh-99553: Fix bug where anExceptionGroup subclass can wrap aBaseException.

  • gh-99547: Add a function to os.path to check if a path is a junction:isjunction. Add similar functionality to pathlib.Path as is_junction.

  • gh-99370: Fix zip path for venv created from a non-installed python onPOSIX platforms.

  • gh-99377: Add audit events for thread creation and clear operations.

  • gh-98686: Remove theBINARY_OP_GENERIC andCOMPARE_OP_GENERIC"specializations".

  • gh-99298: Remove the remaining error paths for attribute specializations,and refuse to specialize attribute accesses on types that haven't hadPyType_Ready() called on them yet.

  • gh-99127: Allow some features ofsyslog to the main interpreteronly. Patch by Donghee Na.

  • gh-91053: Optimizing interpreters and JIT compilers may need to invalidateinternal metadata when functions are modified. This change adds theability to provide a callback that will be invoked each time a function iscreated, modified, or destroyed.

  • gh-90994: Improve error messages when there's a syntax error with callarguments. The following three cases are covered: - No value is assignedto a named argument, egfoo(a=). - A value is assigned to a starargument, egfoo(*args=[0]). - A value is assigned to a double-starkeyword argument, egfoo(**kwarg={'a':0}).

  • bpo-45026: Optimize therange object iterator. It is now smaller,faster iteration of ranges containing large numbers. Smaller pickles,faster unpickling.

  • bpo-31718: RaiseValueError instead ofSystemError whenmethods of uninitializedio.IncrementalNewlineDecoder objects arecalled. Patch by Oren Milman.

  • bpo-38031: Fix a possible assertion failure inio.FileIO when theopener returns an invalid file descriptor.

Library

  • gh-100001: Also escape s in the http.serverBaseHTTPRequestHandler.log_message so that it is technically possible toparse the line and reconstruct what the original data was. Without this axHH is ambiguous as to if it is a hex replacement we put in or thecharacters r"x" came through in the original request line.

  • gh-99957: Addfrozen_default parameter totyping.dataclass_transform().

  • gh-79033: Fixasyncio.Server.wait_closed() to actually do what thedocs promise -- wait for all existing connections to complete, afterclosing the server.

  • gh-51524: Fix bug when calling trace.CoverageResults with valid infile.

  • gh-99645: Fix a bug in handling class cleanups inunittest.TestCase. NowaddClassCleanup() uses separate listsfor differentTestCase subclasses, anddoClassCleanups() onlycleans up the particular class.

  • gh-99508: FixTypeError inLib/importlib/_bootstrap_external.pywhile calling_imp.source_hash().

  • gh-66285: Fixasyncio to not share event loop and signal wakeupfdin forked processes. Patch by Kumar Aditya.

  • gh-97001: Release the GIL when calling termios APIs to avoid blockingthreads.

  • gh-92647: Use final status of an enum to determine lookup or creationbranch of functional API.

  • gh-99388: Addloop_factory parameter toasyncio.run() to allowspecifying a custom event loop factory. Patch by Kumar Aditya.

  • gh-99341: Fixast.increment_lineno() to also coverast.TypeIgnore when changing line numbers.

  • gh-99382: Check the number of arguments in substitution in user genericscontaining aTypeVarTuple and one or moreTypeVar.

  • gh-99379: Fix substitution ofParamSpec followed byTypeVarTuple in generic aliases.

  • gh-99344: Fix substitution ofTypeVarTuple andParamSpec together in user generics.

  • gh-99284: Remove_use_broken_old_ctypes_structure_semantics_ olduntested and undocumented hack fromctypes.

  • gh-99201: FixIndexError when initializing the config variables onWindows ifHAVE_DYNAMIC_LOADING is not set.

  • gh-99240: Fix double-free bug in Argument Clinicstr_converter byextracting memory clean up to a newpost_parsing section.

  • gh-64490: Fix refcount error when arguments are packed to tuple inArgument Clinic.

  • gh-99029:pathlib.PurePath.relative_to() now treats naked Windowsdrive paths as relative. This brings its behaviour in line with otherparts of pathlib.

  • gh-98253: The implementation of the typing module is now more resilient toreference leaks in binary extension modules.

    Previously, a reference leak in a typed C API-based extension module couldleak internals of the typing module, which could in turn introduce leaksin essentially any other package with typed function signatures. Althoughthe typing package is not the original source of the problem, suchnon-local dependences exacerbate debugging of large-scale projects, andthe implementation was therefore changed to reduce harm by providingbetter isolation.

  • gh-98458: Fix infinite loop in unittest when a self-referencing chainedexception is raised

  • gh-93453:asyncio.get_event_loop() and many otherasynciofunctions likeasyncio.ensure_future(),asyncio.shield() orasyncio.gather(), and also theget_event_loop() method ofasyncio.BaseDefaultEventLoopPolicy now raise aRuntimeError if called when there is no running event loop and thecurrent event loop was not set. Previously they implicitly created and seta new current event loop.DeprecationWarning is no longer emittedif there is no running event loop but the current event loop was set.

  • gh-97966: Onuname_result, restored expectation that_fields and_asdict would include all six properties includingprocessor.

  • gh-98248: Provide informative error messages instruct.pack() whenits integral arguments are not in range.

  • gh-98108:zipfile.Path is now pickleable if its initializationparameters were pickleable (e.g. for file system paths).

  • gh-98098: Created packages from zipfile and test_zipfile modules,separatingzipfile.Path functionality.

  • gh-82836: Fixis_private properties in theipaddress module. Previously non-private networks (0.0.0.0/0) wouldreturnTrue from this method; now they correctly returnFalse.

  • gh-96828: Add anOP_ENABLE_KTLS option for enabling the useof the kernel TLS (kTLS). Patch by Illia Volochii.

  • gh-88863: To avoid apparent memory leaks whenasyncio.open_connection() raises, break reference cycles generatedby local exception and future instances (which has exception instance asits member var). Patch by Dong Uk, Kang.

  • gh-91078:TarFile.next() now returnsNone when called on anempty tarfile.

  • bpo-47220: Document the optionalcallback parameter ofWeakMethod. Patch by Géry Ogam.

  • bpo-44817: Ignore WinError 53 (ERROR_BAD_NETPATH), 65(ERROR_NETWORK_ACCESS_DENIED) and 161 (ERROR_BAD_PATHNAME) when usingntpath.realpath().

  • bpo-41260: Rename thefmt parameter of the pure Python implementation ofdatetime.date.strftime() toformat.

  • bpo-15999: All built-in functions now accept arguments of any type insteadof justbool andint for boolean parameters.

Documentation

  • gh-99931: Usesphinxext-opengraph to generateOpenGraphmetadata.

  • gh-89682: Reworded docstring of the default__contains__ to clarifythat it returns abool.

  • gh-88330: Improved the description of what a resource is inimportlib.resources docs.

  • gh-92892: Document that calling variadic functions with ctypes requiresspecial care on macOS/arm64 (and possibly other platforms).

  • bpo-41825: Restructured the documentation for theos.wait* family of functions, and improved the docs foros.waitid() with more explanation of the possible argumentconstants.

Tests

  • gh-99892: Skip test_normalization() of test_unicodedata if it fails todownload NormalizationTest.txt file from pythontest.net. Patch by VictorStinner.

  • gh-99934: Correct test_marsh on (32 bit) x86: test_deterministic sets wasfailing.

  • gh-99741: We've implemented multi-phase init (PEP 489/630/687) for theinternal (for testing) _xxsubinterpreters module.

  • gh-99659: Optional big memory tests intest_sqlite3 now catch thecorrectsqlite.DataError exception type in case of too largestrings and/or blobs passed.

  • gh-99593: Cover the Unicode C API with tests.

  • gh-96002: Add functional test for Argument Clinic.

Build

  • gh-99086: Fix-Wimplicit-int,-Wstrict-prototypes, and-Wimplicit-function-declaration compiler warnings inconfigure checks.

  • gh-99337: Fix a compilation issue with GCC 12 on macOS.

  • gh-99289: Add aCOMPILEALL_OPTS variable in Makefile to overridecompileall options (default:-j0) inmakeinstall. Alsomerged thecompileall commands into a single command building .pycfiles for the all optimization levels (0, 1, 2) at once. Patch by VictorStinner.

  • gh-98872: Fix a possible fd leak inPrograms/_freeze_module.cintroduced in Python 3.11.

  • gh-88226: Always defineTARGET_* labels inPython/ceval.c, even ifUSE_COMPUTED_GOTOS is disabled. This allows breakpoints to be set atthose labels in (for instance)gdb.

Windows

macOS

  • gh-87235: On macOSpython3/dev/fd/99</path/to/script.py failed forany script longer than a couple of bytes.

  • gh-98940: FixMac/Extras.install.py file filter bug.

Tools/Demos

  • gh-64490: Argument Clinic varargs bugfixes

    • Fix out-of-bounds error in_PyArg_UnpackKeywordsWithVararg().

    • Fix incorrect check which allowed more than one varargs in clinic.py.

    • Fix miscalculation ofnoptargs in generated code.

    • Do not generatenoptargs when there is a vararg argument and no optional argument.

C API

  • gh-98680:PyBUF_* constants were marked as part of Limited API ofPython 3.11+. These were available in 3.11.0 withPy_LIMITED_API defined for 3.11, and are necessary to use thebuffer API.

  • gh-99612: FixPyUnicode_DecodeUTF8Stateful() for ASCII-only data:*consumed was not set.

  • gh-47146: Thestructmember.h header is deprecated. Its non-deprecatedcontents are now available just by includingPython.h, with aPy_prefix added if it was missing. (Deprecated contents areT_OBJECT,T_NONE, and no-op flags.) Patch by PetrViktorin, based on earlier work by Alexander Belopolsky and MatthiasBraun.

Python 3.12.0 alpha 2

Release date: 2022-11-14

Security

  • gh-98433: The IDNA codec decoder used on DNS hostnames bysocket orasyncio related name resolution functions no longer involves aquadratic algorithm. This prevents a potential CPU denial of service if anout-of-spec excessive length hostname involving bidirectional characterswere decoded. Some protocols such asurllib http3xxredirects potentially allow for an attacker to supply such a name.

    Individual labels within an IDNA encoded DNS name will now raise an errorearly during IDNA decoding if they are longer than 1024 unicode charactersgiven that each decoded DNS label must be 63 or fewer characters and theentire decoded DNS name is limited to 255. Only an application presentinga hostname or label consisting primarily ofRFC 3454 section 3.1"Nothing" characters to be removed would run into of this new limit. SeealsoRFC 5894 section 6 andRFC 3491.

  • gh-98739: Update bundled libexpat to 2.5.0

Core and Builtins

  • gh-81057: The docs clearly say thatPyImport_Inittab,PyImport_AppendInittab(), andPyImport_ExtendInittab()should not be used afterPy_Initialize() has been called. We nowenforce this for the two functions. Additionally, the runtime now uses aninternal copy ofPyImport_Inittab, to guard against modification.

  • gh-99298: Fix an issue that could potentially cause incorrect errorhandling for some bytecode instructions.

  • gh-99254: The compiler now removes all unused constants from code objects(except the first one, which may be a docstring).

  • gh-99205: Fix an issue that preventedPyThreadState andPyInterpreterState memory from being freed properly.

  • gh-81057: The 18 global C variables holding the state of the allocatorshave been moved to_PyRuntimeState. This is a strictly internalchange with no change in behavior.

  • gh-99181: Fix failure inexcept* with unhashableexceptions.

  • gh-99204: Fix calculation ofsys._base_executable when inside aPOSIX virtual environment using copies of the python binary when the baseinstallation does not provide the executable name used by the venv.Calculation will fall back to alternative names ("python<MAJOR>","python<MAJOR>.<MINOR>").

  • gh-96055: Updatefaulthandler to emit an error message with theproper unexpected signal number. Patch by Donghee Na.

  • gh-99153: Fix location ofSyntaxError for atry blockwith bothexcept andexcept*.

  • gh-98686: Merge the adaptive opcode logic into each instruction'sunquickened variant, and merge the logic inEXTENDED_ARG_QUICK intoEXTENDED_ARG. With these changes, the quickening that happens atcode object creation is now only responsible for initializing warmupcounters and inserting superinstructions.

  • gh-99103: Fix the error reporting positions of specialized tracebackanchors when the source line contains Unicode characters.

  • gh-99139: Improve the error suggestion forNameError exceptions forinstances. Now if aNameError is raised in a method and theinstance has an attribute that's exactly equal to the name in theexception, the suggestion will includeself.<NAME> instead of theclosest match in the method scope. Patch by Pablo Galindo

  • gh-98401: Octal escapes with value larger than0o377 (ex:"\477"),deprecated in Python 3.11, now produce aSyntaxWarning, instead ofDeprecationWarning. In a future Python version they will beeventually aSyntaxError. Patch by Victor Stinner.

  • gh-98401: A backslash-character pair that is not a valid escape sequencenow generates aSyntaxWarning, instead ofDeprecationWarning. For example,re.compile("\d+\.\d+") nowemits aSyntaxWarning ("\d" is an invalid escape sequence), useraw strings for regular expression:re.compile(r"\d+\.\d+"). In afuture Python version,SyntaxError will eventually be raised,instead ofSyntaxWarning. Patch by Victor Stinner.

  • gh-96793: Handle StopIteration and StopAsyncIteration raised in generatoror coroutines in the bytecode, rather than in wrapping C code.

  • gh-98931: Improve theSyntaxError error message when the user typesimportxfromy instead offromyimportx. Patch by Pablo Galindo

  • gh-98852: Fix subscription of type aliases containing bare generic typesor types likeTypeVar: for exampletuple[A,T][int]andtuple[TypeVar,T][int], whereA is a generic type, andTis a type variable.

  • gh-98925: Lower the recursion depth for marshal on WASI to support(in-development) wasmtime 2.0.

  • gh-98783: Fix multiple crashes in debug mode whenstr subclasses areused instead ofstr itself.

  • gh-98811: Use complete source locations to simplify detection of__future__ imports which are not at the beginning of the file. Alsocorrects the offset in the exception raised in one case, which was off byone and impeded highlighting.

  • gh-96793: Add specialization ofFOR_ITER for generators. Savesmultiple layers of dispatch and checking to get from theFOR_ITER instruction in the caller to theRESUME inthe generator.

  • gh-98762: Fix source locations ofmatch sub-patterns.

  • gh-98586: Added the methodsPyObject_Vectorcall() andPyObject_VectorcallMethod() to theLimited APIalong with the auxiliary macro constantPY_VECTORCALL_ARGUMENTS_OFFSET.

    The availability of these functions enables more efficientPEP 590vector calls from binary extension modules that avoid argumentboxing/unboxing overheads.

  • gh-99257: Fix an issue where member descriptors (such as those for__slots__) could behave incorrectly or crash instead ofraising aTypeError when accessed via an instance of an invalidtype.

  • gh-93143: Rather than changingco_code, theinterpreter will now display aRuntimeWarning and assignNone to any fast locals that are left unbound after jumps ordel statements executed while tracing.

  • gh-96421: When calling into Python code from C code, throughPyEval_EvalFrameEx() or a related C-API function, a shim frame ininserted into the call stack. This occurs in the_PyEval_EvalFrameDefault() function. The extra frame should beinvisible to all Python and most C extensions, but out-of-processprofilers and debuggers need to be aware of it. These shim frames can bedetected by checkingframe->owner==FRAME_OWNED_BY_CSTACK.

    Extensions implementing their own interpreters using PEP 523 need to beaware of this shim frame and the changes to the semantics ofRETURN_VALUE,YIELD_VALUE, andRETURN_GENERATOR, which now clear the frame.

  • gh-98415: Fix detection of MAC addresses foruuid on certain OSs.Patch by Chaim Sanders

  • gh-98686: Quicken all code objects, and specialize adaptive bytecodeinstructions more aggressively.

  • gh-92119: Print exception class name instead of its string representationwhen raising errors fromctypes calls.

  • gh-91058:ImportError raised from failedfrom<module>import<name> now include suggestions for the value of<name> based on theavailable names in<module>. Patch by Pablo Galindo

  • gh-96793: TheFOR_ITER now leaves the iterator on the stack ontermination of the loop. This is to assist specialization of loops forgenerators.

  • gh-90716: Add _pylong.py module. It includes asymptotically fasteralgorithms that can be used for operations on integers with many digits.It is used by longobject.c to speed up some operations.

  • gh-95389: ExposeETH_P_ALL and some of theETHERTYPE_* constants insocket.Patch by Noam Cohen.

  • gh-93696: Allowpdb to locate source for frozen modules in thestandard library.

Library

Documentation

  • gh-98832: Changes wording of docstring forpathlib.Path.iterdir().

  • gh-97966: Update uname docs to clarify the special nature of the platformattribute and to indicate when it became late-bound.

Tests

  • gh-98903: The Python test suite now fails with exit code 4 if no testsran. It should help detecting typos in test names and test methods.

  • gh-98713: Fix a bug in thetyping tests where a test relying onCPython-specific implementation details was not decorated with@cpython_only and was not skipped on other implementations.

  • gh-87390: Add tests for star-unpacking with PEP 646, and some othermiscellaneous PEP 646 tests.

  • gh-96853: Added explicit coverage ofPy_Initialize (and hencePy_InitializeEx) back to the embedding tests (all other embeddingtests migrated toPy_InitializeFromConfig in Python 3.11)

  • bpo-34272: Some C API tests were moved into the new Lib/test/test_capi/directory.

Build

  • gh-99086: Fix-Wimplicit-int compiler warning inconfigurecheck forPTHREAD_SCOPE_SYSTEM.

  • gh-99016: Fix build withPYTHON_FOR_REGEN=python3.8.

  • gh-97731: Specify the full path to the source location formakedocclean (needed for cross-builds).

  • gh-98949: Drop unused build dependency onreadelf.

  • gh-98989: Usepython3.11, if available, for regeneration and freezing.

  • gh-98831: Add new tooling, inTools/cases_generator, to generate theinterpreter switch statement from a list of opcode definitions. This onlyaffects adding, modifying or removing instruction definitions. Theinstruction definitions now live inPython/bytecodes.c, in the form ofacustom DSL (under development).The tooling reads this file and writesPython/generated_cases.c.h,which is then included byPython/ceval.c to provide most of the casesof the main interpreter switch.

  • gh-98817: Remove PCbuild/lib.pyproj: it's not used for anything, is only aminor convenience for Visual Studio users (who probably mostly don't evenknow about it), and it takes a lot of maintenance effort to keep updated.

  • gh-98776: Fixmakeregen-test-levenshtein for out-of-tree builds.

  • gh-98707: Don't use vendoredlibmpdec headers if--with-system-libmpdec is passed toconfigure. Don'tuse vendoredlibexpat headers if--with-system-expat ispassed toconfigure.

Windows

  • gh-98689: Update Windows builds to zlib v1.2.13. v1.2.12 hasCVE 2022-37434, but the vulnerableinflateGetHeader API is not usedby Python.

  • gh-98790: Assumes that a missingDLLs directory means that standardextension modules are in the executable's directory.

  • gh-98745: Updatepy.exe launcher to install 3.11 by default and3.12 on request.

  • gh-98692: Fix thePython Launcher for Windows ignoring unrecognized shebang linesinstead of treating them as local paths

  • gh-94328: Update Windows installer to use SQLite 3.39.4.

macOS

  • gh-94328: Update macOS installer to SQLite 3.39.4.

C API

  • gh-98724: ThePy_CLEAR,Py_SETREF andPy_XSETREF macros now only evaluate their argument once. If theargument has side effects, these side effects are no longer duplicated.Patch by Victor Stinner.

  • gh-98978: Fix use-after-free inPy_SetPythonHome(NULL),Py_SetProgramName(NULL) and_Py_SetProgramFullPath(NULL) functioncalls. Issue reported by Benedikt Reinartz. Patch by Victor Stinner.

  • gh-98410: Addgetbufferproc andreleasebufferproc to the stableAPI.

  • gh-98610: Some configurable capabilities of sub-interpreters have changed.They always allow subprocesses (subprocess) now, whereas beforesubprocesses could be optionally disallowed for a sub-interpreter. Insteados.exec() can now be disallowed. Disallowing daemon threads is nowsupported. Disallowing all threads is still allowed, but is never done bydefault. Note that the optional restrictions are only available through_Py_NewInterpreterFromConfig(), which isn't a public API. They do notaffect the main interpreter, norPy_NewInterpreter().

  • gh-98608: A_PyInterpreterConfig has been added and_Py_NewInterpreter() has been renamed to_Py_NewInterpreterFromConfig(). The "isolated_subinterpreters"argument is now a granular config that captures the previous behavior.Note that this is all "private" API.

  • gh-96853:Py_InitializeEx now correctly callsPyConfig_Clear afterinitializing the interpreter (the omission didn't cause a memory leak onlybecause none of the dynamically allocated config fields are populated bythe wrapper function)

  • gh-91248: AddPyFrame_GetVar() andPyFrame_GetVarString()functions to get a frame variable by its name. Patch by Victor Stinner.

Python 3.12.0 alpha 1

Release date: 2022-10-25

Security

  • gh-97616: Fix multiplying a list by an integer (list*=int): detectthe integer overflow when the new allocated length is close to the maximumsize. Issue reported by Jordan Limor. Patch by Victor Stinner.

  • gh-97514: On Linux themultiprocessing module returns to usingfilesystem backed unix domain sockets for communication with theforkserver process instead of the Linux abstract socket namespace. Onlycode that chooses to use the"forkserver" start method is affected.

    Abstract sockets have no permissions and could allow any user on thesystem in the samenetwork namespace (oftenthe whole system) to inject code into the multiprocessingforkserverprocess. This was a potential privilege escalation. Filesystem basedsocket permissions restrict this to theforkserver process user as wasthe default in Python 3.8 and earlier.

    This prevents LinuxCVE 2022-42919.

  • gh-87389:http.server: Fix an open redirection vulnerability in theHTTP server when an URI path starts with//. Vulnerabilitydiscovered, and initial fix proposed, by Hamza Avvan.

  • gh-79096: LWPCookieJar and MozillaCookieJar create files with file mode600 instead of 644 (Microsoft Windows is not affected)

  • gh-92888: Fixmemoryview use after free when accessing the backingbuffer in certain cases.

  • gh-68966: The deprecated mailcap module now refuses to inject unsafe text(filenames, MIME types, parameters) into shell commands. Instead of usingsuch text, it will warn and act as if a match was not found (or for testcommands, as if the test failed).

Core and Builtins

  • gh-98374: Suppress ImportError for invalid query for help() command. Patchby Donghee Na.

  • gh-98461: Fix source location in bytecode for list, set and dictcomprehensions as well as generator expressions.

  • gh-98354: Added unicode check forname attribute ofspec argumentpassed in_imp.create_builtin() function.

  • gh-98398: Fix source location of 'assert' bytecodes.

  • gh-98390: Fix location of sub-expressions of boolean expressions, byreducing their scope to that of the sub-expression.

  • gh-98254: Modules from the standard library are now potentially suggestedas part of the error messages displayed by the interpreter when anNameError is raised to the top level. Patch by Pablo Galindo

  • gh-97997: Add running column offset to the tokenizer state to avoidcalculating AST column information with pointer arithmetic.

  • gh-97973: Modify the tokenizer to return all necessary information theparser needs to set location information in the AST nodes, so that theparser does not have to calculate those doing pointer arithmetic.

  • gh-96078:os.sched_yield() now release the GIL while callingsched_yield(2). Patch by Donghee Na.

  • gh-97955: Migratezoneinfo to Argument Clinic.

  • gh-97912: The compiler now avoids quadratic behavior when finding whichinstructions should use theLOAD_FAST_CHECK opcode.

  • gh-97002: Fix an issue where several frame objects could be backed by thesame interpreter frame, possibly leading to corrupted memory and hardcrashes of the interpreter.

  • gh-97943: Bugfix:PyFunction_GetAnnotations() should return aborrowed reference. It was returning a new reference.

  • gh-97922: The Garbage Collector now runs only on the eval breakermechanism of the Python bytecode evaluation loop instead on objectallocations. The GC can also run whenPyErr_CheckSignals() iscalled so C extensions that need to run for a long time without executingany Python code also have a chance to execute the GC periodically.

  • gh-65961: When__package__ is different than__spec__.parent,raise aDeprecationWarning instead ofImportWarning.

    Also removeimportlib.util.set_package() which was scheduled forremoval.

  • gh-97850: Long deprecated,module_repr() should now be completelyeradicated.

  • gh-86298: In cases wherewarnings.warn_explicit() consults themodule's loader, anDeprecationWarning is issued whenm.__loader__differs fromm.__spec__.loader.

  • gh-97779: Ensure that all Python frame objects are backed by "complete"frames.

  • gh-91052: Add API for subscribing to modification events on selecteddictionaries.

  • gh-97752: Fix possible data corruption or crashes when accessing thef_back member of newly-created generator or coroutine frames.

  • gh-97591: Fixed a missing incref/decref pair inException.__setstate__(). Patch by Ofey Chan.

  • gh-97670: Remove thesys.getdxp() function and theTools/scripts/analyze_dxp.py script. DXP stands for "dynamic executionpairs". They were related toDYNAMIC_EXECUTION_PROFILE andDXPAIRSmacros which have been removed in Python 3.11. Python can now be builtwith./configure--enable-pystats to gatherstatistics on Python opcodes. Patch by Victor Stinner.

  • gh-94526: Fix the Python path configuration used to initializedsys.path at Python startup. Paths are no longer encoded toUTF-8/strict to avoid encoding errors if it contains surrogate characters(bytes paths are decoded with the surrogateescape error handler). Patch byVictor Stinner.

  • gh-96670: The parser now raisesSyntaxError when parsing sourcecode containing null bytes. Patch by Pablo Galindo

  • gh-96975: Fix a crash occurring whenPyEval_GetFrame() is calledwhile the topmost Python frame is in a partially-initialized state.

  • gh-96848: Fix command line parsing: reject-Xint_max_str_digits option with no value (invalid) when thePYTHONINTMAXSTRDIGITS environment variable is set to a validlimit. Patch by Victor Stinner.

  • gh-95921: Fix overly-broad source position information for chainedcomparisons used as branching conditions.

  • gh-96821: Fix undefined behaviour inaudioop.c.

  • gh-96821: Fix undefined behaviour in_testcapimodule.c.

  • gh-95778: WhenValueError is raised if an integer is larger thanthe limit, mention thesys.set_int_max_str_digits() function in theerror message. Patch by Victor Stinner.

  • gh-96387: At Python exit, sometimes a thread holding the GIL can waitforever for a thread (usually a daemon thread) which requested to drop theGIL, whereas the thread already exited. To fix the race condition, thethread which requested the GIL drop now resets its request before exiting.Issue discovered and analyzed by Mingliang ZHAO. Patch by Victor Stinner.

  • gh-96864: Fix a possible assertion failure, fatal error, orSystemError if a line tracing event raises an exception whileopcode tracing is enabled.

  • gh-95778: ThePyLong_FromString function was refactored to make itmore maintainable and extensible.

  • gh-96678: Fix undefined behaviour in C code of null pointer arithmetic.

  • gh-96754: Make sure that all frame objects created are created from validinterpreter frames. Prevents the possibility of invalid frames inbacktraces and signal handlers.

  • gh-90997: Improve the performance of reading and writing inline bytecodecaches on some platforms.

  • gh-96751: Remove dead code fromCALL_FUNCTION_EX opcode.

  • gh-90751:memoryview now supports half-floats. Patch by DongheeNa and Antoine Pitrou.

  • gh-96678: Fix case of undefined behavior in ceval.c

  • gh-64373: Convert_functools to argument clinic.

  • gh-96641: Do not exposeKeyWrapper in_functools.

  • gh-96636: Ensure that tracing,sys.setrace(), is turned onimmediately. In pre-release versions of 3.11, some tracing events mighthave been lost when turning on tracing in a__del__ method orinterrupt.

  • gh-96572: Fix use after free in trace refs build mode. Patch by KumarAditya.

  • gh-96611: When loading a file with invalid UTF-8 inside a multi-linestring, a correct SyntaxError is emitted.

  • gh-96612: Make sure that incomplete frames do not show up in tracemalloctraces.

  • gh-90230: Fix compiler warnings and test failures when building with--enable-pystats.

  • gh-96587: Correctly raiseSyntaxError on exception groups (PEP 654)on python versions prior to 3.11

  • gh-96569: Remove two cases of undefined behavior, by adding NULL checks.

  • gh-96582: Fix possibleNULL pointer dereference in_PyThread_CurrentFrames. Patch by Kumar Aditya.

  • gh-91079: Separate Python recursion checking from C recursion checkingwhich reduces the chance of C stack overflow and allows the recursionlimit to be increased safely.

  • gh-93911: Fix an issue that could preventLOAD_ATTR fromspecializing properly when accessing properties.

  • gh-96348: Emit a DeprecationWarning whenthrow(),throw() orathrow() are called with more thanone argument.

  • gh-95196: Disable incorrect pickling of the C implemented classmethoddescriptors.

  • gh-96364: Fix text signatures oflist.__getitem__ anddict.__getitem__.

  • gh-96352: FixAttributeError missingname andobjattributes inobject.__getattribute__(). Patch by Philip Georgi.

  • gh-93554: Change the jump opcodes so that all conditional jumps areforward jumps. Backward jumps are converted by the assembler into aconditional forward jump whose target is the fallthrough block (and with areversed condition), followed by an unconditional backward jump. Forexample:

    POP_JUMP_IF_TRUEBACKWARD_TARGET becomesPOP_JUMP_IF_FALSENEXT_BLOCK;JUMPBACKWARD_TARGET.

    All the directed conditional jump opcodes were removed:POP_JUMP_FORWARD_IF_TRUE,POP_JUMP_BACKWARD_IF_TRUE,POP_JUMP_FORWARD_IF_FALSE,POP_JUMP_BACKWARD_IF_FALSE,POP_JUMP_FORWARD_IF_NONE,POP_JUMP_BACKWARD_IF_NONE,POP_JUMP_FORWARD_IF_NOT_NONE,POP_JUMP_BACKWARD_IF_NOT_NONE.

    The corresponding opcodes without direction are no longerpseudo-instructions, and they implement the forward conditional jumps.

  • gh-96268: Loading a file with invalid UTF-8 will now report the brokencharacter at the correct location.

  • gh-96237: The internal field_PyInterpreterFrame.f_func is renamed to_PyInterpreterFrame.f_funcobj and may be any object. Thef_globalsandf_builtin fields may hold junk values.

    It is safest to treat the_PyInterpreterFrame struct as opaque.

  • gh-96187: Fixed a bug that caused_PyCode_GetExtra to return garbagefor negative indexes. Patch by Pablo Galindo

  • gh-96143: Add a new-Xperf Python command line option as well assys.activate_stack_trampoline() andsys.deactivate_stack_trampoline() function in thesys modulethat allows to set/unset the interpreter in a way that the Linuxperfprofiler can detect Python calls. The newsys.is_stack_trampoline_active() function allows to query the stateof the perf trampoline. Design by Pablo Galindo. Patch by Pablo Galindoand Christian Heimes with contributions from Gregory P. Smith [Google] andMark Shannon.

  • gh-96071: Fix a deadlock inPyGILState_Ensure() when allocatingnew thread state. Patch by Kumar Aditya.

  • gh-96046:PyType_Ready() now initializesht_cached_keys andperforms additional checks to ensure that type objects are properlyconfigured. This avoids crashes in 3rd party packages that don't useregular API to create new types.

  • gh-96005: On WASIENOTCAPABLE is now mapped toPermissionError. Theerrno modules exposes the new errornumber.getpath.py now ignoresPermissionError when it cannotopen landmark filespybuilddir.txt andpyenv.cfg.

  • gh-93678: Added test a harness for direct unit tests of the compiler'soptimization stage. The_testinternalcapi.optimize_cfg() function runsthe optimiser on a sequence of instructions. TheCfgOptimizationTestCase class intest.support has utilities forinvoking the optimizer and checking the output.

  • gh-95245: Reduces the size of a "simple" Python object from 8 to 6 wordsby moving the weakreflist pointer into the pre-header directly before theobject's dict/values pointer.

  • gh-90997: Compile virtualtry/except blocks tohandle exceptions raised duringclose() orthrow() calls through a suspended frame.

  • gh-95977: Optimized calling__get__() with vectorcall. Patchby Kumar Aditya.

  • gh-91210: Improve error message when a parameter without a default valuefollows one with a default value, and show the same message, even when thenon-default/default sequence is preceded by positional-only parameters.

  • gh-95922: Fixed bug where the compiler'seliminate_empty_basic_blocksfunction ignores the last block of the code unit.

  • gh-95818: Skip over incomplete frames inPyThreadState_GetFrame().

  • gh-95876: Fix format string in_PyPegen_raise_error_known_locationthat can lead to memory corruption on some 64bit systems. The function wasbuilding a tuple withi (int) instead ofn (Py_ssize_t) forPy_ssize_t arguments.

  • gh-95605: Fix misleading contents of error message when converting anall-whitespace string tofloat.

  • gh-95150: Update code object hashing and equality to consider alldebugging and exception handling tables. This fixes an issue where certainnon-identical code objects could be "deduplicated" during compilation.

  • gh-91146: Reduce allocation size oflist fromstr.split()andstr.rsplit(). Patch by Donghee Na and Inada Naoki.

  • gh-87092: Create a 'jump target label' abstraction in the compiler so thatthe compiler's codegen stage does not work directly with basic blocks.This prepares the code for changes to the underlying CFG generationmechanism.

  • gh-95355:_PyPegen_Parser_New now properly detects token memoryallocation errors. Patch by Honglin Zhu.

  • gh-90081: Run Python code in tracer/profiler function at full speed. Fixesslowdown in earlier versions of 3.11.

  • gh-95324: Emit a warning in debug mode if an object does not callPyObject_GC_UnTrack() before deallocation. Patch by Pablo Galindo.

  • gh-95245: Merge managed dict and values pointer into a single taggedpointer to save one word in the pre-header.

  • gh-93678: Add cfg_builder struct and refactor the relevant code so that acfg can be constructed without an instance of the compiler struct.

  • gh-95185: Prevented crashes in the AST constructor when compiling someabsurdly long expressions like"+0"*1000000.RecursionError isnow raised instead. Patch by Pablo Galindo

  • gh-93351:ast.AST node positions are now validated when providedtocompile() and other related functions. If invalid positions aredetected, aValueError will be raised.

  • gh-94438: Fix an issue that caused extended opcode arguments and someconditional pops to be ignored when calculating valid jump targets forassignments to thef_lineno attribute of frame objects. In some cases,this could cause inconsistent internal state, resulting in a hard crash ofthe interpreter.

  • gh-95060: UndocumentedPyCode_Addr2Location function now properlyreturns whenaddrq argument is less than zero.

  • gh-95113: Replace allEXTENDED_ARG_QUICK instructions with basicEXTENDED_ARG instructions in unquickened code. Consumers ofnon-adaptive bytecode should be able to handle extended arguments the sameway they were handled in CPython 3.10 and older.

  • gh-91409: Fix incorrect source location info caused by certainoptimizations in the bytecode compiler.

  • gh-95023: Implementos.setns() andos.unshare() for Linux.Patch by Noam Cohen.

  • gh-94036: Fix incorrect source location info for some multi-line attributeaccesses and method calls.

  • gh-94938: Fix error detection in some builtin functions when keywordargument name is an instance of a str subclass with overloaded__eq__and__hash__. Previously it could cause SystemError or other undesiredbehavior.

  • gh-94996:ast.parse() will no longer parse function definitions withpositional-only params when passedfeature_version less than(3,8). Patch by Shantanu Jain.

  • gh-94739: Allow jumping within, out of, and across exception handlers inthe debugger.

  • gh-94949:ast.parse() will no longer parse parenthesized contextmanagers when passedfeature_version less than(3,9). Patch byShantanu Jain.

  • gh-94947:ast.parse() will no longer parse assignment expressionswhen passedfeature_version less than(3,8). Patch by ShantanuJain.

  • gh-91256: Ensures the program name is known for help text duringinterpreter startup.

  • gh-94869: Fix the column offsets for some expressions in multi-linef-stringsast nodes. Patch by Pablo Galindo.

  • gh-94893: Fix an issue where frame object manipulations could corruptinline bytecode caches.

  • gh-94822: Fix an issue where lookups of metaclass descriptors may beignored when an identically-named attribute also exists on the classitself.

  • gh-91153: Fix an issue where abytearray item assignment couldcrash if it's resized by the new value's__index__() method.

  • gh-90699: Fix reference counting bug inbool.__repr__(). Patch byKumar Aditya.

  • gh-94694: Fix an issue that could cause code with multi-line methodlookups to have misleading or incorrect column offset information. In somecases (when compiling a hand-built AST) this could have resulted in a hardcrash of the interpreter.

  • gh-93252: Fix an issue that caused internal frames to outlive failedPython function calls, possibly resulting in memory leaks or hardinterpreter crashes.

  • gh-94215: Fix an issue where exceptions raised by line-tracing eventswould cause frames to be left in an invalid state, possibly resulting in ahard crash of the interpreter.

  • gh-92228: Disable the compiler's inline-small-exit-blocks optimization forexit blocks that are associated with source code lines. This fixes a bugwhere the debugger cannot tell where an exception handler ends and thefollowing code block begins.

  • gh-94485: Line number of a module'sRESUME instruction is set to 0 asspecified inPEP 626.

  • gh-94438: Account for instructions that can push NULL to the stack whensetting line number in a frame. Prevents some (unlikely) crashes.

  • gh-91719: Reloadopcode when raisingunknownopcodeerror in theinterpreter main loop, for C compilers to generate dispatching codeindependently.

  • gh-94329: Compile and run code with unpacking of extremely large sequences(1000s of elements). Such code failed to compile. It now compiles and runscorrectly.

  • gh-94360: Fixed a tokenizer crash when reading encoded files with syntaxerrors fromstdin with non utf-8 encoded text. Patch by Pablo Galindo

  • gh-88116: Fix an issue when reading line numbers from code objects if theencoded line numbers are close toINT_MIN. Patch by Pablo Galindo

  • gh-94262: Don't create frame objects for incomplete frames. Prevents thecreation of generators and closures from being observable to Python and Cextensions, restoring the behavior of 3.10 and earlier.

  • gh-94192: Fix error for dictionary literals with invalid expression asvalue.

  • gh-87995:types.MappingProxyType instances are now hashable ifthe underlying mapping is hashable.

  • gh-93883: Revise the display strategy of traceback enhanced errorlocations. The indicators are only shown when the location doesn't spanthe whole line.

  • gh-94163: AddBINARY_SLICE andSTORE_SLICEinstructions for more efficient handling and better specialization ofslicing operations, where the slice is explicit in the source code.

  • gh-94021: Fix unreachable code warning inPython/specialize.c.

  • gh-93911: SpecializeLOAD_ATTR for objects with custom__getattribute__.

  • gh-93955: Improve performance of attribute lookups on objects with custom__getattribute__ and__getattr__. Patch by Ken Jin.

  • gh-93911: SpecializeLOAD_ATTR forproperty() attributes.

  • gh-93678: Refactor compiler optimisation code so that it no longer needsthestructassembler andstructcompiler passed around. Instead,each function takes the CFG and other data that it actually needs. Thiswill make it possible to test this code directly.

  • gh-93841: When built with-enable-pystats,sys._stats_on(),sys._stats_off(),sys._stats_clear() andsys._stats_dump()functions have been added to enable gathering stats for parts of programs.

  • gh-93516: Store offset of first traceable instruction in code object toavoid having to recompute it for each instruction when tracing.

  • gh-93516: Lazily create a table mapping bytecode offsets to line numbersto speed up calculation of line numbers when tracing.

  • gh-89828:types.GenericAlias no longer relays the__class__attribute. For example,isinstance(list[int],type) no longer returnsTrue.

  • gh-93678: Refactor the compiler to reduce boilerplate and repetition.

  • gh-93671: Fix some exponential backtrace case happening with deeply nestedsequence patterns in match statements. Patch by Pablo Galindo

  • gh-93662: Make sure that the end column offsets are correct in multi-linemethod calls. Previously, the end column could precede the column offset.

  • gh-93461:importlib.invalidate_caches() now drops entries fromsys.path_importer_cache with a relative path as name. This solvesa caching issue when a process changes its current working directory.

    FileFinder no longer inserts a dot in the path, e.g./egg/./spamis now/egg/spam.

  • gh-93621: Change order of bytecode instructions emitted forwith andasyncwith to reduce the number of entriesin the exception table.

  • gh-93533: Reduce the size of the inline cache forLOAD_METHOD by 2bytes.

  • gh-93444: Removed redundant fields from the compiler's basicblock struct:b_nofallthrough,b_exit,b_return. They can be easilycalculated from the opcode of the last instruction of the block.

  • gh-93429:LOAD_METHOD instruction has been removed. It was merged backintoLOAD_ATTR.

  • gh-93418: Fixed an assert where an f-string has an equal sign '='following an expression, but there's no trailing brace. For example,f"{i=".

  • gh-93382: Cache the result ofPyCode_GetCode() function to restoretheO(1) lookup of theco_code attribute.

  • gh-93359: Ensure that customast nodes without explicit endpositions can be compiled. Patch by Pablo Galindo.

  • gh-93356: Code for exception handlers is emitted at the end of the codeunit's bytecode. This avoids one jump when no exception is raised.

  • gh-93354: Use exponential backoff for specialization counters in theinterpreter. Can reduce the number of failed specializations significantlyand avoid slowdown for those parts of a program that are not suitable forspecialization.

  • gh-93283: Improve error message for invalid syntax of conversion characterin f-string expressions.

  • gh-93345: Fix a crash in substitution of aTypeVar in nested genericalias afterTypeVarTuple.

  • gh-93223: When a bytecode instruction jumps to an unconditional jumpinstruction, the first instruction can often be optimized to target theunconditional jump's target directly. For tracing reasons, this wouldpreviously only occur if both instructions have the same line number. Thisalso now occurs if the unconditional jump is artificial, i.e., if it hasno associated line number.

  • gh-84694: The--experimental-isolated-subinterpreters configure optionandEXPERIMENTAL_ISOLATED_SUBINTERPRETERS macro have been removed.

  • gh-91924: Fix__lltrace__ debug feature if the stdout encoding is notUTF-8. Patch by Victor Stinner.

  • gh-93040: Wraps unused parameters inObjects/obmalloc.c withPy_UNUSED.

  • gh-93143: AvoidNULL checks for uninitialized local variables bydetermining at compile time which variables must be initialized.

  • gh-93061: Backward jumps afterasyncfor loops are no longer givendubious line numbers.

  • gh-93065: Fix contextvars HAMT implementation to handle iteration overdeep trees.

    The bug was discovered and fixed by Eli Libman. SeeMagicStack/immutables#84 for more details.

  • gh-93012: Added the new functionPyType_FromMetaclass(), whichgeneralizes the existingPyType_FromModuleAndSpec() using anadditional metaclass argument. This is useful for language binding tools,where it can be used to intercept type-related operations like subclassingor static attribute access by specifying a metaclass with custom slots.

    Importantly,PyType_FromMetaclass() is available in the LimitedAPI, which provides a path towards migrating more binding tools onto theStable ABI.

  • gh-93021: Fix the__text_signature__ for__get__() methodsimplemented in C. Patch by Jelle Zijlstra.

  • gh-89914: The operand of theYIELD_VALUE instruction is set to thestack depth. This is done to help frame handling onyield and mayassist debuggers.

  • gh-92955: Fix memory leak in code object's lines and positions iteratorsas they were not finalized at exit. Patch by Kumar Aditya.

  • gh-92930: Fixed a crash in_pickle.c from mutating collections during__reduce__ orpersistent_id.

  • gh-90690: The PRECALL instruction has been removed. It offered only asmall advantage for specialization and is not needed in the vast majorityof cases.

  • gh-92914: Always round the allocated size for lists up to the nearest evennumber.

  • gh-92858: Improve error message for some suites with syntax error before':'

  • gh-90473: Decrease default recursion limit on WASI to address limited callstack size.

  • gh-92804: Fix memory leak inmemoryview iterator as it was notfinalized at exit. Patch by Kumar Aditya.

  • gh-92777: SpecializeLOAD_METHOD for objects with lazy dictionaries.Patch by Ken Jin.

  • gh-92658: Add support for connecting and binding to Hyper-V sockets onWindows Hyper-V hosts and guests.

  • gh-92236: Remove spurious "LINE" event when starting a generator orcoroutine, visible tracing functions implemented in C.

  • gh-91102:_warnings.warn_explicit() is ported to Argument Clinic.

  • gh-92619: Make the compiler duplicate an exit block only if none of itsinstructions have a lineno (previously only the first instruction in theblock was checked, leading to unnecessarily duplicated blocks).

  • gh-88750: The deprecated debug build onlyPYTHONTHREADDEBUGenvironment variable no longer does anything.

  • gh-92261: Fix hang when trying to iterate over atyping.Union.

  • gh-91432: Specialized theFOR_ITER opcode using the PEP 659machinery

  • gh-91399: Removed duplicate '{0, 0, 0, 0, 0, 0}' entry in'Objects/unicodetype_db.h'.

  • gh-91578: Updates the error message for abstract class.

  • bpo-47091: Improve performance of repetition oflist andtuple by usingmemcpy to copy data and performing thereference increments in one step.

  • bpo-46142: Make--help output shorter by moving some info to the new--help-env and--help-xoptions command-line options. Also add--help-all option to print complete usage.

  • bpo-42316: Document some places where an assignment expression needsparentheses.

Library

  • gh-89237: Fix hang on Windows insubprocess.wait_closed() inasyncio withProactorEventLoop. Patch by KumarAditya.

  • gh-97928:tkinter.Text.count() raises now an exception for optionsstarting with "-" instead of silently ignoring them.

  • gh-98393: Theos module no longer accepts bytes-like paths, likebytearray andmemoryview types: only the exactbytes type is accepted for bytes strings. Patch by VictorStinner.

  • gh-98363: Added itertools.batched() to batch data into lists of a givenlength with the last list possibly being shorter than the others.

  • gh-98331: Update the bundled copies of pip and setuptools to versions 22.3and 65.5.0 respectively.

  • gh-98307: AcreateSocket() methodwas added toSysLogHandler.

  • gh-96035: Fix bug inurllib.parse.urlparse() that causes certainport numbers containing whitespace, underscores, plus and minus signs, ornon-ASCII digits to be incorrectly accepted.

  • gh-98257: Makesys.setprofile() andsys.settrace() functionsreentrant. They can no long fail with:RuntimeError("Cannotinstallatracefunctionwhileanothertracefunctionisbeinginstalled"). Patchby Victor Stinner.

  • gh-98251: Allowvenv to pass alongPYTHON* variables toensurepip andpip when they do not impact path resolution

  • gh-94597: Deprecatedasyncio.AbstractEventLoopPolicy.get_child_watcher() andasyncio.AbstractEventLoopPolicy.set_child_watcher() methods to beremoved in Python 3.14. Patch by Kumar Aditya.

  • gh-98178: On macOS, fix a crash insyslog.syslog() in multi-threadedapplications. On macOS, the libcsyslog() function is not thread-safe,sosyslog.syslog() no longer releases the GIL to call it. Patch byVictor Stinner.

  • gh-44098: Release the GIL when creatingmmap.mmap objects onUnix.

  • gh-87730: Wrap network errors consistently in urllib FTP support, so thetest suite doesn't fail when a network is available but the publicinternet is not reachable.

  • gh-94597: The child watcher classesMultiLoopChildWatcher,FastChildWatcher andSafeChildWatcherare deprecated and will be removed in Python 3.14. Patch by Kumar Aditya.

  • gh-98023: Change default child watcher toPidfdChildWatcher on Linux systems which supports it.Patch by Kumar Aditya.

  • gh-90985: Earlier in 3.11 we deprecatedasyncio.Task.cancel("message"). We realized we were too harsh, andhave undeprecated it.

  • gh-65961: Do not rely solely on__cached__ on modules; code will alsosupport__spec__.cached.

  • gh-97646: Replace deprecatedapplication/javascript withtext/javascript inmimetypes. SeeRFC 9239. Patch by NoamCohen.

  • gh-97930: Apply changes from importlib_resources 5.8 and 5.9:Traversable.joinpath provides a concrete implementation.as_filenow supports directories of resources.

  • gh-97850: Remove deprecatedimportlib.util.set_loader() andimportlib.util.module_for_loader() fromimportlib.util.

  • gh-97837: Change deprecate warning message inunittest from

    Itisdeprecatedtoreturnavalue!=None

    to

    ItisdeprecatedtoreturnavaluethatisnotNonefromatestcase

  • gh-97825: FixesAttributeError whensubprocess.check_output()is used with argumentinput=None and either of the argumentsencoding orerrors are used.

  • gh-97008:NameError andAttributeError spelling suggestionsprovided sincegh-82711 are now also emitted by the pure Pythontraceback module. Tests for those suggestions now exercise bothimplementations to ensure they are equivalent. Patch by Carl FriedrichBolz-Tereick and Łukasz Langa.

  • gh-97799:dataclass now usesinspect.get_annotations() toexamine the annotations on class objects.

  • gh-97781: Removed deprecated interfaces inimportlib.metadata (entrypoints accessed as dictionary, implicit dictionary construction ofsequence ofEntryPoint objects, mutablility ofEntryPoints result,access of entry point by index).entry_points now has a simpler, morestraightforward API (returningEntryPoints).

  • gh-96827: Avoid spurious tracebacks fromasyncio when defaultexecutor cleanup is delayed until after the event loop is closed (e.g. asthe result of a keyboard interrupt).

  • gh-95534:gzip.GzipFile.read() reads 10% faster.

  • gh-97592: Avoid a crash in the C version ofasyncio.Future.remove_done_callback() when an evil argument ispassed.

  • gh-97639: Removetokenize.NL check fromtabnanny.

  • gh-97545: Make Semaphore run faster.

  • gh-73588: Fix generation of the default name oftkinter.Checkbutton. Previously, checkbuttons in different parentwidgets could have the same short name and share the same state ifarguments "name" and "variable" are not specified. Now they are globallyunique.

  • gh-96865: fix Flag to use boundary CONFORM

    This restores previous Flag behavior of allowing flags with non-sequentialvalues to be combined; e.g.

    class Skip(Flag): TWO = 2 EIGHT = 8

    Skip.TWO | Skip.EIGHT -> <Skip.TWO|EIGHT: 10>

  • gh-97005: Update bundled libexpat to 2.4.9

  • gh-85760: Fix race condition inasyncio whereprocess_exited() called before thepipe_data_received() leading toinconsistent output. Patch by Kumar Aditya.

  • gh-96704: Pass the correctcontextvars.Context when aasyncioexception handler is called on behalf of a task or callback handle. Thisadds a newTask method,get_context, and also a newHandlemethod with the same name. If this method is not found on a task object(perhaps because it is a third-party library that does not yet providethis method), the context prevailing at the time the exception handler iscalled is used.

  • gh-96819: Fixed check inmultiprocessing.resource_tracker thatguarantees that the length of a write to a pipe is not greater thanPIPE_BUF.

  • gh-95865: Reduceurllib.parse.quote_from_bytes() memory use on largevalues.

    Contributed by Dennis Sweeney.

  • gh-96741: Corrected type annotation for dataclass attributepstats.FunctionProfile.ncalls to bestr.

  • gh-96734: Updateunicodedata database to Unicode 15.0.0.

  • gh-96735: Fix undefined behaviour instruct.unpack().

  • gh-46412: Improve performance ofbool(db) for large ndb/gdb databases.Previously this would calllen(db) which would iterate over all keys-- the answer (empty or not) is known after the first key.

  • gh-96652: Fix the faulthandler implementation offaulthandler.register(signal,chain=True) if thesigaction()function is not available: don't call the previous signal handler if it'sNULL. Patch by Victor Stinner.

  • gh-68163: Correct conversion ofnumbers.Rational's tofloat.

  • gh-96538: Speed upbisect.bisect() functions by taking advantage oftype-stability.

  • gh-96465: Fraction hashes are now cached.

  • gh-96079: Intyping, fix missing fieldname and incorrect__module__ in _AnnotatedAlias.

  • gh-96415: Removetypes._cell_factory from module namespace.

  • gh-95987: Fixrepr ofAny subclasses.

  • gh-96388: Work around missing socket functions insocket's__repr__.

  • gh-96385: FixTypeVarTuple.__typing_prepare_subst__.TypeError wasnot raised when using more than oneTypeVarTuple, like[*T,*V] intype alias substitutions.

  • gh-96142: Addmatch_args,kw_only,slots, andweakref_slotto_DataclassParams.

  • gh-96073: Ininspect, fix overeager replacement of "typing." informatting annotations.

  • gh-89258: Added agetChildren() method tologging.Logger, to get the immediate child loggers of a logger.

  • gh-96346: Use double caching for compiled RE patterns.

  • gh-96349: Fixed a minor performance regression inthreading.Event.__init__()

  • gh-90467: Fixasyncio.streams.StreamReaderProtocol to keep astrong reference to the created task, so that it's not garbage collected

  • gh-96172: Fix a bug inunicodedata:east_asian_width used toreturn the wrong value for unassigned characters; and for yet unassigned,but reserved characters.

  • gh-96159: Fix a performance regression in loggingTimedRotatingFileHandler. Only check for special files when the rollovertime has passed.

  • gh-96175: Fix unusedlocalName parameter in theAttr class inxml.dom.minidom.

  • gh-96145: Add AttrDict to JSON module for use with object_hook.

  • gh-96052: Fix handling compiler warnings (SyntaxWarning andDeprecationWarning) incodeop.compile_command() when checking forincomplete input. Previously it emitted warnings and raised a SyntaxError.Now it always returnsNone for incomplete input without emitting anywarnings.

  • gh-96125: Fix incorrect condition that causessys.thread_info.name tobe wrong on pthread platforms.

  • gh-96019: Fix a bug in themakeunicodedata.py script leading to about13 KiB of space saving in theunicodedata module, specifically thecharacter decomposition data.

  • gh-95463: Remove an incompatible change frombpo-28080 that caused aregression that ignored the utf8 inZipInfo.flag_bits. Patch by PabloGalindo.

  • gh-69142: Add%:z strftime format code (generates tzoffset with colonsas separator), seestrftime() 與 strptime() 的行為.

  • gh-95899: Fixasyncio.Runner to callasyncio.set_event_loop() only once to avoid callingattach_loop() multiple times on childwatchers. Patch by Kumar Aditya.

  • gh-95736: Fixunittest.IsolatedAsyncioTestCase to set event loopbefore calling setup functions. Patch by Kumar Aditya.

  • gh-95865: Speed upurllib.parse.quote_from_bytes() by replacing alist comprehension withmap().

  • gh-95861: Add support for computing Spearman's correlation coefficient tothe existing statistics.correlation() function.

  • gh-95804: Fixlogging shutdown handler so it respectsMemoryHandler.flushOnClose.

  • gh-95704: When a task catchesasyncio.CancelledError and raisessome other error, the other error should generally not silently besuppressed.

  • gh-95149: TheHTTPStatus enum offers a coupleof properties to indicate the HTTP status category e.g.HTTPStatus.OK.is_success.

  • gh-95609: Update bundled pip to 22.2.2.

  • gh-95289: Fixasyncio.TaskGroup to propagate exception whenasyncio.CancelledError was replaced with another exception by acontext manager. Patch by Kumar Aditya and Guido van Rossum.

  • gh-94909: Fix incorrect joining of relative Windows paths with drives inpathlib.PurePath initializer.

  • gh-95385: Fasterjson.dumps() when sorting of keys is not requested(default).

  • gh-83901: ImproveSignature.bind errormessage for missing keyword-only arguments.

  • gh-95339: Update bundled pip to 22.2.1.

  • gh-95045: Fix GC crash when deallocating_lsprof.Profiler byuntracking it before calling any callbacks. Patch by Kumar Aditya.

  • gh-95231: Fail gracefully ifEPERM orENOSYS is raised when loadingcrypt methods. Thismay happen when trying to loadMD5 on a Linux kernel withFIPS enabled.

  • gh-95097: Fixasyncio.run() forasyncio.Taskimplementations withoutuncancel() method. Patch byKumar Aditya.

  • gh-95087: Fix IndexError in parsing invalid date in theemailmodule.

  • gh-95199: Upgrade bundled setuptools to 63.2.0.

  • gh-95194: Upgrade bundled pip to 22.2.

  • gh-93899: Fix check for existence ofos.EFD_CLOEXEC,os.EFD_NONBLOCK andos.EFD_SEMAPHORE flags on olderkernel versions where these flags are not present. Patch by Kumar Aditya.

  • gh-95166: Fixconcurrent.futures.Executor.map() to cancel thecurrently waiting on future on an error - e.g. TimeoutError orKeyboardInterrupt.

  • gh-95132: Fix asqlite3 regression where*args and**kwdswere incorrectly relayed fromconnect() to theConnection factory. The regression was introduced in3.11a1 with PR 24421 (gh-85128). Patch by Erlend E. Aasland.

  • gh-93157: Fixfileinput module didn't supporterrors optionwheninplace is true.

  • gh-91212: Fixed flickering of the turtle window when the tracer is turnedoff. Patch by Shin-myoung-serp.

  • gh-95077: Add deprecation warning for enummember.member access (e.g.Color.RED.BLUE). RemoveEnumMeta.__getattr__.

  • gh-95109: Ensure that timeouts scheduled withasyncio.Timeoutthat have already expired are delivered promptly.

  • gh-95105:wsgiref.types.InputStream.__iter__() should returnIterator[bytes], notIterable[bytes]. Patch by Shantanu Jain.

  • gh-95066: Replaced assert with exception inast.parse(), whenfeature_version has an invalid major version. Patch by Shantanu Jain.

  • gh-77617: Addsqlite3command-line interface.Patch by Erlend Aasland.

  • gh-95005: Replace_PyAccu with_PyUnicodeWriter inJSON encoder and StringIO and remove the_PyAccu implementation.

  • gh-90085: Remove-c/--clock and-t/--time CLI options oftimeit. The options had been deprecated since Python 3.3 and thefunctionality was removed in Python 3.7. Patch by Shantanu Jain.

  • gh-94857: Fix refleak in_io.TextIOWrapper.reconfigure. Patch by KumarAditya.

  • gh-94821: Fix binding of unix socket to empty address on Linux to use anavailable address from the abstract namespace, instead of "0".

  • gh-94736: Fix crash when deallocating an instance of a subclass of_multiprocessing.SemLock. Patch by Kumar Aditya.

  • gh-81620: Add random.binomialvariate().

  • gh-74116: Allowasyncio.StreamWriter.drain() to be awaitedconcurrently by multiple tasks. Patch by Kumar Aditya.

  • gh-87822: When called withcapture_locals=True, thetracebackmodule functions swallow exceptions raised from calls torepr() onlocal variables of frames. This is in order to prioritize the originalexception over rendering errors. An indication of the failure is printedin place of the missing value. (Patch by Simon-Martin Schroeder).

  • gh-88050: Fixasyncio subprocess transport to kill process cleanlywhen process is blocked and avoidRuntimeError when loop is closed.Patch by Kumar Aditya.

  • gh-94637:SSLContext.set_default_verify_paths() now releases the GILaroundSSL_CTX_set_default_verify_paths call. The function callperforms I/O and CPU intensive work.

  • gh-94309: Deprecate aliasestyping.Hashable andtyping.Sized

  • gh-92546: An undocumentedpython-mpprint benchmark is moved intopprint suite of pyperformance. Patch by Oleg Iarygin.

  • gh-94607: Fix subclassing complex generics with type variables intyping. Previously an error message sayingSometypevariables...arenotlistedinGeneric[...] was shown.typing no longerpopulates__parameters__ with the__parameters__ of a Pythonclass.

  • gh-94619: Remove the long-deprecatedmodule_repr() fromimportlib.

  • gh-93910: The ability to access the other values of an enum on an enum(e.g.Color.RED.BLUE) has been restored in order to fix a performanceregression.

  • gh-93896: Fixasyncio.run() andunittest.IsolatedAsyncioTestCase to always the set event loop asit was done in Python 3.10 and earlier. Patch by Kumar Aditya.

  • gh-94343: Allow setting the attributes ofreprlib.Repr during objectinitialization

  • gh-94382: Port static types of_multiprocessing module to heap types.Patch by Kumar Aditya.

  • gh-78724: Fix crash instruct.Struct when it was not completelyinitialized by initializing it in__new__(). Patch by KumarAditya.

  • gh-94510: Re-entrant calls tosys.setprofile() andsys.settrace() now raiseRuntimeError. Patch by PabloGalindo.

  • gh-92336: Fix bug wherelinecache.getline() fails on bad files withUnicodeDecodeError orSyntaxError. It now returns an emptystring as per the documentation.

  • gh-94398: Once aasyncio.TaskGroup has started shutting down(i.e., at least one task has failed and the task group has startedcancelling the remaining tasks), it should not be possible to add newtasks to the task group.

  • gh-94383:xml.etree: Remove theElementTree.Element.copy()method of the pure Python implementation, deprecated in Python 3.10, usethecopy.copy() function instead. The C implementation ofxml.etree has nocopy() method, only a__copy__() method.Patch by Victor Stinner.

  • gh-94379:zipimport: Removefind_loader() andfind_module()methods, deprecated in Python 3.10: use thefind_spec() methodinstead. SeePEP 451 for the rationale. Patch by Victor Stinner.

  • gh-94352:shlex.split(): PassingNone fors argument nowraises an exception, rather than readingsys.stdin. The featurewas deprecated in Python 3.9. Patch by Victor Stinner.

  • gh-94318: Strip trailing spaces inpydoc text output.

  • gh-89988: Fix memory leak inpickle.Pickler when looking updispatch_table. Patch by Kumar Aditya.

  • gh-90016: Deprecatesqlite3default adapters and converters. Patch by Erlend E. Aasland.

  • gh-94254: Fixed types ofstruct module to be immutable. Patch byKumar Aditya.

  • gh-93259: Now raiseValueError whenNone or an empty string arepassed toDistribution.from_name (and other callers).

  • gh-74696:shutil.make_archive() now passes theroot_dir argumentto custom archivers which support it.

  • gh-94216: Thedis module now has the opcodes for pseudoinstructions (those which are used by the compiler during code generationbut then removed or replaced by real opcodes before the final bytecode isemitted).

  • gh-93096: Removed undocumentedpython-mcodecs. Usepython-munittesttest.test_codecs.EncodedFileTest instead.

  • gh-94207: Made_struct.Struct GC-tracked in order to fix areference leak in the_struct module.

  • gh-93096: Removed undocumented-t argument ofpython-mbase64.Usepython-munittesttest.test_base64.LegacyBase64TestCase.test_encodebytes instead.

  • gh-94226: Remove thelocale.format() function, deprecated in Python3.7: uselocale.format_string() instead. Patch by Victor Stinner.

  • gh-94199: Remove thessl.match_hostname() function. Thessl.match_hostname() was deprecated in Python 3.7. OpenSSL performshostname matching since Python 3.7, Python no longer uses thessl.match_hostname() function. Patch by Victor Stinner.

  • gh-94214: Document thecontext object used in thevenv.EnvBuilderclass, and add the new environment's library path to it.

  • gh-94199: Remove thessl.wrap_socket() function, deprecated inPython 3.7: instead, create assl.SSLContext object and call itsssl.SSLContext.wrap_socket method. Any package that still usesssl.wrap_socket() is broken and insecure. The function neither sendsa SNI TLS extension nor validates server hostname. Code is subject toCWE 295 Improper Certificate Validation. Patch by Victor Stinner.

  • gh-94199: Remove thessl.RAND_pseudo_bytes() function, deprecated inPython 3.6: useos.urandom() orssl.RAND_bytes() instead.Patch by Victor Stinner.

  • gh-94199:hashlib: Remove the pure Python implementation ofhashlib.pbkdf2_hmac(), deprecated in Python 3.10. Python 3.10 andnewer requires OpenSSL 1.1.1 (PEP 644): this OpenSSL version provides aC implementation ofpbkdf2_hmac() which is faster. Patch byVictor Stinner.

  • gh-94196:gzip: Remove thefilename attribute ofgzip.GzipFile, deprecated since Python 2.6, use thename attribute instead. In write mode, thefilename attribute added'.gz' file extension if it was notpresent. Patch by Victor Stinner.

  • gh-94182: run theasyncio.PidfdChildWatcher on the running loop,this allows event loops to run subprocesses when there is no default eventloop running on the main thread

  • gh-94169: Removeio.OpenWrapper and_pyio.OpenWrapper, deprecatedin Python 3.10: just useopen() instead. Theopen()(io.open()) function is a built-in function. Since Python 3.10,_pyio.open() is also a static method. Patch by Victor Stinner.

  • gh-91742: Fixpdb crash after jump caused by a null pointerdereference. Patch by Kumar Aditya.

  • gh-94101: Manual instantiation ofssl.SSLSession objects is nolonger allowed as it lead to misconfigured instances that crashed theinterpreter when attributes where accessed on them.

  • gh-84753:inspect.iscoroutinefunction(),inspect.isgeneratorfunction(), andinspect.isasyncgenfunction() now properly returnTrue forduck-typed function-like objects like instances ofunittest.mock.AsyncMock.

    This makesinspect.iscoroutinefunction() consistent with thebehavior ofasyncio.iscoroutinefunction(). Patch by Mehdi ABAAKOUK.

  • gh-94028: Fix a regression in thesqlite3 where statement objectswere not properly cleared and reset after use in cursor iters. Theregression was introduced by PR 27884 in Python 3.11a1. Patch by Erlend E.Aasland.

  • gh-93973: Add keyword argumentall_errors toasyncio.create_connection so that multiple connection errors can beraised as anExceptionGroup.

  • gh-93963: Officially deprecate fromimportlib.abc classes moved toimportlib.resources.abc.

  • gh-93858: Prevent error when activating venv in nested fish instances.

  • gh-93820: Pickleenum.Flag by name.

  • gh-93847: Fix repr of enum of generic aliases.

  • gh-91404: Revert there memory leak when a match is terminated by asignal or memory allocation failure as the implemented fix caused a majorperformance regression.

  • gh-83499: Fix double closing of file description intempfile.

  • gh-93820: Fixed a regression whencopy.copy()-ingenum.Flagwith multiple flag members.

  • gh-79512: Fixed names and__module__ value ofweakref classesReferenceType,ProxyType,CallableProxyType. It makes them pickleable.

  • gh-91389: Fix an issue wheredis utilities could report missing orincorrect position information in the presence ofCACHE entries.

  • gh-93626: Set__future__.annotations to have aNonemandatoryRelease to indicate that it is currently 'TBD'.

  • gh-90473: Emscripten and WASI have no home directory and cannot providePEP 370 user site directory.

  • gh-90494:copy.copy() andcopy.deepcopy() now always raise aTypeError if__reduce__() returns a tuple with length 6 instead ofsilently ignore the 6th item or produce incorrect result.

  • gh-90549: Fix a multiprocessing bug where a global named resource (such asa semaphore) could leak when a child process is spawned (as opposed toforked).

  • gh-93521: Fixed a case where dataclasses would try to add__weakref__into the__slots__ for a dataclass that specifiedweakref_slot=True when it was already defined in one of its bases.This resulted in aTypeError upon the new class being created.

  • gh-79579:sqlite3 now correctly detects DML queries with leadingcomments. Patch by Erlend E. Aasland.

  • gh-93421: Updatesqlite3.Cursor.rowcount when a DML statement hasrun to completion. This fixes the row count for SQL queries likeUPDATE...RETURNING. Patch by Erlend E. Aasland.

  • gh-93475: ExposeFICLONE andFICLONERANGE constants infcntl. Patch by Illia Volochii.

  • gh-93370: Deprecatesqlite3.version andsqlite3.version_info.

  • gh-91810: Suppress writing an XML declaration in open files inElementTree.write() withencoding='unicode' andxml_declaration=None.

  • gh-91162: Support splitting of unpacked arbitrary-length tuple overTypeVar andTypeVarTuple parameters. For example:

    • A[T,*Ts][*tuple[int,...]] ->A[int,*tuple[int,...]]

    • A[*Ts,T][*tuple[int,...]] ->A[*tuple[int,...],int]

  • gh-93353: Fix theimportlib.resources.as_file() context manager toremove the temporary file if destroyed late during Python finalization:keep a local reference to theos.remove() function. Patch by VictorStinner.

  • gh-83658: Makemultiprocessing.Pool raise an exception ifmaxtasksperchild is notNone or a positive int.

  • gh-93312: Addos.PIDFD_NONBLOCK flag to open a file descriptorfor a process withos.pidfd_open() in non-blocking mode. Patch byKumar Aditya.

  • gh-88123: ImplementEnum.__contains__ that returnsTrue orFalse to replace the deprecated behaviour that would sometimes raise aTypeError.

  • gh-93297: Make asyncio task groups prevent child tasks from being GCed

  • gh-85308: Changedargparse.ArgumentParser to usefilesystem encoding and error handler instead of default textencoding to read arguments from file (e.g.fromfile_prefix_charsoption). This change affects Windows; argument file should be encoded withUTF-8 instead of ANSI Codepage.

  • gh-93156: Accessing thepathlib.PurePath.parents sequence of anabsolute path using negative index values produced incorrect results.

  • gh-93162: Add the ability forlogging.config.dictConfig() tousefully configureQueueHandler andQueueListener as a pair, and addlogging.getHandlerByName() andlogging.getHandlerNames() APIsto allow access to handlers by name.

  • gh-93243: Thesmtpd module was removed per the schedule inPEP 594.

  • gh-92886: Replaceassert statements withraiseAssertionError() inBaseHandler so that the tested behaviour is maintainedrunning with optimizations(-O).

  • gh-90155: Fix brokenasyncio.Semaphore when acquire is cancelled.

  • gh-90817: Thelocale.resetlocale() function is deprecated and willbe removed in Python 3.13. Uselocale.setlocale(locale.LC_ALL,"")instead. Patch by Victor Stinner.

  • gh-91513: AddedtaskName attribute tologging module for usewithasyncio tasks.

  • gh-74696:shutil.make_archive() no longer temporarily changes thecurrent working directory during creation of standard.zip or tararchives.

  • gh-92728: There.template() function and the correspondingre.TEMPLATE andre.T flags are restored after they wereremoved in 3.11.0b1, but they are now deprecated, so they might be removedfrom Python 3.13.

  • gh-93033: Search in some strings (platform dependent i.e [U+0xFFFF,U+0x0100] on Windows or [U+0xFFFFFFFF, U+0x00010000] on Linux 64-bit) arenow up to 10 times faster.

  • gh-89973: Fixre.error raised infnmatch if the patterncontains a character range with upper bound lower than lower bound (e.g.[c-a]). Now such ranges are interpreted as empty ranges.

  • gh-93044: No longer convert the database argument ofsqlite3.connect() to bytes before passing it to the factory.

  • gh-93010: In a very special case, the email package tried to append thenonexistentInvalidHeaderError to the defect list. It should have beenInvalidHeaderDefect.

  • gh-92986: Fixast.unparse() whenImportFrom.level isNone

  • gh-92932: Nowdis() andget_instructions() handleoperand values for instructions prefixed byEXTENDED_ARG_QUICK. Patchby Sam Gross and Donghee Na.

  • gh-92675: Fixvenv.ensure_directories() to acceptpathlib.Path arguments in addition tostr paths. Patchby David Foster.

  • gh-87901: Removed theencoding argument fromos.popen() that wasadded in 3.11b1.

  • gh-91922: Fix functionsqlite.connect() and thesqlite.Connection constructor on non-UTF-8 locales. Also, theynow support bytes paths non-decodable with the current FS encoding.

  • gh-92869: Addedc_time_t toctypes, which has thesame size as thetime_t type in C.

  • gh-92839: Fixed crash resulting from calling bisect.insort() orbisect.insort_left() with the key argument not equal toNone.

  • gh-90473:subprocess now fails early on Emscripten and WASIplatforms to work around missingos.pipe() on WASI.

  • gh-89325: Removed many old deprecatedunittest features:TestCase method aliases, undocumented and brokenTestCase methodassertDictContainsSubset,undocumentedTestLoader.loadTestsFromModule parameteruse_load_tests, andan underscored alias of theTextTestResult class.

  • gh-92734: Allow multi-element reprs emitted byreprlib to bepretty-printed using configurable indentation.

  • gh-92671: Fixedast.unparse() for empty tuples in the assignmenttarget context.

  • gh-91581:utcfromtimestamp() no longer attemptsto resolvefold in the pure Python implementation, since the fold isnever 1 in UTC. In addition to being slightly faster in the common case,this also prevents some errors when the timestamp is close todatetime.min. Patch by Paul Ganssle.

  • gh-86388: Removed randrange() functionality deprecated since Python 3.10.Formerly, randrange(10.0) losslessly converted to randrange(10). Now, itraises a TypeError. Also, the exception raised for non-integral valuessuch as randrange(10.5) or randrange('10') has been changed fromValueError to TypeError.

  • gh-90385: Addpathlib.Path.walk() as an alternative toos.walk().

  • gh-92550: Fixpathlib.Path.rglob() for empty pattern.

  • gh-92591: Allowlogging filters to return alogging.LogRecord instance so that filters attached tologging.Handlers can enrich records without side effects onother handlers.

  • gh-92445: Fix a bug inargparse wherenargs="*" would raise anerror instead of returning an empty list when 0 arguments were supplied ifchoice was also defined inparser.add_argument.

  • gh-92547: Remove undocumentedsqlite3 features deprecated in Python3.10:

    • sqlite3.enable_shared_cache()

    • sqlite3.OptimizedUnicode

    Patch by Erlend E. Aasland.

  • gh-92530: Fix an issue that occurred after interruptingthreading.Condition.notify().

  • gh-92531: The statistics.median_grouped() function now always return afloat. Formerly, it did not convert the input type when for sequences oflength one.

  • gh-84131: Thepathlib.Path deprecated methodlink_to has beenremoved. Use 3.10'shardlink_to() method instead asits semantics are consistent with that ofsymlink_to().

  • gh-89336: Removedconfigparser module APIs: theSafeConfigParser class alias, theParsingError.filename propertyand parameter, and theConfigParser.readfp method, all of which weredeprecated since Python 3.2.

  • gh-92391: Add__class_getitem__() tocsv.DictReader andcsv.DictWriter, allowing them to beparameterized at runtime. Patch by Marc Mueller.

  • gh-91968: AddSO_RTABLE andSO_USER_COOKIE constants tosocket.

  • gh-91810:ElementTree methodwrite() and functiontostring() now use the text file's encoding("UTF-8" if not available) instead of locale encoding in XML declarationwhenencoding="unicode" is specified.

  • gh-81790:os.path.splitdrive() now understands DOS device paths withUNC links (beginning\\?\UNC\). Contributed by Barney Gale.

  • gh-91760: Apply more strict rules for numerical group references and groupnames in regular expressions. Only sequence of ASCII digits is nowaccepted as a numerical reference. The group name in bytes patterns andreplacement strings can now only contain ASCII letters and digits andunderscore.

  • gh-90622: Worker processes forconcurrent.futures.ProcessPoolExecutor are no longer spawned ondemand (a feature added in 3.9) when the multiprocessing context startmethod is"fork" as that can lead to deadlocks in the child processesdue to a fork happening while threads are running.

  • gh-91577: Move imports inSharedMemory methodsto module level so that they can be executed late in python finalization.

  • gh-91581: Remove an unhandled error case in the C implementation of callstodatetime.fromtimestamp withno time zone (i.e. getting a local time from an epoch timestamp). Thisshould have no user-facing effect other than giving a possibly moreaccurate error message when called with timestamps that fall on10000-01-01 in the local time. Patch by Paul Ganssle.

  • gh-91539: Improve performance ofurllib.request.getproxies_environmentwhen there are many environment variables

  • gh-91524: Speed up the regular expression substitution (functionsre.sub() andre.subn() and correspondingre.Patternmethods) for replacement strings containing group references by 2--3times.

  • gh-91447: Fix findtext in the xml module to only give an empty string whenthe text attribute is set toNone.

  • gh-91456: Deprecate current default auto() behavior: In 3.13 the defaultwill be for for auto() to always return the largest member valueincremented by 1, and to raise if incompatible value types are used.

  • bpo-47231: Fixed an issue with inconsistent trailing slashes in tarfilelongname directories.

  • bpo-39064:zipfile.ZipFile now raiseszipfile.BadZipFileinstead ofValueError when reading a corrupt zip file in which thecentral directory offset is negative.

  • bpo-41287: Fix handling of thedoc argument in subclasses ofproperty().

  • gh-90005:ctypes dependencylibffi is now detected withpkg-config.

  • bpo-32547: The constructors forDictWriter andDictReader now coerce thefieldnames argument to alist if it is an iterator.

  • bpo-35540: Fixdataclasses.asdict() crash whencollections.defaultdict is present in the attributes.

  • bpo-47063: Add an index_pages parameter to support using non-default indexpage names.

  • bpo-47025: Drop support forbytes onsys.path.

  • bpo-46951: Order the contents of zipapp archives, to make builds morereproducible.

  • bpo-42777: Implementpathlib.Path.is_mount() for Windows paths.

  • bpo-46755: InQueueHandler, clearstack_info fromLogRecord to prevent stack trace from being written twice.

  • bpo-45393: Fix the formatting forawaitx andnotx in theoperator precedence table when using thehelp() system.

  • bpo-46642: Improve error message when trying to subclass an instance oftyping.TypeVar,typing.ParamSpec,typing.TypeVarTuple, etc. Based on patch by Gregory Beauregard.

  • bpo-46364: Restrict use of sockets instead of pipes for stdin ofsubprocesses created byasyncio to AIX platform only.

  • bpo-28249: Setdoctest.DocTest.lineno toNone when an objectdoes not have__doc__.

  • bpo-46197: Fixensurepip environment isolation for subprocessrunningpip.

  • bpo-45924: Fixasyncio incorrect traceback when future's exceptionis raised multiple times. Patch by Kumar Aditya.

  • bpo-45046: Add support of context managers inunittest: methodsenterContext() andenterClassContext() of classTestCase, methodenterAsyncContext() of classIsolatedAsyncioTestCase and functionunittest.enterModuleContext().

  • bpo-44173: Enable fast seeking of uncompressed unencryptedzipfile.ZipExtFile

  • bpo-42627: Fix incorrect parsing of Windows registry proxy settings

  • bpo-42047: Addthreading.get_native_id() support for DragonFly BSD.Patch by David Carlier.

  • bpo-14243: Thetempfile.NamedTemporaryFile function has a newoptional parameterdelete_on_close

  • bpo-41246: Give the same callback function for when the overlappedoperation is done to the functionsrecv,recv_into,recvfrom,sendto,send andsendfile insideIocpProactor.

  • bpo-39264: Fixedcollections.UserDict.get() to not call__missing__() when a value is not found. This matches the behaviorofdict. Patch by Bar Harel.

  • bpo-38693:importlib now uses f-strings internally instead ofstr.format.

  • bpo-38267: Addtimeout parameter toasyncio.loop.shutdown_default_executor(). The default value isNone, which means the executor will be given an unlimited amount oftime. When called fromasyncio.Runner orasyncio.run(), thedefault timeout is 5 minutes.

  • bpo-34828:sqlite3.Connection.iterdump() now handles databases thatuseAUTOINCREMENT in one or more tables.

  • bpo-32990: Support reading wave files with theWAVE_FORMAT_EXTENSIBLEformat in thewave module.

  • bpo-26253: Allow adjustable compression level for tarfile streams intarfile.open().

Documentation

  • gh-85525: Remove extra row

  • gh-86404: Deprecated toolsmakesuspicious andrstlint.py are nowremoved. They have been replaced bysphinx-lint.

  • gh-97741: Fix! in c domain ref target syntax via aconf.py patch,so it works as intended to disable ref target resolution.

  • gh-96432: Fraction literals now support whitespace around the forwardslash,Fraction('2/3').

  • gh-96098: Improve discoverability of the higher level concurrent.futuresmodule by providing clearer links from the lower level threading andmultiprocessing modules.

  • gh-95957: What's New 3.11 now has instructions for how to provide compilerand linker flags for Tcl/Tk and OpenSSL on RHEL 7 and CentOS 7.

  • gh-95588: Clarified the conflicting advice given in theastdocumentation aboutast.literal_eval() being "safe" for use onuntrusted input while at the same time warning that it can crash theprocess. The latter statement is true and is deemed unfixable without alarge amount of work unsuitable for a bugfix. So we keep the warning andno longer claim thatliteral_eval is safe.

  • gh-91207: Fix stylesheet not working in Windows CHM htmlhelp docs and addwarning that they are deprecated. Contributed by C.A.M. Gerlach.

  • gh-95454: Replaced incorrectly written true/false values in documentation.Patch by Robert O'Shea

  • gh-95451: Update library documentation withavailability information on WebAssembly platformswasm32-emscripten andwasm32-wasi.

  • gh-95415: Use consistent syntax for platform availability. The directivenow supports a content body and emits a warning when it encounters anunknown platform.

  • gh-94321: Document thePEP 246 style protocol typesqlite3.PrepareProtocol.

  • gh-86128: Document a limitation in ThreadPoolExecutor where its exithandler is executed before any handlers in atexit.

  • gh-61162: Clarifysqlite3 behavior whenHow to use the connection context manager.

  • gh-87260: Alignsqlite3 argument specs with the actualimplementation.

  • gh-86986: The minimum Sphinx version required to build the documentationis now 3.2.

  • gh-88831: Augmented documentation of asyncio.create_task(). Clarified theneed to keep strong references to tasks and added a code snippet detailinghow to do this.

  • gh-86438: Clarify that-W andPYTHONWARNINGS arematched literally and case-insensitively, rather than as regularexpressions, inwarnings.

  • gh-93031: Update tutorial introduction output to use 3.10+ SyntaxErrorinvalid range.

  • gh-92240: Added release dates for "What's New in Python 3.X" for 3.0, 3.1,3.2, 3.8 and 3.10

  • bpo-47161: Document thatpathlib.PurePath does not collapseinitial double slashes because they denote UNC paths.

  • bpo-40838: Document thatinspect.getdoc(),inspect.getmodule(), andinspect.getsourcefile() might returnNone.

  • bpo-43689: TheDiffer documentation now also mentions other whitespacecharacters, which make it harder to understand the diff output.

  • bpo-38056: Overhaul theError Handlers documentation incodecs.

  • bpo-13553: Document tkinter.Tk args.

Tests

  • gh-95027: On Windows, when the Python test suite is run with the-jNoption, the ANSI code page is now used as the encoding for the stdouttemporary file, rather than using UTF-8 which can lead to decoding errors.Patch by Victor Stinner.

  • gh-96624: Fixed the failure of repeated runs oftest.test_unittestcaused by side effects intest_dotted_but_module_not_loaded.

  • gh-95243: Mitigate the inherent race condition from usingfind_unused_port() in testSockName() by trying to find an unused port afew times before failing. Patch by Ross Burton.

  • gh-95573:Lib/test/test_asyncio/test_ssl.py exposed a bug in themacOS kernel where intense concurrent load on non-blocking socketsoccasionally causeserrno.ENOBUFS ("No buffer space available")to be emitted. FB11063974 filed with Apple, in the mean time as aworkaround buffer size used in tests on macOS is decreased to avoidintermittent failures. Patch by Fantix King.

  • gh-95280: Fix problem withtest_ssltest_get_ciphers on systemsthat require perfect forward secrecy (PFS) ciphers.

  • gh-95212: Make multiprocessing test casetest_shared_memory_recreateparallel-safe.

  • gh-95218: Move tests for importlib.resources intotest_importlib.resources.

  • gh-93963: Updated tests to use preferred location forimportlib.resources ABCs.

  • gh-94675: Add a regression test forre exponentional slowdown whenusing rjsmin.

  • gh-91330: Added more tests fordataclasses to cover behavior withdata descriptor-based fields.

  • gh-94208:test_ssl is now checking for supported TLS version andprotocols in more tests.

  • gh-94315: Tests now check for DAC override capability instead of relyingonos.geteuid().

  • gh-54781: Rename test_tk to test_tkinter, and rename test_ttk_guionly totest_ttk. Patch by Victor Stinner.

  • gh-93839: MoveLib/ctypes/test/ toLib/test/test_ctypes/. Patch byVictor Stinner.

  • gh-93951: In test_bdb.StateTestCase.test_skip, avoid including auxiliaryimporters.

  • gh-93957: Provide nicer error reporting from subprocesses intest_venv.EnsurePipTest.test_with_pip.

  • gh-93884: Add test cases forPyNumber_ToBase() that take a largenumber or a non-int object as parameter.

  • gh-93852: test_asyncio, test_logging, test_socket and test_socketservernow create AF_UNIX domains in the current directory to no longer fail withOSError("AF_UNIXpathtoolong") if the temporary directory (theTMPDIR environment variable) is too long. Patch by VictorStinner.

  • gh-93353: regrtest now checks if a test leaks temporary files ordirectories if run with -jN option. Patch by Victor Stinner.

  • gh-84461:run_tests.py now handles cross compiling env vars correctlyand passHOSTRUNNER to regression tests.

  • gh-93616:test_modulefinder now creates a temporary directory inModuleFinderTest.setUp() instead of module scope.

  • gh-93575: Fix issue with test_unicode test_raiseMemError. The test casenow usetest.support.calcobjsize to calculate size of PyUnicodestructs.sys.getsizeof() may return different size when string hasUTF-8 memory.

  • gh-90473: WASI does not have achmod(2) syscall.os.chmod() isnow a dummy function on WASI. Skip all tests that depend on workingos.chmod().

  • gh-90473: Skip tests on WASI that require symlinks with absolute paths.

  • gh-57539: Increase calendar test coverage forcalendar.LocaleTextCalendar.formatweekday().

  • gh-90473: Skip symlink tests on WASI. wasmtime usesopenat2(2) withRESOLVE_BENEATH flag, which prevents symlinks with absolute paths.

  • gh-89858: Fixtest_embed for out-of-tree builds. Patch by KumarAditya.

  • gh-92886: Fixing tests that fail when running with optimizations (-O)intest_imaplib.py.

  • gh-92886: Fixing tests that fail when running with optimizations (-O)intest_zipimport.py

  • gh-92886: Fixing tests that fail when running with optimizations (-O)intest_py_compile.py

  • gh-92886: Fixing tests that fail when running with optimizations (-O)intest_sys_settrace.py.

  • gh-92886: Fixing tests that fail when running with optimizations (-O)in_test_multiprocessing.py

  • gh-92670: Skiptest_shutil.TestCopy.test_copyfile_nonexistent_dir teston AIX as the test uses a trailing slash to force the OS consider the pathas a directory, but on AIX the trailing slash has no effect and isconsidered as a file.

  • gh-92514: Remove unusedtest.support.BasicTestRunner. Patch by JelleZijlstra.

  • bpo-47016: Create a GitHub Actions workflow for verifying bundled pip andsetuptools. Patch by Illia Volochii and Adam Turner.

Build

  • gh-96761: Fix the build process of clang compiler for_bootstrap_python if LTO optimization is applied. Patch byMatthias Görgens and Donghee Na.

  • gh-96883:wasm32-emscripten builds for browsers now includeconcurrent.futures forasyncio andunittest.mock.

  • gh-85936: CPython now uses the ThinLTO option as the default policy if theClang compiler accepts the flag. Patch by Donghee Na.

  • gh-96729: Ensure that Windows releases built withTools\msi\buildrelease.bat are upgradable to and from official Pythonreleases.

  • gh-96269: Shared module targets now depend on newMODULE_DEPSvariable, which includesEXPORTSYMS. This fixes a build order issue onunsupported AIX platform.

  • gh-84461:wasm32-emscripten platform no longer buildsresourcemodule,getresuid(),getresgid(), and their setters.The APIs are stubs and not functional.

  • gh-95973: Add a new--with-dsymutil configure option to link debuginformation in macOS. Patch by Pablo Galindo.

  • gh-90536: Use the BOLT post-link optimizer to improve performance,particularly on medium-to-large applications.

  • gh-93744: Remove theconfigure--with-cxx-main build option: it didn'twork for many years. Remove theMAINCC variable fromconfigure andMakefile. Patch by Victor Stinner.

  • gh-94801: Fix a regression inconfigure script that caused some headerchecks to ignore customCPPFLAGS. The regression was introduced ingh-94802.

  • gh-95145: wasm32-wasi builds no longer depend on WASIX's pthread stubs.Python now has its own stubbed pthread API.

  • gh-95174: Python now detects missingdup function in WASI and worksaround some missingerrno,select, andsocketconstants.

  • gh-95174: Python now skips missingsocket functions and methods onWASI. WASI can only create sockets from existing fd / accept and has nonetdb.

  • gh-95085: Platformswasm32-unknown-emscripten andwasm32-unknown-wasi have been promoted toPEP 11 tier 3 platformsupport.

  • gh-94847: Fixed_decimal module build issue on GCC when compiling withLTO and pydebug. Debug builds no longer force inlining of functions.

  • gh-94841: Fix the possible performance regression ofPyObject_Free() compiled with MSVC version 1932.

  • gh-94801:configure now uses custom flags likeZLIB_CFLAGS andZLIB_LIBS when searching for headers and libraries.

  • gh-94773:deepfreeze.py now supports code object with frozensets thatcontain incompatible, unsortable types.

  • gh-94682: Build and test with OpenSSL 1.1.1q

  • gh-90005: Dependencies ofreadline andcurses module are nowdetected inconfigure script withpkg-config. Onlyncurses /ncursesw are detected automatically. The oldcurses library is notconfigured automatically. Workaround for missingtermcap ortinfolibrary has been removed.

  • gh-90005: Fix building_ctypes extension withoutpkg-config.

  • gh-90005:_dbm module dependencies are now detected by configure.

  • gh-94404:makesetup now works around an issue with sed on macOS anduses correct CFLAGS for object files that end up in a shared extension.Module CFLAGS are used before PY_STDMODULE_CFLAGS to avoid clashes withsystem headers.

  • gh-93939: C extension modules are now built byconfigure andmakeinstead ofdistutils andsetup.py.

  • gh-93939: The2to3,idle, andpydoc scripts are now generatedand installed byMakefile instead ofsetup.py.

  • gh-94280: Updated pegen regeneration script on Windows to find and usePython 3.9 or higher. Prior to this, pegen regeneration already required3.9 or higher, but the script may have used lower versions of Python.

  • gh-93584: Address race condition inMakefile when installing a PGObuild. Alltest andinstall targets now depend onall target.

  • gh-93491:configure now detects and reportsPEP 11 support tiers.

  • gh-69093: FixModules/Setup.stdlib.in rule for_sqlite3 extension.

  • gh-93207:va_start() with two parameters, likeva_start(args,format), is now required to build Python.va_start() is no longercalled with a single parameter. Patch by Kumar Aditya.

  • gh-93202: Python now always use the%zu and%zd printf formats toformat asize_t orPy_ssize_t number. Building Python 3.12requires a C11 compiler, so these printf formats are now always supported.Patch by Victor Stinner.

  • gh-90473: Disable pymalloc and increase stack size onwasm32-wasi.

  • bpo-34449: Drop invalid compiler switch-fPIC for HP aCC on HP-UX.Patch by Michael Osipov.

Windows

  • gh-98360: Fixesmultiprocessing spawning child processes on Windowsfrom a virtual environment to ensure that child processes that also usemultiprocessing to spawn more children will recognize that they arein a virtual environment.

  • gh-98414: Fixpy.exe launcher handling of-V:<company>/option when default preferences have been set in environment variables orconfiguration files.

  • gh-97728: Fix possible crashes caused by the use of uninitializedvariables when pass invalid arguments inos.system() on Windows andin Windows-specific modules (likewinreg).

  • gh-90989: MadePython Launcher for Windows install per-user by default (unless an allusers install already exists), and clarify some text in the installer.

  • gh-97649: TheTools directory is no longer installed on Windows

  • gh-96965: Update libffi to 3.4.3

  • gh-96577: Fixes a potential buffer overrun inmsilib.

  • gh-96559: Fixes the Windows launcher not using the compatibleinterpretation of default tags found in configuration files when no tagwas passed to the command.

  • gh-94781: Fixpcbuild.proj to clean previous instances of outputfiles inPython\deepfreeze andPython\frozen_modules directorieson Windows. Patch by Charlie Zhao.

  • gh-89545: Updatesplatform code getting the Windows version to usenative Windows Management Instrumentation (WMI) queries to determine OSversion, type, and architecture.

  • gh-95733: Make certain requirements of the Windows Store package optionalto allow installing on earlier updates of Windows.

  • gh-95656: Enable theenable_load_extension()sqlite3 API.

  • gh-95587: Fixes some issues where the Windows installer would incorrectlydetect certain features of an existing install when upgrading.

  • gh-94399: Restores the behaviour ofPython Launcher for Windows for/usr/bin/envshebang lines, which will now searchPATH for an executablematching the given command. If none is found, the usual search process isused.

  • gh-95445: Fixes the unsuccessful removal of the HTML document directorywhen uninstalling with Windows msi.

  • gh-95359: FixPython Launcher for Windows handling ofpy.ini commands (it wasincorrectly expecting apy_ prefix on keys) and crashes when readingper-user configuration file.

  • gh-95285: FixPython Launcher for Windows handling of command lines where it is onlypassed a short executable name.

  • gh-90844: Allow virtual environments to correctly launch when they havespaces in the path.

  • gh-94772: Fix incorrect handling of shebang lines in py.exe launcher

  • gh-94018:zipfile will now remove trailing spaces from pathcomponents when extracting files on Windows.

  • gh-93824: Drag and drop of files onto Python files in Windows Explorer hasbeen enabled for Windows ARM64.

  • gh-43414:os.get_terminal_size() now attempts to read the size fromany provided handle, rather than only supporting file descriptors 0, 1 and2.

  • gh-92817: Ensures thatpy.exe will prefer an active virtualenvironment over default tags specified with environment variables orthrough apy.ini file.

  • gh-92984: Explicitly disable incremental linking for non-Debug builds

  • gh-92841:asyncio no longer throwsRuntimeError:Eventloopisclosed on interpreter exit after asynchronous socket activity. Patch byOleg Iarygin.

  • bpo-46907: Update Windows installer to use SQLite 3.38.4.

  • gh-91061: Accept os.PathLike for the argument to winsound.PlaySound

  • bpo-42658: Support native Windows case-insensitive path comparisons byusingLCMapStringEx instead ofstr.lower() inntpath.normcase(). AddLCMapStringEx to the_winapimodule.

  • bpo-38704: Prevent installation on unsupported Windows versions.

macOS

  • gh-97897: The macOS 13 SDK includes support for themkfifoat andmknodat system calls. Using thedir_fd option with eitheros.mkfifo() oros.mknod() could result in a segfault ifcpython is built with the macOS 13 SDK but run on an earlier version ofmacOS. Prevent this by adding runtime support for detection of thesesystem calls ("weaklinking") as is done for other newer syscalls on macOS.

IDLE

  • gh-97527: Fix a bug in the previous bugfix that caused IDLE to not startwhen run with 3.10.8, 3.12.0a1, and at least Microsoft Python 3.10.2288.0installed without the Lib/test package. 3.11.0 was never affected.

  • gh-65802: Document handling of extensions in Save As dialogs.

  • gh-95191: Include prompts when saving Shell (interactive input andoutput).

  • gh-95511: Fix the Shell context menu copy-with-prompts bug of copying anextra line when one selects whole lines.

  • gh-95471: In the Edit menu, moveSelectAll and add a new separator.

  • gh-95411: Enable using IDLE's module browser with .pyw files.

  • gh-89610: Add .pyi as a recognized extension for IDLE on macOS. Thisallows opening stub files by double clicking on them in the Finder.

Tools/Demos

  • gh-68686: Remove ptags and eptags scripts.

  • gh-97681: Remove theTools/demo/ directory which contained old demoscripts. A copy can be found in theold-demos project. Patch by Victor Stinner.

  • gh-97669: Remove outdated example scripts of theTools/scripts/directory. A copy can be found in theold-demos project. Patch by Victor Stinner.

  • gh-95853: Thewasm_build.py script now pre-builds Emscripten ports,checks for broken EMSDK versions, and warns about pkg-config env vars.

  • gh-95853: The new toolTools/wasm/wasm_builder.py automates configure,compile, and test steps for building CPython on WebAssembly platforms.

  • gh-95731: Fix handling of module docstrings inTools/i18n/pygettext.py.

  • gh-93939: Add scriptTools/scripts/check_modules.py to check andvalidate builtin and shared extension modules. The script also handlesModules/Setup and will eventually replacesetup.py.

  • gh-94538: Fix Argument Clinic output to custom file destinations. Patch byErlend E. Aasland.

  • gh-94430: Allow parameters namedmodule andself with custom Cnames in Argument Clinic. Patch by Erlend E. Aasland

  • gh-86087: TheTools/scripts/parseentities.py script used to parseHTML4 entities has been removed.

C API

Python 3.11.0 beta 1

Release date: 2022-05-06

Security

Core and Builtins

  • gh-89519: Chaining classmethod descriptors (introduced inbpo-19072) isdeprecated. It can no longer be used to wrap other descriptors such asproperty(). The core design of this feature was flawed, and it caused anumber of downstream problems.

  • gh-92345:pymain_run_python() now importsreadline andrlcompleter before sys.path is extended to include the current workingdirectory of an interactive interpreter. Non-interactive interpreters arenot affected.

  • bpo-43857: Improve theAttributeError message when deleting amissing attribute. Patch by Géry Ogam.

  • gh-92245: Make sure that PEP 523 is respected in all cases. In 3.11a7,specialization may have prevented Python-to-Python calls respecting PEP523.

  • gh-92203: Add a closure keyword-only parameter toexec(). It canonly be specified when exec-ing a code object that uses free variables.When specified, it must be a tuple, with exactly the number of cellvariables referenced by the code object. closure has a default value ofNone, and it must beNone if the code object doesn't refer to anyfree variables.

  • gh-91173: Disable frozen modules in debug builds. Patch by Kumar Aditya.

  • gh-92114: Improve error message when subscript a type with__class_getitem__ set toNone.

  • gh-92112: Fix crash triggered by an evil custommro() on a metaclass.

  • gh-92063: ThePRECALL_METHOD_DESCRIPTOR_FAST_WITH_KEYWORDS instructionnow ensures methods are called only on objects of the correct type.

  • gh-92031: Deoptimize statically allocated code objects duringPy_FINALIZE() so that future_PyCode_Quicken calls always startwith unquickened code.

  • gh-92036: Fix a crash in subinterpreters related to the garbage collector.When a subinterpreter is deleted, untrack all objects tracked by its GC.To prevent a crash in deallocator functions expecting objects to betracked by the GC, leak a strong reference to these objects on purpose, sothey are never deleted and their deallocator functions are not called.Patch by Victor Stinner.

  • gh-92032: The interpreter can now autocomplete soft keywords, as of nowmatch,case, and_ (wildcard pattern) fromPEP 634.

  • gh-87999: The warning emitted by the Python parser for a numeric literalimmediately followed by keyword has been changed from deprecation warningto syntax warning.

  • gh-91869: Fix an issue where specialized opcodes with extended argumentscould produce incorrect tracing output or lead to assertion failures.

  • gh-91603: Speed uptypes.UnionType instantiation. Based on patchprovided by Yurii Karabas.

  • gh-89373: If Python is built in debug mode, Python now ensures thatdeallocator functions leave the current exception unchanged. Patch byVictor Stinner.

  • gh-91632: Fix a minor memory leak at exit: release the memory of thegeneric_alias_iterator type. Patch by Donghee Na.

  • gh-81548: Octal escapes with value larger than0o377 now produce aDeprecationWarning. In a future Python version they will be aSyntaxWarning and eventually aSyntaxError.

  • bpo-43950: Use a single compact table for line starts, ends and columnoffsets. Reduces memory consumption for location info by half

  • gh-91102: Use Argument Clinic forEncodingMap. Patch by OlegIarygin.

  • gh-91636: Fixed a crash in a garbage-collection edge-case, in which aPyFunction_Type.tp_clear function could leave a python function objectin an inconsistent state.

  • gh-91603: Speed upisinstance() andissubclass() checks fortypes.UnionType. Patch by Yurii Karabas.

  • gh-91625: Fixed a bug in which adaptive opcodes ignored any precedingEXTENDED_ARGs on specialization failure.

  • gh-78607: The LLTRACE special build now looks for the name__lltrace__defined in module globals, rather than the name__ltrace__, which hadbeen introduced as a typo.

  • gh-91576: Speed up iteration of ascii strings by 50%. Patch by KumarAditya.

  • gh-89279: Improve interpreter performance on Windows by inlining a fewspecific macros.

  • gh-91502: Add a new_PyFrame_IsEntryFrame() API function, tocheck if aPyFrameObject is an entry frame. Patch by PabloGalindo.

  • gh-91266: Refactor thebytearray strip methodsstrip,lstripandrstrip to use a common implementation.

  • gh-91479: Replaced the__note__ field ofBaseException (addedin an earlier version of 3.11) with the final design ofPEP 678.Namely,BaseException gets anadd_note() method, and its__notes__ field is created when necessary.

  • gh-46055: Speed up right shift of negative integers, by removingunnecessary creation of temporaries. Original patch by Xinhang Xu,reworked by Mark Dickinson.

  • gh-91462: Make the interpreter's low-level tracing (lltrace) featureoutput more readable by displaying opcode names (rather than justnumbers), and by displaying stack contents before each opcode.

  • gh-89455: Fixed an uninitialized bool value in the traceback printing codepath that was introduced by the initialbpo-45292 exception groups work.

  • gh-91421: Fix a potential integer overflow in _Py_DecodeUTF8Ex.

  • gh-91428: Addstaticconstchar*const_PyOpcode_OpName[256]={...};toopcode.h for debug builds to assist in debugging the Pythoninterpreter. It is now more convenient to make various forms of debuggingoutput more human-readable by including opcode names rather than just thecorresponding decimal digits.

  • bpo-47120: MakePOP_JUMP_IF_TRUE,POP_JUMP_IF_FALSE,POP_JUMP_IF_NONE andPOP_JUMP_IF_NOT_NONE virtual,mapping to new relative jump opcodes.

  • bpo-45317: Add internal documentation explaining design of new (for 3.11)frame stack.

  • bpo-47197: ctypes used to mishandlevoid return types, so that forinstance a function declared likectypes.CFUNCTYPE(None,ctypes.c_int)would be called with signatureintf(int) instead ofvoidf(int).Wasm targets require function pointers to be called with the correctsignatures so this led to crashes. The problem is now fixed.

  • bpo-47120: Make opcodesJUMP_IF_TRUE_OR_POP andJUMP_IF_FALSE_OR_POP relative rather than absolute.

  • bpo-47177: Replace thef_lasti member of the internal_PyInterpreterFrame structure with aprev_instr pointer, whichreduces overhead in the main interpreter loop. The f_lasti attributeof Python-layer frame objects is preserved for backward-compatibility.

  • bpo-46961: Integer mod/remainder operations, including the three-argumentform ofpow(), now consistently return ints from the global smallinteger cache when applicable.

  • bpo-46962: Classes and functions that unconditionally declared theirdocstrings ignoring the--without-doc-strings compilation flag nolonger do so.

    The classes affected arectypes.UnionType,pickle.PickleBuffer,testcapi.RecursingInfinitelyError,andtypes.GenericAlias.

    The functions affected are 24 methods inctypes.

    Patch by Oleg Iarygin.

  • bpo-46942: Use Argument Clinic for thetypes.MethodTypeconstructor. Patch by Oleg Iarygin.

  • bpo-46764: Fix wrapping bound methods with @classmethod

  • bpo-43464: Optimizeset.intersection() for non-set arguments.

  • bpo-46721: Optimizeset.issuperset() for non-set argument.

  • bpo-46509: Add type-specialized versions of thePy_DECREF(), and usethem forfloat,int,str,bool, andNone to avoidpointer-chasing at runtime where types are known at C compile time.

  • bpo-46045: Do not use POSIX semaphores on NetBSD

  • bpo-36819: Fix crashes in built-in encoders with error handlers thatreturn position less or equal than the starting position of non-encodablecharacters.

  • bpo-34093:marshal.dumps() usesFLAG_REF for all interned strings.This makes output more deterministic and helps reproducible build.

  • bpo-26579: Addedobject.__getstate__ which provides the defaultimplementation of the__getstate__() method.

    Copying and pickling instances of subclasses of builtin types bytearray,set, frozenset, collections.OrderedDict, collections.deque,weakref.WeakSet, and datetime.tzinfo now copies and pickles instanceattributes implemented as slots.

Library

  • gh-87901: Add theencoding parameter toos.popen().

  • gh-90997: Fix an issue wheredis utilities may interpret populatedinline cache entries as valid instructions.

  • gh-92332: Deprecatetyping.Text (removal of the class iscurrently not planned). Patch by Alex Waygood.

  • gh-78157: Deprecate nested classes in enum definitions becoming members --in 3.13 they will be normal classes; addmember andnonmemberfunctions to allow control over results now.

  • gh-92356: Fixed a performance regression in ctypes function calls.

  • gh-90997: Show the actual named values stored in inline caches whenshow_caches=True is passed todis utilities.

  • gh-92301: Preferclose_range() to iterating over procfs for filedescriptor closing insubprocess for better performance.

  • gh-67248: Sort the miscellaneous topics in Cmd.do_help()

  • gh-92210: Portsocket.__init__ to Argument Clinic. Patch by Cinder.

  • gh-80010: Add support for generalized ISO 8601 parsing todatetime.datetime.fromisoformat(),datetime.date.fromisoformat() anddatetime.time.fromisoformat(). Patch by Paul Ganssle.

  • gh-92118: Fix a 3.11 regression incontextmanager(),which caused it to propagate exceptions with incorrect tracebacks.

  • gh-90887: AddingCOPYFILE_STAT,COPYFILE_ACL andCOPYFILE_XATTR constants foros.fcopyfile() available in macOs.

  • gh-91215: For@dataclass, addweakref_slot. The new parameter defaults toFalse. If true, and ifslots=True, add a slot named"__weakref__", which will allowinstances to be weakref'd. Contributed by Eric V. Smith

  • gh-85984: New function os.login_tty() for Unix.

  • gh-92128: Add__class_getitem__() tologging.LoggerAdapter andlogging.StreamHandler,allowing them to be parameterized at runtime. Patch by Alex Waygood.

  • gh-92049: Forbid pickling constantsre._constants.SUCCESS etc.Previously, pickling did not fail, but the result could not be unpickled.

  • gh-92062:inspect.Parameter now raisesValueError ifname is a keyword, in addition to the existing check that it is anidentifier.

  • gh-87390: Add an__unpacked__ attribute totypes.GenericAlias. Patch by Jelle Zijlstra.

  • gh-88089: Add support for generictyping.NamedTuple.

  • gh-91996: New http.HTTPMethod enum to represent all the available HTTPrequest methods in a convenient way

  • gh-91984: Modified test strings in test_argparse.py to not containtrailing spaces before end of line.

  • gh-91952: Addencoding="locale" support toTextIOWrapper.reconfigure().

  • gh-91954: Addencoding anderrors arguments tosubprocess.getoutput() andsubprocess.getstatusoutput().

  • bpo-47029: Always close the read end of the pipe used bymultiprocessing.Queueafter the last write of buffered data tothe write end of the pipe to avoidBrokenPipeError at garbagecollection and atmultiprocessing.Queue.close() calls. Patch by GéryOgam.

  • gh-91928: Adddatetime.UTC alias fordatetime.timezone.utc.

    Patch by Kabir Kwatra.

  • gh-68966: Themailcap module is now deprecated and will be removedin Python 3.13. SeePEP 594 for the rationale and themimetypesmodule for an alternative. Patch by Victor Stinner.

  • gh-91401: Provide a way to disablesubprocess use ofvfork()just in case it is ever needed and document the existing mechanism forposix_spawn().

  • gh-64783: Fixsignal.NSIG value on FreeBSD to accept signalnumbers greater than 32, likesignal.SIGRTMIN andsignal.SIGRTMAX. Patch by Victor Stinner.

  • gh-91910: Add missing f prefix to f-strings in error messages from themultiprocessing andasyncio modules.

  • gh-91860: Addtyping.dataclass_transform(), implementingPEP 681.Patch by Jelle Zijlstra.

  • gh-91832: Addrequired attribute toargparse.Action reproutput.

  • gh-91827: In thetkinter module add methodinfo_patchlevel()which returns the exact version of the Tcl library as a named tuplesimilar tosys.version_info.

  • gh-84461: Add--enable-wasm-pthreads to enable pthreads supportfor WASM builds.Emscripten/node no longer has threading enabled bydefault. Include additional file systems.

  • gh-91821: Fix unstabletest_from_tuple test intest_decimal.py.

  • gh-91217: Deprecate the xdrlib module.

  • gh-91217: Deprecate the uu module.

  • gh-91760: More strict rules will be applied for numerical group referencesand group names in regular expressions. For now, a deprecation warning isemitted for group references and group names which will be errors infuture Python versions.

  • gh-84461: Add provisionalsys._emscripten_info named tuple withbuild-time and run-time information about Emscripten platform.

  • gh-90623:signal.raise_signal() andos.kill() now checkimmediately for pending signals. Patch by Victor Stinner.

  • gh-91734: Fix OSS audio support on Solaris.

  • gh-90633: Include the passed value in the exception thrown bytyping.assert_never(). Patch by Jelle Zijlstra.

  • gh-91700: Compilation of regular expression containing a conditionalexpression(?(group)...) now raises an appropriatere.error ifthe group number refers to not defined group. Previously an internalRuntimeError was raised.

  • gh-91231: Add an optional keywordshutdown_timeout parameter to themultiprocessing.BaseManager constructor. Kill the process ifterminate() takes longer than the timeout. Patch by Victor Stinner.

  • gh-91621: Fixtyping.get_type_hints() forcollections.abc.Callable. Patch by Shantanu Jain.

  • gh-90568: Parsing\N escapes of Unicode Named Character Sequences in aregularexpression raises nowre.error instead ofTypeError.

  • gh-91670: Remove deprecatedSO config variable insysconfig.

  • gh-91217: Deprecate the telnetlib module.

  • gh-91217: Deprecate the sunau module.

  • gh-91217: Deprecate the spwd module.

  • gh-91217: Deprecate the sndhdr module, as well as inline neededfunctionality foremail.mime.MIMEAudio.

  • gh-91616:re module, fixfullmatch() mismatchwhen using Atomic Grouping or Possessive Quantifiers.

  • gh-91217: Deprecate the 'pipes' module.

  • gh-91217: Deprecate the ossaudiodev module.

  • bpo-47256:re module, limit the maximum capturing group to1,073,741,823 in 64-bit build, this increases the depth of backtracking.

  • gh-91217: Deprecate the nis module.

  • gh-91595: Fix the comparison of character and integer insideTools.gdb.libpython.write_repr(). Patch by Yu Liu.

  • gh-74166: Add option to raise all errors fromcreate_connection() in anExceptionGroup when itfails to create a connection. The default remains to raise only the lasterror that had occurred when multiple addresses were tried.

  • gh-91487: Optimize asyncio UDP speed, over 100 times faster whentransferring a large file.

  • gh-91575: Update case-insensitive matching in there module to thelatest Unicode version.

  • gh-90622: Inconcurrent.futures.process.ProcessPoolExecutor disallowthe "fork" multiprocessing start method when the newmax_tasks_per_child feature is used as the mix of threads+fork canhang the child processes. Default to using the safe "spawn" start methodin that circumstance if nomp_context was supplied.

  • gh-89022: Insqlite3,SQLITE_MISUSE result codes are now mappedtoInterfaceError instead ofProgrammingError. Also, more accurate exceptions areraised when binding parameters fail. Patch by Erlend E. Aasland.

  • gh-91526: Stop callingos.device_encoding(file.fileno()) inTextIOWrapper. It was complex, never documented, and didn't workfor most cases. (Patch by Inada Naoki.)

  • gh-88116: Change the frame-related functions in theinspect moduleto return a regular object (that is backwards compatible with the oldtuple-like interface) that include the extendedPEP 657 positioninformation (end line number, column and end column). The affectedfunctions are:inspect.getframeinfo(),inspect.getouterframes(),inspect.getinnerframes(),inspect.stack() andinspect.trace(). Patch by Pablo Galindo.

  • gh-69093: Add indexing and slicing support tosqlite3.Blob. Patchby Aviv Palivoda and Erlend E. Aasland.

  • gh-69093: Addcontext manager support tosqlite3.Blob.Patch by Aviv Palivoda and Erlend E. Aasland.

  • gh-91217: Deprecate nntplib.

  • gh-91217: Deprecate msilib.

  • gh-91404: Improve the performance ofre matching by using computedgotos (or "threaded code") on supported platforms and removing expensivepointer indirections.

  • gh-91217: Deprecate the imghdr module.

  • gh-91217: Deprecate the crypt module.

  • gh-91276: Make space for longer opcodes indis output.

  • bpo-47000: MakeTextIOWrapper uses locale encoding whenencoding="locale" is specified even in UTF-8 mode.

  • gh-91230:warnings.catch_warnings() now accepts arguments forwarnings.simplefilter(), providing a more concise way to locallyignore warnings or convert them to errors.

  • gh-91217: Deprecate the chunk module.

  • gh-91498: Add theTCP_CONNECTION_INFO option (available on macOS) tosocket.

  • bpo-47260: Fixos.closerange() potentially being a no-op in a Linuxseccomp sandbox.

  • bpo-47087: Implementtyping.Required andtyping.NotRequired(PEP 655). Patch by David Foster and Jelle Zijlstra.

  • bpo-47061: Deprecate cgi and cgitb.

  • bpo-47061: Deprecate audioop.

  • bpo-47000: Addlocale.getencoding() to get the current localeencoding. It is similar tolocale.getpreferredencoding(False) butignores thePython UTF-8 Mode.

  • bpo-42012: Addwsgiref.types, containing WSGI-specific types forstatic type checking.

  • bpo-47227: Suppress expression chaining for morere parsing errors.

  • bpo-47211: Remove undocumented and never working functionre.template() and flagre.TEMPLATE. This was later reverted in3.11.0b2 and deprecated instead.

  • bpo-47135:decimal.localcontext() now accepts context attributes viakeyword arguments

  • bpo-43323: Fix errors in theemail module if the charset itselfcontains undecodable/unencodable characters.

  • bpo-46841: Disassembly of quickened code.

  • bpo-46681: Forward gzip.compress() compresslevel to zlib.

  • bpo-45100: Addtyping.get_overloads() andtyping.clear_overloads(). Patch by Jelle Zijlstra.

  • bpo-44807:typing.Protocol no longer silently replaces__init__() methods defined on subclasses. Patch by Adrian GarciaBadaracco.

  • bpo-46787: Fixconcurrent.futures.ProcessPoolExecutor exceptionmemory leak

  • bpo-46720: Add support for path-like objects tomultiprocessing.set_executable() for Windows to be on a par withUnix-like systems. Patch by Géry Ogam.

  • bpo-46696: AddSO_INCOMING_CPU constant tosocket.

  • bpo-46053: Fix OSS audio support on NetBSD.

  • bpo-45639:image/avif andimage/webp were added tomimetypes.

  • bpo-46285: Add command-line option-p/--protocol to modulehttp.server which specifies the HTTP version to which the server isconformant (HTTP/1.1 conformant servers can now be run from thecommand-line interface of modulehttp.server). Patch by Géry Ogam.

  • bpo-44791: Accept ellipsis as the last argument oftyping.Concatenate.

  • bpo-46547: Remove variables leaking intopydoc.Helper class namespace.

  • bpo-46415: Fix ipaddress.ip_{address,interface,network} raising TypeErrorinstead of ValueError if given invalid tuple as address parameter.

  • bpo-46075:CookieJar withDefaultCookiePolicy now can processcookies from localhost with domain=localhost explicitly specified inSet-Cookie header.

  • bpo-45995: Add a "z" option to the string formatting specification thatcoerces negative zero floating-point values to positive zero afterrounding to the format precision. Contributed by John Belmonte.

  • bpo-26175: Fully implement theio.BufferedIOBase orio.TextIOBase interface fortempfile.SpooledTemporaryFile objects. This lets them workcorrectly with higher-level layers (like compression modules). Patch byCarey Metcalfe.

  • bpo-45138: Fix a regression in thesqlite3 trace callback wherebound parameters were not expanded in the passed statement string. Theregression was introduced in Python 3.10 bybpo-40318. Patch byErlend E. Aasland.

  • bpo-44863: AllowTypedDict subclasses to also includeGeneric as a base class in class based syntax. Therebyallowing the user to define a genericTypedDict, just like auser-defined generic but withTypedDict semantics.

  • bpo-44587: Fix BooleanOptionalAction to not automatically add a defaultstring. If a default string is desired, use a formatter to add it.

  • bpo-43827: All positional-or-keyword parameters toABCMeta.__new__ arenow positional-only to avoid conflicts with keyword arguments to be passedto__init_subclass__().

  • bpo-43218: Prevent creation of a venv whose path contains the PATHseparator. This could affect the usage of the activate script. Patch byDustin Rodrigues.

  • bpo-38435: Add aprocess_group parameter tosubprocess.Popento help move more things off of the unsafepreexec_fn parameter.

  • bpo-42066: Fix cookies getting sorted inCookieJar.__iter__() whichis an extra behavior and not mentioned in RFC 2965 or Netscape cookieprotocol. Now the cookies inCookieJar follows the order of theSet-Cookie header. Patch by Iman Kermani.

  • bpo-40617: Addcreate_window_function() tosqlite3.Connection for creating aggregate window functions. Patchby Erlend E. Aasland.

  • bpo-40676: Convertcsv to use Argument Clinic forcsv.field_size_limit(),csv.get_dialect(),csv.unregister_dialect() andcsv.list_dialects().

  • bpo-39716: Raise anArgumentError when the same subparser name isadded twice to anargparse.ArgumentParser. This is consistent withthe (default) behavior when the same option string is added twice to anArgumentParser.

  • bpo-36073: RaiseProgrammingError instead of segfaultingon recursive usage of cursors insqlite3 converters. Patch bySergey Fedoseev.

  • bpo-34975: Adds astart_tls() method toStreamWriter, which upgrades the connection withTLS using the givenSSLContext.

  • bpo-22276:Path methodsglob() andrglob() return only directories ifpattern ends witha pathname components separator (/ orsep). Patch byEisuke Kawashima.

  • bpo-24905: Addblobopen() tosqlite3.Connection.sqlite3.Blob allows incremental I/Ooperations on blobs. Patch by Aviv Palivoda and Erlend E. Aasland.

Documentation

Tests

  • gh-92169: Usewarnings_helper.import_deprecated() to import deprecatedmodules uniformly in tests. Patch by Hugo van Kemenade.

  • gh-84461: When multiprocessing is enabled, libregrtest can now use aPython executable other thansys.executable via the--pythonflag.

  • gh-91904: Fix initialization ofPYTHONREGRTEST_UNICODE_GUARDwhich prevented running regression tests on non-UTF-8 locale.

  • gh-91752: Added @requires_zlib to test.test_tools.test_freeze.TestFreeze.

  • gh-91607: Fixtest_concurrent_futures to test the correctmultiprocessing start method context in several cases where the test logicmixed this up.

  • bpo-40280: Threading tests are now skipped on WASM targets without pthreadsupport.

  • bpo-47109: Test forctypes.macholib.dyld,ctypes.macholib.dylib, andctypes.macholib.framework arebrought from manual pre-unittest times toctypes.testlocation and structure. Patch by Oleg Iarygin.

  • bpo-29890: Add tests foripaddress.IPv4Interface andipaddress.IPv6Interface construction with tuple arguments.Original patch and tests by louisom.

Build

  • gh-89452: gdbm-compat is now preferred over ndbm if both are available onthe system. This allows avoiding the problematic ndbm.h on macOS.

  • gh-91731: Python is now built with-std=c11 compiler option, ratherthan-std=c99. Patch by Victor Stinner.

  • bpo-47152: Add script and make target for generatingsre_constants.h.

  • bpo-47103: WindowsPGInstrument builds now copy a required DLL intothe output directory, making it easier to run the profile stage of a PGObuild.

Windows

  • bpo-46907: Update Windows installer to use SQLite 3.38.3.

  • bpo-47239: Fixed --list and --list-paths output forPython Launcher for Windows whenused in an active virtual environment.

  • bpo-46907: Update Windows installer to use SQLite 3.38.2.

  • bpo-46785: Fix race condition betweenos.stat() and unlinking a fileon Windows, by using errors codes returned byFindFirstFileW() whenappropriate inwin32_xstat_impl.

  • bpo-40859: Update Windows build to use xz-5.2.5

macOS

  • bpo-46907: Update macOS installer to SQLite 3.38.4.

Tools/Demos

  • gh-91583: Fix regression in the code generated by Argument Clinic forfunctions with thedefining_class parameter.

  • gh-91575: Add scriptTools/scripts/generate_re_casefix.py and the maketargetregen-re for generating additional data for case-insensitivematching according to the current Unicode version.

  • gh-91551: Remove the ancient Pynche color editor. It has moved tohttps://gitlab.com/warsaw/pynche

C API

  • gh-88279: Deprecate the C functions:PySys_SetArgv(),PySys_SetArgvEx(),PySys_SetPath(). Patch by VictorStinner.

  • gh-92154: Added thePyCode_GetCode() function. This function doesthe equivalent of the Python codegetattr(code_object,'co_code').

  • gh-92173: Fix theclosure argument toPyEval_EvalCodeEx().

  • gh-91320: Fix C++ compiler warnings about "old-style cast" (g++-Wold-style-cast) in the Python C API. Use C++reinterpret_cast<>andstatic_cast<> casts when the Python C API is used in C++. Patch byVictor Stinner.

  • gh-80527: Mark functions as deprecated byPEP 623:PyUnicode_AS_DATA(),PyUnicode_AS_UNICODE(),PyUnicode_GET_DATA_SIZE(),PyUnicode_GET_SIZE(). Patchby Victor Stinner.

  • gh-91768:Py_REFCNT(),Py_TYPE(),Py_SIZE() andPy_IS_TYPE() functions argument type is nowPyObject*, ratherthanconstPyObject*. Patch by Victor Stinner.

  • gh-91020: AddPyBytes_Type.tp_alloc to initializePyBytesObject.ob_shash for bytes subclasses.

  • bpo-40421: AddPyFrame_GetLasti C-API function to access frameobject'sf_lasti attribute safely from C code.

  • bpo-35134: Remove theInclude/code.h header file. C extensions shouldonly include the main<Python.h> header file. Patch by Victor Stinner.

  • bpo-47169:PyOS_CheckStack() is now exported in the Stable ABI onWindows.

  • bpo-47169:PyThread_get_thread_native_id() is excluded from thestable ABI on platforms where it doesn't exist (like Solaris).

  • bpo-46343: AddedPyErr_GetHandledException() andPyErr_SetHandledException() as simpler alternatives toPyErr_GetExcInfo() andPyErr_SetExcInfo().

    They are included in the stable ABI.

Python 3.11.0 alpha 7

Release date: 2022-04-05

Core and Builtins

  • bpo-47212: RaiseIndentationError instead ofSyntaxError fora bareexcept with no following indent. ImproveSyntaxErrorlocations for an un-parenthesized generator used as arguments. Patch byMatthieu Dartiailh.

  • bpo-47186: ReplaceJUMP_IF_NOT_EG_MATCH byCHECK_EG_MATCH + jump.

  • bpo-47176: Emscripten builds cannot handle signals in the usual way due toplatform limitations. Python can now handle signals. To use, setModule.Py_EmscriptenSignalBuffer to be a single byte SharedArrayBuffer andset Py_EMSCRIPTEN_SIGNAL_HANDLING to 1. Writing a number into theSharedArrayBuffer will cause the corresponding signal to be raised intothe Python thread.

  • bpo-47186: ReplaceJUMP_IF_NOT_EXC_MATCH byCHECK_EXC_MATCH + jump.

  • bpo-47120: Replace the absolute jump opcodeJUMP_NO_INTERRUPT bythe relativeJUMP_BACKWARD_NO_INTERRUPT.

  • bpo-46841: Avoid unnecessary allocations when comparing code objects.

  • bpo-47182: Fix a crash when using a named unicode character like"\N{digitnine}" after the main interpreter has been initialized asecond time.

  • bpo-47162: WebAssembly cannot deal with bad function pointer casts(different count or types of arguments). Python can now use calltrampolines to mitigate the problem. DefinePY_CALL_TRAMPOLINEto enable call trampolines.

  • bpo-46775: Some Windows system error codes(>= 10000) are now mapped intothe correct errno and may now raise a subclass ofOSError. Patch byDonghee Na.

  • bpo-47129: Improve error messages in f-string syntax errors concerningempty expressions.

  • bpo-47117: Fix a crash if we fail to decode characters in interactive modeif the tokenizer buffers are uninitialized. Patch by Pablo Galindo.

  • bpo-47127: Speed up calls to c functions with keyword arguments by 25%with specialization. Patch by Kumar Aditya.

  • bpo-47120: ReplacedJUMP_ABSOLUTE by the relative jumpJUMP_BACKWARD.

  • bpo-42197:PyFrame_FastToLocalsWithError() andPyFrame_LocalsToFast() are no longer called during profiling nortracing. C code can access thef_locals attribute ofPyFrameObject by callingPyFrame_GetLocals().

  • bpo-47070: Improve performance ofarray_inplace_repeat by reducing thenumber of invocations ofmemcpy. Refactor therepeat and inplacerepeat methods ofarray,bytes,bytearray andunicodeobject to use the common_PyBytes_Repeat.

  • bpo-47053: Reduce de-optimization in the specializedBINARY_OP_INPLACE_ADD_UNICODE opcode.

  • bpo-47045: Remove thef_state field from the _PyInterpreterFramestruct. Add theowner field to the _PyInterpreterFrame struct to makeownership explicit to simplify clearing and deallocing frames andgenerators.

  • bpo-46968: Check for the existence of the "sys/auxv.h" header infaulthandler to avoid compilation problems in systems where thisheader doesn't exist. Patch by Pablo Galindo

  • bpo-46329: Use low bit ofLOAD_GLOBAL to indicate whether to push aNULL before the global. Helps streamline the call sequence a bit.

  • bpo-46841: Quicken bytecode in-place by storing it as part of thecorrespondingPyCodeObject.

  • bpo-47012: Speed up iteration ofbytes andbytearray by30%. Patch by Kumar Aditya.

  • bpo-47009: Improved the performance oflist.append() and listcomprehensions by optimizing for the common case, where no resize isneeded. Patch by Dennis Sweeney.

  • bpo-47005: Improve performance ofbytearray_repeat andbytearray_irepeat by reducing the number of invocations ofmemcpy.

  • bpo-46829: Deprecate passing a message intoasyncio.Future.cancel()andasyncio.Task.cancel()

  • bpo-46993: Speed upbytearray creation fromlist andtuple by 40%. Patch by Kumar Aditya.

  • bpo-39829: Removed the__len__() call when initializing a list andmoved initializing tolist_extend. Patch by Jeremiah Pascual.

  • bpo-46944: Speed up throwing exception in generator withMETH_FASTCALL calling convention. Patch by Kumar Aditya.

  • bpo-46841: ModifySTORE_SUBSCR to use an inline cache entry(rather than its oparg) as an adaptive counter.

  • bpo-46841: Use inline caching forPRECALL andCALL,and remove the internal machinery for managing the (now unused) non-inlinecaches.

  • bpo-46881: Statically allocate and initialize the latin1 characters.

  • bpo-46838: Improve syntax errors for incorrect function definitions. Patchby Pablo Galindo

  • bpo-43721: Fix docstrings ofgetter,setter, anddeleter to clarify thatthey create a new copy of the property.

  • bpo-43224: Make grammar changes required for PEP 646.

Library

  • bpo-47208: Allow vendors to overrideCTYPES_MAX_ARGCOUNT.

  • bpo-23689:re module: fix memory leak when a match is terminated bya signal or memory allocation failure. Patch by Ma Lin.

  • bpo-47167: Allow overriding a future compliance check inasyncio.Task.

  • bpo-47151: When subprocess tries to use vfork, it now falls back to forkif vfork returns an error. This allows use in situations where vfork isn'tallowed by the OS kernel.

  • bpo-47152: Convert there module into a package. Deprecate modulessre_compile,sre_constants andsre_parse.

  • bpo-4833: AddZipFile.mkdir()

  • bpo-27929: Fixasyncio.loop.sock_connect() to only resolve names forsocket.AF_INET orsocket.AF_INET6 families. Resolutionmay not make sense for other families, likesocket.AF_BLUETOOTHandsocket.AF_UNIX.

  • bpo-14265: Adds the fully qualified test name to unittest output

  • bpo-47061: Deprecate the aifc module.

  • bpo-39622: Handle Ctrl+C in asyncio programs to interrupt the main task.

  • bpo-47101:hashlib.algorithms_available now lists only algorithmsthat are provided by activated crypto providers on OpenSSL 3.0. Legacyalgorithms are not listed unless the legacy provider has been loaded intothe default OSSL context.

  • bpo-47099: AllURLError exception messages raised inurllib.request.URLopener now contain a colon betweenftperror and the rest of the message. Previously,open_ftp() missed the colon. Patch by OlegIarygin.

  • bpo-47099: Exception chaining is changed fromException.with_traceback()/sys.exc_info() toPEP 3134.Patch by Oleg Iarygin.

  • bpo-47095:hashlib's internal_blake2 module now preferslibb2 fromhttps://www.blake2.net/ over Python's vendored copy ofblake2.

  • bpo-47098: The Keccak Code Package forhashlib's internal_sha3module has been replaced with tiny_sha3. The module is used as fallbackwhen Python is built without OpenSSL.

  • bpo-47088: Implementtyping.LiteralString, part ofPEP 675.Patch by Jelle Zijlstra.

  • bpo-42885: Optimizere.search(),re.split(),re.findall(),re.finditer() andre.sub() for regularexpressions starting with\A or^.

  • bpo-23691: Protect there.finditer() iterator from re-entering.

  • bpo-47067: Optimize callingGenericAlias objects by usingPEP 590vectorcall and by replacingPyObject_SetAttrString withPyObject_SetAttr.

  • bpo-28080: Add themetadata_encoding parameter in thezipfile.ZipFile constructor and the--metadata-encodingoption in thezipfile CLI to allow reading zipfiles usingnon-standard codecs to encode the filenames within the archive.

  • bpo-47000: Makeio.text_encoding() returns "utf-8" when UTF-8 modeis enabled.

  • bpo-42369: Fix thread safety ofzipfile._SharedFile.tell() to avoida "zipfile.BadZipFile: Bad CRC-32 for file" exception when reading aZipFile from multiple threads.

  • bpo-38256: Fixbinascii.crc32() when it is compiled to use zlib'ccrc32 to work properly on inputs 4+GiB in length instead of returning thewrong result. The workaround prior to this was to always feed the functiondata in increments smaller than 4GiB or to just call the zlib modulefunction.

    We also havebinascii.crc32() release the GIL when computing onlarger inputs aszlib.crc32() andhashlib do.

    This also boosts performance on Windows as it now uses the zlib crc32implementation forbinascii.crc32() for a 2-3x speedup.

    That the stdlib has a crc32 API in two modules is a known historicaloddity. This moves us closer to a single implementation behind them.

  • bpo-47066: Global inline flags (e.g.(?i)) can now only be used at thestart of the regular expressions. Using them not at the start ofexpression was deprecated since Python 3.6.

  • bpo-39394: A warning about inline flags not at the start of the regularexpression now contains the position of the flag.

  • bpo-433030: Add support of atomic grouping ((?>...)) and possessivequantifiers (*+,++,?+,{m,n}+) inregularexpressions.

  • bpo-47062: Implementasyncio.Runner context manager.

  • bpo-46382:dataclass()slots=True now correctlyomits slots already defined in base classes. Patch by Arie Bovenberg.

  • bpo-47057: Use FASTCALL convention forFutureIter.throw()

  • bpo-47061: Deprecate the various modules listed byPEP 594:

    aifc, asynchat, asyncore, audioop, cgi, cgitb, chunk, crypt, imghdr,msilib, nntplib, nis, ossaudiodev, pipes, smtpd, sndhdr, spwd, sunau,telnetlib, uu, xdrlib

  • bpo-34790: Remove passing coroutine objects toasyncio.wait().

  • bpo-47039: Normalizerepr() of asyncio future and task objects.

  • bpo-2604: Fix bug where doctests using globals would fail when runmultiple times.

  • bpo-45150: Addhashlib.file_digest() helper for efficient hashing offile object.

  • bpo-34861: Made cumtime the default sorting key for cProfile

  • bpo-45997: Fixasyncio.Semaphore re-aquiring FIFO order.

  • bpo-47022: Theasynchat,asyncore andsmtpdmodules have been deprecated since at least Python 3.6. Theirdocumentation and deprecation warnings and have now been updated to notethey will removed in Python 3.12 (PEP 594).

  • bpo-43253: Fix a crash when closing transports where the underlying sockethandle is already invalid on the Proactor event loop.

  • bpo-40280:select.select() now passesNULL toselect foreach empty fdset.

  • bpo-47004: Apply bugfixes from importlib_metadata 4.11.3, including bugfixfor EntryPoint.extras, which was returning match objects and not theextras strings.

  • bpo-46998: Allow subclassing oftyping.Any. Patch by ShantanuJain.

  • bpo-46995: Deprecate missingasyncio.Task.set_name() for third-partytask implementations, schedule making it mandatory in Python 3.13.

  • bpo-46994: Accept explicit contextvars.Context inasyncio.create_task() andasyncio.loop.create_task().

  • bpo-46981:typing.get_args(typing.Tuple[()]) now returns()instead of((),).

  • bpo-46968: Addos.sysconf_names['SC_MINSIGSTKSZ'].

  • bpo-46985: Upgrade pip wheel bundled with ensurepip (pip 22.0.4)

  • bpo-46968:faulthandler: On Linux 5.14 and newer, dynamicallydetermine size of signal handler stack size CPython allocates usinggetauxval(AT_MINSIGSTKSZ). This changes allows for Python extension'srequest to Linux kernel to use AMX_TILE instruction set on Sapphire RapidsXeon processor to succeed, unblocking use of the ISA in frameworks.

  • bpo-46917: Themath.nan value is now always available. Patch byVictor Stinner.

  • bpo-46955: Exposeasyncio.base_events.Server asasyncio.Server. Patch by Stefan Zabka.

  • bpo-23325: Thesignal module no longer assumes thatSIG_IGN andSIG_DFL are small intsingletons.

  • bpo-46932: Update bundled libexpat to 2.4.7

  • bpo-46933: Thepwd module is now optional.os.path.expanduser() returns the path when thepwd module isnot available.

  • bpo-40059:PEP 680, thetomllib module. Adds support for parsingTOML.

  • bpo-464471:asyncio.timeout() andasyncio.timeout_at() contextmanagers added. Patch by Tin Tvrtković and Andrew Svetlov.

  • bpo-46805: Added raw datagram socket functions for asyncio:sock_sendto(),sock_recvfrom() andsock_recvfrom_into().

  • bpo-46644: No longer require valid typeforms to be callable. This allowstyping.Annotated to wraptyping.ParamSpecArgs anddataclasses.InitVar. Patch by Gregory Beauregard.

  • bpo-46581: BringsParamSpec propagation forGenericAliasin line withConcatenate (and others).

  • bpo-45413: Defineposix_venv andnt_venvsysconfig installationschemes to be used for bootstrapping new virtualenvironments. Addvenv sysconfig installation scheme to get theappropriate one of the above. The schemes are identical to thepre-existingposix_prefix andnt install schemes. Thevenvmodule now uses thevenv scheme to create new virtual environmentsinstead of hardcoding the paths depending only on the platform. DownstreamPython distributors customizing theposix_prefix ornt install schemein a way that is not compatible with the install scheme used in virtualenvironments are encouraged not to customize thevenv schemes. WhenPython itself runs in a virtual environment,sysconfig.get_default_scheme() andsysconfig.get_preferred_scheme() withkey="prefix" returnsvenv.

  • bpo-43224: Implement support for PEP 646 in typing.py.

  • bpo-43224: Allow unpacking types.GenericAlias objects, e.g.*tuple[int,str].

  • bpo-46557: Warnings captured by the logging module are now logged withouta format string to prevent systems that group logs by the msg argumentfrom grouping captured warnings together.

  • bpo-41370:typing.get_type_hints() now supports evaluating stringsas forward references inPEP 585 generic aliases.

  • bpo-46607: AddDeprecationWarning toLegacyInterpolation,deprecated in the docstring since Python 3.2. Will be removed in Python3.13. UseBasicInterpolation orExtendedInterpolationinstead.

  • bpo-26120:pydoc now excludes __future__ imports from the module'sdata items.

  • bpo-46480: Addtyping.assert_type(). Patch by Jelle Zijlstra.

  • bpo-46421: Fix a unittest issue where if the command was invoked aspython-munittest and the filename(s) began with a dot (.), aValueError is returned.

  • bpo-46245: Add optional parameterdir_fd inshutil.rmtree().

  • bpo-22859:unittest.TestProgram.usageExit() is marked asdeprecated, to be removed in Python 3.13.

  • bpo-46170: Improve the error message when you try to subclass an instanceoftyping.NewType.

  • bpo-40296: Fix supporting generic aliases inpydoc.

  • bpo-20392: Fix inconsistency with uppercase file extensions inMimeTypes.guess_type(). Patch by Kumar Aditya.

  • bpo-46030: AddLOCAL_CREDS,LOCAL_CREDS_PERSISTENT andSCM_CREDS2 FreeBSD constants to the socket module.

  • bpo-44439: Fix.write() method of a member file inZipFile, whenthe input data is an object that supports the buffer protocol, the filelength may be wrong.

  • bpo-45171: Fix handling of thestacklevel argument to loggingfunctions in thelogging module so that it is consistent across alllogging functions and, as advertised, similar to thestacklevelargument used inwarn().

  • bpo-24959: Fix bug whereunittest sometimes drops frames fromtracebacks of exceptions raised in tests.

  • bpo-44859: Raise more accurate andPEP 249 compatible exceptions insqlite3.

  • bpo-44493: Add missing terminated NUL in sockaddr_un's length

    This was potentially observable when using non-abstract AF_UNIX datagramsockets to processes written in another programming language.

  • bpo-41930: Addserialize() anddeserialize() support tosqlite3. Patchby Erlend E. Aasland.

  • bpo-33178: Addedctypes.BigEndianUnion andctypes.LittleEndianUnion classes, as originally documented in thelibrary docs but not yet implemented.

  • bpo-43352: Add an Barrier object in synchronization primitives ofasyncio Lib in order to be consistent with Barrier fromthreading andmultiprocessing libs*

  • bpo-35859:re module, fix a few bugs about capturing group. In rarecases, capturing group gets an incorrect string. Patch by Ma Lin.

Documentation

Tests

Build

  • bpo-40280: Add configure option--enable-wasm-dynamic-linking toenabledlopen and MAIN_MODULE / SIDE_MODULE onwasm32-emscripten.

  • bpo-46023:makesetup now detects and skips all duplicated moduledefinitions. The first entry wins.

  • bpo-40280: Add SOABIwasm32-emscripten for Emscripten andwasm32-wasi for WASI on 32bit WASM as well aswasm64 counterparts.

  • bpo-47032: Ensure Windows install builds fail correctly with a non-zeroexit code when part of the build fails.

  • bpo-47024: Update OpenSSL to 1.1.1n for macOS installers and all Windowsbuilds.

  • bpo-46996: Thetkinter package now requires Tcl/Tk version 8.5.12or newer.

  • bpo-46973: Addregen-configure make target to regenerate configurescript with Christian's container imagequay.io/tiran/cpython_autoconf:269.

  • bpo-46917: Building Python now requires support of IEEE 754 floating-pointnumbers. Patch by Victor Stinner.

  • bpo-45774:configure now verifies that all SQLite C APIs needed forthesqlite3 extension module are found.

Windows

  • bpo-47194: Updatezlib to v1.2.12 to resolveCVE 2018-25032.

  • bpo-47171: Enables installing thepy.exe launcher on WindowsARM64.

  • bpo-46566: UpgradedPython Launcher for Windows to support a new-V:company/tagargument for fullPEP 514 support and to detect ARM64 installs. The-64 suffix on arguments is deprecated, but still selects anynon-32-bit install. SettingPYLAUNCHER_ALLOW_INSTALL andspecifying a version that is not installed will attempt to install therequested version from the Microsoft Store.

  • bpo-47086: The installer for Windows now includes documentation as looseHTML files rather than a single compiled.chm file.

  • bpo-46907: Update Windows installer to use SQLite 3.38.1.

  • bpo-44549: Update bzip2 to 1.0.8 in Windows builds to mitigateCVE 2016-3189 andCVE 2019-12900.

  • bpo-46948: PreventCVE 2022-26488 by ensuring the Add to PATH option inthe Windows installer uses the correct path when being repaired.

macOS

  • bpo-46890: Fix a regression in the setting ofsys._base_executable inframework builds, and thereby fix a regression invenv virtualenvironments with such builds.

  • bpo-46907: Update macOS installer to SQLite 3.38.1.

Tools/Demos

  • bpo-40280: Replace Emscripten's limited shell with Katie Bell's browser-uiREPL from python-wasm project.

C API

  • bpo-40421: AddPyFrame_GetBuiltins,PyFrame_GetGenerator andPyFrame_GetGlobals C-API functions to access frame object attributessafely from C code.

  • bpo-46850: Move the private_PyFrameEvalFunction type, and private_PyInterpreterState_GetEvalFrameFunc() and_PyInterpreterState_SetEvalFrameFunc() functions to the internal CAPI. The_PyFrameEvalFunction callback function type now uses the_PyInterpreterFrame type which is part of the internal C API. Patch byVictor Stinner.

  • bpo-46850: Move the private undocumented_PyEval_EvalFrameDefault()function to the internal C API. The function now uses the_PyInterpreterFrame type which is part of the internal C API. Patch byVictor Stinner.

  • bpo-46850: Remove the private undocumented function_PyEval_CallTracing() from the C API. Call the publicsys.call_tracing() function instead. Patch by Victor Stinner.

  • bpo-46850: Remove the private undocumented function_PyEval_GetCoroutineOriginTrackingDepth() from the C API. Call thepublicsys.get_coroutine_origin_tracking_depth() function instead.Patch by Victor Stinner.

  • bpo-46850: Remove the following private undocumented functions from the CAPI:

    • _PyEval_GetAsyncGenFirstiter()

    • _PyEval_GetAsyncGenFinalizer()

    • _PyEval_SetAsyncGenFirstiter()

    • _PyEval_SetAsyncGenFinalizer()

    Call the publicsys.get_asyncgen_hooks() andsys.set_asyncgen_hooks() functions instead. Patch by Victor Stinner.

  • bpo-46987: Remove private functions_PySys_GetObjectId() and_PySys_SetObjectId(). Patch by Donghee Na.

  • bpo-46906: Add new functions to pack and unpack C double (serialize anddeserialize):PyFloat_Pack2(),PyFloat_Pack4(),PyFloat_Pack8(),PyFloat_Unpack2(),PyFloat_Unpack4() andPyFloat_Unpack8(). Patch by VictorStinner.

Python 3.11.0 alpha 6

Release date: 2022-03-07

Core and Builtins

  • bpo-46940: Avoid overridingAttributeError metadata information fornested attribute access calls. Patch by Pablo Galindo.

  • bpo-46927: Include the type's name in the error message for subscriptingnon-generic types.

  • bpo-46921: Support vectorcall forsuper(). Patch by Ken Jin.

  • bpo-46841: Fix incorrect handling of inline cache entries whenspecializingBINARY_OP.

  • bpo-46841: Use an oparg to simplify the construction of helpful errormessages inGET_AWAITABLE.

  • bpo-46903: Make sure that str subclasses can be used as attribute namesfor instances with virtual dictionaries. Fixes regression in 3.11alpha

  • bpo-46841: Add more detailed specialization failure stats forCOMPARE_OP followed byEXTENDED_ARG.

  • bpo-46891: Fix bug introduced during 3.11alpha where subclasses oftypes.ModuleType with__slots__ were not initialized correctly,resulting in an interpreter crash.

  • bpo-46841: Use inline caching forLOAD_ATTR,LOAD_METHOD, andSTORE_ATTR.

  • bpo-46841: Use inline cache forBINARY_SUBSCR.

  • bpo-46841: Use inline caching forCOMPARE_OP.

  • bpo-46864: DeprecatePyBytesObject.ob_shash. It will be removed inPython 3.13.

  • bpo-46841: Use inline caching forUNPACK_SEQUENCE.

  • bpo-46845: Reduces dict size by removing hash value from hash table whenall inserted keys are Unicode. For example,sys.getsizeof(dict.fromkeys("abcdefg")) becomes 272 bytes from 352bytes on 64bit platform.

  • bpo-46841: Use inline cache forLOAD_GLOBAL.

  • bpo-46852: Rename the private undocumentedfloat.__set_format__()method tofloat.__setformat__() to fix a typo introduced in Python3.7. The method is only used by test_float. Patch by Victor Stinner.

  • bpo-46852: Remove the undocumented privatefloat.__set_format__()method, previously known asfloat.__setformat__() in Python 3.7. Itsdocstring said: "You probably don't want to use this function. It existsmainly to be used in Python's test suite." Patch by Victor Stinner.

  • bpo-40116: Fix regression that dict.update(other) may don't respectiterate order of other when other is key sharing dict.

  • bpo-46712: Share global string identifiers in deep-frozen modules.

  • bpo-46430: Fix memory leak in interned strings of deep-frozen modules.

  • bpo-46841: StoreBINARY_OP caches inline using a newCACHE instruction.

  • bpo-45107: SpecializeLOAD_METHOD for instances with a dict.

  • bpo-44337: Reduce the memory usage of specializedLOAD_ATTR andSTORE_ATTR instructions.

  • bpo-46729: Add number of sub-exceptions toBaseException.__str__().

  • bpo-45885: Don't un-adaptCOMPARE_OP when collectingspecialization stats.

  • bpo-46329: Fix specialization stats gathering forPRECALLinstructions.

  • bpo-46794: Bump up the libexpat version into 2.4.6

  • bpo-46823: Implement a specialized combined opcodeLOAD_FAST__LOAD_ATTR_INSTANCE_VALUE. Patch by Dennis Sweeney.

  • bpo-46820: Fix parsing a numeric literal immediately (without spaces)followed by "not in" keywords, like in1notinx. Now the parser onlyemits a warning, not a syntax error.

  • bpo-46329: MoveKW_NAMES beforePRECALL instruction in callsequence. Changeoperand ofCALL to matchPRECALL for easierspecialization.

  • bpo-46808: Remove theNEXT_BLOCK macro from compile.c, and make thecompiler automatically generate implicit blocks when they are needed.

  • bpo-46329: AddPUSH_NULL instruction. This is used as a prefix whenevaluating a callable, so that the stack has the same shape for methodsand other calls.PRECALL_FUNCTION andPRECALL_METHOD are mergedinto a singlePRECALL instruction.

    There is no change in semantics.

  • bpo-46762: Fix an assert failure in debug builds when a '<', '>', or '='is the last character in an f-string that's missing a closing right brace.

  • bpo-46730: Message of AttributeError caused by getting, setting ordeleting a property without the corresponding function now mentions thatthe attribute is in fact a property and also specifies type of the classthat it belongs to.

  • bpo-46724: Make sure that all backwards jumps use theJUMP_ABSOLUTEinstruction, rather thanJUMP_FORWARD with an argument of(2**32)+offset.

  • bpo-46732: Correct the docstring for the__bool__() method.Patch by Jelle Zijlstra.

  • bpo-46072: Add more detailed specialization failure statistics forBINARY_OP.

  • bpo-46707: Avoid potential exponential backtracking when producing somesyntax errors involving lots of brackets. Patch by Pablo Galindo.

  • bpo-46323:ctypes now allocates memory on the stack instead of onthe heap to pass arguments while calling a Python callback function. Patchby Donghee Na.

  • bpo-45923: Add a quickened form ofRESUME that skips quickeningchecks.

  • bpo-46702: SpecializeUNPACK_SEQUENCE fortuple andlist unpackings.

  • bpo-46072: Opcode pair stats are now gathered with--enable-pystats.DefiningDYNAMIC_EXECUTION_PROFILE orDXPAIRS no longer has anyeffect.

  • bpo-46675: Allow more than 16 items in a split dict before it is combined.The limit is now 254.

  • bpo-40479: Add a missing call tova_end() inModules/_hashopenssl.c.

  • bpo-46323: UsePyObject_Vectorcall() while calling ctypes callbackfunction. Patch by Donghee Na.

  • bpo-46615: When iterating over sets internally insetobject.c, acquirestrong references to the resulting items from the set. This preventscrashes in corner-cases of various set operations where the set getsmutated.

  • bpo-45828: The bytecode compiler now attempts to apply runtime stackmanipulations at compile-time (whenever it is feasible to do so).

  • bpo-30496: Fixed a minor portability issue in the implementation ofPyLong_FromLong(), and added a fast path for single-digit integerstoPyLong_FromLongLong().

Library

Documentation

  • bpo-42238:Doc/tools/rstlint.py has moved to its own repository and isnow packaged on PyPI assphinx-lint.

Tests

  • bpo-46913: Fix test_faulthandler.test_sigfpe() if Python is built withundefined behavior sanitizer (UBSAN): disable UBSAN on thefaulthandler_sigfpe() function. Patch by Victor Stinner.

  • bpo-46760: Remove bytecode offsets from expected values in test.test_dismodule. Reduces the obstacles to modifying the VM or compiler.

  • bpo-46708: Prevent default asyncio event loop policy modification warningaftertest_asyncio execution.

  • bpo-46678: The functionmake_legacy_pyc inLib/test/support/import_helper.py no longer fails whenPYTHONPYCACHEPREFIX is set to a directory on a different device fromwhere tempfiles are stored.

  • bpo-46623: Skip test_pair() and test_speech128() of test_zlib on s390xsince they fail if zlib uses the s390x hardware accelerator. Patch byVictor Stinner.

Build

  • bpo-46860: Respect--with-suffix when building on case-insensitivefile systems.

  • bpo-46656: Building Python now requires a C11 compiler. Optional C11features are not required. Patch by Victor Stinner.

  • bpo-46656: Building Python now requires support for floating-pointNot-a-Number (NaN): remove thePy_NO_NAN macro. Patch by VictorStinner.

  • bpo-46640: Building Python now requires a C99<math.h> header fileproviding aNAN constant, or the__builtin_nan() built-infunction. Patch by Victor Stinner.

  • bpo-46608: Exclude marshalled-frozen data if deep-freezing to save 300 KBdisk space. This includes adding a newis_package field to_frozen. Patch by Kumar Aditya.

  • bpo-40280: Fix wasm32-emscripten test failures and platform issues. -Disable syscalls that are not supported or don't work, e.g. wait,getrusage, prlimit, mkfifo, mknod, setres[gu]id, setgroups. - Use fd_countto count open fds. - Add more checks for subprocess and fork. - Addworkarounds for missing _multiprocessing and failing socket.accept(). -Enable bzip2. - Disable large file support. - Disable signal.alarm.

  • bpo-46430: Intern strings in deep-frozen modules. Patch by Kumar Aditya.

Windows

  • bpo-46744: The default all users install directory for ARM64 is now underthe nativeProgramFiles folder, rather thanProgramFiles(Arm)which is intended for ARM (32-bit) files.

  • bpo-46567: Adds Tcl and Tk support for Windows ARM64. This also adds IDLEto the installation.

  • bpo-46638: Ensures registry virtualization is consistently disabled. For3.10 and earlier, it remains enabled (some registry writes are protected),while for 3.11 and later it is disabled (registry modifications affect allapplications).

IDLE

  • bpo-46630: Make query dialogs on Windows start with a cursor in the entrybox.

  • bpo-45447: Apply IDLE syntax highlighting to.pyi files. Patch by AlexWaygood and Terry Jan Reedy.

C API

  • bpo-46748: Python's public headers no longer import<stdbool.h>,leaving code that embeds/extends Python free to definebool,trueandfalse.

  • bpo-46836: Move thePyFrameObject type definition (struct_frame) to the internal C APIpycore_frame.h header file. Patch byVictor Stinner.

  • bpo-45459: RenameInclude/buffer.h header file toInclude/pybuffer.h to avoid conflicts with projects having an existingbuffer.h header file. Patch by Victor Stinner.

  • bpo-45412: Remove theHAVE_PY_SET_53BIT_PRECISION macro (moved to theinternal C API). Patch by Victor Stinner.

  • bpo-46613: Added functionPyType_GetModuleByDef(), which allowsaccess to module state when a method's defining class is not available.

Python 3.11.0 alpha 5

Release date: 2022-02-03

Core and Builtins

  • bpo-45773: Remove two invalid "peephole" optimizations from the bytecodecompiler.

  • bpo-46564: Do not create frame objects when creatingsuperobject. Patch by Kumar Aditya.

  • bpo-45885: Added more fined-grained specialization failure stats regardingtheCOMPARE_OP bytecode.

  • bpo-44977: The delegation ofint() to__trunc__() is nowdeprecated. Callingint(a) whentype(a) implements__trunc__() but not__int__() or__index__() now raisesaDeprecationWarning.

  • bpo-46458: Reorder code emitted by the compiler for atry-except block so that theelse block'scode immediately follows thetry body (without a jump). This ismore optimal for the happy path.

  • bpo-46527: Allow passingiterable as a keyword argument toenumerate() again. Patch by Jelle Zijlstra.

  • bpo-46528: Replace several stack manipulation instructions (DUP_TOP,DUP_TOP_TWO,ROT_TWO,ROT_THREE,ROT_FOUR, andROT_N)with newCOPY andSWAP instructions.

  • bpo-46329: Use two or three bytecodes to implement most calls.

    Calls without named arguments are implemented as a sequence of twoinstructions:PRECALL;CALL. Calls with named arguments areimplemented as a sequence of three instructions:PRECALL;KW_NAMES;CALL. There are two differentPRECALL instructions:PRECALL_FUNTION andPRECALL_METHOD. The latter pairs withLOAD_METHOD.

    This partition into pre-call and call allows better specialization, andthus better performance ultimately.

    There is no change in semantics.

  • bpo-46503: Fix an assert when parsing some invalid N escape sequences inf-strings.

  • bpo-46431: Improve error message on invalid calls toBaseExceptionGroup.__new__().

  • bpo-46476: Fix memory leak in code objects generated by deepfreeze. Patchby Kumar Aditya.

  • bpo-46481: Speed up calls toweakref.ref.__call__() by using thePEP 590vectorcall calling convention. Patch by Donghee Na.

  • bpo-46417: Fix a race condition on setting a type__bases__ attribute:the internal functionadd_subclass() now gets thePyTypeObject.tp_subclasses member after callingPyWeakref_NewRef() which can trigger a garbage collection whichcan indirectly modifyPyTypeObject.tp_subclasses. Patch by VictorStinner.

  • bpo-46417:python-Xshowrefcount now shows the total reference countafter clearing and destroyed the main Python interpreter. Previously, itwas shown before. Patch by Victor Stinner.

  • bpo-43683: Add ASYNC_GEN_WRAP opcode to wrap the value to be yielded inasync generators. Removes the need to special case async generators in theYIELD_VALUE instruction.

  • bpo-46407: Optimize some modulo operations inObjects/longobject.c.Patch by Jeremiah Vivian.

  • bpo-46409: Add newRETURN_GENERATOR bytecode to make generators.Simplifies calling Python functions in the VM, as they no longer any needto special case generator functions.

    Also addJUMP_NO_INTERRUPT bytecode that acts likeJUMP_ABSOLUTE,but does not check for interrupts.

  • bpo-46406: The integer division// implementation has been optimizedto better let the compiler understand its constraints. It can be 20%faster on the amd64 platform when dividing an int by a value smaller than2**30.

  • bpo-46383: Fix invalid signature of_zoneinfo'smodule_freefunction to resolve a crash on wasm32-emscripten platform.

  • bpo-46361: Ensure that "small" integers created byint.from_bytes()anddecimal.Decimal are properly cached.

  • bpo-46161: Fix the class building error when the arguments are constantsand CALL_FUNCTION_EX is used.

  • bpo-46028: Fixes calculation ofsys._base_executable when inside avirtual environment that uses symlinks with different binary names thanthe base environment provides.

  • bpo-46091: Correctly calculate indentation levels for lines withwhitespace character that are ended by line continuation characters. Patchby Pablo Galindo

  • bpo-30512: Add CAN Socket support for NetBSD.

  • bpo-46045: Do not use POSIX semaphores on NetBSD

  • bpo-44024: Improve theTypeError message for non-string secondarguments passed to the built-in functionsgetattr() andhasattr(). Patch by Géry Ogam.

Library

Documentation

  • bpo-46463: Fixesescape4chm.py script used when building the CHMdocumentation file

Tests

  • bpo-43478: Mocks can no longer be provided as the specs for other Mocks.As a result, an already-mocked object cannot be passed tomock.Mock().This can uncover bugs in tests since these Mock-derived Mocks will alwayspass certain tests (e.g. isinstance) and builtin assert functions (e.g.assert_called_once_with) will unconditionally pass.

  • bpo-46616: Ensurestest_importlib.test_windows cleans up registry keysafter completion.

  • bpo-44359: test_ftplib now silently ignores socket errors to preventlogging unhandled threading exceptions. Patch by Victor Stinner.

  • bpo-46600: Fix test_gdb.test_pycfunction() for Python built withclang-Og. Tolerate inlined functions in the gdb traceback. Patch by VictorStinner.

  • bpo-46542: Fix a Python crash in test_lib2to3 when using Python built indebug mode: limit the recursion limit. Patch by Victor Stinner.

  • bpo-46576: test_peg_generator now disables compiler optimization whentesting compilation of its own C extensions to significantly speed up thetesting on non-debug builds of CPython.

  • bpo-46542: Fixtest_json tests checking forRecursionError:modify these tests to usesupport.infinite_recursion(). Patch byVictor Stinner.

  • bpo-13886: Skip test_builtin PTY tests on non-ASCII characters if thereadline module is loaded. The readline module changes input() behavior,but test_builtin is not intended to test the readline module. Patch byVictor Stinner.

  • bpo-40280: Addtest.support.requires_fork() decorators to mark teststhat require a workingos.fork().

  • bpo-40280: Addtest.support.requires_subprocess() decorator to marktests which require workingsubprocess module oros.spawn*. Thewasm32-emscripten platform has no support for processes.

  • bpo-46126: Disable 'descriptions' when running tests internally.

Build

  • bpo-46602: Tidied up configure.ac so that conftest.c is truncated ratherthan appended. This assists in the case where the 'rm' of conftest.c failsto happen between tests. Downstream issues such as a clobbered SOABI canresult.

  • bpo-46600: Fix the test checking if the C compiler supports-Og optionin the./configure script to also use-Og on clang which supportsit. Patch by Victor Stinner.

  • bpo-38472: Fix GCC detection in setup.py when cross-compiling. The Ccompiler is now run with LC_ALL=C. Previously, the detection failed with aGerman locale.

  • bpo-46513:configure no longer usesAC_C_CHAR_UNSIGNEDmacro andpyconfig.h no longer defines reserved symbol__CHAR_UNSIGNED__.

  • bpo-46471: Use global singletons for single byte bytes objects indeepfreeze.

  • bpo-46443: Deepfreeze now uses cached small integers as it saves somespace for common small integers.

  • bpo-46429: Merge all deep-frozen files into one for space savings. Patchby Kumar Aditya.

  • bpo-45569: The build now defaults to using 30-bit digits for Pythonintegers. Previously either 15-bit or 30-bit digits would be selected,depending on the platform. 15-bit digits may still be selected using the--enable-big-digits=15 option to theconfigure script, or bydefiningPYLONG_BITS_IN_DIGIT inpyconfig.h.

  • bpo-45925: Update Windows installer to use SQLite 3.37.2.

  • bpo-43112: Detect musl libc as a separate SOABI (tagged aslinux-musl).

Windows

  • bpo-33125: The traditional EXE/MSI based installer for Windows is nowavailable for ARM64

  • bpo-46362: os.path.abspath("C:CON") is now fixed to return "\.CON", notthe same path. The regression was true of all legacy DOS devices such asCOM1, LPT1, or NUL.

  • bpo-44934: The installer now offers a command-line only option to add theinstallation directory to the end ofPATH instead of at thestart.

macOS

  • bpo-45925: Update macOS installer to SQLite 3.37.2.

IDLE

  • bpo-45296: Clarify close, quit, and exit in IDLE. In the File menu,'Close' and 'Exit' are now 'Close Window' (the current one) and 'Exit' isnow 'Exit IDLE' (by closing all windows). In Shell, 'quit()' and 'exit()'mean 'close Shell'. If there are no other windows, this also exits IDLE.

C API

  • bpo-40170: Remove thePyHeapType_GET_MEMBERS() macro. It was exposedin the public C API by mistake, it must only be used by Python internally.Use thePyTypeObject.tp_members member instead. Patch by VictorStinner.

  • bpo-40170: Move _Py_GetAllocatedBlocks() and _PyObject_DebugMallocStats()private functions to the internal C API. Patch by Victor Stinner.

  • bpo-46433: The internal function _PyType_GetModuleByDef now correctlyhandles inheritance patterns involving static types.

  • bpo-45459:Py_buffer and variousPy_buffer related functionsare now part of the limited API and stable ABI.

  • bpo-14916: Fixed bug in the tokenizer that preventedPyRun_InteractiveOne from parsing from the provided FD.

Python 3.11.0 alpha 4

Release date: 2022-01-13

Core and Builtins

  • bpo-46070:Py_EndInterpreter() now explicitly untracks all objectscurrently tracked by the GC. Previously, if an object was used later byanother interpreter, callingPyObject_GC_UnTrack() on the objectcrashed if the previous or the next object of thePyGC_Headstructure became a dangling pointer. Patch by Victor Stinner.

  • bpo-46347: Fix memory leak in PyEval_EvalCodeEx.

  • bpo-46339: Fix a crash in the parser when retrieving the error text formulti-line f-strings expressions that do not start in the first line ofthe string. Patch by Pablo Galindo

  • bpo-46331: Do not set line number of instruction storing doc-string. Fixesregression introduced in 3.11 alpha.

  • bpo-46314: Remove spurious "call" event when creating a lambda functionthat was accidentally introduced in 3.11a4.

  • bpo-46289: ASDL declaration ofFormattedValue has changed to reflectconversion field is not optional.

  • bpo-46297: Fixed an interpreter crash on bootup with multiple PythonPathsset in the Windows registry. Patch by Derzsi Dániel.

  • bpo-46237: Fix the line number of tokenizer errors inside f-strings. Patchby Pablo Galindo.

  • bpo-46263: We always expect the "use_frozen_modules" config to be set, nowthat getpath.c was rewritten in pure Python and the logic improved.

  • bpo-46006: Fix a regression when a type method like__init__() ismodified in a subinterpreter. Fix a regression in_PyUnicode_EqualToASCIIId() and typeupdate_slot(). Revert thechange which made the Unicode dictionary of interned strings compatiblewith subinterpreters: the internal interned dictionary is shared again byall interpreters. Patch by Victor Stinner.

  • bpo-45923: Add RESUME opcode. This is a logical no-op. It is emitted bythe compiler anywhere a Python function can be entered. It is used by theinterpreter to perform tracing and optimizer checks.

  • bpo-46208: Fix the regression of os.path.normpath("A/../../B") notreturning expected "../B" but "B".

  • bpo-46240: Correct the error message for unclosed parentheses when thetokenizer doesn't reach the end of the source when the error is reported.Patch by Pablo Galindo

  • bpo-46009: Remove theGEN_START opcode.

  • bpo-46235: Certain sequence multiplication operations like[0]*1_000are now faster due to reference-counting optimizations. Patch by DennisSweeney.

  • bpo-46221:PREP_RERAISE_STAR no longer pusheslasti to thestack.

  • bpo-46202: RemovePOP_EXCEPT_AND_RERAISE and replace it by anequivalent sequence of other opcodes.

  • bpo-46085: Fix iterator cache mechanism ofOrderedDict.

  • bpo-46055: Speed up shifting operation involving integers less thanPyLong_BASE. Patch by Xinhang Xu.

  • bpo-46110: Add a maximum recursion check to the PEG parser to avoid stackoverflow. Patch by Pablo Galindo

  • bpo-46107: Fix bug whereExceptionGroup.split() andExceptionGroup.subgroup() did not copy the exception group's__note__ field to the parts.

  • bpo-45711: The interpreter state's representation of handled exceptions(a.k.a exc_info, or _PyErr_StackItem) now has only theexc_valuefield,exc_type andexc_traceback have been removed as theirvalues can be derived fromexc_value.

  • bpo-44525: Replace the four call bytecode instructions which one pre-callinstruction and two call instructions.

    RemovesCALL_FUNCTION,CALL_FUNCTION_KW,CALL_METHOD andCALL_METHOD_KW.

    AddsCALL_NO_KW andCALL_KW call instructions, andPRECALL_METHOD prefix for pairing withLOAD_METHOD.

  • bpo-46039: Remove theYIELD_FROM instruction and replace it with theSEND instruction which performs the same operation, but without theloop.

  • bpo-45635: The code called from_PyErr_Display() was refactoredto improve error handling. It now exits immediately upon an unrecoverableerror.

  • bpo-46054: Fix parser error when parsing non-utf8 characters in sourcefiles. Patch by Pablo Galindo.

  • bpo-46042: Improve the location of the caret inSyntaxErrorexceptions emitted by the symbol table. Patch by Pablo Galindo.

  • bpo-46049: Ensure._pth files work as intended on platforms otherthan Windows.

  • bpo-46048: Fixes parsing of._pth files on startup so thatsingle-character paths are correctly read.

  • bpo-37971: Fix a bug where the line numbers given in a traceback when adecorator application raised an exception were wrong.

  • bpo-46031: AddPOP_JUMP_IF_NOT_NONE andPOP_JUMP_IF_NONE opcodes to speed up conditional jumps.

  • bpo-45654: Deepfreezerunpy, patch by Kumar Aditya.

  • bpo-46025: Fix a crash in theatexit module involving functionsthat unregister themselves before raising exceptions. Patch by PabloGalindo.

  • bpo-46000: Improve compatibility of thecurses module with NetBSDcurses.

  • bpo-44525: Specialize the CALL_FUNCTION instruction for calls to builtintypes with a single argument. Speeds uprange(x),list(x), andspecificallytype(obj).

  • bpo-42918: Fix bug where the built-incompile() function did notalways raise aSyntaxError when passed multiple statements in'single' mode. Patch by Weipeng Hong.

  • bpo-45953: The main interpreter in _PyRuntimeState.interpreters is nowstatically allocated (as part of _PyRuntime). Likewise for the initialthread state of each interpreter. This means less allocation duringruntime init, as well as better memory locality for these key stateobjects.

  • bpo-45292: Complete thePEP 654 implementation: addexcept*.

  • bpo-43413: Revert changes inset.__init__. Subclass ofsetneeds to define a__init__() method if it defines a__new__()method with additional keyword parameters.

  • bpo-43931: Added thePy_Version constant which bears the samevalue asPY_VERSION_HEX. Patch by Gabriele N. Tornetta.

Library

  • bpo-46342: The@typing.final decorator now sets the__final__attribute on the decorated object to allow runtime introspection. Patch byJelle Zijlstra.

  • bpo-46328: Added thesys.exception() method which returns the activeexception instance.

  • bpo-46307: Addstring.Template.is_valid() andstring.Template.get_identifiers() methods.

  • bpo-46306: Assume thattypes.CodeType always hastypes.CodeType.co_firstlineno indoctest.

  • bpo-40479: Fixhashlibusedforsecurity option to work correctlywith OpenSSL 3.0.0 in FIPS mode.

  • bpo-46070: Fix possible segfault when importing theasyncio modulefrom different sub-interpreters in parallel. Patch by Erlend E. Aasland.

  • bpo-46244: Removed__slots__ fromtyping.ParamSpec andtyping.TypeVar. They served no purpose. Patch by Arie Bovenberg.

  • bpo-46278: Reflectcontext argument inAbstractEventLoop.call_*()methods. Loop implementations already support it.

  • bpo-46269: Remove special-casing of__new__ inenum.Enum.__dir__().

  • bpo-46266: Improve day constants incalendar.

    Now all constants (MONDAY ...SUNDAY) are documented, tested, andadded to__all__.

  • bpo-46257: Optimized the mean, variance, and stdev functions in thestatistics module. If the input is an iterator, it is consumed in a singlepass rather than eating memory by conversion to a list. The single passalgorithm is about twice as fast as the previous two pass code.

  • bpo-41011: Added two new variables topyvenv.cfg which is generated byvenv module:executable for the executable andcommand for thecommand line used to create the environment.

  • bpo-46239: Improve error message when importingasyncio.windows_events on non-Windows.

  • bpo-46238: Reuse_winapi constants inasyncio.windows_events.

  • bpo-46222: AddingSF_NOCACHE sendfile constant for FreeBSD for theposixmodule.

  • bpo-37295: Add fast path for0<=k<=n<=67 formath.comb().

  • bpo-46176: Adding theMAP_STACK constant for the mmap module.

  • bpo-43424: Deprecatewebbrowser.MacOSXOSAScript._name and usename instead.

  • bpo-45321: Added missing error codes to modulexml.parsers.expat.errors.

  • bpo-46125: Refactor tests to test traversable API directly. Includeschanges from importlib 5.4.0.

  • bpo-46118: Moved importlib.resources and its related functionality to apackage.

  • bpo-37578: Addinclude_hidden parameter toglob() andiglob() to match hidden files and directories when usingspecial characters like*,**,? and[].

  • bpo-20369:concurrent.futures.wait() no longer blocks forever whengiven duplicate Futures. Patch by Kumar Aditya.

  • bpo-46105: Honor spec when generating requirement specs with urls andextras (importlib_metadata 4.8.3).

  • bpo-44893: EntryPoint objects are no longer tuples. Recommended means toaccess is by attribute ('.name', '.group') or accessor ('.load()'). Accessby index is deprecated and will raise deprecation warning.

  • bpo-22815: Print unexpected successes together with failures and errors insummary inunittest.TextTestResult.

  • bpo-22047: Callingadd_argument_group() on an argument group isdeprecated. Callingadd_argument_group() oradd_mutually_exclusive_group() on a mutually exclusive group isdeprecated.

    These features were never supported and do not always work correctly. Thefunctions exist on the API by accident through inheritance and will beremoved in the future.

  • bpo-26952:argparse raisesValueError with clear messagewhen trying to render usage for an empty mutually exclusive group.Previously it raised a crypticIndexError.

  • bpo-45615: Functions in thetraceback module raiseTypeErrorrather thanAttributeError when an exception argument is not oftypeBaseException.

  • bpo-16594: Add allow allow_reuse_port flag in socketserver.

  • bpo-27718: Fix help for thesignal module. Some functions (e.g.signal() andgetsignal()) were omitted.

  • bpo-46032: Theregistry() method offunctools.singledispatch()functions checks now the first argument or the first parameter annotationand raises a TypeError if it is not supported. Previously unsupported"types" were ignored (e.g.typing.List[int]) or caused an error atcalling time (e.g.list[int]).

  • bpo-46014: Add ability to usetyping.Union andtypes.UnionType asdispatch argument tofunctools.singledispatch. Patch provided by YuriiKarabas.

  • bpo-27062: Add__all__ toinspect, patch by Kumar Aditya.

  • bpo-46018: Ensure thatmath.expm1() does not raise on underflow.

  • bpo-46016: AddingF_DUP2FD andF_DUP2FD_CLOEXECconstants from FreeBSD into thefcntl module.

  • bpo-45755:typing generic aliases now reveal the class attributesof the original generic class when passed todir(). This was thebehavior up to Python 3.6, but was changed in 3.7-3.9.

  • bpo-45874: The empty query string, consisting of no query arguments, isnow handled correctly inurllib.parse.parse_qsl. This caused problemsbefore when strict parsing was enabled.

  • bpo-44674: Change how dataclasses disallows mutable default values. Itused to use a list of known types (list, dict, set). Now it disallowsunhashable objects to be defaults. It's using unhashability as a proxyfor mutability. Patch by Eric V. Smith, idea by Raymond Hettinger.

  • bpo-23882: Remove namespace package (PEP 420) support from unittestdiscovery. It was introduced in Python 3.4 but has been broken sincePython 3.7.

  • bpo-25066: Added a__repr__() method tomultiprocessing.Event objects, patch by Kumar Aditya.

  • bpo-45643: Addedsignal.SIGSTKFLT on platforms where this signalis defined.

  • bpo-44092: Fetch across rollback no longer raisesInterfaceError. Instead we leave it to the SQLite libraryto handle these cases. Patch by Erlend E. Aasland.

  • bpo-42413: Replaceconcurrent.futures.TimeoutError andasyncio.TimeoutError with builtinTimeoutError, keep thesenames as deprecated aliases.

Documentation

Tests

  • bpo-46296: Add a test case forenum with_use_args_==True and_member_type_==object.

  • bpo-46205: Fix hang in runtest_mp due to race condition

  • bpo-46263: Fix test_capi on FreeBSD 14-dev: instruct jemalloc to not fillfreed memory with junk byte.

  • bpo-46262: CoverValueError path in tests forenum.Flag._missing_().

  • bpo-46150: Nowfakename intest_pathlib.PosixPathTest.test_expanduser is checked to benon-existent.

  • bpo-46129: Rewriteasyncio.locks tests withunittest.IsolatedAsyncioTestCase usage.

  • bpo-23819: Fixedasyncio tests in python optimized mode. Patch byKumar Aditya.

  • bpo-46114: Fix test case for OpenSSL 3.0.1 version. OpenSSL 3.0 uses0xMNN00PP0L.

Build

  • bpo-44133: When Python is configured with--without-static-libpython, the Python static library(libpython.a) is no longer built. Patch by Victor Stinner.

  • bpo-44133: When Python is built without--enable-shared, thepython program is now linked to object files, rather than being linkedto the Python static library (libpython.a), to make sure that all symbolsare exported. Previously, the linker omitted some symbols like thePy_FrozenMain() function. Patch by Victor Stinner.

  • bpo-40280: Theconfigure script has a new option--with-emscripten-target to select browser or node as Emscripten buildtarget.

  • bpo-46315: Added and fixed#ifdefHAVE_FEATURE checks forfunctionality that is not available on WASI platform.

  • bpo-45723: Fixed a regression inconfigure check forselect.epoll().

  • bpo-46263:configure no longer setsMULTIARCH on FreeBSDplatforms.

  • bpo-46106: Updated OpenSSL to 1.1.1m in Windows builds, macOS installerbuilds, and CI. Patch by Kumar Aditya.

  • bpo-46088: Automatically detect or install bootstrap Python runtime whenbuilding from Visual Studio.

  • bpo-46072: Add a --with-pystats configure option to turn on internalstatistics gathering.

  • bpo-40280: A new directoryTools/wasm contains WebAssembly-relatedhelpers likeconfig.site override for wasm32-emscripten, wasm assetsgenerator to bundle the stdlib, and a README.

  • bpo-46023:makesetup no longer builds extensions that have beenmarked asdisabled. This allows users to disable modules inModules/Setup.local.

  • bpo-45949: Use pure Pythonfreeze_module for all but importlibbootstrap files.--with-freeze-moduleconfigure option isno longer needed for cross builds.

Windows

  • bpo-46217: Removed parameter that is unsupported on Windows 8.1 and earlyWindows 10 and may have caused build or runtime failures.

macOS

  • bpo-40477: The Python Launcher app for macOS now properly launches scriptsand, if necessary, the Terminal app when running on recent macOS releases.

C API

Python 3.11.0 alpha 3

Release date: 2021-12-08

Core and Builtins

  • bpo-46009: Restore behavior from 3.9 and earlier when sending non-None tonewly started generator. In 3.9 this did not affect the state of thegenerator. In 3.10.0 and 3.10.1gen_func().send(0) is equivalent togen_func().throw(TypeError(...) which exhausts the generator. In3.10.2 onward, the behavior has been reverted to that of 3.9.

  • bpo-46004: Fix theSyntaxError location for errors involving forloops with invalid targets. Patch by Pablo Galindo

  • bpo-45711:_PyErr_ChainStackItem() no longer normalizesexc_info (including setting the traceback on the exception instance)becauseexc_info is always normalized.

  • bpo-45607: The__note__ field was added toBaseException. It isNone by default but can be set to a string which is added to theexception's traceback.

  • bpo-45947: Place pointers to dict and values immediately before GC header.This reduces number of dependent memory loads to access either dict orvalues from 3 to 1.

  • bpo-45915:is_valid_fd now uses fasterfcntl(fd,F_GETFD) onLinux, macOS, and Windows.

  • bpo-44530: Reverts a change to thecode.__new__audit event from an earlier prerelease.

  • bpo-42268: Fail the configure step if the selected compiler doesn'tsupport memory sanitizer. Patch by Pablo Galindo

  • bpo-45711: The three values ofexc_info are now always consistent witheach other. In particular, thetype andtraceback fields are nowderived from the exception instance. This impacts the return values ofsys.exc_info() andPyErr_GetExcInfo() if the exceptioninstance is modified while the exception is handled, as well asPyErr_SetExcInfo(), which now ignores thetype andtraceback arguments provided to it.

  • bpo-45727: Refine the custom syntax error that suggests that a comma maybe missing to trigger only when the expressions are detected betweenparentheses or brackets. Patch by Pablo Galindo

  • bpo-45885: Specialized theCOMPARE_OP opcode using the PEP 659machinery.

  • bpo-45786: Allocate space for the interpreter frame in the frame object,to avoid an additional allocation when the frame object outlives the frameactivation.

  • bpo-45614: Fixtraceback display for exceptions with invalid modulename.

  • bpo-45813: Fix crash when calling coro.cr_frame.clear() after coroutinehas been freed.

  • bpo-45811: Improve the tokenizer errors when encountering invisiblecontrol characters in the parser. Patch by Pablo Galindo

  • bpo-45848: Allow the parser to obtain error lines directly from encodedfiles. Patch by Pablo Galindo

  • bpo-45709: Restore behavior from 3.10 when tracing an exception raisedwithin a with statement.

  • bpo-44525: Adds newCOPY_FREE_VARS opcode, to make copying offree variables from function to frame explicit. Helps optimization ofcalls to Python function.

  • bpo-45829: SpecializeBINARY_SUBSCR for classes with a__getitem__ method implemented in Python

  • bpo-45826: Fixed a crash when calling.with_traceback(None) onNameError. This occurs internally inunittest.TestCase.assertRaises().

  • bpo-45822: Fixed a bug in the parser that was causing it to not respectPEP 263 coding cookies when no flags are provided. Patch by PabloGalindo

  • bpo-45820: Fix a segfault when the parser fails without reading any input.Patch by Pablo Galindo

  • bpo-45636: Simplify the implementation ofBINARY_OP by indexinginto an array of function pointers (rather than switching on the oparg).

  • bpo-42540: Fix crash whenos.fork() is called with an activenon-default memory allocator.

  • bpo-45738: Fix computation of error location for invalid continuationcharacters in the parser. Patch by Pablo Galindo.

  • bpo-45636: Remove an existing "fast path" for old-style string formatting,since it no longer appears to have any measurable impact.

  • bpo-45753: Make recursion checks a bit more efficient by tracking amountof calls left before overflow.

  • bpo-45773: Fix a compiler hang when attempting to optimize certain jumppatterns.

  • bpo-45764: The parser now gives a better error message when leaving outthe opening parenthesis( after adef-statement:

    >>>deff:  File"<stdin>", line1deff:^SyntaxError:expected '('

  • bpo-45609: Specialized theSTORE_SUBSCR opcode using the PEP 659machinery.

  • bpo-45636: Replace all numericBINARY_* andINPLACE_* instructionswith a singleBINARY_OP implementation.

  • bpo-45582: Path calculation (known asgetpath) has been reimplementedas a frozen Python module. This should have no visible impact, but mayaffect calculation of all paths referenced insys andsysconfig.

  • bpo-45450: Improve the syntax error message for parenthesized arguments.Patch by Pablo Galindo.

Library

  • bpo-27946: Fix possible crash when getting an attribute ofxml.etree.ElementTree.Element simultaneously with replacing theattrib dict.

  • bpo-45711: Makeasyncio normalize exceptions as soon as they arecaptured withPyErr_Fetch(), and before they are stored as anexc_info triplet. This bringsasyncio in line with the rest of thecodebase, where an exc_info triplet is always normalized.

  • bpo-23819: Replaced asserts with exceptions in asyncio, patch by KumarAditya.

  • bpo-13236:unittest.TextTestResult andunittest.TextTestRunner flush now the output stream more often.

  • bpo-45917: Addedmath.exp2():, which returns 2 raised to the powerof x.

  • bpo-37658: Fix issue when on certain conditionsasyncio.wait_for() mayallow a coroutine to complete successfully, but fail to return the result,potentially causing memory leaks or other issues.

  • bpo-45876: Improve the accuracy of stdev() and pstdev() in the statisticsmodule. When the inputs are floats or fractions, the output is acorrectly rounded float

  • bpo-44649: Handle dataclass(slots=True) with a field that has default adefault value, but for which init=False.

  • bpo-45803: Added missing kw_only parameter todataclasses.make_dataclass().

  • bpo-45837: Theturtle.RawTurtle.settiltangle() is deprecated sincePython 3.1, it now emits a deprecation warning and will be removed inPython 3.13.

    Useturtle.RawTurtle.tiltangle() instead.

    turtle.RawTurtle.tiltangle() was earlier incorrectly marked asdeprecated, its docstring has been corrected.

    Patch by Hugo van Kemenade.

  • bpo-45831:faulthandler can now write ASCII-only strings (likefilenames and function names) with a single write() syscall when dumping atraceback. It reduces the risk of getting an unreadable dump when twothreads or two processes dump a traceback to the same file (like stderr)at the same time. Patch by Victor Stinner.

  • bpo-45828:sqlite C callbacks now use unraisable exceptions ifcallback tracebacks are enabled. Patch by Erlend E. Aasland.

  • bpo-41735: Fix thread lock inzlib.Decompress.flush() method beforePyObject_GetBuffer.

  • bpo-45235: Reverted an argparse bugfix that caused regression in thehandling of default arguments for subparsers. This prevented leaf levelarguments from taking precedence over root level arguments.

  • bpo-45754: Fix a regression in Python 3.11a1 and 3.11a2 wheresqlite3 incorrectly would useSQLITE_LIMIT_LENGTH when checkingSQL statement lengths. Now,SQLITE_LIMIT_SQL_LENGTH is used. Patch byErlend E. Aasland.

  • bpo-45766: Addedproportional option tostatistics.linear_regression().

  • bpo-45765: In importlib.metadata, fix distribution discovery for an emptypath.

  • bpo-45757: Fix bug wheredis produced an incorrect oparg whenEXTENDED_ARG is followed by an opcode that does not use itsargument.

  • bpo-45644: In-place JSON file formatting usingpython3-mjson.toolinfileinfile now works correctly, previously it left the file empty.Patch by Chris Wesseling.

  • bpo-45703: When a namespace package is imported before another module fromthe same namespace is created/installed in a differentsys.pathlocation while the program is running, calling theimportlib.invalidate_caches() function will now also guarantee thenew module is noticed.

  • bpo-45535: Improve output ofdir() with Enums.

  • bpo-45664: Fixtypes.resolve_bases() andtypes.new_class() fortypes.GenericAlias instance as a base.

  • bpo-45663: Fixdataclasses.is_dataclass() for dataclasses which aresubclasses oftypes.GenericAlias.

  • bpo-45662: Fix the repr ofdataclasses.InitVar with a type aliasto the built-in class, e.g.InitVar[list[int]].

  • bpo-43137: Launch GNOME web browsers via gio tool instead of obsoletegvfs-open

  • bpo-45429: On Windows,time.sleep() now uses a waitable timer whichsupports high-resolution timers. Patch by Donghee Na and Eryk Sun.

  • bpo-37295: Optimizemath.comb() andmath.perm().

  • bpo-45514: Deprecated legacy functions inimportlib.resources.

  • bpo-45507: Add tests for truncated/missing trailers in gzip.decompressimplementation.

  • bpo-45359: ImplementPEP 585 forgraphlib.TopologicalSorter.

  • bpo-44733: Addmax_tasks_per_child toconcurrent.futures.ProcessPoolExecutor. This allows users tospecify the maximum number of tasks a single process should execute beforethe process needs to be restarted.

  • bpo-28806: Improve netrc library. netrc file no longer needs to containall tokens. And if the login name is anonymous, security check is nolonger need.

  • bpo-43498: Avoid a possible"RuntimeError: dictionary changed size duringiteration" when adjusting the process count ofProcessPoolExecutor.

  • bpo-42158: Add MIME types for N-quads, N-triples, Notation3 and TriG tomimetypes.

  • bpo-30533: Addinspect.getmembers_static() , it return all memberswithout triggering dynamic lookup via the descriptor protocol. Patch byWeipeng Hong.

Documentation

  • bpo-42238:make-CDocsuspicious will be removed soon in favor ofmake-CDoccheck, mark it as deprecated.

  • bpo-45840: Improve cross-references in the documentation for the datamodel.

  • bpo-45640: Properly marked-up grammar tokens in the documentation are nowclickable and take you to the definition of a given piece of grammar.Patch by Arthur Milchior.

  • bpo-45788: Link doc for sys.prefix to sysconfig doc on installation paths.

  • bpo-45772:socket.socket documentation is corrected to a class from afunction.

  • bpo-45392: Update the docstring of thetype built-in to remove aredundant line and to mention keyword arguments for the constructor.

  • bpo-45250: Update the documentation to note that CPython does notconsistently require iterators to define__iter__.

  • bpo-25381: In the extending chapter of the extending doc, update aparagraph about the global variables containing exception information.

  • bpo-43905: Expandedastuple() andasdict() docs, warning about deepcopy being applied andproviding a workaround.

Tests

  • bpo-45695: Out-of-tree builds with a read-only source directory are nowtested by CI.

  • bpo-19460: Add new Test forLib/email/mime/nonmultipart.py::MIMENonMultipart.

  • bpo-45835: Fix race condition in test_queue tests with multiple "feeder"threads.

  • bpo-45783: The test for the freeze tool now handles file moves anddeletions.

  • bpo-45745: Remove the--findleaks command line option of regrtest: usethe--fail-env-changed option instead. Since Python 3.7, it was adeprecated alias to the--fail-env-changed option.

  • bpo-45701: Add tests withtuple type withfunctools.lru_cache()totest_functools.

Build

  • bpo-44035: CI now verifies that autoconf files have been regenerated witha current and unpatched autoconf package.

  • bpo-45950: The build system now uses a_bootstrap_pythoninterpreter for freezing and deepfreezing again. To speed up build processthe build tools_bootstrap_python and_freeze_moduleare no longer build with LTO.

  • bpo-45881: Theconfigure script now accepts--with-build-python and--with-freeze-module options to make crosscompiling easier.

  • bpo-40280: Emscripten platform now uses.wasm suffix by default.

  • bpo-40280: Disable unusable core extension modules on WASM/Emscriptentargets.

  • bpo-40280:configure now checks for socketshutdown function. Thecheck makes it possible to disableSYS_shutdown withac_cv_func_shutdown=no in CONFIG_SITE.

  • bpo-40280:configure now checks for functionsfork1,getegid,geteuid,getgid,getppid,getuid,opendir,pipe,system,wait,ttyname.

  • bpo-33393: Updateconfig.guess to 2021-06-03 andconfig.sub to2021-08-14.Makefile now has anupdate-config target to makeupdating more convenient.

  • bpo-45866:makeregen-all now produces the same output when run from adirectory other than the source tree: when building Python out of thesource tree. pegen now strips directory of the "generated by pygen from<FILENAME>" header Patch by Victor Stinner.

  • bpo-40280:configure now accepts machinewasm32 orwasm64 andOSwasi oremscripten for cross building, e.g.wasm32-unknown-emscripten,wasm32-wasi, orwasm32-unknown-wasi.

  • bpo-41498: Python now compiles on platforms withoutsigset_t. Severalfunctions insignal are not available whensigset_t is missing.

    Based on patch by Roman Yurchak for pyodide.

  • bpo-45881:setup.py now usesCC from environment first to discovermultiarch and cross compile paths.

  • bpo-45886: The_freeze_module program path can now be overridden onthe command line, e.g.makeFREEZE_MODULE=../x86_64/Program/_freeze_module.

  • bpo-45873: Get rid of the_bootstrap_python build step. Thedeepfreeze.py script is now run using$(PYTHON_FOR_REGEN) which can bePython 3.7 or newer (on Windows, 3.8 or newer).

  • bpo-45847: Port builtin hashlib extensions toPY_STDLIB_MOD macro andaddext().

  • bpo-45723: Addautoconf helpers for saving and restoring environmentvariables:

    • SAVE_ENV: Save$CFLAGS,$LDFLAGS,$LIBS, and$CPPFLAGS.

    • RESTORE_ENV: Restore$CFLAGS,$LDFLAGS,$LIBS, and$CPPFLAGS.

    • WITH_SAVE_ENV([SCRIPT]): RunSCRIPT wrapped withSAVE_ENV andRESTORE_ENV.

    Patch by Erlend E. Aasland.

  • bpo-45573: Mandatory core modules, that are required to bootstrap Python,are now inModules/Setup.bootstrap.

  • bpo-45573:configure now createsModules/Setup.stdlib withconditionally enabled/disabled extension module lines. The file is notused, yet.

  • bpo-45573:configure now uses a unified format to set state, compilerflags, and linker flags in Makefile. The new macroPY_STDLIB_MOD setsthree variables that are consumed byModules/Setup andsetup.py.

  • bpo-45816: Python now supports building with Visual Studio 2022 (MSVCv143, VS Version 17.0). Patch by Jeremiah Vivian.

  • bpo-45800: Settings forpyexpat C extension are now detected byconfigure. The bundledexpat library is built inMakefile.

  • bpo-45798: Settings fordecimal internal C extension are nowdetected byconfigure. The bundledlibmpdec library is built inMakefile.

  • bpo-45723:configure has a new option--with-pkg-config todisable or require pkg-config.

  • bpo-45774: The build dependencies forsqlite3 are now detected byconfigure andpkg-config. Patch by Erlend E. Aasland.

  • bpo-45763: The build dependencies forzlib,bz2, andlzma are now detected byconfigure.

  • bpo-45747: gdbm and dbm build dependencies are now detected byconfigure.

  • bpo-45743: On macOS, the build system no longer passessearch_paths_first to the linker. The flag has been the default sinceXcode 4 / macOS 10.6.

  • bpo-45723:configure.ac is now compatible with autoconf 2.71.Deprecated checksSTDC_HEADERS andAC_HEADER_TIME have beenremoved.

  • bpo-45723:configure now prints a warning when pkg-config is missing.

  • bpo-45731:configure--enable-loadable-sqlite-extensions is nowhandled by newPY_SQLITE_ENABLE_LOAD_EXTENSION macro instead of logicin setup.py.

  • bpo-45723: configure.ac now uses custom helper macros andAC_CACHE_CHECK to simplify and speed up configure runs.

  • bpo-45696: Skip the marshal step for frozen modules by generating C codethat produces a set of ready-to-use code objects. This speeds up startuptime by another 10% or more.

  • bpo-45561: Run smelly.py tool from $(srcdir).

Windows

  • bpo-46105: Fixed calculation ofsys.path in a venv on Windows.

  • bpo-45901: When installed through the Microsoft Store and set as thedefault app for*.py files, command line arguments will now bepassed to Python when invoking a script without explicitly launchingPython (that is,script.pyargs rather thanpythonscript.pyargs).

  • bpo-45616: Fix Python Launcher's ability to distinguish between versions3.1 and 3.10 when either one is explicitly requested. Previously, 3.1would be used if 3.10 was requested but not installed, and 3.10 would beused if 3.1 was requested but 3.10 was installed.

  • bpo-45850: Implement changes to build with deep-frozen modules on Windows.Note that we now require Python 3.10 as the "bootstrap" or "host" Python.

  • bpo-45732: Updates bundled Tcl/Tk to 8.6.12.

  • bpo-45720: Internal reference toshlwapi.dll was dropped to helpimprove startup time. This DLL will no longer be loaded at the start ofevery Python process.

macOS

  • bpo-45732: Update python.org macOS installer to use Tcl/Tk 8.6.12.

C API

  • bpo-39026: Fix Python.h to build C extensions with Xcode: remove arelative include fromInclude/cpython/pystate.h.

Python 3.11.0 alpha 2

Release date: 2021-11-05

Core and Builtins

  • bpo-45716: Improve theSyntaxError message when usingTrue,None orFalse as keywords in a function call. Patch by PabloGalindo.

  • bpo-45688:sys.stdlib_module_names now contains the macOS-specificmodule_scproxy.

  • bpo-45379: ClarifyImportError message when we try to explicitlyimport a frozen module but frozen modules are disabled.

  • bpo-44525: Specialize simple calls to Python functions (no starargs,keyword dict, or closure)

  • bpo-45530: Cases of sorting using tuples as keys may now be significantlyfaster in some cases. Patch by Tim Peters.

    The order of the result may differ from earlier releases if the tupleelements don't define a total ordering (seeValue comparisons for information on total ordering).It's generally true that the result of sorting simply isn't well-definedin the absence of a total ordering on list elements.

  • bpo-45526: In obmalloc, set ADDRESS_BITS to not ignore any bits (ignored16 before). That is safer in the case that the kernel gives user-spacevirtual addresses that span a range greater than 48 bits.

  • bpo-30570: Fixed a crash inissubclass() from infinite recursion whensearching pathological__bases__ tuples.

  • bpo-45521: Fix a bug in the obmalloc radix tree code. On 64-bit machines,the bug causes the tree to hold 46-bits of virtual addresses, rather thanthe intended 48-bits.

  • bpo-45494: Fix parser crash when reporting errors involving invalidcontinuation characters. Patch by Pablo Galindo.

  • bpo-45445: Python now fails to initialize if it finds an invalid-X option in the command line. Patch by Pablo Galindo.

  • bpo-45340: Object attributes are held in an array instead of a dictionary.An object's dictionary are created lazily, only when needed. Reduces thememory consumption of a typical Python object by about 30%. Patch by MarkShannon.

  • bpo-45408: Fix a crash in the parser when reporting tokenizer errors thatoccur at the same time unclosed parentheses are detected. Patch by PabloGalindo.

  • bpo-29410: Add SipHash13 for string hash algorithm and use it by default.

  • bpo-45385: Fix reference leak from descr_check. Patch by Donghee Na.

  • bpo-45367: Specialized theBINARY_MULTIPLY opcode toBINARY_MULTIPLY_INT andBINARY_MULTIPLY_FLOAT using the PEP 659machinery.

  • bpo-21736: Frozen stdlib modules now have__file__ to the .py filethey would otherwise be loaded from, if possible. For packages,__path__ now has the correct entry instead of being an empty list,which allows unfrozen submodules to be imported. These are set only ifthe stdlib directory is known when the runtime is initialized. Note thatthe file at__file__ is not guaranteed to exist. None of this affectsnon-stdlib frozen modules nor, for now, frozen modules imported usingPyImport_ImportFrozenModule(). Also, at the momentco_filename isnot updated for the module.

  • bpo-45020: For frozen stdlib modules, record the original module name asmodule.__spec__.loader_state.origname. If the value is different thanmodule.__spec__.name then the module was defined as an alias inTools/scripts/freeze_modules.py. If it isNone then the module comesfrom a source file outside the stdlib.

  • bpo-45324: In FrozenImporter.find_spec(), we now preserve the informationneeded in exec_module() to load the module. This change mostly impactsinternal details, rather than changing the importer's behavior.

  • bpo-45292: ImplementPEP 654. AddExceptionGroup andBaseExceptionGroup. Update traceback display code.

  • bpo-40116: Change to the implementation of split dictionaries. Classeswhere the instances differ either in the exact set of attributes, or inthe order in which those attributes are set, can still share keys. Thisshould have no observable effect on users of Python or the C-API. Patch byMark Shannon.

  • bpo-44050: Extensions that indicate they use global state (by settingm_size to -1) can again be used in multiple interpreters. This revertsto behavior of Python 3.8.

  • bpo-44525: Setup initial specialization infrastructure for theCALL_FUNCTION opcode. Implemented initial specializations for Cfunction calls:

    • CALL_FUNCTION_BUILTIN_O forMETH_O flag.

    • CALL_FUNCTION_BUILTIN_FAST forMETH_FASTCALL flag without keywords.

    • CALL_FUNCTION_LEN forlen(o).

    • CALL_FUNCTION_ISINSTANCE forisinstance(o,t).

  • bpo-44511: Improve the generated bytecode for class and mapping patterns.

  • bpo-43706: Speed up calls toenumerate() by using thePEP 590vectorcall calling convention. Patch by Donghee Na.

Library

  • bpo-45679: Fix caching of multi-valuetyping.Literal.Literal[True,2] is no longer equal toLiteral[1,2].

  • bpo-42064: Convertsqlite3 to multi-phase initialisation (PEP 489).Patches by Erlend E. Aasland.

  • bpo-45438: Fix typing.Signature string representation for generic builtintypes.

  • bpo-45613:sqlite3 now setssqlite3.threadsafety based onthe default threading mode the underlying SQLite library has been compiledwith. Patch by Erlend E. Aasland.

  • bpo-45574: Fix warning aboutprint_escape being unused.

  • bpo-45581:sqlite3.connect() now correctly raisesMemoryErrorif the underlying SQLite API signals memory error. Patch by Erlend E.Aasland.

  • bpo-45557:pprint.pprint() now handlesunderscore_numberscorrectly. Previously it was always setting it toFalse.

  • bpo-44019: Addoperator.call() tooperator.__all__. Patch byKreusada.

  • bpo-42174:shutil.get_terminal_size() now falls back to sane valuesif the column or line count are 0.

  • bpo-35673: Improve the introspectability of the__loader__ attributefor namespace packages.importlib.machinery.NamespaceLoader isnow public, and implements theimportlib.abc.InspectLoaderinterface._NamespaceLoader is kept for backward compatibility.

  • bpo-45515: Add references tozoneinfo in thedatetimedocumentation, mostly replacing outdated references todateutil.tz.Change by Paul Ganssle.

  • bpo-45475: Reverted optimization of iteratinggzip.GzipFile,bz2.BZ2File, andlzma.LZMAFile (seebpo-43787) becauseit caused regression when user iterate them without having reference ofthem. Patch by Inada Naoki.

  • bpo-45489: UpdateForwardRef to support| operator.Patch by Donghee Na.

  • bpo-42222: Removed deprecated support for float arguments inrandrange().

  • bpo-45428: Fix a regression in py_compile when reading filenames fromstandard input.

  • bpo-45467: Fix incremental decoder and stream reader in the"raw-unicode-escape" codec. Previously they failed if the escape sequencewas split.

  • bpo-45461: Fix incremental decoder and stream reader in the"unicode-escape" codec. Previously they failed if the escape sequence wassplit.

  • bpo-45239: Fixedemail.utils.parsedate_tz() crashing withUnboundLocalError on certain invalid input instead of returningNone. Patch by Ben Hoyt.

  • bpo-45417: Fix quadratic behaviour in the enum module: Creation of enumclasses with a lot of entries was quadratic.

  • bpo-45249: Fix the behaviour oftraceback.print_exc() whendisplaying the caret when theend_offset in the exception is set to 0.Patch by Pablo Galindo

  • bpo-45416: Fix use ofasyncio.Condition with explicitasyncio.Lock objects, which was a regression due to removal ofexplicit loop arguments. Patch by Joongi Kim.

  • bpo-20028: Empty escapechar/quotechar is not allowed when initializingcsv.Dialect. Patch by Vajrasky Kok and Donghee Na.

  • bpo-44904: Fix bug in thedoctest module that caused it to fail ifa docstring included an example with aclassmethodproperty. Patchby Alex Waygood.

  • bpo-45406: Makeinspect.getmodule() catchFileNotFoundErrorraised byinspect.getabsfile(), and returnNone to indicate thatthe module could not be determined.

  • bpo-45411: Add extensions for files containing subtitles - .srt & .vtt -to the mimetypes.py module.

  • bpo-10716: Migrated pydoc to HTML5 (without changing the look of it). Sideeffect is to update xmlrpc'sServerHTMLDoc which now uses the CSS too.cgitb now relies less on pydoc (as it can't use the CSS file).

  • bpo-27580: Add support of null characters incsv.

  • bpo-45262: Prevent use-after-free in asyncio. Make sure the cached runningloop holder gets cleared on dealloc to prevent use-after-free inget_running_loop

  • bpo-45386: Makexmlrpc.client more robust to C runtimes where theunderlying Cstrftime function results in aValueError whentesting for year formatting options.

  • bpo-20028: Improve error message ofcsv.Dialect wheninitializing. Patch by Vajrasky Kok and Donghee Na.

  • bpo-45343: Update bundled pip to 21.2.4 and setuptools to 58.1.0

  • bpo-45328: Fixedhttp.client.HTTPConnection to work properly inOSs that don't support theTCP_NODELAY socket option.

  • bpo-45243: Addsetlimit() andgetlimit() tosqlite3.Connection forsetting and getting SQLite limits by connection basis. Patch by Erlend E.Aasland.

  • bpo-45320: Removed from theinspect module:

    Patch by Hugo van Kemenade.

  • bpo-45192: Fix thetempfile._infer_return_type function so that thedir argument of thetempfile functions accepts an objectimplementing theos.PathLike protocol.

    Patch by Kyungmin Lee.

  • bpo-45160: When tracing a tkinter variable used by a ttk OptionMenu,callbacks are no longer made twice.

  • bpo-25625: Added non parallel-safechdir() contextmanager to change the current working directory and then restore it onexit. Simple wrapper aroundchdir().

  • bpo-24139: Add support for SQLite extended result codes insqlite3.Error. Patch by Erlend E. Aasland.

  • bpo-24444: Fixed an error raised inargparse help display when helpfor an option is set to 1+ blank spaces or whenchoices arg is an emptycontainer.

  • bpo-44547: ImplementFraction.__int__, so that afractions.Fraction instancef passes anisinstance(f,typing.SupportsInt) check.

  • bpo-40321: Adds support for HTTP 308 redirects tourllib. SeeRFC 7538 for details. Patch by Jochem Schulenklopper.

  • bpo-41374: Ensure thatsocket.TCP_* constants are exposed on Cygwin3.1.6 and greater.

  • bpo-35970: Add help flag to the base64 module's command line interface.Patch contributed by Robert Kuska.

Documentation

Tests

  • bpo-45678: Add tests for scenarios in whichfunctools.singledispatchmethod is stacked on top of a method thathas already been wrapped by two other decorators. Patch by Alex Waygood.

  • bpo-45578: Add tests fordis.distb()

  • bpo-45678: Add tests to ensure thatfunctools.singledispatchmethodcorrectly wraps the attributes of the target function.

  • bpo-45668: PGO tests now pass when Python is built without test extensionmodules.

  • bpo-45577: Add subtests for allpickle protocols intest_zoneinfo.

  • bpo-45566: Fixtest_frozen_pickle intest_dataclasses to check allpickle versions.

  • bpo-43592:test.libregrtest now raises the soft resource limit forthe maximum number of file descriptors when the default is too low for ourtest suite as was often the case on macOS.

  • bpo-39679: Add more test cases for@functools.singledispatchmethodwhen combined with@classmethod or@staticmethod.

  • bpo-45410: When libregrtest spawns a worker process, stderr is now writteninto stdout to keep messages order. Use a single pipe for stdout andstderr, rather than two pipes. Previously, messages were out of orderwhich made analysis of buildbot logs harder Patch by Victor Stinner.

  • bpo-45402: Fix test_tools.test_sundry() when Python is built out of tree:fix how the freeze_modules.py tool locates the _freeze_module program.Patch by Victor Stinner.

  • bpo-45403: Fix test_sys.test_stdlib_dir() when Python is built outside thesource tree: compare normalized paths. Patch by Victor Stinner.

  • bpo-45400: Fixtest_name_error_suggestions_do_not_trigger_for_too_many_locals() oftest_exceptions if a directory name contains "a1" (like"Python-3.11.0a1"): use a stricter regular expression. Patch by VictorStinner.

  • bpo-10572: Renamesqlite3 tests fromtest_sqlite totest_sqlite3, and relocate them toLib/test/test_sqlite3. Patch byErlend E. Aasland.

Build

  • bpo-43158:setup.py now uses values from configure script to build the_uuid extension module. Configure now detects util-linux'slibuuid, too.

  • bpo-45666: Fix warning ofswprintf and%s usage in_testembed.c

  • bpo-45548:Modules/Setup andModules/makesetup have been improved.TheSetup file now contains working rules for all extensions. Outdatedcomments have been removed. Rules defined bymakesetup trackdependencies correctly.

  • bpo-45548: Themath andcmath implementation now require aC99 compatiblelibm and no longer ship with workarounds for missingacosh, asinh, atanh, expm1, and log1p functions.

  • bpo-45595:setup.py andmakesetup now track build dependencies onall Python header files and module specific header files.

  • bpo-45571:Modules/Setup now usePY_CFLAGS_NODIST instead ofPY_CFLAGS to compile shared modules.

  • bpo-45570:pyexpat and_elementtree no longer defineobsolete macrosHAVE_EXPAT_CONFIG_H andUSE_PYEXPAT_CAPI.XML_POOR_ENTROPY is now defined inexpat_config.h.

  • bpo-43974:setup.py no longer definesPy_BUILD_CORE_MODULE.Instead every module, that uses the internal API, defines the macro.

  • bpo-45548: Fill in missing entries in Modules/Setup.

  • bpo-45532: Updatesys.version to usemain as fallbackinformation. Patch by Jeong YunWon.

  • bpo-45536: Theconfigure script now checks whether OpenSSL headers andlibraries provide required APIs. Most common APIs are verified. The checkdetects outdated or missing OpenSSL. Failures do not stop configure.

  • bpo-45221: Fixed regression in handling ofLDFLAGS andCPPFLAGSoptions whereargparse.parse_known_args() could interpret an optionas one of the built-in command line argument, for example-h for help.

  • bpo-45440: Building Python now requires a C99<math.h> header fileproviding the following functions:copysign(),hypot(),isfinite(),isinf(),isnan(),round(). Patch by VictorStinner.

  • bpo-45405: Preventinternalconfigureerror when runningconfigurewith recent versions of non-Apple clang. Patch by David Bohman.

  • bpo-45433: Avoid linking libpython with libcrypt.

Windows

  • bpo-43652: Update Tcl/Tk to 8.6.11, actually this time. The previousupdate incorrectly included 8.6.10.

  • bpo-45337: venv now warns when the created environment may need to beaccessed at a different path, due to redirections, links or junctions. Italso now correctly installs or upgrades components when the alternate pathis required.

  • bpo-43851: Build SQLiteSQLITE_OMIT_AUTOINIT on Windows. Patch byErlend E. Aasland.

macOS

  • bpo-44828: Avoid tkinter file dialog failure on macOS 12 Monterey whenusing the Tk 8.6.11 provided by python.org macOS installers. Patch by MarcCuller of the Tk project.

IDLE

  • bpo-45495: Add context keywords 'case' and 'match' to completions list.

C API

  • bpo-29103:PyType_FromSpec* nowcopies the class name from the spec to a buffer owned by the class, so theoriginal can be safely deallocated. Patch by Petr Viktorin.

  • bpo-45522: The internal freelists for frame, float, list, dict, asyncgenerators, and context objects can now be disabled.

  • bpo-35134: ExcludePyWeakref_GET_OBJECT() from the limited C API.It never worked since thePyWeakReference structure is opaquein the limited C API.

  • bpo-35081: Move theinterpreteridobject.h header file fromInclude/ toInclude/internal/. It only provides private functions.Patch by Victor Stinner.

  • bpo-35134: The non-limited API filescellobject.h,classobject.h,context.h,funcobject.h,genobject.h andlongintrepr.hhave been moved to theInclude/cpython directory. Moreover, theeval.h header file was removed. These files must not be includeddirectly, as they are already included inPython.h:IncludeFiles. If they have been included directly, considerincludingPython.h instead. Patch by Victor Stinner.

  • bpo-45474: The following items are no longer available whenPy_LIMITED_API is defined:

    These are not part of thelimited API.

    Patch by Victor Stinner.

  • bpo-45434: Remove thepystrhex.h header file. It only contains privatefunctions. C extensions should only include the main<Python.h> headerfile. Patch by Victor Stinner.

  • bpo-45440: Remove thePy_FORCE_DOUBLE() macro. It was used by thePy_IS_INFINITY() macro. Patch by Victor Stinner.

  • bpo-45434:<Python.h> no longer includes the header files<stdlib.h>,<stdio.h>,<errno.h> and<string.h> when thePy_LIMITED_API macro is set to0x030b0000 (Python 3.11) or higher.C extensions should explicitly include the header files after#include<Python.h>. Patch by Victor Stinner.

  • bpo-41123: RemovePy_UNICODE_COPY() andPy_UNICODE_FILL() macros,deprecated since Python 3.3. UsePyUnicode_CopyCharacters() ormemcpy() (wchar_t* string), andPyUnicode_Fill() functionsinstead. Patch by Victor Stinner.

  • bpo-45412: Remove the following math macros using theerrno variable:

    • Py_ADJUST_ERANGE1()

    • Py_ADJUST_ERANGE2()

    • Py_OVERFLOWED()

    • Py_SET_ERANGE_IF_OVERFLOW()

    • Py_SET_ERRNO_ON_MATH_ERROR()

    Patch by Victor Stinner.

  • bpo-45395: Custom frozen modules (the array set toPyImport_FrozenModules) are now treated as additions, rather thanreplacing all the default frozen modules. Frozen stdlib modules can stillbe disabled by setting the "code" field of the custom array entry to NULL.

  • bpo-43760: Add newPyThreadState_EnterTracing(), andPyThreadState_LeaveTracing() functions to the limited C API tosuspend and resume tracing and profiling. Patch by Victor Stinner.

  • bpo-44220:PyStructSequence_UnnamedField is added to the StableABI.

Python 3.11.0 alpha 1

Release date: 2021-10-05

Security

  • bpo-42278: Replaced usage oftempfile.mktemp() withTemporaryDirectory to avoid a potential race condition.

  • bpo-44600: Fix incorrect line numbers while tracing some failed patternsinmatch statements. Patch by Charles Burkland.

  • bpo-41180: Add auditing events to themarshal module, and stopraisingcode.__init__ events for every unmarshalled code object.Directly instantiated code objects will continue to raise an event, andaudit event handlers should inspect or collect the raw marshal data. Thisreduces a significant performance overhead when loading from.pycfiles.

  • bpo-44394: Update the vendored copy of libexpat to 2.4.1 (from 2.2.8) toget the fix for theCVE 2013-0340 "Billion Laughs" vulnerability. Thiscopy is most used on Windows and macOS.

  • bpo-43124: Made the internalputcmd function insmtplibsanitize input for presence of\r and\n characters to avoid(unlikely) command injection.

  • bpo-44022:http.client now avoids infinitely reading potential HTTPheaders after a100Continue status response from the server.

Core and Builtins

  • bpo-43760: The number of hardware branches per instruction dispatch isreduced from two to one by adding a special instruction for tracing. Patchby Mark Shannon.

  • bpo-45061: Add a deallocator to the bool type to detect refcount bugs in Cextensions which call Py_DECREF(Py_True) or Py_DECREF(Py_False) bymistake. Detect also refcount bugs when the empty tuple singleton or theUnicode empty string singleton is destroyed by mistake. Patch by VictorStinner.

  • bpo-24076: sum() was further optimised for summing up single digitintegers.

  • bpo-45190: Update Unicode databases to Unicode 14.0.0.

  • bpo-45167: Fix deepcopying oftypes.GenericAlias objects.

  • bpo-45155:int.to_bytes() andint.from_bytes() now take adefault value of"big" for thebyteorder argument.int.to_bytes() also takes a default value of1 for thelength argument.

  • bpo-44219: Release the GIL while performingisatty system calls onarbitrary file descriptors. In particular, this affectsos.isatty(),os.device_encoding() andio.TextIOWrapper. By extension,io.open() in text mode is also affected. This change solves adeadlock inos.isatty(). Patch by Vincent Michel inbpo-44219.

  • bpo-44959: Added fallback to extension modules with '.sl' suffix on HP-UX

  • bpo-45121: Fix issue whereProtocol.__init__ raisesRecursionErrorwhen it's called directly or viasuper(). Patch provided by YuriiKarabas.

  • bpo-44348: The deallocator function of theBaseException type nowuses the trashcan mechanism to prevent stack overflow. For example, when aRecursionError instance is raised, it can be linked to anotherRecursionError through the__context__ attribute or the__traceback__ attribute, and then a chain of exceptions is created.When the chain is destroyed, nested deallocator function calls can crashwith a stack overflow if the chain is too long compared to the availablestack memory. Patch by Victor Stinner.

  • bpo-45123: Fix PyAiter_Check to only check for the __anext__ presence (notfor __aiter__). Rename PyAiter_Check to PyAIter_Check, PyObject_GetAiter-> PyObject_GetAIter.

  • bpo-1514420: Interpreter no longer attempts to open files with names inangle brackets (like "<string>" or "<stdin>") when formatting anexception.

  • bpo-41031: Match C and Python code formatting of unprintable exceptionsand exceptions in the__main__ module.

  • bpo-37330:open(),io.open(),codecs.open() andfileinput.FileInput no longer accept'U' ("universalnewline") in the file mode. This flag was deprecated since Python 3.3.Patch by Victor Stinner.

  • bpo-45083: When the interpreter renders an exception, its name now has acomplete qualname. Previously only the class name was concatenated to themodule name, which sometimes resulted in an incorrect full name beingdisplayed.

    (This issue impacted only the C code exception rendering, thetraceback module was using qualname already).

  • bpo-34561: List sorting now uses the merge-ordering strategy from Munroand Wild'spowersort(). Unlike the former strategy, this is provablynear-optimal in the entropy of the distribution of run lengths. Most usesoflist.sort() probably won't see a significant time difference, butmay see significant improvements in cases where the former strategy wasexceptionally poor. However, as these are all fast linear-timeapproximations to a problem that's inherently at best quadratic-time tosolve truly optimally, it's also possible to contrive cases where theformer strategy did better.

  • bpo-45056: Compiler now removes trailing unused constants from co_consts.

  • bpo-45020: Add a new command line option, "-X frozen_modules=[on|off]" toopt out of (or into) using optional frozen modules. This defaults to "on"(or "off" if it's running out of the source tree).

  • bpo-45012: Inposix, release GIL duringstat(),lstat(),andfstatat() syscalls made byos.DirEntry.stat(). Patch byStanisław Skonieczny.

  • bpo-45018: Fixed pickling of range iterators that iterated for over2**32 times.

  • bpo-45000: ASyntaxError is now raised when trying to delete__debug__. Patch by Donghee Na.

  • bpo-44963: Implementsend() andthrow() methods foranext_awaitable objects. Patch by Pablo Galindo.

  • bpo-44962: Fix a race in WeakKeyDictionary, WeakValueDictionary andWeakSet when two threads attempt to commit the last pending removal. Thisfixes asyncio.create_task and fixes a data loss in asyncio.run whereshutdown_asyncgens is not run

  • bpo-24234: Implement the__bytes__() special method on thebytes type, so a bytes objectb passes anisinstance(b,typing.SupportsBytes) check.

  • bpo-24234: Implement the__complex__() special method on thecomplex type, so a complex numberz passes anisinstance(z,typing.SupportsComplex) check.

  • bpo-44954: Fixed a corner case bug where the result offloat.fromhex('0x.8p-1074') was rounded the wrong way.

  • bpo-44947: Refine the syntax error for trailing commas in importstatements. Patch by Pablo Galindo.

  • bpo-44945: Specialize the BINARY_ADD instruction using the PEP 659machinery. Adds five new instructions:

    • BINARY_ADD_ADAPTIVE

    • BINARY_ADD_FLOAT

    • BINARY_ADD_INT

    • BINARY_ADD_UNICODE

    • BINARY_ADD_UNICODE_INPLACE_FAST

  • bpo-44929: Fix some edge cases ofenum.Flag string representation inthe REPL. Patch by Pablo Galindo.

  • bpo-44914: Class version tags are no longer recycled.

    This means that a version tag serves as a unique identifier for the stateof a class. We rely on this for effective specialization of the LOAD_ATTRand other instructions.

  • bpo-44698: Restore behaviour of complex exponentiation with integer-valuedexponent of typefloat orcomplex.

  • bpo-44895: A debug variablePYTHONDUMPREFSFILE is added forcreating a dump file which is generated by--with-trace-refs.Patch by Donghee Na.

  • bpo-44900: Add five superinstructions for PEP 659 quickening:

    • LOAD_FAST LOAD_FAST

    • STORE_FAST LOAD_FAST

    • LOAD_FAST LOAD_CONST

    • LOAD_CONST LOAD_FAST

    • STORE_FAST STORE_FAST

  • bpo-44889: Initial implementation of adaptive specialization ofLOAD_METHOD. The following specialized forms were added:

    • LOAD_METHOD_CACHED

    • LOAD_METHOD_MODULE

    • LOAD_METHOD_CLASS

  • bpo-44890: Specialization stats are always collected in debug builds.

  • bpo-44885: Correct the ast locations of f-strings with format specs andrepeated expressions. Patch by Pablo Galindo

  • bpo-44878: Remove the loop from the bytecode interpreter. All instructionsend with a DISPATCH macro, so the loop is now redundant.

  • bpo-44878: Remove switch statement for interpreter loop when usingcomputed gotos. This makes sure that we only have one dispatch table inthe interpreter.

  • bpo-44874: Deprecate the old trashcan macros(Py_TRASHCAN_SAFE_BEGIN/Py_TRASHCAN_SAFE_END). They should bereplaced by the new macrosPy_TRASHCAN_BEGIN andPy_TRASHCAN_END.

  • bpo-44872: Use new trashcan macros (Py_TRASHCAN_BEGIN/END) inframeobject.c instead of the old ones (Py_TRASHCAN_SAFE_BEGIN/END).

  • bpo-33930: Fix segmentation fault with deep recursion when cleaning methodobjects. Patch by Augusto Goulart and Pablo Galindo.

  • bpo-25782: Fix bug wherePyErr_SetObject hangs when the currentexception has a cycle in its context chain.

  • bpo-44856: Fix reference leaks in the error paths ofupdate_bases()and__build_class__. Patch by Pablo Galindo.

  • bpo-44826: Initial implementation of adaptive specialization of STORE_ATTR

    Three specialized forms of STORE_ATTR are added:

    • STORE_ATTR_SLOT

    • STORE_ATTR_SPLIT_KEYS

    • STORE_ATTR_WITH_HINT

  • bpo-44838: Fixed a bug that was causing the parser to raise an incorrectcustomSyntaxError for invalid 'if' expressions. Patch by PabloGalindo.

  • bpo-44821: Create instance dictionaries (__dict__) eagerly, to improveregularity of object layout and assist specialization.

  • bpo-44792: Improve syntax errors for if expressions. Patch by Miguel Brito

  • bpo-34013: Generalize the invalid legacy statement custom error message(like the one generated when "print" is called without parentheses) toinclude more generic expressions. Patch by Pablo Galindo

  • bpo-44732: Renametypes.Union totypes.UnionType.

  • bpo-44725: Expose specialization stats in python via_opcode.get_specialization_stats().

  • bpo-44717: Improve AttributeError on circular imports of submodules.

  • bpo-44698: Fix undefined behaviour in complex object exponentiation.

  • bpo-44653: Supporttyping types in parameter substitution in theunion type.

  • bpo-44676: Add ability to serialisetypes.Union objects. Patchprovided by Yurii Karabas.

  • bpo-44633: Parameter substitution of the union type with wrong types nowraisesTypeError instead of returningNotImplemented.

  • bpo-44661: Updateproperty_descr_set to use vectorcall if possible.Patch by Donghee Na.

  • bpo-44662: Add__module__ totypes.Union. This also fixestypes.Union issues withtyping.Annotated. Patch provided by YuriiKarabas.

  • bpo-44655: Include the name of the type in unset __slots__ attributeerrors. Patch by Pablo Galindo

  • bpo-44655: Don't include a missing attribute with the same name as thefailing one when offering suggestions for missing attributes. Patch byPablo Galindo

  • bpo-44646: Fix the hash of the union type: it no longer depends on theorder of arguments.

  • bpo-44636: Collapse union of equal types. E.g. the result ofint|intis nowint. Fix comparison of the union type with non-hashableobjects. E.g.int|str=={} no longer raises a TypeError.

  • bpo-44611: On Windows,os.urandom(): uses BCryptGenRandom APIinstead of CryptGenRandom API which is deprecated from Microsoft WindowsAPI. Patch by Donghee Na.

  • bpo-44635: ConvertNone totype(None) in the union typeconstructor.

  • bpo-26280: Implement adaptive specialization for BINARY_SUBSCR

    Three specialized forms of BINARY_SUBSCR are added:

    • BINARY_SUBSCR_LIST_INT

    • BINARY_SUBSCR_TUPLE_INT

    • BINARY_SUBSCR_DICT

  • bpo-44589: Mapping patterns inmatch statements with two or more equalliteral keys will now raise aSyntaxError at compile-time.

  • bpo-44606: Fix__instancecheck__ and__subclasscheck__ for theunion type.

  • bpo-42073: The@classmethod decorator can now wrap otherclassmethod-like descriptors.

  • bpo-41972: Tuned the string-searching algorithm of fastsearch.h to have ashorter inner loop for most cases.

  • bpo-44590: All necessary data for executing a Python function (localvariables, stack, etc) is now kept in a per-thread stack. Frame objectsare lazily allocated on demand. This increases performance by about 7% onthe standard benchmark suite. Introspection and debugging are unaffectedas frame objects are always available when needed. Patch by Mark Shannon.

  • bpo-44584: The threading debug (PYTHONTHREADDEBUG environmentvariable) is deprecated in Python 3.10 and will be removed in Python 3.12.This feature requires a debug build of Python. Patch by Victor Stinner.

  • bpo-43895: An obsolete internal cache of shared object file handles addedin 1995 that attempted, but did not guarantee, that a .so would not bedlopen'ed twice to work around flaws in mid-1990s posix-ish operatingsystems has been removed from dynload_shlib.c.

  • bpo-44490:typing now searches for type parameters intypes.Union objects.get_type_hints will also properly resolveannotations with nestedtypes.Union objects. Patch provided by YuriiKarabas.

  • bpo-43950: Code objects can now provide the column information forinstructions when available. This is levaraged during traceback printingto show the expressions responsible for errors.

    Contributed by Pablo Galindo, Batuhan Taskaya and Ammar Askar as part ofPEP 657.

  • bpo-44562: Remove uses ofPyObject_GC_Del() in error path wheninitializingtypes.GenericAlias.

  • bpo-41486: Fix a memory consumption and copying performance regression inearlier 3.10 beta releases if someone used an output buffer larger than4GiB with zlib.decompress on input data that expands that large.

  • bpo-43908: Heap types with thePy_TPFLAGS_IMMUTABLETYPE flagcan now inherit thePEP 590 vectorcall protocol. Previously, this wasonly possible forstatic types. Patch by Erlend E.Aasland.

  • bpo-44553: Implement GC methods fortypes.Union to break referencecycles and prevent memory leaks.

  • bpo-44490: Add__parameters__ attribute and__getitem__ operatortotypes.Union. Patch provided by Yurii Karabas.

  • bpo-44523: Remove the pass-through forhash() ofweakref.proxy objects to prevent unintended consequences when theoriginal referred object dies while the proxy is part of a hashableobject. Patch by Pablo Galindo.

  • bpo-44483: Fix a crash intypes.Union objects when creating a union ofan object with bad__module__ field.

  • bpo-44486: Modules will always have a dictionary, even when created bytypes.ModuleType.__new__()

  • bpo-44472: Fix ltrace functionality when exceptions are raised. Patch byPablo Galindo

  • bpo-12022: ATypeError is now raised instead of anAttributeError inwith andasyncwithstatements for objects which do not support thecontext manager orasynchronous context manager protocols correspondingly.

  • bpo-44297: Make sure that the line number is set when entering acomprehension scope. This ensures that backtraces including generatorexpressions show the correct line number.

  • bpo-44456: Improve the syntax error when mixing positional and keywordpatterns. Patch by Pablo Galindo.

  • bpo-44409: Fix error location information for tokenizer errors raised oninitialization of the tokenizer. Patch by Pablo Galindo.

  • bpo-44396: Fix a possible crash in the tokenizer when raising syntaxerrors for unclosed strings. Patch by Pablo Galindo.

  • bpo-44376: Exact integer exponentiation (likei**2 orpow(i,2))with a small exponent is much faster, due to reducing overhead in suchcases.

  • bpo-44313: Directly imported objects and modules (through import and fromimport statements) don't generateLOAD_METHOD/CALL_METHOD fordirectly accessed objects on their namespace. They now use the regularLOAD_ATTR/CALL_FUNCTION.

  • bpo-44338: Implement adaptive specialization for LOAD_GLOBAL

    Two specialized forms of LOAD_GLOBAL are added:

    • LOAD_GLOBAL_MODULE

    • LOAD_GLOBAL_BUILTIN

  • bpo-44368: Improve syntax errors for invalid "as" targets. Patch by PabloGalindo

  • bpo-44349: Fix an edge case when displaying text from files with encodingin syntax errors. Patch by Pablo Galindo.

  • bpo-44337: Initial implementation of adaptive specialization of LOAD_ATTR

    Four specialized forms of LOAD_ATTR are added:

    • LOAD_ATTR_SLOT

    • LOAD_ATTR_SPLIT_KEYS

    • LOAD_ATTR_WITH_HINT

    • LOAD_ATTR_MODULE

  • bpo-44335: Fix a regression when identifying incorrect characters insyntax errors. Patch by Pablo Galindo

  • bpo-43693: Computation of the offsets of cell variables is done in thecompiler instead of at runtime. This reduces the overhead of handling celland free variables, especially in the case where a variable is both anargument and cell variable.

  • bpo-44317: Improve tokenizer error with improved locations. Patch by PabloGalindo.

  • bpo-44304: Fix a crash in thesqlite3 module that happened when thegarbage collector clearssqlite.Statement objects. Patch by PabloGalindo

  • bpo-44305: Improve error message fortry blocks withoutexcept orfinally blocks. Patch by Pablo Galindo.

  • bpo-43413: Constructors of subclasses of some builtin classes (e.g.tuple,list,frozenset) no longer acceptarbitrary keyword arguments. [reverted in 3.11a4] Subclass ofsetcan now define a__new__() method with additional keyword parameterswithout overriding also__init__().

  • bpo-43667: Improve Unicode support in non-UTF locales on Oracle Solaris.This issue does not affect other Solaris systems.

  • bpo-43693: A new opcode MAKE_CELL has been added that effectively movessome of the work done on function entry into the compiler and into theeval loop. In addition to creating the required cell objects, the newopcode converts relevant arguments (and other locals) to cell variables onfunction entry.

  • bpo-44232: Fix a regression intype() when a metaclass raises anexception. The C functiontype_new() must properly report theexception when a metaclass constructor raises an exception and the winnerclass is not the metaclass. Patch by Victor Stinner.

  • bpo-44201: Avoid side effects of checking for specialized syntax errors inthe REPL that was causing it to ask for extra tokens after a syntax errorhad been detected. Patch by Pablo Galindo

  • bpo-43693:PyCodeObject gainedco_fastlocalnames andco_fastlocalkinds as the authoritative source of fast locals info.Marshaled code objects have changed accordingly.

  • bpo-44184: Fix a crash at Python exit when a deallocator function removesthe last strong reference to a heap type. Patch by Victor Stinner.

  • bpo-44187: Implement quickening in the interpreter. This offers noadvantages as yet, but is an enabler of future optimizations. See PEP 659for full explanation.

  • bpo-44180: The parser doesn't report generic syntax errors that happen ina position further away that the one it reached in the first pass. Patchby Pablo Galindo

  • bpo-44168: Fix error message in the parser involving keyword argumentswith invalid expressions. Patch by Pablo Galindo

  • bpo-44156: String caches incompile.c are now subinterpretercompatible.

  • bpo-44143: Fixed a crash in the parser that manifest when raisingtokenizer errors when an existing exception was present. Patch by PabloGalindo.

  • bpo-44032: Move 'fast' locals and other variables from the frame object toa per-thread datastack.

  • bpo-44114: Fix incorrect dictkeys_reversed and dictitems_reversed functionsignatures in C code, which broke webassembly builds.

  • bpo-44110: Improvestr.__getitem__() error message

  • bpo-26110: AddCALL_METHOD_KW opcode to speed up method calls withkeyword arguments. Idea originated from PyPy. A side effect is executingCALL_METHOD is now branchless in the evaluation loop.

  • bpo-28307: Compiler now optimizes simple C-style formatting with literalformat containing only format codes %s, %r and %a by converting them tof-string expressions.

  • bpo-43149: Correct the syntax error message regarding multiple exceptiontypes to not refer to "exception groups". Patch by Pablo Galindo

  • bpo-43822: The parser will prioritize tokenizer errors over custom syntaxerrors when raising exceptions. Patch by Pablo Galindo.

  • bpo-40222: "Zero cost" exception handling.

    • Uses a lookup table to determine how to handle exceptions.

    • Removes SETUP_FINALLY and POP_TOP block instructions, eliminating the runtime overhead of try statements.

    • Reduces the size of the frame object by about 60%.

    Patch by Mark Shannon

  • bpo-43918: Document the signature anddefault argument in thedocstring of the newanext builtin.

  • bpo-43833: Emit a deprecation warning if the numeric literal isimmediately followed by one of keywords: and, else, for, if, in, is, or.Raise a syntax error with more informative message if it is immediatelyfollowed by other keyword or identifier.

  • bpo-43879: Add native_thread_id to PyThreadState. Patch by Gabriele N.Tornetta.

  • bpo-43693: Compute cell offsets relative to locals in compiler. Allows theinterpreter to treats locals and cells a single array, which is slightlymore efficient. Also make the LOAD_CLOSURE opcode an alias for LOAD_FAST.Preserving LOAD_CLOSURE helps keep bytecode a bit more readable.

  • bpo-17792: More accurate error messages for access of unbound locals orfree vars.

  • bpo-28146: Fix a confusing error message instr.format().

  • bpo-11105: When compilingast.AST objects with recursivereferences throughcompile(), the interpreter doesn't crash anymoreinstead it raises aRecursionError.

  • bpo-39091: Fix crash when using passing a non-exception to a generator'sthrow() method. Patch by Noah Oxer

  • bpo-33346: Asynchronous comprehensions are now allowed insidecomprehensions in asynchronous functions. Outer comprehensions implicitlybecome asynchronous.

Library

  • bpo-45371: Fix clang rpath issue indistutils. The UnixCCompiler nowuses correct clang option to add a runtime library directory (rpath) to ashared library.

  • bpo-45329: Fix freed memory access inpyexpat.xmlparser whenbuilding it with an installed expat library <= 2.2.0.

  • bpo-41710: On Unix, if thesem_clockwait() function is available inthe C library (glibc 2.30 and newer), thethreading.Lock.acquire()method now uses the monotonic clock (time.CLOCK_MONOTONIC) forthe timeout, rather than using the system clock(time.CLOCK_REALTIME), to not be affected by system clockchanges. Patch by Victor Stinner.

  • bpo-1596321: Fix thethreading._shutdown() function when thethreading module was imported first from a thread different thanthe main thread: no longer log an error at Python exit.

  • bpo-45274: Fix a race condition in theThread.join() method of thethreading module. If thefunction is interrupted by a signal and the signal handler raises anexception, make sure that the thread remains in a consistent state toprevent a deadlock. Patch by Victor Stinner.

  • bpo-21302: In Unix operating systems,time.sleep() now uses thenanosleep() function, ifclock_nanosleep() is not available butnanosleep() is available.nanosleep() allows to sleep withnanosecond precision.

  • bpo-21302: On Windows,time.sleep() now uses a waitable timer whichhas a resolution of 100 nanoseconds (10-7 seconds). Previously,it had a resolution of 1 millisecond (10-3 seconds). Patch byBenjamin Szőke and Victor Stinner.

  • bpo-45238: Fixunittest.IsolatedAsyncioTestCase.debug(): it runs nowasynchronous methods and callbacks.

  • bpo-36674:unittest.TestCase.debug() raises now aunittest.SkipTest if the class or the test method are decoratedwith the skipping decorator.

  • bpo-45235: Fix an issue where argparse would not preserve values in aprovided namespace when using a subparser with defaults.

  • bpo-45183: Have zipimport.zipimporter.find_spec() not raise an exceptionwhen the underlying zip file has been deleted and the internal cache hasbeen reset via invalidate_cache().

  • bpo-45234: Fixed a regression incopyfile(),copy(),copy2() raisingFileNotFoundError when source is a directory, which should raiseIsADirectoryError

  • bpo-45228: Fix stack buffer overflow in parsing J1939 network address.

  • bpo-45225: use map function instead of genexpr in capwords.

  • bpo-42135: Fix typo:importlib.find_loader is really slated forremoval in Python 3.12 not 3.10, like the others in PR 25169.

    Patch by Hugo van Kemenade.

  • bpo-20524: Improves error messages on.format() operation forstr,float,int, andcomplex. New format now shows the problematicpattern and the object type.

  • bpo-45168: Changedis.dis() output to omit op arg values that cannotbe resolved due toco_consts,co_names etc not being provided.Previously the oparg itself was repeated in the value field, which is notuseful and can be confusing.

  • bpo-21302: In Unix operating systems,time.sleep() now uses theclock_nanosleep() function, if available, which allows to sleep for aninterval specified with nanosecond precision.

  • bpo-45173: Remove from theconfigparser module: theSafeConfigParser class, thefilename property of theParsingError class, thereadfp() method oftheConfigParser class, deprecated since Python3.2.

    Patch by Hugo van Kemenade.

  • bpo-44987: Pure ASCII strings are now normalized in constant time byunicodedata.normalize(). Patch by Donghee Na.

  • bpo-35474: Callingmimetypes.guess_all_extensions() withstrict=False no longer affects the result of the following call withstrict=True. Also, mutating the returned list no longer affects theglobal state.

  • bpo-45166:typing.get_type_hints() now works withFinal wrapped inForwardRef.

  • bpo-45162: Remove many old deprecatedunittest features:

    • "fail*" and "assert*" aliases ofTestCase methods.

    • Broken from startTestCase methodassertDictContainsSubset().

    • Ignored<unittest.TestLoader.loadTestsFromModule>TestLoader.loadTestsFromModule() parameteruse_load_tests.

    • Old alias_TextTestResult ofTextTestResult.

  • bpo-38371: Remove the deprecatedsplit() method of_tkinter.TkappType. Patch by Erlend E. Aasland.

  • bpo-20499: Improve the speed and accuracy of statistics.pvariance().

  • bpo-45132: Remove__getitem__() methods ofxml.dom.pulldom.DOMEventStream,wsgiref.util.FileWrapperandfileinput.FileInput, deprecated since Python 3.9.

    Patch by Hugo van Kemenade.

  • bpo-45129: Due to significant security concerns, thereuse_addressparameter ofasyncio.loop.create_datagram_endpoint(), disabled inPython 3.9, is now entirely removed. This is because of the behavior ofthe socket optionSO_REUSEADDR in UDP.

    Patch by Hugo van Kemenade.

  • bpo-45124: Thebdist_msi command, deprecated in Python 3.9, is nowremoved.

    Usebdist_wheel (wheel packages) instead.

    Patch by Hugo van Kemenade.

  • bpo-30856:unittest.TestResult methodsaddFailure(),addError(),addSkip() andaddSubTest() are now called immediately afterraising an exception in test or finishing a subtest. Previously they werecalled only after finishing the test clean up.

  • bpo-45034: Changes how error is formatted forstruct.pack with'H'and'h' modes and too large / small numbers. Now it shows the actualnumeric limits, while previously it was showing arithmetic expressions.

  • bpo-25894:unittest now always reports skipped and failed subtestsseparately: separate characters in default mode and separate lines inverbose mode. Also the test description is now output for errors in testmethod, class and module cleanups.

  • bpo-45081: Fix issue when dataclasses that inherit fromtyping.Protocol subclasses have wrong__init__. Patch provided byYurii Karabas.

  • bpo-45085: Thebinhex module, deprecated in Python 3.9, is nowremoved. The followingbinascii functions, deprecated in Python3.9, are now also removed:

    • a2b_hqx(),b2a_hqx();

    • rlecode_hqx(),rledecode_hqx().

    Thebinascii.crc_hqx() function remains available.

    Patch by Victor Stinner.

  • bpo-40360: Thelib2to3 package is now deprecated and may not beable to parse Python 3.10 or newer. See thePEP 617 (New PEG parser forCPython). Patch by Victor Stinner.

  • bpo-45075: Renametraceback.StackSummary.format_frame() totraceback.StackSummary.format_frame_summary(). This method was addedfor 3.11 so it was not released yet.

    Updated code and docs to better distinguish frame and FrameSummary.

  • bpo-31299: Add option to completely drop frames from a traceback byreturningNone from aformat_frame()override.

  • bpo-41620:run() now always return aTestResult instance. Previously it returnedNone ifthe test class or method was decorated with a skipping decorator.

  • bpo-45021: Fix a potential deadlock at shutdown of forked children whenusingconcurrent.futures module

  • bpo-43913: Fix bugs in cleaning up classes and modules inunittest:

    • Functions registered withaddModuleCleanup() were not called unless the user definestearDownModule() in their test module.

    • Functions registered withaddClassCleanup() were not called iftearDownClass is set toNone.

    • Buffering inTestResult did not work with functions registered withaddClassCleanup() andaddModuleCleanup().

    • Errors in functions registered withaddClassCleanup() andaddModuleCleanup() were not handled correctly in buffered and debug modes.

    • Errors insetUpModule() and functions registered withaddModuleCleanup() were reported in wrong order.

    • And several lesser bugs.

  • bpo-45030: Fix integer overflow in pickling and copying the rangeiterator.

  • bpo-45001: Made email date parsing more robust against malformed input,namely a whitespace-onlyDate: header. Patch by Wouter Bolsterlee.

  • bpo-45010: Remove support of special method__div__ inunittest.mock. It is not used in Python 3.

  • bpo-39218: Improve accuracy of variance calculations by usingx*xinstead ofx**2.

  • bpo-43613: Improve the speed ofgzip.compress() andgzip.decompress() by compressing and decompressing at once in memoryinstead of in a streamed fashion.

  • bpo-37596: Ensure thatset andfrozenset objects arealwaysmarshalled reproducibly.

  • bpo-44019: A new functionoperator.call has been added, such thatoperator.call(obj,*args,**kwargs)==obj(*args,**kwargs).

  • bpo-42255:webbrowser.MacOSX is deprecated and will be removedin Python 3.13. It is untested and undocumented and also not used bywebbrowser itself. Patch by Donghee Na.

  • bpo-44955: MethodstopTestRun() is now alwayscalled in pair with methodstartTestRun() forTestResult objects implicitly created inrun(). Previously it was not called for testmethods and classes decorated with a skipping decorator.

  • bpo-39039: tarfile.open raisesReadError when a zlib erroroccurs during file extraction.

  • bpo-44935:subprocess on Solaris now also usesos.posix_spawn() for better performance.

  • bpo-44911:IsolatedAsyncioTestCase will no longer throwan exception while cancelling leaked tasks. Patch by Bar Harel.

  • bpo-41322: AddedDeprecationWarning for tests and async tests thatreturn a value!=None (as this may indicate an improperly written test, forexample a test written as a generator function).

  • bpo-44524: Make exception message more useful when subclass from typingspecial form alias. Patch provided by Yurii Karabas.

  • bpo-38956:argparse.BooleanOptionalAction's default value is nolonger printed twice when used withargparse.ArgumentDefaultsHelpFormatter.

  • bpo-44860: Fix theposix_user scheme insysconfig to not dependonsys.platlibdir.

  • bpo-44859: Improve error handling insqlite3 and raise moreaccurate exceptions.

    • MemoryError is now raised instead ofsqlite3.Warning when memory is not enough for encoding a statement to UTF-8 inConnection.__call__() andCursor.execute().

    • UnicodEncodeError is now raised instead ofsqlite3.Warning when the statement contains surrogate characters inConnection.__call__() andCursor.execute().

    • TypeError is now raised instead ofValueError for non-string script argument inCursor.executescript().

    • ValueError is now raised for script containing the null character instead of truncating it inCursor.executescript().

    • Correctly handle exceptions raised when getting boolean value of the result of the progress handler.

    • Add many tests covering different corner cases.

  • bpo-44581: Upgrade bundled pip to 21.2.3 and setuptools to 57.4.0

  • bpo-44849: Fix theos.set_inheritable() function on FreeBSD 14 forfile descriptor opened with theO_PATH flag: ignore theEBADF error onioctl(), fallback on thefcntl()implementation. Patch by Victor Stinner.

  • bpo-44605: The @functools.total_ordering() decorator now works withmetaclasses.

  • bpo-44524: Fixed an issue wherein the__name__ and__qualname__attributes of subscribed specialforms could beNone.

  • bpo-44839:MemoryError raised in user-defined functions will nowproduce aMemoryError insqlite3.OverflowError willnow be converted toDataError. PreviouslyOperationalError was produced in these cases.

  • bpo-44822:sqlite3 user-defined functions and aggregators returningstrings with embedded NUL characters are no longertruncated. Patch by Erlend E. Aasland.

  • bpo-44801: Ensure that theParamSpec variable in Callablecan only be substituted with a parameters expression (a list of types, anellipsis, ParamSpec or Concatenate).

  • bpo-44806: Non-protocol subclasses oftyping.Protocol ignore nowthe__init__ method inherited from protocol base classes.

  • bpo-27275:collections.OrderedDict.popitem() andcollections.OrderedDict.pop() no longer call__getitem__ and__delitem__ methods of the OrderedDict subclasses.

  • bpo-44793: Fix checking the number of arguments when subscribe a generictype withParamSpec parameter.

  • bpo-44784: In importlib.metadata tests, override warnings behavior underexpected DeprecationWarnings (importlib_metadata 4.6.3).

  • bpo-44667: Thetokenize.tokenize() doesn't incorrectly generate aNEWLINE token if the source doesn't end with a new line character butthe last line is a comment, as the function is already generating aNLtoken. Patch by Pablo Galindo

  • bpo-44771: Addedimportlib.simple module implementing adapters from alow-level resources reader interface to aTraversableResourcesinterface. Legacy API (path,contents, ...) is now supportedentirely by the.files() API with a compatibility shim supplied forresource loaders without that functionality. Feature parity withimportlib_resources 5.2.

  • bpo-44752:rcompleter does not callgetattr() onproperty objects to avoid the side-effect of evaluating thecorresponding method.

  • bpo-44747: Refactor usage ofsys._getframe intyping module. Patchprovided by Yurii Karabas.

  • bpo-42378: Fixes the issue with log file being overwritten whenlogging.FileHandler is used inatexit withfilemode setto'w'. Note this will cause the message inatexit not being loggedif the log stream is already closed due to shutdown of logging.

  • bpo-44720:weakref.proxy objects referencing non-iterators now raiseTypeError rather than dereferencing the nulltp_iternext slot andcrashing.

  • bpo-44704: The implementation ofcollections.abc.Set._hash() nowmatches that offrozenset.__hash__().

  • bpo-44666: Fixed issue incompileall.compile_file() whensys.stdout is redirected. Patch by Stefan Hölzl.

  • bpo-44688:sqlite3.Connection.create_collation() now acceptsnon-ASCII collation names. Patch by Erlend E. Aasland.

  • bpo-44690: Adoptbinacii.a2b_base64's strict mode inbase64.b64decode.

  • bpo-42854: Fixed a bug in the_ssl module that was throwingOverflowError when using_ssl._SSLSocket.write() and_ssl._SSLSocket.read() for a big value of thelen parameter.Patch by Pablo Galindo.

  • bpo-44686: Replaceunittest.mock._importer withpkgutil.resolve_name.

  • bpo-44353: MakeNewType.__call__ faster by implementing it in C. Patchprovided by Yurii Karabas.

  • bpo-44682: Change thepdbcommands directive to disallow settingcommands for an invalid breakpoint and to display an appropriate error.

  • bpo-44353: Refactortyping.NewType from function into callable class.Patch provided by Yurii Karabas.

  • bpo-44678: Added a separate error message for discontinuous padding inbinascii.a2b_base64 strict mode.

  • bpo-44524: Add missing__name__ and__qualname__ attributes totyping module classes. Patch provided by Yurii Karabas.

  • bpo-40897: Give priority to using the current class constructor ininspect.signature(). Patch by Weipeng Hong.

  • bpo-44638: Add a reference to the zipp project and hint as to how to useit.

  • bpo-44648: Fixed wrong error being thrown byinspect.getsource()when examining a class in the interactive session. Instead ofTypeError, it should beOSError with appropriate errormessage.

  • bpo-44608: Fix memory leak in_tkinter._flatten() if it is calledwith a sequence or set, but not list or tuple.

  • bpo-44594: Fix an edge case ofExitStack andAsyncExitStack exception chaining. They will now matchwithblock behavior when__context__ is explicitly set toNone when theexception is in flight.

  • bpo-42799: Infnmatch, the cache size for compiled regex patterns(functools.lru_cache()) was bumped up from 256 to 32768, affectingfunctions:fnmatch.fnmatch(),fnmatch.fnmatchcase(),fnmatch.filter().

  • bpo-41928: Updateshutil.copyfile() to raiseFileNotFoundError instead of confusingIsADirectoryErrorwhen a path ending with aos.path.sep does not exist;shutil.copy() andshutil.copy2() are also affected.

  • bpo-44569: Added theStackSummary.format_frame() function intraceback. This allows users to customize the way individual linesare formatted in tracebacks without re-implementing logic to handlerecursive tracebacks.

  • bpo-44566: handle StopIteration subclass raised from@contextlib.contextmanager generator

  • bpo-44558: Make the implementation consistency ofindexOf() between C and Python versions. Patch by DongheeNa.

  • bpo-41249: FixesTypedDict to work withtyping.get_type_hints()and postponed evaluation of annotations across modules.

  • bpo-44554: Refactor argument processing inpdb.main() to simplifydetection of errors in input loading and clarify behavior around module orscript invocation.

  • bpo-34798: Break up paragraph aboutpprint.PrettyPrinterconstruction parameters to make it easier to read.

  • bpo-44539: Added support for recognizing JPEG files without JFIF or Exifmarkers.

  • bpo-44461: Fix bug withpdb's handling of import error due to apackage which does not have a__main__ module

  • bpo-43625: Fix a bug in the detection of CSV file headers bycsv.Sniffer.has_header() and improve documentation of same.

  • bpo-44516: Update vendored pip to 21.1.3

  • bpo-42892: Fixed an exception thrown while parsing a malformed multipartemail byemail.message.EmailMessage.

  • bpo-44468:typing.get_type_hints() now finds annotations in classesand base classes with unexpected__module__. Previously, it skippedthose MRO elements.

  • bpo-44491: Allow clearing thesqlite3 authorizer callback bypassingNone toset_authorizer(). Patchby Erlend E. Aasland.

  • bpo-43977: Set the properPy_TPFLAGS_MAPPING andPy_TPFLAGS_SEQUENCE flags for subclasses created before aparent has been registered as acollections.abc.Mapping orcollections.abc.Sequence.

  • bpo-44482: Fix very unlikely resource leak inglob in alternatePython implementations.

  • bpo-44466: Thefaulthandler module now detects if a fatal erroroccurs during a garbage collector collection. Patch by Victor Stinner.

  • bpo-44471: ATypeError is now raised instead of anAttributeError incontextlib.ExitStack.enter_context() andcontextlib.AsyncExitStack.enter_async_context() for objects which donot support thecontext manager orasynchronous contextmanager protocols correspondingly.

  • bpo-44404:tkinter'safter() method now supports callableswithout the__name__ attribute.

  • bpo-41546: Makepprint (like the builtinprint) not attempt towrite tostdout when it isNone.

  • bpo-44458:BUFFER_BLOCK_SIZE is now declared static, to avoid linkingcollisions when bz2, lmza or zlib are statically linked.

  • bpo-44464: Remove exception for flake8 in deprecated importlib.metadatainterfaces. Sync with importlib_metadata 4.6.

  • bpo-44446: Take into account thatlineno might beNone intraceback.FrameSummary.

  • bpo-44439: Fix inbz2.BZ2File.write() /lzma.LZMAFile.write()methods, when the input data is an object that supports the bufferprotocol, the file length may be wrong.

  • bpo-44434: _thread.start_new_thread() no longer callsPyThread_exit_thread() explicitly at the thread exit, the call wasredundant. On Linux with the glibc, pthread_exit() aborts the wholeprocess if dlopen() fails to open libgcc_s.so file (ex: EMFILE error).Patch by Victor Stinner.

  • bpo-42972: The _thread.RLock type now fully implement the GC protocol: adda traverse function and thePy_TPFLAGS_HAVE_GC flag. Patch byVictor Stinner.

  • bpo-44422: Thethreading.enumerate() function now uses a reentrantlock to prevent a hang on reentrant call. Patch by Victor Stinner.

  • bpo-38291: Importing typing.io or typing.re now prints aDeprecationWarning.

  • bpo-37880: argparse actions store_const and append_const each receive adefault value ofNone when theconst kwarg is not provided.Previously, this raised aTypeError.

  • bpo-44389: Fix deprecation ofssl.OP_NO_TLSv1_3

  • bpo-27827:pathlib.PureWindowsPath.is_reserved() now identifies agreater range of reserved filenames, including those with trailing spacesor colons.

  • bpo-44395: Fixas_string() to pass unixfromproperly. Patch by Donghee Na.

  • bpo-34266: Handle exceptions from parsing the arg ofpdb'srun/restart command.

  • bpo-44362: Improvessl module's deprecation messages, errorreporting, and documentation for deprecations.

  • bpo-44342: [Enum] Change pickling from by-value to by-name.

  • bpo-44356: [Enum] Allow multiple data-type mixins if they are all thesame.

  • bpo-44351: Restore backparse_makefile() indistutils.sysconfigbecause it behaves differently than the similar implementation insysconfig.

  • bpo-35800:smtpd.MailmanProxy is now removed as it is unusablewithout an external module,mailman. Patch by Donghee Na.

  • bpo-44357: Added a function that returns cube root of the given numbermath.cbrt()

  • bpo-44339: Changemath.pow(±0.0,-math.inf) to returninf insteadof raisingValueError. This brings the special-case handling ofmath.pow into compliance with the IEEE 754 standard.

  • bpo-44242: Remove missing flag check from Enum creation and move into averify decorator.

  • bpo-44246: Inimportlib.metadata, restore compatibility in the resultfromDistribution.entry_points (EntryPoints) to honor expectationsin older implementations and issuing deprecation warnings for these cases:A.EntryPoints objects are once again mutable, allowing forsort() and other list-based mutation operations. Avoid deprecationwarnings by casting to a mutable sequence (e.g.list(dist.entry_points).sort()). B.EntryPoints results once againallow for access by index. To avoid deprecation warnings, cast theresult to a Sequence first (e.g.tuple(dist.entry_points)[0]).

  • bpo-44246: In importlib.metadata.entry_points, de-duplication ofdistributions no longer requires loading the full metadata forPathDistribution objects, improving entry point loading performance by~10x.

  • bpo-43858: Added a function that returns a copy of a dict of logginglevels:logging.getLevelNamesMapping()

  • bpo-44260: Therandom.Random constructor no longer reads systementropy without need.

  • bpo-44254: On Mac, give turtledemo button text a color that works on bothlight or dark background. Programmers cannot control the latter.

  • bpo-44258: Support PEP 515 for Fraction's initialization from string.

  • bpo-44235: Remove deprecated functions in thegettext. Patch byDonghee Na.

  • bpo-38693: Prefer f-strings to.format in importlib.resources.

  • bpo-33693: Importlib.metadata now prefers f-strings to .format.

  • bpo-44241: Incorporate minor tweaks from importlib_metadata 4.1:SimplePath protocol, support for Metadata 2.2.

  • bpo-43216: Remove the@asyncio.coroutinedecorator enabling legacy generator-based coroutines to becompatible with async/await code; removeasyncio.coroutines.CoroWrapper used for wrapping legacy coroutineobjects in the debug mode. The decorator has been deprecated since Python3.8 and the removal was initially scheduled for Python 3.10. Patch byIllia Volochii.

  • bpo-44210: Make importlib.metadata._meta.PackageMetadata public.

  • bpo-43643: Declare readers.MultiplexedPath.name as a property per thespec.

  • bpo-27334: Thesqlite3 context manager now performs a rollback(thus releasing the database lock) if commit failed. Patch by Luca Citiand Erlend E. Aasland.

  • bpo-4928: Documented existing behavior on POSIX: NamedTemporaryFiles arenot deleted when creating process is killed with SIGKILL

  • bpo-44154: Optimizefractions.Fraction pickling for largecomponents.

  • bpo-33433: For IPv4 mapped IPv6 addresses (RFC 4291 Section 2.5.5.2),theipaddress.IPv6Address.is_private check is deferred to themapped IPv4 address. This solves a bug where public mapped IPv4 addresseswere considered private by the IPv6 check.

  • bpo-44150: Add optionalweights argument to statistics.fmean().

  • bpo-44142:ast.unparse() will now drop the redundant parentheseswhen tuples used as assignment targets (e.g in for loops).

  • bpo-44145:hmac computations were not releasing the GIL whilecalling the OpenSSLHMAC_Update C API (a new feature in 3.9). Thisunintentionally prevented parallel computation as otherhashlibalgorithms support.

  • bpo-44095:zipfile.Path now supportszipfile.Path.stem,zipfile.Path.suffixes, andzipfile.Path.suffix attributes.

  • bpo-44077: It's now possible to receive the type of service (ToS), a.k.a.differentiated services (DS), a.k.a. differentiated services code point(DSCP) and explicit congestion notification (ECN) IP header fields withsocket.IP_RECVTOS.

  • bpo-37788: Fix a reference leak when a Thread object is never joined.

  • bpo-38908: Subclasses oftyping.Protocol which only have datavariables declared will now raise aTypeError when checked withisinstance unless they are decorated withruntime_checkable().Previously, these checks passed silently. Patch provided by Yurii Karabas.

  • bpo-44098:typing.ParamSpec will no longer be found in the__parameters__ of mosttyping generics except in valid uselocations specified byPEP 612. This prevents incorrect usage liketyping.List[P][int]. This change means incorrect usage which may havepassed silently in 3.10 beta 1 and earlier will now error.

  • bpo-44089: Allow subclassingcsv.Error in 3.10 (it was allowed in 3.9and earlier but was disallowed in early versions of 3.10).

  • bpo-44081:ast.unparse() now doesn't use redundant spaces toseparatelambda and the: if there are no parameters.

  • bpo-44061: Fix regression in previous release when callingpkgutil.iter_modules() with a list ofpathlib.Path objects

  • bpo-44059: Register the SerenityOS Browser in thewebbrowsermodule.

  • bpo-36515: Thehashlib module no longer does unaligned memoryaccesses when compiled for ARM platforms.

  • bpo-40465: Remove random module features deprecated in Python 3.9.

  • bpo-44018: random.seed() no longer mutates bytearray inputs.

  • bpo-38352: AddIO,BinaryIO,TextIO,Match, andPattern totyping.__all__. Patch by Jelle Zijlstra.

  • bpo-44002:urllib.parse now usesfunctool.lru_cache() for itsinternal URL splitting and quoting caches instead of rolling its own likeits the '90s.

    The undocumented internalurllib.parseQuoted class API is nowdeprecated, for removal in 3.14.

  • bpo-43972: Whenhttp.server.SimpleHTTPRequestHandler sends a301(MovedPermanently) for a directory path not ending with/,add aContent-Length:0 header. This improves the behavior for certainclients.

  • bpo-28528: Fix a bug inpdb wherecheckline() raisesAttributeError if it is called afterreset().

  • bpo-43853: Improved string handling forsqlite3 user-definedfunctions and aggregates:

    • It is now possible to pass strings with embedded null characters to UDFs

    • Conversion failures now correctly raiseMemoryError

    Patch by Erlend E. Aasland.

  • bpo-43666: AIX:Lib/_aix_support.get_platform() may fail in an AIXWPAR. The fileset bos.rte appears to have a builddate in both LPAR andWPAR so this fileset is queried rather than bos.mp64. To prevent a similarsituation (no builddate in ODM) a value (9988) sufficient for completing abuild is provided. Patch by M Felt.

  • bpo-43650: FixMemoryError inshutil.unpack_archive() whichfails insideshutil._unpack_zipfile() on large files. Patch by IgorBolshakov.

  • bpo-43612:zlib.compress() now accepts a wbits parameter whichallows users to compress data as a raw deflate block without zlib headersand trailers in one go. Previously this required instantiating azlib.compressobj. It also provides a faster alternative togzip.compress when wbits=31 is used.

  • bpo-43392:importlib._bootstrap._find_and_load() now implements atwo-step check to avoid locking when modules have been already importedand are ready. This improves performance of repeated calls toimportlib.import_module() andimportlib.__import__().

  • bpo-43318: Fix a bug wherepdb does not always echo clearedbreakpoints.

  • bpo-43234: Prohibit passingnon-concurrent.futures.ThreadPoolExecutor executors toloop.set_default_executor() following a deprecation in Python 3.8.Patch by Illia Volochii.

  • bpo-43232: Prohibit previously deprecated potentially disruptiveoperations onasyncio.trsock.TransportSocket. Patch by IlliaVolochii.

  • bpo-30077: Added support for Apple's aifc/sowt pseudo-compression

  • bpo-42971: Add definition oferrno.EQFULL for platforms that definethis constant (such as macOS).

  • bpo-43086: Added a new optionalstrict_mode parameter tobinascii.a2b_base64. Whenscrict_mode is set toTrue,thea2b_base64 function will accept only valid base64 content. Moredetails about what "valid base64 content" is, can be found in thefunction's documentation.

  • bpo-43024: Improve the help signature oftraceback.print_exception(),traceback.format_exception() andtraceback.format_exception_only().

  • bpo-33809: Add thetraceback.TracebackException.print() method whichprints the formatted exception information.

  • bpo-42862:sqlite3 now utilizesfunctools.lru_cache() toimplement the connection statement cache. As a small optimisation, thedefault statement cache size has been increased from 100 to 128. Patch byErlend E. Aasland.

  • bpo-41818: Soumendra Ganguly: add termios.tcgetwinsize(),termios.tcsetwinsize().

  • bpo-40497:subprocess.check_output() now raisesValueErrorwhen the invalid keyword argumentcheck is passed by user code.Previously such use would fail later with aTypeError. Patch byRémi Lapeyre.

  • bpo-37449:ensurepip now usesimportlib.resources.files()traversable APIs

  • bpo-40956: Use Argument Clinic insqlite3. Patches by Erlend E.Aasland.

  • bpo-41730:DeprecationWarning is now raised when importingtkinter.tix, which has been deprecated in documentation sincePython 3.6.

  • bpo-20684: Remove unused_signature_get_bound_param function frominspect - by Anthony Sottile.

  • bpo-41402: Fixemail.message.EmailMessage.set_content() when calledwith binary data and7bit content transfer encoding.

  • bpo-32695: Thecompresslevel andpreset keyword arguments oftarfile.open() are now both documented and tested.

  • bpo-41137: Use utf-8 encoding while reading .pdbrc files. Patch bySrinivas Reddy Thatiparthy

  • bpo-24391: Improved reprs ofthreading synchronization objects:Semaphore,BoundedSemaphore,Event andBarrier.

  • bpo-5846: Deprecated the followingunittest functions, scheduledfor removal in Python 3.13:

    • findTestCases()

    • makeSuite()

    • getTestCaseNames()

    UseTestLoader methods instead:

    Patch by Erlend E. Aasland.

  • bpo-40563: Support pathlike objects on dbm/shelve. Patch by Hakan Çelikand Henry-Joseph Audéoud.

  • bpo-34990: Fixed a Y2k38 bug in the compileall module where it would failto compile files with a modification time after the year 2038.

  • bpo-39549: Whereas the code for reprlib.Repr had previously used ahardcoded string value of '...', this PR updates it to use of a“fillvalue” attribute, whose value defaults to '...' and can be reset ineither individual reprlib.Repr instances or in subclasses thereof.

  • bpo-37022:pdb now displays exceptions fromrepr() with itsp andpp commands.

  • bpo-38840: Fixtest___all__ on platforms lacking a shared memoryimplementation.

  • bpo-39359: Add one missing check that the password is a bytes object foran encrypted zipfile.

  • bpo-38741:configparser: using ']' inside a section header will nolonger cut the section name short at the ']'

  • bpo-38415: Added missing behavior tocontextlib.asynccontextmanager() to matchcontextlib.contextmanager() so decorated functions can themselves bedecorators.

  • bpo-30256: Pass multiprocessing BaseProxy argumentmanager_ownedthrough AutoProxy.

  • bpo-27513:email.utils.getaddresses() now acceptsemail.header.Header objects along with string values. Patch byZackery Spytz.

  • bpo-16379: Add SQLite error code and name tosqlite3 exceptions.Patch by Aviv Palivoda, Daniel Shahaf, and Erlend E. Aasland.

  • bpo-26228: pty.spawn no longer hangs on FreeBSD, macOS, and Solaris.

  • bpo-33349: lib2to3 now recognizes async generators everywhere.

  • bpo-29298: FixTypeError when required subparsers withoutdest donot receive arguments. Patch by Anthony Sottile.

Documentation

  • bpo-45216: Remove extra documentation listing methods indifflib. Itwas rendering twice in pydoc and was outdated in some places.

  • bpo-45024:collections.abc documentation has been expanded toexplicitly cover how instance and subclass checks work, with additionaldoctest examples and an exhaustive list of ABCs which test membershippurely by presence of the rightspecial methods. Patch by RaymondHettinger.

  • bpo-44957: Promote PEP 604 union syntax by using it where possible. Also,mentionX|Y more prominently in section aboutUnion and mentionX|None at all in section aboutOptional.

  • bpo-16580: Added code equivalents for theint.to_bytes() andint.from_bytes() methods, as well as tests ensuring that these codeequivalents are valid.

  • bpo-44903: Removed theothergui.rst file, any references to it, andthe list of GUI frameworks in the FAQ. In their place I've added links tothe Python Wikipage on GUI frameworks.

  • bpo-33479: Tkinter documentation has been greatly expanded with new"Architecture" and "Threading model" sections.

  • bpo-36700:base64 RFC references were updated to point toRFC 4648; a section was added to point users to the new "securityconsiderations" section of the RFC.

  • bpo-44740: Replaced occurrences of uppercase "Web" and "Internet" withlowercase versions per the 2016 revised Associated Press Style Book.

  • bpo-44693: Update the definition of __future__ in the glossary byreplacing the confusing word "pseudo-module" with a more accuratedescription.

  • bpo-35183: Add typical examples to os.path.splitext docs

  • bpo-30511: Clarify thatshutil.make_archive() is not thread-safe dueto reliance on changing the current working directory.

  • bpo-44561: Update of three expired hyperlinks inDoc/distributing/index.rst: "Project structure", "Building and packagingthe project", and "Uploading the project to the Python Packaging Index".

  • bpo-44651: Delete entry "coercion" in Doc/glossary.rst for its outdateddefinition.

  • bpo-42958: Updated the docstring and docs offilecmp.cmp() to bemore accurate and less confusing especially in respect toshallow arg.

  • bpo-44631: Refactored therepr() code of the_Environ (os module).

  • bpo-44613: importlib.metadata is no longer provisional.

  • bpo-44558: Match the docstring and python implementation ofcountOf() to the behavior of its c implementation.

  • bpo-44544: List all kwargs fortextwrap.wrap(),textwrap.fill(), andtextwrap.shorten(). Now, there are navlinks to attributes ofTextWrap, which makes navigation mucheasier while minimizing duplication in the documentation.

  • bpo-38062: Clarify that atexit uses equality comparisons internally.

  • bpo-40620: Convert examples in tutorial controlflow.rst section 4.3 to beinterpreter-demo style.

  • bpo-43066: Added a warning tozipfile docs: filename arg with aleading slash may cause archive to be un-openable on Windows systems.

  • bpo-39452: RewroteDoc/library/__main__.rst. Broadened scope of thedocument to explicitly discuss and differentiate between__main__.pyin packages versus the__name__=='__main__' expression (and theidioms that surround it).

  • bpo-13814: In the Design FAQ, answer "Why don't generators support thewith statement?"

  • bpo-27752: Documentation of csv.Dialect is more descriptive.

  • bpo-44453: Fix documentation for the return type ofsysconfig.get_path().

  • bpo-44392: Added a new section in the C API documentation for types usedin type hinting. DocumentedPy_GenericAlias andPy_GenericAliasType.

  • bpo-38291: Marktyping.io andtyping.re as deprecated since Python3.8 in the documentation. They were never properly supported by typecheckers.

  • bpo-44322: Document that SyntaxError args have a details tuple and thatdetails are adjusted for errors in f-string field replacement expressions.

  • bpo-42392: Document the deprecation and removal of theloop parameterfor many functions and classes inasyncio.

  • bpo-44195: Corrected references toTraversableResources in docs. Thereis noTraversableReader.

  • bpo-41963: Document thatConfigParser strips off comments when readingconfiguration files.

  • bpo-44072: Correct where in the numeric ABC hierarchy** support isadded, i.e., in numbers.Complex, not numbers.Integral.

  • bpo-43558: Add the remark todataclasses documentation that the__init__() of any base class has to be called in__post_init__(), along with a code example.

  • bpo-44025: Clarify when '_' in match statements is a keyword, and whennot.

  • bpo-41706: Fix docs about how methods like__add__ are invoked whenevaluating operator expressions.

  • bpo-41621: Document thatcollections.defaultdict parameterdefault_factory defaults toNone and is positional-only.

  • bpo-41576: document BaseException in favor of bare except

  • bpo-21760: The description for __file__ fixed. Patch by Furkan Onder

  • bpo-39498: Add a "Security Considerations" index which links to standardlibrary modules that have explicitly documented security considerations.

  • bpo-33479: Remove the unqualified claim that tkinter is threadsafe. It hasnot been true for several years and likely never was. An explanation ofwhat is true may be added later, after more discussion, and possibly afterpatching _tkinter.c,

Tests

  • bpo-40173: Fixtest.support.import_helper.import_fresh_module().

  • bpo-45280: Add a test case for emptytyping.NamedTuple.

  • bpo-45269: Cover case when invalidmarkers type is supplied toc_make_encoder.

  • bpo-45128: Fixtest_multiprocessing_fork failure due totest_logging andsys.modules manipulation.

  • bpo-45209: FixUserWarning:resource_tracker warning in_test_multiprocessing._TestSharedMemory.test_shared_memory_cleaned_after_process_termination

  • bpo-45185: EnablesTestEnumerations test cases intest_ssl suite.

  • bpo-45195: Fix test_readline.test_nonascii(): sometimes, the newlinecharacter is not written at the end, so don't expect it in the output.Patch by Victor Stinner.

  • bpo-45156: Fixes infinite loop onunittest.mock.seal() of mockscreated bycreate_autospec().

  • bpo-45125: Improves pickling tests and docs ofSharedMemory andSharableList objects.

  • bpo-44860: Updatetest_sysconfig.test_user_similar() for theposix_user scheme:platlib doesn't usesys.platlibdir. Patchby Victor Stinner.

  • bpo-45052:WithProcessesTestSharedMemory.test_shared_memory_basicstest was ignored, becauseself.assertEqual(sms.size,sms2.size) linewas failing. It is now removed and test is unskipped.

    The main motivation for this line to be removed from the test is that thesize ofSharedMemory is not ever guaranteed to be the same. It isdecided by the platform.

  • bpo-44895: libregrtest now clears the type cache later to reduce the riskof false alarm when checking for reference leaks. Previously, the typecache was cleared too early and libregrtest raised a false alarm aboutreference leaks under very specific conditions. Patch by Irit Katriel andVictor Stinner.

  • bpo-45042: Fixes that test classes decorated with@hashlib_helper.requires_hashdigest were skipped all the time.

  • bpo-25130: Add calls ofgc.collect() in tests to support PyPy.

  • bpo-45011: Made tests relying on the_asyncio C extension moduleoptional to allow running on alternative Python implementations. Patch bySerhiy Storchaka.

  • bpo-44949: Fix auto history tests of test_readline: sometimes, the newlinecharacter is not written at the end, so don't expect it in the output.

  • bpo-44891: Tests were added to clarifyid() is preserved whenobj*1 is used onstr andbytes objects. Patch by NikitaSobolev.

  • bpo-44852: Add ability to wholesale silence DeprecationWarnings whilerunning the regression test suite.

  • bpo-40928: Notify users running test_decimal regression tests on macOS ofpotential harmless "malloc can't allocate region" messages spewed bytest_decimal.

  • bpo-44734: Fixed floating-point precision issue in turtle tests.

  • bpo-44708: Regression tests, when run with -w, are now re-running only theaffected test methods instead of re-running the entire test file.

  • bpo-42095: Added interop tests for Apple plists: generate plist files withPython plistlib and parse with Apple plutil; and the other way round.

  • bpo-44647: Added a permanent Unicode-valued environment variable toregression tests to ensure they handle this use case in the future. Ifyour test environment breaks because of that, report a bug to us, andtemporarily set PYTHONREGRTEST_UNICODE_GUARD=0 in your test environment.

  • bpo-44515: Adjust recently added contextlib tests to avoid assuming theuse of a refcounted GC

  • bpo-44287: Fix asyncio test_popen() of test_windows_utils by using alonger timeout. Use military grade battle-testedtest.support.SHORT_TIMEOUT timeout rather than a hardcoded timeoutof 10 seconds: it's 30 seconds by default, but it is made longer on slowbuildbots. Patch by Victor Stinner.

  • bpo-44451: ResetDeprecationWarning filters intest.test_importlib.test_metadata_api.APITests.test_entry_points_by_indexto avoidStopIteration error ifDeprecationWarnings are ignored.

  • bpo-44363: Account for address sanitizer in test_capi. test_capi nowpasses when run GCC address sanitizer.

  • bpo-44364: Add non integral tests formath.sqrt() function.

  • bpo-43921: Fix test_ssl.test_wrong_cert_tls13(): usesuppress_ragged_eofs=False, sinceread() can raisessl.SSLEOFError on Windows. Patch by Victor Stinner.

  • bpo-43921: Fix test_pha_required_nocert() of test_ssl: catch two more EOFcases (when therecv() method returns an empty string). Patch byVictor Stinner.

  • bpo-44131: Add test_frozenmain to test_embed to test thePy_FrozenMain() C function. Patch by Victor Stinner.

  • bpo-31904: Ignore error string case in test_file_not_exists().

  • bpo-42083: Add test to check thatPyStructSequence_NewType accepts aPyStructSequence_Desc withdoc field set toNULL.

  • bpo-35753: Fix crash in doctest when doctest parses modules that includeunwrappable functions by skipping those functions.

  • bpo-30256: Add test for nested queues when usingmultiprocessingshared objectsAutoProxy[Queue] insideListProxy andDictProxy

Build

  • bpo-45220: Avoid building with the Windows 11 SDK previews automatically.This may be overridden by setting theDefaultWindowsSDKVersionenvironment variable before building.

  • bpo-45020: Freeze stdlib modules that are imported during startup. Thisprovides significant performance improvements to startup. If necessary,use the previously added "-X frozen_modules=off" commandline option toforce importing the source modules.

  • bpo-45188: Windows builds now regenerate frozen modules as the first partof the build. Previously the regeneration was later in the build, whichwould require it to be restarted if any modules had changed.

  • bpo-45163: Fixes Haiku platform build.

  • bpo-45067: The ncurses function extended_color_content was introduced in2017

    (https://invisible-island.net/ncurses/NEWS.html#index-t20170401). The

    ncurses-devel package in CentOS 7 had a older version ncurses resulted incompilation error. For compiling ncurses with extended color support, weverify the version of the ncurses library >= 20170401.

  • bpo-45019: Generate lines in relevant files for frozen modules. Up untilnow each of the files had to be edited manually. This change makes iteasier to add to and modify the frozen modules.

  • bpo-44340: Add support for building with clang thin lto via--with-lto=thin/full. Patch by Donghee Na and Brett Holman.

  • bpo-44535: Enable building using a Visual Studio 2022 install on Windows.

  • bpo-43298: Improved error message when building without a Windows SDKinstalled.

  • bpo-44381: The Windows build now acceptsEnableControlFlowGuardset toguard to enable CFG.

  • bpo-41282: Fix brokenmakeinstall that caused standard libraryextension modules to be unnecessarily and incorrectly rebuilt during theinstall phase of cpython.

Windows

macOS

  • bpo-45007: Update macOS installer builds to use OpenSSL 1.1.1l.

  • bpo-34602: When building CPython on macOS with./configure--with-undefined-behavior-sanitizer--with-pydebug, the stack size isnow quadrupled to allow for the entire test suite to pass.

  • bpo-44848: Update macOS installer to use SQLite 3.36.0.

  • bpo-44689:ctypes.util.find_library() now works correctly on macOS11 Big Sur even if Python is built on an older version of macOS.Previously, when built on older macOS systems,find_library was notable to find macOS system libraries when running on Big Sur due tochanges in how system libraries are stored.

  • bpo-41972: The framework build's user header path in sysconfig is changedto add a 'pythonX.Y' component to match distutils's behavior.

  • bpo-43109: Allow --with-lto configure option to work with Apple-suppliedXcode or Command Line Tools.

  • bpo-34932: Add socket.TCP_KEEPALIVE support for macOS. Patch by ShaneHarvey.

IDLE

  • bpo-45296: On Windows, change exit/quit message to suggest Ctrl-D, whichworks, instead of <Ctrl-Z Return>, which does not work in IDLE.

  • bpo-45193: Make completion boxes appear on Ubuntu again.

  • bpo-40128: Mostly fix completions on macOS when not using tcl/tk 8.6.11(as with 3.9). The added update_idletask call should be harmless andpossibly helpful otherwise.

  • bpo-33962: Move the indent space setting from the Font tab to the newWindows tab. Patch by Mark Roseman and Terry Jan Reedy.

  • bpo-40468: Split the settings dialog General tab into Windows and Shell/EDtabs. Move help sources, which extend the Help menu, to the Extensionstab. Make space for new options and shorten the dialog. The latter makesthe dialog better fit small screens.

  • bpo-41611: Avoid uncaught exceptions inAutoCompleteWindow.winconfig_event().

  • bpo-41611: Fix IDLE sometimes freezing upon tab-completion on macOS.

  • bpo-44010: Highlight the newmatch statement'ssoftkeywords:match,case, and_. However, this highlighting is notperfect and will be incorrect in some rare cases, including some_-sincase patterns.

  • bpo-44026: Include interpreter's typo fix suggestions in message line forNameErrors and AttributeErrors. Patch by E. Paine.

Tools/Demos

  • bpo-44786: Fix a warning in regular expression in the c-analyzer script.

  • bpo-44967: pydoc now returns a non-zero status code when a module cannotbe found.

  • bpo-44978: Allow the Argument Clinic tool to handle__complex__special methods.

  • bpo-43425: Removed the 'test2to3' demo project that demonstrated usinglib2to3 to support Python 2.x and Python 3.x from a single source in adistutils package. Patch by Donghee Na

  • bpo-44074: Make patchcheck automatically detect the correct base branchname (previously it was hardcoded to 'master')

  • bpo-20291: Added support for variadic positional parameters in ArgumentClinic.

C API

  • bpo-41710: The PyThread_acquire_lock_timed() function now clamps thetimeout if it is too large, rather than aborting the process. Patch byVictor Stinner.

  • bpo-44687:BufferedReader.peek() no longer raisesValueErrorwhen the entire file has already been buffered.

  • bpo-45116: Add thePy_ALWAYS_INLINE macro to ask the compilerto always inline a static inline function. The compiler can ignore it anddecides to not inline the function. Patch by Victor Stinner.

  • bpo-45094: Add thePy_NO_INLINE macro to disable inlining on afunction. Patch by Victor Stinner.

  • bpo-45061: Add a deallocator to thebool type to detect refcountbugs in C extensions which callPy_DECREF(Py_True); orPy_DECREF(Py_False); by mistake. Patch by Victor Stinner.

  • bpo-42035: Add a newPyType_GetQualName() function to get type'squalified name.

  • bpo-41103: Reverts removal of the old buffer protocol because they arepart of stable ABI.

  • bpo-44751: Removecrypt.h include from the publicPython.h header.

  • bpo-42747: ThePy_TPFLAGS_HAVE_VERSION_TAG type flag now does nothing.ThePy_TPFLAGS_HAVE_AM_SEND flag (which was added in 3.10) is removed.Both were unnecessary because it is not possible to have type objects withthe relevant fields missing.

  • bpo-44530: Added theco_qualname to thePyCodeObject structure topropagate the qualified name from the compiler to code objects.

    Patch by Gabriele N. Tornetta

  • bpo-44441:Py_RunMain() now resetsPyImport_Inittab toits initial value at exit. It must be possible to callPyImport_AppendInittab() orPyImport_ExtendInittab() ateach Python initialization. Patch by Victor Stinner.

  • bpo-39947: Remove 4 private trashcan C API functions which were only keptfor the backward compatibility of the stable ABI with Python 3.8 andolder, since the trashcan API was not usable with the limited C API onPython 3.8 and older. The trashcan API was excluded from the limited C APIin Python 3.9.

    Removed functions:

    • _PyTrash_deposit_object()

    • _PyTrash_destroy_chain()

    • _PyTrash_thread_deposit_object()

    • _PyTrash_thread_destroy_chain()

    The trashcan C API was never usable with the limited C API, since oldtrashcan macros accessed directlyPyThreadState members like_tstate->trash_delete_nesting, whereas thePyThreadStatestructure is opaque in the limited C API.

    Exclude also thePyTrash_UNWIND_LEVEL constant from the C API.

    Patch by Victor Stinner.

  • bpo-40939: Removed documentation for the removedPyParser_* C API.

  • bpo-43795: The list in受限 API 的內容 now shows the public namePyFrameObject rather than_frame. The non-existing entry_node no longer appears in the list.

  • bpo-44378:Py_IS_TYPE() no longer usesPy_TYPE() to avoida compiler warning: no longer castconstPyObject* toPyObject*.Patch by Victor Stinner.

  • bpo-39573: Convert thePy_TYPE() andPy_SIZE() macros tostatic inline functions. ThePy_SET_TYPE() andPy_SET_SIZE() functions must now be used to set an object type andsize. Patch by Victor Stinner.

  • bpo-44263: ThePyType_Ready() function now raises an error if atype is defined with thePy_TPFLAGS_HAVE_GC flag set but has notraverse function (PyTypeObject.tp_traverse). Patch by VictorStinner.

  • bpo-43795: The undocumented functionPy_FrozenMain() is removedfrom the Limited API.

  • bpo-44113: Deprecate the following functions to configure the Pythoninitialization:

    • PySys_AddWarnOptionUnicode()

    • PySys_AddWarnOption()

    • PySys_AddXOption()

    • PySys_HasWarnOptions()

    • Py_SetPath()

    • Py_SetProgramName()

    • Py_SetPythonHome()

    • Py_SetStandardStreamEncoding()

    • _Py_SetProgramFullPath()

    Use the newPyConfig API of thePython InitializationConfiguration instead (PEP 587).

  • bpo-44094: RemovePyErr_SetFromErrnoWithUnicodeFilename(),PyErr_SetFromWindowsErrWithUnicodeFilename(), andPyErr_SetExcFromWindowsErrWithUnicodeFilename(). They are notdocumented and have been deprecated since Python 3.3.

  • bpo-43795:PyCodec_Unregister() is now properly exported as afunction in the Windows Stable ABI DLL.

  • bpo-44029: Remove deprecatedPy_UNICODE APIs:PyUnicode_Encode,PyUnicode_EncodeUTF7,PyUnicode_EncodeUTF8,PyUnicode_EncodeUTF16,PyUnicode_EncodeUTF32,PyUnicode_EncodeLatin1,PyUnicode_EncodeMBCS,PyUnicode_EncodeDecimal,PyUnicode_EncodeRawUnicodeEscape,PyUnicode_EncodeCharmap,PyUnicode_EncodeUnicodeEscape,PyUnicode_TransformDecimalToASCII,PyUnicode_TranslateCharmap,PyUnicodeEncodeError_Create,PyUnicodeTranslateError_Create. SeePEP 393 andPEP 624 for reference.

  • bpo-42035: Add a newPyType_GetName() function to get type's shortname.

Python 3.10.0 beta 1

Release date: 2021-05-03

Security

  • bpo-43434: Creatingsqlite3.Connection objects now also producessqlite3.connect andsqlite3.connect/handleauditing events. Previously these events were only produced bysqlite3.connect() calls. Patch by Erlend E. Aasland.

  • bpo-43998: Thessl module sets more secure cipher suites defaults.Ciphers without forward secrecy and with SHA-1 MAC are disabled bydefault. Security level 2 prohibits weak RSA, DH, and ECC keys with lessthan 112 bits of security.SSLContext defaults to minimumprotocol version TLS 1.2. Settings are based on Hynek Schlawack'sresearch.

  • bpo-43882: The presence of newline or tab characters in parts of a URLcould allow some forms of attacks.

    Following the controlling specification for URLs defined by WHATWGurllib.parse() now removes ASCII newlines and tabs from URLs,preventing such attacks.

  • bpo-43472: Ensures interpreter-level audit hooks receive thecpython.PyInterpreterState_New event when called through the_xxsubinterpreters module.

  • bpo-43362: Fix invalid free in _sha3 module. The issue was introduced in3.10.0a1. Python 3.9 and earlier are not affected.

  • bpo-43762: Add audit events forsqlite3.connect/handle(),sqlite3.Connection.enable_load_extension(), andsqlite3.Connection.load_extension(). Patch by Erlend E. Aasland.

  • bpo-43756: Add new audit eventglob.glob/2 to incorporate the newroot_dir anddir_fd arguments added toglob.glob() andglob.iglob().

  • bpo-36384:ipaddress module no longer accepts any leading zeros inIPv4 address strings. Leading zeros are ambiguous and interpreted as octalnotation by some libraries. For example the legacy functionsocket.inet_aton() treats leading zeros as octal notation. glibcimplementation of moderninet_pton() does not accept anyleading zeros. For a while theipaddress module used to acceptambiguous leading zeros.

  • bpo-43075: Fix Regular Expression Denial of Service (ReDoS) vulnerabilityinurllib.request.AbstractBasicAuthHandler. The ReDoS-vulnerableregex has quadratic worst-case complexity and it allows cause a denial ofservice when identifying crafted invalid RFCs. This ReDoS issue is on theclient side and needs remote attackers to control the HTTP server.

  • bpo-42800: Audit hooks are now fired for frame.f_code, traceback.tb_frame,and generator code/frame attribute access.

  • bpo-37363: Add audit events to thehttp.client module.

Core and Builtins

  • bpo-43977: Prevent classes being both a sequence and a mapping whenpattern matching.

  • bpo-43977: Usetp_flags on the class object todetermine if the subject is a sequence or mapping when pattern matching.Avoids the need to importcollections.abc when pattern matching.

  • bpo-43892: Restore proper validation of complex literal value patternswhen parsingmatch blocks.

  • bpo-43933: Set frame.f_lineno to the line number of the 'with' kweywordwhen executing the call to__exit__.

  • bpo-43933: If the current position in a frame has no line number then setthe f_lineno attribute to None, instead of -1, to conform to PEP 626. Thisshould not normally be possible, but might occur in some unusualcircumstances.

  • bpo-43963: Importing the_signal module in a subinterpreter has nolonger side effects.

  • bpo-42739: The internal representation of line number tables is changed tonot use sentinels, and an explicit length parameter is added to the out ofprocess API functionPyLineTable_InitAddressRange. This makes thehandling of line number tables more robust in some circumstances.

  • bpo-43908: Makere types immutable. Patch by Erlend E. Aasland.

  • bpo-43908: Make thearray.array type immutable. Patch by ErlendE. Aasland.

  • bpo-43901: Change class and module objects to lazy-create emptyannotations dicts on demand. The annotations dicts are stored in theobject's __dict__ for backwards compatibility.

  • bpo-43892: Match patterns now use new dedicated AST nodes (MatchValue,MatchSingleton,MatchSequence,MatchStar,MatchMapping,MatchClass) rather than reusing expression AST nodes.MatchAs andMatchOr are now defined as pattern nodes rather than as expressionnodes. Patch by Nick Coghlan.

  • bpo-42725: Usage ofawait/yield/yieldfrom and namedexpressions within an annotation is now forbidden when PEP 563 isactivated.

  • bpo-43754: When performing structural pattern matching (PEP 634),captured names are now left unbound until theentire pattern has matchedsuccessfully.

  • bpo-42737: Annotations for complex targets (everything beside simplenames) no longer cause any runtime effects withfrom__future__importannotations.

  • bpo-43914:SyntaxError exceptions raised by the interpreter willhighlight the full error range of the expression that constitutes thesyntax error itself, instead of just where the problem is detected. Patchby Pablo Galindo.

  • bpo-38605: Revert makingfrom__future__importannotations thedefault. This follows the Steering Council decision to postpone PEP 563changes to at least Python 3.11. See the original email for moreinformation regarding the decision:https://mail.python.org/archives/list/python-dev@python.org/thread/CLVXXPQ2T2LQ5MP2Y53VVQFCXYWQJHKZ/.Patch by Pablo Galindo.

  • bpo-43475: Hashes of NaN values now depend on object identity. Formerly,they always hashed to 0 even though NaN values are not equal to oneanother. Having the same hash for unequal values caused pile-ups in hashtables.

  • bpo-43859: Improve the error message forIndentationErrorexceptions. Patch by Pablo Galindo

  • bpo-41323: Constant tuple folding in bytecode optimizer now reuses tuplein constant table.

  • bpo-43846: Data stack usage is much reduced for large literal and callexpressions.

  • bpo-38530: When printingNameError raised by the interpreter,PyErr_Display() will offer suggestions of similar variable namesin the function that the exception was raised from. Patch by Pablo Galindo

  • bpo-43823: Improve syntax errors for invalid dictionary literals. Patch byPablo Galindo.

  • bpo-43822: Improve syntax errors in the parser for missing commas betweenexpressions. Patch by Pablo Galindo.

  • bpo-43798:ast.alias nodes now include source location metadataattributes e.g. lineno, col_offset.

  • bpo-43797: ImproveSyntaxError error messages for invalid comparisons.Patch by Pablo Galindo.

  • bpo-43760: Move the flag for checking whether tracing is enabled to the Cstack, from the heap. Should speed up dispatch in the interpreter.

  • bpo-43682: Static methods (@staticmethod) and classmethods (@classmethod) now inherit the methodattributes (__module__,__name__,__qualname__,__doc__,__annotations__) and have a new__wrapped__ attribute. Patch byVictor Stinner.

  • bpo-43751: Fixed a bug whereanext(ait,default) would erroneouslyreturn None.

  • bpo-42128:__match_args__ is no longer allowed to be alist.

  • bpo-43683: Add GEN_START opcode. Marks start of generator, includingasync, or coroutine and handles sending values to a newly createdgenerator or coroutine.

  • bpo-43105: Importlib now resolves relative paths when creating module specobjects from file locations.

  • bpo-43682: Static methods (@staticmethod) are nowcallable as regular functions. Patch by Victor Stinner.

  • bpo-42609: Prevented crashes in the AST validator and optimizer whencompiling some absurdly long expressions like"+0"*1000000.RecursionError is now raised instead.

  • bpo-38530: When printingAttributeError,PyErr_Display()will offer suggestions of similar attribute names in the object that theexception was raised from. Patch by Pablo Galindo

Library

  • bpo-44015: In @dataclass(), raise a TypeError if KW_ONLY is specified morethan once.

  • bpo-25478: Added atotal() method to collections.Counter() to computethe sum of the counts.

  • bpo-43733: Changenetrc.netrc to use UTF-8 encoding before usinglocale encoding.

  • bpo-43979: Removed an unnecessary list comprehension before looping fromurllib.parse.parse_qsl(). Patch by Christoph Zwerschke and DongheeNa.

  • bpo-43993: Update bundled pip to 21.1.1.

  • bpo-43957: [Enum] DeprecateTypeError when non-member is used in acontainment check; In 3.12True orFalse will be returned instead,and containment will returnTrue if the value is either a member ofthat enum or one of its members' value.

  • bpo-42904: For backwards compatibility with previous minor versions ofPython, iftyping.get_type_hints() receives no namespace dictionaryarguments,typing.get_type_hints() will search through the globalthen local namespaces during evaluation of stringized type annotations(string forward references) inside a class.

  • bpo-43945: [Enum] Deprecate non-standard mixin format() behavior: in 3.12the enum member, not the member's value, will be used for format() calls.

  • bpo-41139: Deprecate undocumentedcgi.log() API.

  • bpo-43937: Fixed theturtle module working with non-default rootwindow.

  • bpo-43930: Update bundled pip to 21.1 and setuptools to 56.0.0

  • bpo-43907: Fix a bug in the pure-Python pickle implementation when usingprotocol 5, where bytearray instances that occur several time in thepickled object graph would incorrectly unpickle into repeated copies ofthe bytearray object.

  • bpo-43926: Inimportlib.metadata, provide a uniform interface toDescription, allow for any field to be encoded with multiline values,remove continuation lines from multiline values, and add a.jsonproperty for easy access to the PEP 566 JSON-compatible form. Sync withimportlib_metadata4.0.

  • bpo-43920: OpenSSL 3.0.0:load_verify_locations()now returns a consistent error message when cadata contains no validcertificate.

  • bpo-43607:urllib can now convert Windows paths with\\?\prefixes into URL paths.

  • bpo-43817: Addinspect.get_annotations(), which safely computes theannotations defined on an object. It works around the quirks of accessingthe annotations from various types of objects, and makes very fewassumptions about the object passed in.inspect.get_annotations()can also correctly un-stringize stringized annotations.

    inspect.signature(),inspect.from_callable(), andinspect.from_function() now callinspect.get_annotations() toretrieve annotations. This meansinspect.signature() andinspect.from_callable() can now un-stringize stringized annotations,too.

  • bpo-43284: platform.win32_ver derives the windows version fromsys.getwindowsversion().platform_version which in turn derives the versionfrom kernel32.dll (which can be of a different version than Windowsitself). Therefore change the platform.win32_ver to determine the versionusing the platform module's _syscmd_ver private function to return anaccurate version.

  • bpo-42854: Thessl module now usesSSL_read_ex andSSL_write_ex internally. The functions support reading and writing ofdata larger than 2 GB. Writing zero-length data no longer fails with aprotocol violation error.

  • bpo-42333: Port_ssl extension module to multiphase initialization.

  • bpo-43880:ssl now raises DeprecationWarning for OP_NO_SSL/TLS*options, old TLS versions, old protocols, and other features that havebeen deprecated since Python 3.6, 3.7, or OpenSSL 1.1.0.

  • bpo-41559:PEP 612 is now implemented purely in Python; builtintypes.GenericAlias objects no longer includetyping.ParamSpec in__parameters__ (with the exception ofcollections.abc.Callable'sGenericAlias). This means previously invalid uses ofParamSpec(such aslist[P]) which worked in earlier versions of Python 3.10alpha, will now raiseTypeError during substitution.

  • bpo-43867: ThemultiprocessingServer class now explicitlycatchesSystemExit and closes the client connection in this case.It happens when theServer.serve_client() method reaches the end offile (EOF).

  • bpo-40443: Remove unused imports: pyclbr no longer uses copy, and typingno longer uses ast. Patch by Victor Stinner.

  • bpo-43820: Remove an unneeded copy of the namespace passed todataclasses.make_dataclass().

  • bpo-43787: Add__iter__() method tobz2.BZ2File,gzip.GzipFile, andlzma.LZMAFile. It makes iteratingthem about 2x faster. Patch by Inada Naoki.

  • bpo-43680: Deprecate io.OpenWrapper and _pyio.OpenWrapper: use io.open and_pyio.open instead. Until Python 3.9, _pyio.open was not a static methodand builtins.open was set to OpenWrapper to not become a bound method whenset to a class variable. _io.open is a built-in function whereas_pyio.open is a Python function. In Python 3.10, _pyio.open() is now astatic method, and builtins.open() is now io.open().

  • bpo-43680: The Python_pyio.open() function becomes a static methodto behave asio.open() built-in function: don't become a boundmethod when stored as a class variable. It becomes possible since staticmethods are now callable in Python 3.10. Moreover,_pyio.OpenWrapper() becomes a simple alias to_pyio.open().Patch by Victor Stinner.

  • bpo-41515: FixKeyError raised intyping.get_type_hints() dueto synthetic modules that don't appear insys.modules.

  • bpo-43776: Whensubprocess.Popen args are provided as a string oraspathlib.Path, the Popen instance repr now shows the rightthing.

  • bpo-42248: [Enum] ensure exceptions raised in_missing__ are released

  • bpo-43744: fix issue with enum member name matching the start of a privatevariable name

  • bpo-43772: Fixed the return value ofTypeVar.__ror__. Patch by JelleZijlstra.

  • bpo-43764: Add match_args parameter to @dataclass decorator to allowsuppression of __match_args__ generation.

  • bpo-43799: OpenSSL 3.0.0: defineOPENSSL_API_COMPAT 1.1.1 to suppressdeprecation warnings. Python requires OpenSSL 1.1.1 APIs.

  • bpo-43478: Mocks can no longer be used as the specs for other Mocks. As aresult, an already-mocked object cannot have an attribute mocked usingautospec=True or be the subject of acreate_autospec(...) call.This can uncover bugs in tests since these Mock-derived Mocks will alwayspass certain tests (e.g.isinstance()) and builtin assert functions(e.g. assert_called_once_with) will unconditionally pass.

  • bpo-43794: Addssl.OP_IGNORE_UNEXPECTED_EOF constants (OpenSSL3.0.0)

  • bpo-43785: Improvebz2.BZ2File performance by removing the RLock fromBZ2File. This makes BZ2File thread unsafe in the face of multiplesimultaneous readers or writers, just like its equivalent classes ingzip andlzma have always been. Patch by Inada Naoki.

  • bpo-43789: OpenSSL 3.0.0: Don't call the password callback function asecond time when first call has signaled an error condition.

  • bpo-43788: The header files forssl error codes are now OpenSSLversion-specific. Exceptions will now show correct reason and librarycodes. Themake_ssl_data.py script has been rewritten to use OpenSSL'stext file with error codes.

  • bpo-43766: ImplementPEP 647 in thetyping module by addingTypeGuard.

  • bpo-25264:os.path.realpath() now accepts astrict keyword-onlyargument. When set toTrue,OSError is raised if a path doesn'texist or a symlink loop is encountered.

  • bpo-43780: Inimportlib.metadata, incorporate changes fromimportlib_metadata 3.10: Add mtime-based caching during distributiondiscovery. Flagged use of dict result fromentry_points() asdeprecated.

  • gh-47383: TheP.args andP.kwargs attributes oftyping.ParamSpec are now instances of the new classestyping.ParamSpecArgs andtyping.ParamSpecKwargs, whichenables a more usefulrepr(). Patch by Jelle Zijlstra.

  • bpo-43731: Add anencoding parameterlogging.fileConfig().

  • bpo-43712: Addencoding anderrors parameters tofileinput.input() andfileinput.FileInput.

  • bpo-38659: Asimple_enum decorator is added to theenum module toconvert a normal class into an Enum.test_simple_enum added to testsimple enums against a corresponding normal Enum. Standard librarymodules updated to usesimple_enum.

  • bpo-43764: Fix an issue where__match_args__ generationcould fail for somedataclasses.

  • bpo-43752: Fixsqlite3 regression for zero-sized blobs withconverters, whereb"" was returned instead ofNone. The regressionwas introduced by PR 24723. Patch by Erlend E. Aasland.

  • bpo-43655:tkinter dialog windows are now recognized as dialogs bywindow managers on macOS and X Window.

  • bpo-43723: The followingthreading methods are now deprecated andshould be replaced:

    Patch by Jelle Zijlstra.

  • bpo-2135: Deprecate find_module() and find_loader() implementations inimportlib and zipimport.

  • bpo-43534:turtle.textinput() andturtle.numinput() create nowa transient window working on behalf of the canvas window.

  • bpo-43532: Add the ability to specify keyword-only fields to dataclasses.These fields will become keyword-only arguments to the generated __init__.

  • bpo-43522: Fix problem withhostname_checks_common_name. OpenSSL does not copyhostflags fromstruct SSL_CTX tostruct SSL.

  • bpo-8978: Improve error message fortarfile.open() whenlzma/bz2 are unavailable. Patch by Anthony Sottile.

  • bpo-42967: Allowbytesseparator argument inurllib.parse.parse_qs andurllib.parse.parse_qsl when parsingstr query strings. Previously, this raised aTypeError.

  • bpo-43296: Improvesqlite3 error handling:sqlite3_value_blob()errors that setSQLITE_NOMEM now raiseMemoryError. Patch byErlend E. Aasland.

  • bpo-43312: New functionssysconfig.get_preferred_scheme() andsysconfig.get_default_scheme() are added to query a platform for itspreferred "user", "home", and "prefix" (default) scheme names.

  • bpo-43265: Improvesqlite3.Connection.backup() error handling. Theerror message for non-existent target database names is nowunknowndatabase<databasename> instead ofSQLlogicerror. Patch by ErlendE. Aasland.

  • bpo-41282: Install schemes indistutils.command.install are now loadedfromsysconfig.

  • bpo-41282:distutils.sysconfig has been merged tosysconfig.

  • bpo-43176: Fixed processing of a dataclass that inherits from a frozendataclass with no fields. It is now correctly detected as an error.

  • bpo-43080:pprint now has support fordataclasses.dataclass. Patch by Lewis Gaul.

  • bpo-39950: Addpathlib.Path.hardlink_to() method that supersedeslink_to(). The new method has the same argument order assymlink_to().

  • bpo-42904:typing.get_type_hints() now checks the local namespace ofa class when evaluatingPEP 563 annotations inside said class.

  • bpo-42269: Addslots parameter todataclasses.dataclass decoratorto automatically generate__slots__ for class. Patch provided by YuriiKarabas.

  • bpo-39529: Deprecated use ofasyncio.get_event_loop() withoutrunning event loop. Emit deprecation warning forasyncio functionswhich implicitly create aFuture orTask objects if there is no running event loop and noexplicitloop argument is passed:ensure_future(),wrap_future(),gather(),shield(),as_completed() and constructors ofFuture,Task,StreamReader,StreamReaderProtocol.

  • bpo-18369: Certificate and PrivateKey classes were added to the sslmodule. Certificates and keys can now be loaded from memory buffer, too.

  • bpo-41486: Use a new output buffer management code forbz2 /lzma /zlib modules, and add.readall() function to_compression.DecompressReader class. These bring some performanceimprovements. Patch by Ma Lin.

  • bpo-31870: Thessl.get_server_certificate() function now has atimeout parameter.

  • bpo-41735: Fix thread locks in zlib module may go wrong in rare case.Patch by Ma Lin.

  • bpo-36470: Fix dataclasses withInitVars andreplace(). Patch by Claudiu Popa.

  • bpo-40849: Expose X509_V_FLAG_PARTIAL_CHAIN ssl flag

  • bpo-35114:ssl.RAND_status() now returns a boolean value (asdocumented) instead of1 or0.

  • bpo-39906:pathlib.Path.stat() andchmod() nowaccept afollow_symlinks keyword-only argument for consistency withcorresponding functions in theos module.

  • bpo-39899:os.path.expanduser() now refuses to guess Windows homedirectories if the basename of current user's home directory does notmatch their username.

    pathlib.Path.expanduser() andhome() nowconsistently raiseRuntimeError exception when a home directorycannot be resolved. Previously aKeyError exception could be raisedon Windows when the"USERNAME" environment variable was unset.

  • bpo-36076: Added SNI support tossl.get_server_certificate().

  • bpo-38490: Covariance, Pearson's correlation, and simple linear regressionfunctionality was added to statistics module. Patch by Tymoteusz Wołodźko.

  • bpo-33731: Provide a locale.localize() function, which converts anormalized number string into a locale format.

  • bpo-32745: Fix a regression in the handling of ctypes'ctypes.c_wchar_p type: embedded null characters would cause aValueError to be raised. Patch by Zackery Spytz.

Documentation

  • bpo-43987: Add "Annotations Best Practices" document as a new HOWTO.

  • bpo-43977: Document the newPy_TPFLAGS_MAPPING andPy_TPFLAGS_SEQUENCE type flags.

  • bpo-43959: The documentation on the PyContextVar C-API was clarified.

  • bpo-43938: Update dataclasses documentation to express thatFrozenInstanceError is derived from AttributeError.

  • bpo-43778: Fix the Sphinx glossary_search extension: create the _static/sub-directory if it doesn't exist.

  • bpo-43755: Update documentation to reflect that unparenthesized lambdaexpressions can no longer be the expression part in anif clause incomprehensions and generator expressions since Python 3.9.

  • bpo-43739: Fixing the example code in Doc/extending/extending.rst todeclare and initialize the pmodule variable to be of the right type.

Tests

  • bpo-43961: Fix test_logging.test_namer_rotator_inheritance() on Windows:useos.replace() rather thanos.rename(). Patch by VictorStinner.

  • bpo-43842: Fix a race condition in the SMTP test of test_logging. Don'tclose a file descriptor (socket) from a different thread whileasyncore.loop() is polling the file descriptor. Patch by Victor Stinner.

  • bpo-43843:test.libregrtest now marks a test as ENV_CHANGED(altered the execution environment) if a thread raises an exception butdoes not catch it. It sets a hook onthreading.excepthook(). Use--fail-env-changed option to mark the test as failed. Patch by VictorStinner.

  • bpo-43811: Tests multiple OpenSSL versions on GitHub Actions. Use ccacheto speed up testing.

  • bpo-43791: OpenSSL 3.0.0: Disable testing of legacy protocols TLS 1.0 and1.1. Tests are failing with TLSV1_ALERT_INTERNAL_ERROR.

Build

  • bpo-43567: Improved generated code refresh (AST/tokens/opcodes/keywords)on Windows.

  • bpo-43669: ImplementPEP 644. Python now requires OpenSSL 1.1.1 ornewer.

Windows

macOS

  • bpo-42119: Fix check for macOS SDK paths when building Python. Narrowsearch to match contents of SDKs, namely only files in/System/Library,/System/IOSSupport, and/usr other than/usr/local. Previously, anything under/System was assumed to bein an SDK which causes problems with the new file system layout in 10.15+where user file systems may appear to be mounted under/System. Pathsin/Library were also incorrectly treated as SDK locations.

  • bpo-43568: Drop support for MACOSX_DEPLOYMENT_TARGET < 10.3

  • bpo-44009: Provide "python3.x-intel64" executable to allow reliablyforcing macOS universal2 framework builds to run under Rosetta 2 Intel-64emulation on Apple Silicon Macs. This can be useful for testing or whenuniversal2 wheels are not yet available.

  • bpo-43851: Build SQLite withSQLITE_OMIT_AUTOINIT on macOS. Patch byErlend E. Aasland.

  • bpo-43492: Update macOS installer to use SQLite 3.35.4.

  • bpo-42235:Mac/BuildScript/build-installer.py will now use"--enable-optimizations" and--with-lto when building on macOS 10.15or later.

IDLE

  • bpo-37903: Add mouse actions to the shell sidebar. Left click andoptional drag selects one or more lines, as with the editor line numbersidebar. Right click after selecting raises a context menu with 'copywith prompts'. This zips together prompts from the sidebar with linesfrom the selected text.

  • bpo-43981: Fix reference leak in test_sidebar and test_squeezer. Patchesby Terry Jan Reedy and Pablo Galindo

  • bpo-37892: Indent IDLE Shell input with spaces instead of tabs

  • bpo-43655: IDLE dialog windows are now recognized as dialogs by windowmanagers on macOS and X Window.

  • bpo-37903: IDLE's shell now shows prompts in a separate side-bar.

C API

  • bpo-43916: Add a newPy_TPFLAGS_DISALLOW_INSTANTIATION typeflag to disallow creating type instances. Patch by Victor Stinner.

  • bpo-43774: Remove the now unusedPYMALLOC_DEBUG macro. Debug hooks onmemory allocators are now installed by default if Python is built in debugmode (ifPy_DEBUG macro is defined). Moreover, they can now be used onPython build in release mode (ex: usingPYTHONMALLOC=debug environmentvariable).

  • bpo-43962: _PyInterpreterState_IDIncref() now calls_PyInterpreterState_IDInitref() and always increments id_refcount.Previously, calling _xxsubinterpreters.get_current() could create anid_refcount inconsistency when a _xxsubinterpreters.InterpreterID objectwas deallocated. Patch by Victor Stinner.

  • bpo-28254: Add new C-API functions to control the state of the garbagecollector:PyGC_Enable(),PyGC_Disable(),PyGC_IsEnabled(), corresponding to the functions in thegc module.

  • bpo-43908: IntroducePy_TPFLAGS_IMMUTABLETYPE flag forimmutable type objects, and modifyPyType_Ready() to set it forstatic types. Patch by Erlend E. Aasland.

  • bpo-43795:PyMem_Calloc() is now available in the limited C API(Py_LIMITED_API).

  • bpo-43868:PyOS_ReadlineFunctionPointer() is no longer exported bylimited C API headers and bypython3.dll on Windows. Like any functionthat takesFILE*, it is not part of the stable ABI.

  • bpo-43795: Stable ABI and limited API definitions are generated from acentral manifest (PEP 652).

  • bpo-43753: Add thePy_Is(x,y) function to test if thex object is they object, the same asxisy in Python. Add alsothePy_IsNone(),Py_IsTrue(),Py_IsFalse()functions to test if an object is, respectively, theNone singleton,theTrue singleton or theFalse singleton. Patch by VictorStinner.

Python 3.10.0 alpha 7

Release date: 2021-04-05

Security

  • bpo-42988:CVE 2021-3426: Remove thegetfile feature of thepydoc module which could be abused to read arbitrary files on thedisk (directory traversal vulnerability). Moreover, even source code ofPython modules can contain sensitive data like passwords. Vulnerabilityreported by David Schwörer.

  • bpo-43285:ftplib no longer trusts the IP address value returnedfrom the server in response to the PASV command by default. This preventsa malicious FTP server from using the response to probe IPv4 address andport combinations on the client network.

    Code that requires the former vulnerable behavior may set atrust_server_pasv_ipv4_address attribute on theirftplib.FTPinstances toTrue to re-enable it.

  • bpo-43439: Add audit hooks forgc.get_objects(),gc.get_referrers() andgc.get_referents(). Patch by PabloGalindo.

Core and Builtins

  • bpo-27129: Update CPython bytecode magic number.

  • bpo-43672: Raise ImportWarning when calling find_loader().

  • bpo-43660: Fix crash that happens when replacingsys.stderr with acallable that can remove the object while an exception is being printed.Patch by Pablo Galindo.

  • bpo-27129: The bytecode interpreter uses instruction, rather byte, offsetsinternally. This reduces the number of EXTENDED_ARG instructions neededand streamlines instruction dispatch a bit.

  • bpo-40645: Fix reference leak in the_hashopenssl extension. Patchby Pablo Galindo.

  • bpo-42134: Calls to find_module() by the import system now raiseImportWarning.

  • bpo-41064: Improve the syntax error for invalid usage of double starredelements ('**') in f-strings. Patch by Pablo Galindo.

  • bpo-43575: Speed up calls tomap() by using thePEP 590vectorcall calling convention. Patch by Donghee Na.

  • bpo-42137: The import system now prefers using__spec__ forModuleType.__repr__ overmodule_repr().

  • bpo-43452: Added micro-optimizations to_PyType_Lookup() to improvecache lookup performance in the common case of cache hits.

  • bpo-43555: Report the column offset forSyntaxError for invalidline continuation characters. Patch by Pablo Galindo.

  • bpo-43517: Fix misdetection of circular imports when usingfrompkg.modimportattr, which caused false positives in non-trivial multi-threadedcode.

  • bpo-43497: Emit SyntaxWarnings for assertions with tuple constants, thisis a regression introduced in python3.7

  • bpo-39316: Tracing now has correct line numbers for attribute accesseswhen the attribute is on a different line from the object. Improvesdebugging and profiling for multi-line method chains.

  • bpo-35883: Python no longer fails at startup with a fatal error if acommand line argument contains an invalid Unicode character. ThePy_DecodeLocale() function now escapes byte sequences which wouldbe decoded as Unicode characters outside the [U+0000; U+10ffff] range.

  • bpo-43410: Fix a bug that was causing the parser to crash when emittingsyntax errors when reading input from stdin. Patch by Pablo Galindo

  • bpo-43406: Fix a possible race condition wherePyErr_CheckSignalstries to execute a non-Python signal handler.

  • bpo-42128: Add__match_args__ tostruct sequence objects. Patch by Pablo Galindo.

  • bpo-43390: CPython now sets theSA_ONSTACK flag inPyOS_setsig forthe VM's default signal handlers. This is friendlier to other in-processcode that an extension module or embedding use could pull in (such asGolang's cgo) where tiny thread stacks are the norm andsigaltstack()has been used to provide for signal handlers. This is a no-op change forthe vast majority of processes that don't use sigaltstack.

  • bpo-43287: Speed up calls tofilter() by using thePEP 590vectorcall calling convention. Patch by Donghee Na.

  • bpo-37448: Add a radix tree based memory map to track in-use obmallocarenas. Use to replace the old implementation of address_in_range(). Theradix tree approach makes it easy to increase pool sizes beyond the OSpage size. Boosting the pool and arena size allows obmalloc to handle asignificantly higher percentage of requests from its ultra-fast paths.

    It also has the advantage of eliminating the memory unsanitary behavior ofthe previous address_in_range(). The old address_in_range() was markedwith the annotations _Py_NO_SANITIZE_ADDRESS, _Py_NO_SANITIZE_THREAD, and_Py_NO_SANITIZE_MEMORY. Those annotations are no longer needed.

    To disable the radix tree map, set a preprocessor flag as follows:-DWITH_PYMALLOC_RADIX_TREE=0.

    Co-authored-by: Tim Peters <tim.peters@gmail.com>

  • bpo-29988: Only handle asynchronous exceptions and requests to drop theGIL when returning from a call or on the back edges of loops. Makes surethat__exit__() is always called in with statements, evenfor interrupts.

Library

  • bpo-43720: Document various stdlib deprecations in imp, pkgutil, andimportlib.util for removal in Python 3.12.

  • bpo-43433:xmlrpc.client.ServerProxy no longer ignores query andfragment in the URL of the server.

  • bpo-31956: Theindex() method ofarray.arraynow has optionalstart andstop parameters.

  • bpo-40066: Enum: adjustrepr() to show only enum and member name (notvalue, nor angle brackets) andstr() to show only member name. Updateand improve documentation to match.

  • bpo-42136: Deprecate all module_repr() methods found in importlib as theiruse is being phased out by Python 3.12.

  • bpo-35930: Raising an exception raised in a "future" instance will createreference cycles.

  • bpo-41369: Finish updating the vendored libmpdec to version 2.5.1. Patchby Stefan Krah.

  • bpo-43422: Revert the _decimal C API which was added inbpo-41324.

  • bpo-43577: Fix deadlock when usingssl.SSLContext debug callbackwithssl.SSLContext.sni_callback().

  • bpo-43571: It's now possible to create MPTCP sockets with IPPROTO_MPTCP

  • bpo-43542:image/heic andimage/heif were added tomimetypes.

  • bpo-40645: Thehmac module now uses OpenSSL's HMAC implementationwhen digestmod argument is a hash name or builtin hash function.

  • bpo-43510: ImplementPEP 597: AddEncodingWarning warning,-Xwarn_default_encoding option,PYTHONWARNDEFAULTENCODINGenvironment variable andencoding="locale" argument value.

  • bpo-43521:ast.unparse can now render NaNs and empty sets.

  • bpo-42914:pprint.pprint() gains a new booleanunderscore_numbers optional argument to emit integers with thousandsseparated by an underscore character for improved readability (for example1_000_000 instead of1000000).

  • bpo-41361:rotate() calls are now slightly fasterdue to faster argument parsing.

  • bpo-43423:subprocess.communicate() no longer raises an IndexErrorwhen there is an empty stdout or stderr IO buffer during a timeout onWindows.

  • bpo-27820: Fixed long-standing bug of smtplib.SMTP where doing AUTH LOGINwith initial_response_ok=False will fail.

    The cause is that SMTP.auth_login _always_ returns a password if providedwith a challenge string, thus non-compliant with the standard for AUTHLOGIN.

    Also fixes bug with the test for smtpd.

  • bpo-43445: Add frozen modules tosys.stdlib_module_names. Forexample, add"_frozen_importlib" and"_frozen_importlib_external"names.

  • bpo-43245: Add keyword arguments support toChainMap.new_child().

  • bpo-29982: Add optional parameterignore_cleanup_errors totempfile.TemporaryDirectory() and allow multiplecleanup()attempts. Contributed by C.A.M. Gerlach.

  • bpo-43428: Include changes fromimportlib_metadata 3.7:

    Performance enhancements to distribution discovery.

    entry_points only returns unique distributions.

    Introduces newEntryPoints object for containing a set of entry pointswith convenience methods for selecting entry points by group or name.entry_points now returns this object if selection parameters aresupplied but continues to return a dict object for compatibility. Usersare encouraged to rely on the selection interface. The dict object resultis likely to be deprecated in the future.

    Added packages_distributions function to return a mapping of packages tothe distributions that provide them.

  • bpo-43332: Improves the networking efficiency ofhttp.client whenusing a proxy viaset_tunnel(). Fewer small sendcalls are made during connection setup.

  • bpo-43420: Improve performance offractions.Fraction arithmeticsfor large components. Contributed by Sergey B. Kirpichev.

  • bpo-43356: Allow passing a signal number to_thread.interrupt_main().

  • bpo-43399: FixElementTree.extend not working on iterators when usingthe Python implementation

  • bpo-43369: Improvesqlite3 error handling: Ifsqlite3_column_text() andsqlite3_column_blob() setSQLITE_NOMEM,MemoryError is now raised. Patch by Erlend E.Aasland.

  • bpo-43368: Fix a regression introduced in PR 24562, where an emptybytestring was fetched asNone instead ofb'' insqlite3.Patch by Mariusz Felisiak.

  • bpo-41282: Fixed stacklevel ofDeprecationWarning emitted fromimportdistutils.

  • bpo-42129:importlib.resources now honors namespace packages, mergingresources from each location in the namespace as introduced inimportlib_resources 3.2 and including incidental changes through5.0.3.

  • bpo-43295:datetime.datetime.strptime() now raisesValueErrorinstead ofIndexError when matching'z' with the%z formatspecifier.

  • bpo-43125: Return empty string if base64mime.body_encode receive emptybytes

  • bpo-43084:curses.window.enclose() returns nowTrue orFalse(as was documented) instead of1 or0.

  • bpo-42994: Add MIME types for opus, AAC, 3gpp and 3gpp2

  • bpo-14678: Add an invalidate_caches() method to the zipimport.zipimporterclass to support importlib.invalidate_caches(). Patch by Desmond Cheong.

  • bpo-42782: Fail fast inshutil.move() to avoid creating destinationdirectories on failure.

  • bpo-40066: Enum'srepr() andstr() have changed:repr() is nowEnumClass.MemberName andstr() isMemberName. Additionally,stdlib Enum's whose contents are available as module attributes, such asRegexFlag.IGNORECASE, have theirrepr() asmodule.name, e.g.re.IGNORECASE.

  • bpo-26053: Fixed bug where thepdb interactive run command echoedthe args from the shell command line, even if those have been overriddenat the pdb prompt.

  • bpo-24160: Fixed bug where breakpoints did not persist across multipledebugger sessions inpdb's interactive mode.

  • bpo-40701: When thetempfile.tempdir global variable is set to avalue of type bytes, it is now handled consistently. Previouslyexceptions could be raised from some tempfile APIs when the directory didnot already exist in this situation. Also ensures that thetempfile.gettempdir() andtempfile.gettempdirb() functionsalways returnstr andbytes respectively.

  • bpo-39342: ExposeX509_V_FLAG_ALLOW_PROXY_CERTS asVERIFY_ALLOW_PROXY_CERTS to allow proxy certificatevalidation as explained inhttps://docs.openssl.org/1.1.1/man7/proxy-certificates/.

  • bpo-31861: Add builtins.aiter and builtins.anext. Patch by Joshua Bronson(@jab), Daniel Pope (@lordmauve), and Justin Wang (@justin39).

Documentation

Tests

  • bpo-37945: Fix test_getsetlocale_issue1813() of test_locale: skip the testifsetlocale() fails. Patch by Victor Stinner.

  • bpo-41561: Add workaround for Ubuntu's custom OpenSSL security levelpolicy.

Build

  • bpo-43179: Introduce and correctly use ALIGNOF_X in place of SIZEOF_X foralignment-related code in optimized string routines. Patch by JessicaClarke.

  • bpo-43631: Update macOS, Windows, and CI to OpenSSL 1.1.1k.

  • bpo-43617: Improve configure.ac: Check for presence of autoconf-archivepackage and remove our copies of M4 macros.

  • bpo-43466: Theconfigure script now supports--with-openssl-rpathoption.

  • bpo-43372: Use_freeze_importlib to generate code for the__hello__ module. This approach ensures the code matches theinterpreter version. Previously, PYTHON_FOR_REGEN was used to generatethe code, which might be wrong. The marshal format for code objects haschanged withbpo-42246, commit 877df851. Update the code and the expectedcode sizes in ctypes test_frozentable.

Windows

  • bpo-43440: Buildsqlite3 with theR*Tree module enabled. Patchby Erlend E. Aasland.

IDLE

  • bpo-42225: Document that IDLE can fail on Unix either from misconfiguredIP masquerade rules or failure displaying complex colored (non-ascii)characters.

C API

  • bpo-43688: The limited C API is now supported if Python is built in debugmode (if thePy_DEBUG macro is defined). In the limited C API, thePy_INCREF() andPy_DECREF() functions are now implementedas opaque function calls, rather than accessing directly thePyObject.ob_refcnt member, if Python is built in debug modeand thePy_LIMITED_API macro targets Python 3.10 or newer. It becamepossible to support the limited C API in debug mode because thePyObject structure is the same in release and debug mode sincePython 3.8 (seebpo-36465).

    The limited C API is still not supported in the--with-trace-refsspecial build (Py_TRACE_REFS macro).

    Patch by Victor Stinner.

  • bpo-43244: Remove thepyarena.h header file with functions:

    • PyArena_New()

    • PyArena_Free()

    • PyArena_Malloc()

    • PyArena_AddPyObject()

    These functions were undocumented, excluded from the limited C API, andwere only used internally by the compiler. Patch by Victor Stinner.

  • bpo-43244: Remove the compiler and parser functions usingstruct_modtype, because the public AST C API was removed:

    • PyAST_Compile()

    • PyAST_CompileEx()

    • PyAST_CompileObject()

    • PyFuture_FromAST()

    • PyFuture_FromASTObject()

    • PyParser_ASTFromFile()

    • PyParser_ASTFromFileObject()

    • PyParser_ASTFromFilename()

    • PyParser_ASTFromString()

    • PyParser_ASTFromStringObject()

    These functions were undocumented and excluded from the limited C API.Patch by Victor Stinner.

  • bpo-43244: Removeast.h,asdl.h, andPython-ast.h headerfiles. These functions were undocumented and excluded from the limited CAPI. Most names defined by these header files were not prefixed byPyand so could create names conflicts. For example,Python-ast.h definedaYield macro which was conflict with theYield name used by theWindows<winbase.h> header. Use the Pythonast module instead.Patch by Victor Stinner.

  • bpo-43541: Fix aPyEval_EvalCodeEx() regression: fix referencecounting on builtins. Patch by Victor Stinner.

  • bpo-43244: Remove thesymtable.h header file and the undocumentedfunctions:

    • PyST_GetScope()

    • PySymtable_Build()

    • PySymtable_BuildObject()

    • PySymtable_Free()

    • Py_SymtableString()

    • Py_SymtableStringObject()

    ThePy_SymtableString() function was part the stable ABI by mistakebut it could not be used, because thesymtable.h header file wasexcluded from the limited C API.

    The Pythonsymtable module remains available and is unchanged.

    Patch by Victor Stinner.

  • bpo-43244: Remove thePyAST_Validate() function. It is no longerpossible to build a AST object (mod_ty type) with the public C API.The function was already excluded from the limited C API (PEP 384).Patch by Victor Stinner.

Python 3.10.0 alpha 6

Release date: 2021-03-01

Security

  • bpo-42967: Fix web cache poisoning vulnerability by defaulting the queryargs separator to&, and allowing the user to choose a customseparator.

Core and Builtins

  • bpo-43321: FixSystemError raised whenPyArg_Parse*() is used with# but withoutPY_SSIZE_T_CLEAN defined.

  • bpo-36346:PyArg_Parse*() functions now emitsDeprecationWarningwhenu orZ format is used. SeePEP 623 for detail.

  • bpo-43277: Add a newPySet_CheckExact() function to the C-API tocheck if an object is an instance ofset but not an instance of asubtype. Patch by Pablo Galindo.

  • bpo-42990: Thetypes.FunctionType constructor now inherits thecurrent builtins if theglobals dictionary has no"__builtins__"key, rather than using{"None":None} as builtins: same behavior aseval() andexec() functions. Defining a function withdeffunction(...):... in Python is not affected, globals cannot beoverridden with this syntax: it also inherits the current builtins. Patchby Victor Stinner.

  • bpo-42990: Functions have a new__builtins__ attribute which is usedto look for builtin symbols when a function is executed, instead oflooking into__globals__['__builtins__']. Patch by Mark Shannon andVictor Stinner.

  • bpo-43149: Improve the error message in the parser for exception groupswithout parentheses. Patch by Pablo Galindo.

  • bpo-43121: Fixed an incorrectSyntaxError message for missing commain literals. Patch by Pablo Galindo.

  • bpo-42819:readline: Explicitly disable bracketed paste in theinteractive interpreter, even if it's set in the inputrc, is enabled bydefault (eg GNU Readline 8.1), or a user callsreadline.read_init_file(). The Python REPL has not implementedbracketed paste support. Also, bracketed mode writes the"\x1b[?2004h"escape sequence into stdout which causes test failures in applicationsthat don't support it. It can still be explicitly enabled by callingreadline.parse_and_bind("setenable-bracketed-pasteon"). Patch byDustin Rodrigues.

  • bpo-42808: Simple calls totype(object) are now faster due to thevectorcall calling convention. Patch by Dennis Sweeney.

  • bpo-42217: Make the compiler merges same co_code and co_linetable objectsin a module like already did for co_consts.

  • bpo-41972: Substring search functions such asstr1instr2 andstr2.find(str1) now sometimes use the "Two-Way" string comparisonalgorithm to avoid quadratic behavior on long strings.

  • bpo-42128: ImplementPEP 634 (structural pattern matching). Patch byBrandt Bucher.

  • bpo-40692: In theconcurrent.futures.ProcessPoolExecutor,validate thatmultiprocess.synchronize() is available on a givenplatform and rely on that check in theconcurrent.futures testsuite so we can run tests that are unrelated toProcessPoolExecutor on those platforms.

  • bpo-38302: Ifobject.__ipow__() returnsNotImplemented, theoperator will correctly fall back toobject.__pow__() andobject.__rpow__() as expected.

Library

  • bpo-43316: Thepython-mgzip command line application now properlyfails when detecting an unsupported extension. It exits with a non-zeroexit code and prints an error message to stderr.

  • bpo-43317: Set the chunk size for thegzip module main function toio.DEFAULT_BUFFER_SIZE. This is slightly faster than the 1024 bytesconstant that was used previously.

  • bpo-43146: Handle None in single-arg versions ofprint_exception() andformat_exception().

  • bpo-43260: Fix TextIOWrapper can not flush internal buffer forever aftervery large text is written.

  • bpo-43258: Prevent needless allocation ofsqlite3 aggregatefunction context when no rows match an aggregate query. Patch by Erlend E.Aasland.

  • bpo-43251: Improvesqlite3 error handling:sqlite3_column_name() failures now result inMemoryError. Patchby Erlend E. Aasland.

  • bpo-40956: Fix segfault insqlite3.Connection.backup() if noargument was provided. The regression was introduced by PR 23838. Patch byErlend E. Aasland.

  • bpo-43172: The readline module now passes its tests when built directlyagainst libedit. Existing irreconcilable API differences remain inreadline.get_begidx() andreadline.get_endidx() behavior basedon libreadline vs libedit use.

  • bpo-43163: Fix a bug incodeop that was causing it to not ask formore input when multi-line snippets have unclosed parentheses. Patch byPablo Galindo

  • bpo-43162: deprecate unsupported ability to access enum members asattributes of other enum members

  • bpo-43146: Fix recent regression in None argument handling intraceback module functions.

  • bpo-43102: The namedtuple __new__ method had its __builtins__ set to Noneinstead of an actual dictionary. This created problems for introspectiontools.

  • bpo-43106: AddedO_EVTONLY,O_FSYNC,O_SYMLINK andO_NOFOLLOW_ANY for macOS. Patch byDonghee Na.

  • bpo-42960: Addsresource.RLIMIT_KQUEUES constant from FreeBSD totheresource module.

  • bpo-42151: Make the pure Python implementation ofxml.etree.ElementTree behave the same as the C implementation(_elementree) regarding default attribute values (by not settingspecified_attributes=1).

  • bpo-29753: In ctypes, now packed bitfields are calculated properly and thefirst item of packed bitfields is now shrank correctly.

Documentation

  • bpo-27646: Clarify that 'yield from <expr>' works with any iterable, notjust iterators.

  • bpo-36346: Update some deprecated unicode APIs which are documented as"will be removed in 4.0" to "3.12". SeePEP 623 for detail.

Tests

  • bpo-43288: Fix test_importlib to correctly skip Unicode file tests if thefilesystem does not support them.

Build

  • bpo-43174: Windows build now uses/utf-8 compiler option.

  • bpo-43103: Add a new configure--without-static-libpython option tonot build thelibpythonMAJOR.MINOR.a static library and not installthepython.o object file.

  • bpo-13501: The configure script can now uselibedit instead ofreadline with the command line option--with-readline=editline.

  • bpo-42603: Make configure script use pkg-config to detect the location ofTcl/Tk headers and libraries, used to build tkinter.

    On macOS, a Tcl/Tk configuration provided by pkg-config will be preferredover Tcl/Tk frameworks installed in/{System/,}Library/Frameworks. Ifboth exist and the latter is preferred, the appropriate--with-tcltk-*configuration options need to be explicitly set.

  • bpo-39448: Add the "regen-frozen" makefile target that regenerates thecode for the frozen__hello__ module.

Windows

macOS

  • bpo-41837: Update macOS installer build to use OpenSSL 1.1.1j.

IDLE

  • bpo-43283: Document why printing to IDLE's Shell is often slower thanprinting to a system terminal and that it can be made faster bypre-formatting a single string before printing.

C API

  • bpo-43278: Always put compiler and system information on the first line ofthe REPL welcome message.

  • bpo-43270: Remove the private_PyErr_OCCURRED() macro: use the publicPyErr_Occurred() function instead.

  • bpo-35134: Move odictobject.h, parser_interface.h, picklebufobject.h,pydebug.h, and pyfpe.h into the cpython/ directory. They must not beincluded directly, as they are already included by Python.h:IncludeFiles.

  • bpo-35134: Move pyarena.h, pyctype.h, and pytime.h into the cpython/directory. They must not be included directly, as they are alreadyincluded by Python.h:Include Files.

  • bpo-40170:PyExceptionClass_Name() is now always declared as afunction, in order to hide implementation details. The macro accessedPyTypeObject.tp_name directly. Patch by Erlend E. Aasland.

  • bpo-43239: ThePyCFunction_New() function is now exported in theABI when compiled with-fvisibility=hidden.

  • bpo-40170:PyIter_Check() is now always declared as a function, inorder to hide implementation details. The macro accessedPyTypeObject.tp_iternext directly. Patch by Erlend E. Aasland.

  • bpo-40170: ConvertPyDescr_IsData() macro to a function to hideimplementation details: The macro accessedPyTypeObject.tp_descr_set directly. Patch by Erlend E.Aasland.

  • bpo-43181: ConvertPyObject_TypeCheck() macro to a static inlinefunction. Patch by Erlend E. Aasland.

Python 3.10.0 alpha 5

Release date: 2021-02-02

Security

Core and Builtins

  • bpo-42990: Refactor thePyEval_ family of functions.

    • An new function_PyEval_Vector is added to simplify calls to Python from C.

    • _PyEval_EvalCodeWithName is removed

    • PyEval_EvalCodeEx is retained as part of the API, but is not used internally

  • bpo-38631: ReplacePy_FatalError() calls in the compiler withregularSystemError exceptions. Patch by Victor Stinner.

  • bpo-42997: Improve error message for missing ":" before blocks. Patch byPablo Galindo.

  • bpo-43017: Improve error message in the parser when using un-parenthesisedtuples in comprehensions. Patch by Pablo Galindo.

  • bpo-42986: Fix parser crash when reporting syntax errors in f-string withnewlines. Patch by Pablo Galindo.

  • bpo-40176: Syntax errors for unterminated string literals now point to thestart of the string instead of reporting EOF/EOL.

  • bpo-42927: The inline cache forLOAD_ATTR now also optimizes access toattributes defined by__slots__. This makes reading such attribute upto 30% faster.

  • bpo-42864: Improve error messages in the parser when parentheses are notclosed. Patch by Pablo Galindo.

  • bpo-42924: Fixbytearray repetition incorrectly copying data from thestart of the buffer, even if the data is offset within the buffer (e.g.after reassigning a slice at the start of thebytearray to a shorterbyte string).

  • bpo-42882: Fix the_PyUnicode_FromId() function(_Py_IDENTIFIER(var) API) whenPy_Initialize() /Py_Finalize() is called multiple times: preserve_PyRuntime.unicode_ids.next_index value.

  • bpo-42827: Fix a crash when working out the error line of aSyntaxError in some multi-line expressions.

  • bpo-42823: frame.f_lineno is correct even if frame.f_trace is set to True

  • bpo-37324: Remove deprecated aliases toCollections Abstract Base Classes from thecollectionsmodule.

  • bpo-41994: Fixed possible leak inimport whensys.modules is not adict.

  • bpo-27772: In string formatting, preceding thewidth field by'0' nolonger affects the default alignment for strings.

Library

  • bpo-43108: Fixed a reference leak in thecurses module. Patch byPablo Galindo

  • bpo-43077: Update the bundled pip to 21.0.1 and setuptools to 52.0.0.

  • bpo-41282: Deprecatedistutils in documentation and add warning onimport.

  • bpo-43014: Improve performance oftokenize by 20-30%. Patch byAnthony Sottile.

  • bpo-42323: Fixmath.nextafter() for NaN on AIX.

  • bpo-42955: Addsys.stdlib_module_names, containing the list of thestandard library module names. Patch by Victor Stinner.

  • bpo-42944: Fixrandom.Random.sample whencounts argument is notNone.

  • bpo-42934: UseTracebackException's newcompactparam inTestResult to reduce time and memory consumedby traceback formatting.

  • bpo-42931: Addrandbytes() torandom.__all__.

  • bpo-38250: [Enum] Flags consisting of a single bit are now consideredcanonical, and will be the only flags returned from listing and iteratingover a Flag class or a Flag member. Multi-bit flags are consideredaliases; they will be returned from lookups and operations that result intheir value. Iteration for both Flag and Flag members is in definitionorder.

  • bpo-42877: Added thecompact parameter to the constructor oftraceback.TracebackException to reduce time and memory for usecases that only need to callTracebackException.format() andTracebackException.format_exception_only().

  • bpo-42923: ThePy_FatalError() function and thefaulthandler module now dump the list of extension modules on afatal error.

  • bpo-42848: Removed recursion fromTracebackExceptionto allow it to handle long exception chains.

  • bpo-42901: [Enum] move member creation fromEnumMeta.__new__ to_proto_member.__set_name__, allowing members to be created and visiblein__init_subclass__.

  • bpo-42780: Fix os.set_inheritable() for O_PATH file descriptors on Linux.

  • bpo-42866: Fix a reference leak in thegetcodec() function of CJKcodecs. Patch by Victor Stinner.

  • bpo-42846: Convert the 6 CJK codec extension modules (_codecs_cn,_codecs_hk, _codecs_iso2022, _codecs_jp, _codecs_kr and _codecs_tw) to themultiphase initialization API (PEP 489). Patch by Victor Stinner.

  • bpo-42851: remove __init_subclass__ support for Enum members

  • bpo-42834: Make internal caches of the_json module compatible withsubinterpreters.

  • bpo-41748: Fix HTMLParser parsing rules for element attributes containingcommas with spaces. Patch by Karl Dubost.

  • bpo-40810: Require SQLite 3.7.15 or newer. Patch by Erlend E. Aasland.

  • bpo-1635741: Convert the _multibytecodec extension module (CJK codecs) tomulti-phase initialization (PEP 489). Patch by Erlend E. Aasland.

  • bpo-42802: The distutilsbdist_wininst command deprecated in Python3.8 has been removed. The distutilsbdist_wheel command is nowrecommended to distribute binary packages on Windows.

  • bpo-24464: The undocumented built-in functionsqlite3.enable_shared_cache is now deprecated, scheduled for removalin Python 3.12. Its use is strongly discouraged by the SQLite3documentation. Patch by Erlend E. Aasland.

  • bpo-42384: Make pdb populate sys.path[0] exactly the same as regularpython execution.

  • bpo-42383: Fix pdb: previously pdb would fail to restart the debuggingtarget if it was specified using a relative path and the current directorychanged.

  • bpo-42005: Fix CLI ofcProfile andprofile to catchBrokenPipeError.

  • bpo-41604: Don't decrement the reference count of the previous user_ptrwhen set_panel_userptr fails.

  • bpo-41149: Allow executing callables that have a boolean value ofFalse when passed toThreading.thread as the target. Patchcontributed by Barney Stratford.

  • bpo-38307: Add an 'end_lineno' attribute to the Class and Function objectsthat appear in the tree returned by pyclbr functions. This and theexisting 'lineno' attribute define the extent of class and def statements.Patch by Aviral Srivastava.

  • bpo-39273: TheBUTTON5_* constants are now exposed in thecurses module if available.

  • bpo-33289: Correct call totkinter.colorchooser to return RGBtriplet of ints instead of floats. Patch by Cheryl Sabella.

Documentation

  • bpo-40304: Fix doc for type(name, bases, dict). Patch by BorisVerkhovskiy and Éric Araujo.

  • bpo-42811: Updated importlib.util.resolve_name() doc to use__spec__.parent instead of __package__. (Thanks Yair Frid.)

Tests

  • bpo-40823: Useunittest.TestLoader().loadTestsFromTestCase() insteadofunittest.makeSuite() insqlite3 tests. Patch by Erlend E.Aasland.

  • bpo-40810: Insqlite3, fixCheckTraceCallbackContent for SQLitepre 3.7.15.

Build

  • bpo-43031: Pass--timeout=$(TESTTIMEOUT) option to the default profiletask./python-mtest--pgo command.

  • bpo-36143:makeregen-all now also runsregen-keyword. Patch byVictor Stinner.

  • bpo-42874: Removed the grep -q and -E flags in the tzpath validationsection of the configure script to better accommodate users of someplatforms (specifically Solaris 10).

  • bpo-31904: Add library search path by wr-cc in add_cross_compiling_paths()for VxWorks.

  • bpo-42856: Add--with-wheel-pkg-dir=PATH option to the./configurescript. If specified, theensurepip module looks forsetuptoolsandpip wheel packages in this directory: if both are present, thesewheel packages are used instead of ensurepip bundled wheel packages.

    Some Linux distribution packaging policies recommend against bundlingdependencies. For example, Fedora installs wheel packages in the/usr/share/python-wheels/ directory and don't install theensurepip._bundled package.

Windows

  • bpo-41837: Updated Windows installer to include OpenSSL 1.1.1i

  • bpo-42584: Upgrade Windows installer to use SQLite 3.34.0.

macOS

  • bpo-42504: Ensure that the value ofsysconfig.get_config_var('MACOSX_DEPLOYMENT_TARGET') is always a string,even in when the value is parsable as an integer.

IDLE

  • bpo-43008: Make IDLE invokesys.excepthook() in normal, 2-processmode. Patch by Ken Hilton.

  • bpo-33065: Fix problem debugging user classes with __repr__ method.

  • bpo-23544: Disable Debug=>Stack Viewer when user code is running orDebugger is active, to prevent hang or crash. Patch by Zackery Spytz.

  • bpo-32631: Finish zzdummy example extension module: make menu entrieswork; add docstrings and tests with 100% coverage.

C API

  • bpo-42979: When Python is built in debug mode (with C assertions), callinga type slot likesq_length (__len__() in Python) now fails with afatal error if the slot succeeded with an exception set, or failed with noexception set. The error message contains the slot, the type name, and thecurrent exception (if an exception is set). Patch by Victor Stinner.

  • bpo-43030: Fixed a compiler warning inPy_UNICODE_ISSPACE() onplatforms with signedwchar_t.

Python 3.10.0 alpha 4

Release date: 2021-01-04

Core and Builtins

  • bpo-42814: Fix undefined behavior inObjects/genericaliasobject.c.

  • bpo-42806: Fix the column offsets for f-stringsast nodessurrounded by parentheses and for nodes that spawn multiple lines. Patchby Pablo Galindo.

  • bpo-40631: Fix regression where a single parenthesized starred expressionwas a valid assignment target.

  • bpo-27794: Improve the error message for failed writes/deletes to propertyobjects. When possible, the attribute name is now shown. Patch provided byYurii Karabas.

  • bpo-42745: Make the type attribute lookup cache per-interpreter. Patch byVictor Stinner.

  • bpo-42246: Jumps to jumps are not eliminated when it would break PEP 626.

  • bpo-42246: Make sure that thef_lasti andf_lineno attributes of aframe are set correctly when an exception is raised or re-raised. Requiredfor PEP 626.

  • bpo-32381: The coding cookie (ex:#coding:latin1) is now ignored inthe command passed to the-c command line option. Patch byVictor Stinner.

  • bpo-30858: Improve error location in expressions that contain assignments.Patch by Pablo Galindo and Lysandros Nikolaou.

  • bpo-42615: Remove jump commands made redundant by the deletion ofunreachable bytecode blocks

  • bpo-42639: Make theatexit module state per-interpreter. It is nowsafe have more than oneatexit module instance. Patch by Donghee Naand Victor Stinner.

  • bpo-32381: Fix encoding name when running a.pyc file on Windows:PyRun_SimpleFileExFlags() now uses the correct encoding todecode the filename.

  • bpo-42195: The__args__ of the parameterized generics fortyping.Callable andcollections.abc.Callable are nowconsistent. The__args__ forcollections.abc.Callable arenow flattened whiletyping.Callable's have not changed. To allowthis change,types.GenericAlias can now be subclassed andcollections.abc.Callable's__class_getitem__ will now return asubclass oftypes.GenericAlias. Tests for typing were also updated tonot subclass things likeCallable[...,T] as that is not a valid baseclass. Finally, bothCallables no longer validate theirargtypes, inCallable[[argtypes],resulttype] to prepare forPEP 612. Patch by Ken Jin.

  • bpo-40137: Convert functools module to usePyType_FromModuleAndSpec().

  • bpo-40077: Convertarray to use heap types, and establish modulestate for these.

  • bpo-42008: Fix _random.Random() seeding.

  • bpo-1635741: Port thepyexpat extension module to multi-phaseinitialization (PEP 489).

  • bpo-40521: Make the Unicode dictionary of interned strings compatible withsubinterpreters. Patch by Victor Stinner.

  • bpo-39465: Make_PyUnicode_FromId() function compatible withsubinterpreters. Each interpreter now has an array of identifier objects(interned strings decoded from UTF-8). Patch by Victor Stinner.

Library

  • bpo-42257: Handle empty string in variable executable inplatform.libc_ver()

  • bpo-42772: randrange() now raises a TypeError when step is specifiedwithout a stop argument. Formerly, it silently ignored the step argument.

  • bpo-42759: Fixed equality comparison oftkinter.Variable andtkinter.font.Font. Objects which belong to different Tclinterpreters are now always different, even if they have the same name.

  • bpo-42756: Configure LMTP Unix-domain socket to use socket global defaulttimeout when a timeout is not explicitly provided.

  • bpo-23328: Allow / character in username, password fields on _PROXYenvars.

  • bpo-42740:typing.get_args() andtyping.get_origin() nowsupportPEP 604 union types andPEP 612 additions toCallable.

  • bpo-42655:subprocessextra_groups is now correctly passed intosetgroups() system call.

  • bpo-42727:EnumMeta.__prepare__ now accepts**kwds to properlysupport__init_subclass__

  • bpo-38308: Add optionalweights tostatistics.harmonic_mean().

  • bpo-42721: When simple query dialogs (tkinter.simpledialog),message boxes (tkinter.messagebox) or color choose dialog(tkinter.colorchooser) are created without argumentsmaster andparent, and the default root window is not yet created, andNoDefaultRoot() was not called, a new temporal hidden rootwindow will be created automatically. It will not be set as the defaultroot window and will be destroyed right after closing the dialog window.It will help to use these simple dialog windows in programs which do notneed other GUI.

  • bpo-25246: Optimizedcollections.deque.remove().

  • bpo-35728: Added a root parameter totkinter.font.nametofont().

  • bpo-15303:tkinter supports now widgets with boolean value False.

  • bpo-42681: Fixed range checks for color and pair numbers incurses.

  • bpo-42685: Improved placing of simple query windows in Tkinter (such astkinter.simpledialog.askinteger()). They are now centered at thecenter of the parent window if it is specified and shown, otherwise at thecenter of the screen.

  • bpo-9694: Argparse help no longer uses the confusing phrase, "optionalarguments". It uses "options" instead.

  • bpo-1635741: Port the_thread extension module to the multiphaseinitialization API (PEP 489) and convert its static types to heaptypes.

  • bpo-37961: Fix crash intracemalloc.Traceback.__repr__() (regressedin Python 3.9).

  • bpo-42630:tkinter functions and constructors which need a defaultroot window raise nowRuntimeError with descriptive message insteadof obscureAttributeError orNameError if it is not createdyet or cannot be created automatically.

  • bpo-42639:atexit._run_exitfuncs() now logs callback exceptionsusingsys.unraisablehook, rather than logging them directly intosys.stderr and raise the last exception.

  • bpo-42644:logging.disable will now validate the types and value ofits parameter. It also now accepts strings representing the levels (asdoeslogging.setLevel) instead of only the numerical values.

  • bpo-42639: At Python exit, if a callback registered withatexit.register() fails, its exception is now logged. Previously,only some exceptions were logged, and the last exception was alwayssilently ignored.

  • bpo-36541: Fixed lib2to3.pgen2 to be able to parse PEP-570 positional onlyargument syntax.

  • bpo-42382: Inimportlib.metadata: -EntryPoint objects now exposea.dist object referencing theDistribution when constructed fromaDistribution. - Add support for package discovery under packagenormalization rules. - The object returned bymetadata() now has aformally defined protocol calledPackageMetadata with declared supportfor the.get_all() method. - Synced with importlib_metadata 3.3.

  • bpo-41877: A check is added against misspellings of autospect, auto_specand set_spec being passed as arguments to patch, patch.object andcreate_autospec.

  • bpo-39717: [tarfile] update nested exception raising to usefromNoneorfrome

  • bpo-41877: AttributeError for suspected misspellings of assertions onmocks are now pointing out that the cause are misspelled assertions andalso what to do if the misspelling is actually an intended attribute name.The unittest.mock document is also updated to reflect the current set ofrecognised misspellings.

  • bpo-41559: ImplementedPEP 612: addedParamSpec andConcatenatetotyping. Patch by Ken Jin.

  • bpo-42385: StrEnum: fix _generate_next_value_ to return a str

  • bpo-31904: Define THREAD_STACK_SIZE for VxWorks.

  • bpo-34750: [Enum]_EnumDict.update() is now supported.

  • bpo-42517: Enum: private names do not become members / do not generateerrors -- they remain normal attributes

  • bpo-42678:Enum: call__init_subclass__ after members have beenadded

  • bpo-28964:ast.literal_eval() adds line number information (ifavailable) in error message for malformed nodes.

  • bpo-42470:random.sample() no longer warns on a sequence which isalso a set.

  • bpo-31904:posixpath.expanduser() returns the inputpath unchangedif user home directory is None on VxWorks.

  • bpo-42388: Fix subprocess.check_output(..., input=None) behavior whentext=True to be consistent with that of the documentation anduniversal_newlines=True.

  • bpo-34463: Fixed discrepancy betweentraceback and the interpreterin formatting of SyntaxError with lineno not set (traceback waschanged to match interpreter).

  • bpo-42393: RaiseOverflowError instead of silent truncation insocket.ntohs() andsocket.htons(). Silent truncation wasdeprecated in Python 3.7. Patch by Erlend E. Aasland

  • bpo-42222: Harmonizedrandom.randrange() argument handling to matchrange().

    • The integer test and conversion inrandrange() now usesoperator.index().

    • Non-integer arguments torandrange() are deprecated.

    • TheValueError is deprecated in favor of aTypeError.

    • It now runs a little faster than before.

    (Contributed by Raymond Hettinger and Serhiy Storchaka.)

  • bpo-42163: Restore compatibility foruname_result around deepcopy and_replace.

  • bpo-42090:zipfile.Path.joinpath now accepts arbitrary arguments, sameaspathlib.Path.joinpath.

  • bpo-1635741: Port the _csv module to the multi-phase initialization API(PEP 489).

  • bpo-42059:typing.TypedDict types created using the alternativecall-style syntax now correctly respect thetotal keyword argumentwhen setting their__required_keys__ and__optional_keys__ classattributes.

  • bpo-41960: Addglobalns andlocalns parameters to theinspect.signature() andinspect.Signature.from_callable().

  • bpo-41907: fixformat() behavior forIntFlag

  • bpo-41891: Ensure asyncio.wait_for waits for task completion

  • bpo-24792: Fixed bug wherezipimporter sometimes reports anincorrect cause of import errors.

  • bpo-31904: Fix site and sysconfig modules for VxWorks RTOS which has nohome directories.

  • bpo-41462: Addos.set_blocking() support for VxWorks RTOS.

  • bpo-40219: Loweredtkinter.ttk.LabeledScale dummy widget toprevent hiding part of the content label.

  • bpo-37193: Fixed memory leak insocketserver.ThreadingMixIn introducedin Python 3.7.

  • bpo-39068: Fix initialization race condition ina85encode() andb85encode() inbase64. Patch by Brandon Stansbury.

Documentation

Tests

  • bpo-42794: Update test_nntplib to use official group name of news.aioe.orgfor testing. Patch by Donghee Na.

  • bpo-31904: Skip some asyncio tests on VxWorks.

  • bpo-42641: Enhancetest_select.test_select(): it now takes 500milliseconds rather than 10 seconds. Use Python rather than a shell tomake the test more portable.

  • bpo-31904: Skip some tests in _test_all_chown_common() on VxWorks.

  • bpo-42199: Fix bytecode helper assertNotInBytecode.

  • bpo-41443: Add more attribute checking in test_posix.py

  • bpo-31904: Disable os.popen and impacted tests on VxWorks

  • bpo-41439: Port test_ssl and test_uuid to VxWorks RTOS.

Build

  • bpo-42692: Fix __builtin_available check on older compilers. Patch byJoshua Root.

  • bpo-27640: Added--disable-test-modules option to theconfigurescript: don't build nor install test modules. Patch by Xavier de Gaye,Thomas Petazzoni and Peixing Xin.

  • bpo-42604: Now all platforms use a value for the "EXT_SUFFIX" buildvariable derived from SOABI (for instance in freeBSD, "EXT_SUFFIX" is now".cpython-310d.so" instead of ".so"). Previously only Linux, Mac andVxWorks were using a value for "EXT_SUFFIX" that included "SOABI".

  • bpo-42598: Fix implicit function declarations in configure which couldhave resulted in incorrect configuration checks. Patch contributed byJoshua Root.

  • bpo-31904: Enable libpython3.so for VxWorks.

  • bpo-29076: Add fish shell support to macOS installer.

macOS

  • bpo-42361: Update macOS installer build to use Tcl/Tk 8.6.11 (rc2,expected to be final release).

  • bpo-41837: Update macOS installer build to use OpenSSL 1.1.1i.

  • bpo-42584: Update macOS installer to use SQLite 3.34.0.

Tools/Demos

  • bpo-42726: Fixed Python 3 compatibility issue with gdb/libpython.pyhandling of attribute dictionaries.

  • bpo-42613: Fixfreeze.py tool to use the prope config and librarydirectories. Patch by Victor Stinner.

C API

  • bpo-42591: Export thePy_FrozenMain() function: fix a Python 3.9.0regression. Python 3.9 uses-fvisibility=hidden and the function wasnot exported explicitly and so not exported.

  • bpo-32381: Remove the private_Py_fopen() function which is nolonger needed. Use_Py_wfopen() or_Py_fopen_obj()instead. Patch by Victor Stinner.

  • bpo-1635741: Portresource extension module to module state

  • bpo-42111: Update thexxlimited module to be a better example of howto use the limited C API.

  • bpo-40052: Fix an alignment build warning/error in functionPyVectorcall_Function(). Patch by Andreas Schneider, Antoine Pitrouand Petr Viktorin.

Python 3.10.0 alpha 3

Release date: 2020-12-07

Security

  • bpo-40791: Addvolatile to the accumulator variable inhmac.compare_digest, making constant-time-defeating optimizations lesslikely.

Core and Builtins

  • bpo-42576:types.GenericAlias will now raise aTypeError whenattempting to initialize with a keyword argument. Previously, this wouldcause the interpreter to crash if the interpreter was compiled with debugsymbols. This does not affect interpreters compiled for release. Patch byKen Jin.

  • bpo-42536: Several built-in and standard library types now ensure thattheir internal result tuples are always tracked by thegarbagecollector:

    Previously, they could have become untracked by a prior garbagecollection. Patch by Brandt Bucher.

  • bpo-42500: Improve handling of exceptions near recursion limit. Converts anumber of Fatal Errors in RecursionErrors.

  • bpo-42246: PEP 626: After a return, the f_lineno attribute of a frame isalways the last line executed.

  • bpo-42435: Speed up comparison of bytes objects with non-bytes objectswhen option-b is specified. Speed up comparison of bytarrayobjects with non-buffer object.

  • bpo-1635741: Port the_warnings extension module to the multi-phaseinitialization API (PEP 489). Patch by Victor Stinner.

  • bpo-41686: On Windows, theSIGINT event,_PyOS_SigintEvent(), isnow created even if Python is configured to not install signal handlers(ifPyConfig.install_signal_handlers equals to 0, orPy_InitializeEx(0)).

  • bpo-42381: Allow assignment expressions in set literals and setcomprehensions as per PEP 572. Patch by Pablo Galindo.

  • bpo-42202: Change function parameters annotations internal representationto tuple of strings. Patch provided by Yurii Karabas.

  • bpo-42374: Fix a regression introduced by the new parser, where anunparenthesized walrus operator was not allowed within generatorexpressions.

  • bpo-42316: Allow an unparenthesized walrus in subscript indexes.

  • bpo-42349: Make sure that the compiler front-end produces a well-formedcontrol flow graph. Be more aggressive in the compiler back-end, as it isnow safe to do so.

  • bpo-42296: On Windows, fix a regression in signal handling which preventedto interrupt a program using CTRL+C. The signal handler can be run in athread different than the Python thread, in which case the test decidingif the thread can handle signals is wrong.

  • bpo-42332:types.GenericAlias objects can now be the targets ofweakrefs.

  • bpo-42282: Optimise constant subexpressions that appear as part of namedexpressions (previously the AST optimiser did not descend into namedexpressions). Patch by Nick Coghlan.

  • bpo-42266: Fixed a bug with the LOAD_ATTR opcode cache that was notrespecting monkey-patching a class-level attribute to make it adescriptor. Patch by Pablo Galindo.

  • bpo-40077: Convertqueue to use heap types.

  • bpo-42246: Improved accuracy of line tracing events and f_lineno attributeof Frame objects. See PEP 626 for details.

  • bpo-40077: Convertmmap to use heap types.

  • bpo-42233: AllowGenericAlias objects to useunion typeexpressions. This allows expressions likelist[int]|dict[float,str] where previously aTypeError would have beenthrown. This also fixes union type expressions not de-duplicatingGenericAlias objects. (Contributed by Ken Jin inbpo-42233.)

  • bpo-26131: The import system triggers aImportWarning when it fallsback to usingload_module().

Library

  • bpo-5054: CGIHTTPRequestHandler.run_cgi() HTTP_ACCEPT improperly parsed.Replace the special purpose getallmatchingheaders with generic get_allmethod and add relevant tests.

    Original Patch by Martin Panter. Modified by Senthil Kumaran.

  • bpo-42562: Fix issue when dis failed to parse function that has no linenumbers. Patch provided by Yurii Karabas.

  • bpo-17735:inspect.findsource() now raisesOSError instead ofIndexError whenco_lineno of a code object is greater thanthe file length. This can happen, for example, when a file is edited afterit was imported. PR by Irit Katriel.

  • bpo-42116: Fix handling of trailing comments byinspect.getsource().

  • bpo-42532: Remove unexpected call of__bool__ when passing aspec_arg argument to a Mock.

  • bpo-38200: Added itertools.pairwise()

  • bpo-41818: Fix test_master_read() so that it succeeds on all platformsthat either raise OSError or return b"" upon reading from master.

  • bpo-42487: ChainMap.__iter__ no longer calls __getitem__ on underlyingmaps

  • bpo-42482:TracebackException no longer holds areference to the exception's traceback object. Consequently, instances ofTracebackException for equivalent but non-equal exceptions now compare asequal.

  • bpo-41818: Make test_openpty() avoid unexpected success due to number ofrows and/or number of columns being == 0.

  • bpo-42392: Remove loop parameter fromasyncio.subprocess andasyncio.tasks functions. Patch provided by Yurii Karabas.

  • bpo-42392: Remove loop parameter fromasyncio.open_connection andasyncio.start_server functions. Patch provided by Yurii Karabas.

  • bpo-28468: Addplatform.freedesktop_os_release() function to parsefreedesktop.orgos-release files.

  • bpo-42299: Removed theformatter module, which was deprecated inPython 3.4. It is somewhat obsolete, little used, and not tested. It wasoriginally scheduled to be removed in Python 3.6, but such removals weredelayed until after Python 2.7 EOL. Existing users should copy whateverclasses they use into their code. Patch by Donghee Na and and Terry J.Reedy.

  • bpo-26131: Deprecate zipimport.zipimporter.load_module() in favour ofexec_module().

  • bpo-41818: Updated tests for the pty library. test_basic() has beenchanged to test_openpty(); this additionally checks if slave termios andslave winsize are being set properly by pty.openpty(). In order to addsupport for FreeBSD, NetBSD, OpenBSD, and Darwin, this also addstest_master_read(), which demonstrates that pty.spawn() should not dependon an OSError to exit from its copy loop.

  • bpo-42392: Remove loop parameter from__init__ in allasyncio.locks andasyncio.Queue classes. Patch provided by YuriiKarabas.

  • bpo-15450: Makefilecmp.dircmp respect subclassing. Now thefilecmp.dircmp.subdirs behaves as expected when subclassingdircmp.

  • bpo-42413: The exceptionsocket.timeout is now an alias ofTimeoutError.

  • bpo-31904: Support signal module on VxWorks.

  • bpo-42406: We fixed an issue inpickle.whichmodule in which importingmultiprocessing could change the how pickle identifies which module anobject belongs to, potentially breaking the unpickling of those objects.

  • bpo-42403: Simplify theimportlib external bootstrap code:importlib._bootstrap_external now uses regular imports to importbuiltin modules. When it is imported, the builtin__import__()function is already fully working and so can be used to import builtinmodules likesys. Patch by Victor Stinner.

  • bpo-1635741: Convert _sre module types to heap types (PEP 384). Patch byErlend E. Aasland.

  • bpo-42375: subprocess module update for DragonFlyBSD support.

  • bpo-41713: Port the_signal extension module to the multi-phaseinitialization API (PEP 489). Patch by Victor Stinner and MohamedKoubaa.

  • bpo-37205:time.time(),time.perf_counter() andtime.monotonic() functions can no longer fail with a Python fatalerror, instead raise a regular Python exception on failure.

  • bpo-42328: Fixedtkinter.ttk.Style.map(). The function accepts nowthe representation of the default state as empty sequence (as returned byStyle.map()). The structure of the result is now the same on allplatform and does not depend on the value ofwantobjects.

  • bpo-42345: Fix various issues withtyping.Literal parameter handling(flatten, deduplicate, use type to cache key). Patch provided by YuriiKarabas.

  • bpo-37205:time.perf_counter() on Windows andtime.monotonic()on macOS are now system-wide. Previously, they used an offset computed atstartup to reduce the precision loss caused by the float type. Usetime.perf_counter_ns() andtime.monotonic_ns() added in Python3.7 to avoid this precision loss.

  • bpo-42318: Fixed support of non-BMP characters intkinter on macOS.

  • bpo-42350: Fix thethreading.Thread class at fork: do nothing ifthe thread is already stopped (ex: fork called at Python exit).Previously, an error was logged in the child process.

  • bpo-42333: Port _ssl extension module to heap types.

  • bpo-42014: Theonerror callback fromshutil.rmtree now receivescorrect function whenos.open fails.

  • bpo-42237: Fixos.sendfile() on illumos.

  • bpo-42308: Addthreading.__excepthook__ to allow retrieving theoriginal value ofthreading.excepthook() in case it is set to abroken or a different value. Patch by Mario Corchero.

  • bpo-42131: Implement PEP 451/spec methods on zipimport.zipimporter:find_spec(), create_module(), and exec_module().

    This also allows for the documented deprecation of find_loader(),find_module(), and load_module().

  • bpo-41877: Mock objects which are not unsafe will now raise anAttributeError if an attribute with the prefix asert, aseert, or assrt isaccessed, in addition to this already happening for the prefixes assert orassret.

  • bpo-42264:sqlite3.OptimizedUnicode has been undocumented and obsoletesince Python 3.3, when it was made an alias tostr. It is nowdeprecated, scheduled for removal in Python 3.12.

  • bpo-42251: Addedthreading.gettrace() andthreading.getprofile() to retrieve the functions set bythreading.settrace() andthreading.setprofile() respectively.Patch by Mario Corchero.

  • bpo-42249: Fixed writing binary Plist files larger than 4 GiB.

  • bpo-42236: On Unix, theos.device_encoding() function now returns'UTF-8' rather than the device encoding if thePython UTF-8 Mode is enabled.

  • bpo-41754: webbrowser: IgnoreNotADirectoryError when callingxdg-settings.

  • bpo-42183: Fix a stack overflow error for asyncio Task or Future repr().

    The overflow occurs under some circumstances when a Task or Futurerecursively returns itself.

  • bpo-42140: Improve asyncio.wait function to create the futures set justone time.

  • bpo-42133: Update various modules in the stdlib to fall back on__spec__.loader when__loader__ isn't defined on a module.

  • bpo-26131: Theload_module() methods found inimportlib nowtrigger aDeprecationWarning.

  • bpo-39825: Windows: Changesysconfig.get_config_var('EXT_SUFFIX') tothe expected fullplatform_tag.extension format. Previously it washard-coded to.pyd, now it is compatible withdistutils.sysconfigand will result in something like.cp38-win_amd64.pyd. This bringswindows into conformance with the other platforms.

  • bpo-26389: Thetraceback.format_exception(),traceback.format_exception_only(), andtraceback.print_exception() functions can now take an exceptionobject as a positional-only argument.

  • bpo-41889: Enum: fix regression involving inheriting a multiply inheritedenum

  • bpo-41861: Convertsqlite3 to use heap types (PEP 384). Patch byErlend E. Aasland.

  • bpo-40624: Added support for the XPath!= operator in xml.etree

  • bpo-28850: Fixpprint.PrettyPrinter.format() overrides being ignoredfor contents of small containers. Thepprint._safe_repr() functionwas removed.

  • bpo-41625: Expose thesplice() asos.splice() in theos module. Patch by Pablo Galindo

  • bpo-34215: Clarify the error message forasyncio.IncompleteReadError whenexpected isNone.

  • bpo-41543: Add async context manager support for contextlib.nullcontext.

  • bpo-21041:pathlib.PurePath.parents now supports negativeindexing. Patch contributed by Yaroslav Pankovych.

  • bpo-41332: Added missing connect_accepted_socket() method toasyncio.AbstractEventLoop.

  • bpo-12800: Extracting a symlink from a tarball should succeed andoverwrite the symlink if it already exists. The fix is to remove theexisting file or symlink before extraction. Based on patch by Chris AtLee,Jeffrey Kintscher, and Senthil Kumaran.

  • bpo-40968:urllib.request andhttp.client now sendhttp/1.1 ALPN extension during TLS handshake when no custom context issupplied.

  • bpo-41001: Addos.eventfd() to provide a low level interface forLinux's event notification file descriptor.

  • bpo-40816: Add AsyncContextDecorator to contextlib to support asynccontext manager as a decorator.

  • bpo-40550: Fix time-of-check/time-of-action issue insubprocess.Popen.send_signal.

  • bpo-39411: Add anis_async identifier topyclbr'sFunctionobjects. Patch by Batuhan Taskaya

  • bpo-35498: Add slice support topathlib.PurePath.parents.

Documentation

  • bpo-42238: Tentative to deprecatemakesuspicious by first removing itfrom the CI and documentation builds, but keeping it around for manualuses.

  • bpo-42153: Fix the URL for the IMAP protocol documents.

  • bpo-41028: Language and version switchers, previously maintained in everycpython branches, are now handled by docsbuild-script.

Tests

  • bpo-41473: Re-enable test_gdb on gdb 9.2 and newer:https://bugzilla.redhat.com/show_bug.cgi?id=1866884 bug is fixed in gdb10.1.

  • bpo-42553: Fixtest_asyncio.test_call_later() race condition: don'tmeasure asyncio performance in thecall_later() unit test. The testfailed randomly on the CI.

  • bpo-31904: Fix test_netrc on VxWorks: create temporary directories usingtemp_cwd().

  • bpo-31904: skip test_getaddrinfo_ipv6_scopeid_symbolic andtest_getnameinfo_ipv6_scopeid_symbolic on VxWorks

  • bpo-31904: skip test_test of test_mailcap on VxWorks

  • bpo-31904: add shell requirement for test_pipes

  • bpo-31904: skip some tests related to fifo on VxWorks

  • bpo-31904: Fix test_doctest.py failures for VxWorks.

  • bpo-40754: Include_testinternalcapi module in Windows installer fortest suite

  • bpo-41561: test_ssl: skip test_min_max_version_mismatch when TLS 1.0 isnot available

  • bpo-31904: Fix os module failures for VxWorks RTOS.

  • bpo-31904: Fix fifo test cases for VxWorks RTOS.

Build

  • bpo-31904: remove libnet dependency from detect_socket() for VxWorks

  • bpo-42398: Fix a race condition in "make regen-all" when make -jN optionis used to run jobs in parallel. The clinic.py script now only use atomicwrite to write files. Moveover, generated files are now left unchanged ifthe content does not change, to not change the file modification time.

  • bpo-41617: Fix buildingpycore_bitutils.h internal header on old clangversion without__builtin_bswap16() (ex: Xcode 4.6.3 on Mac OS X10.7). Patch by Joshua Root and Victor Stinner.

  • bpo-38823: It is no longer possible to build the_ctypes extensionmodule withoutwchar_t type: removeCTYPES_UNICODE macro.Anyway, thewchar_t type is required to build Python. Patch byVictor Stinner.

  • bpo-42087: Support was removed for AIX 5.3 and below. Seebpo-40680.

  • bpo-40998: Addressed three compiler warnings found by undefined behaviorsanitizer (ubsan).

Windows

  • bpo-42120: Remove macro definition ofcopysign (to_copysign) inheaders.

  • bpo-38506: The Windows launcher now properly handles Python 3.10 whenlisting installed Python versions.

macOS

  • bpo-42504: Fix build on macOS Big Sur when MACOSX_DEPLOYMENT_TARGET=11

  • bpo-41116: Ensure distutils.unixxcompiler.find_library_file can findsystem provided libraries on macOS 11.

  • bpo-41100: Add support for macOS 11 and Apple Silicon systems.

    It is now possible to build "Universal 2" binaries using"--enable-universalsdk --with-universal-archs=universal2".

    Binaries build on later macOS versions can be deployed back to olderversions (tested up to macOS 10.9), when using the correct deploymenttarget. This is tested using Xcode 11 and later.

  • bpo-42232: Added Darwin specific madvise options to mmap module.

  • bpo-38443: The--enable-universalsdk and--with-universal-archsoptions for the configure script now check that the specifiedarchitectures can be used.

IDLE

  • bpo-42508: Keep IDLE running on macOS. Remove obsolete workaround thatprevented running files with shortcuts when using new universal2installers built on macOS 11.

  • bpo-42426: Fix reporting offset of the RE error in searchengine.

  • bpo-42415: Get docstrings for IDLE calltips more often by usinginspect.getdoc.

Tools/Demos

  • bpo-42212: The smelly.py script now also checks the Python dynamic libraryand extension modules, not only the Python static library. Make also thescript more verbose: explain what it does.

  • bpo-36310: AllowTools/i18n/pygettext.py to detect calls togettext in f-strings.

C API

Python 3.10.0 alpha 2

Release date: 2020-11-03

Security

  • bpo-42103: Prevented potential DoS attack via CPU and RAM exhaustion whenprocessing malformed Apple Property List files in binary format.

  • bpo-42051: Theplistlib module no longer accepts entitydeclarations in XML plist files to avoid XML vulnerabilities. This shouldnot affect users as entity declarations are not used in regular plistfiles.

Core and Builtins

  • bpo-42236: If thenl_langinfo(CODESET) function returns an emptystring, Python now uses UTF-8 as the filesystem encoding. Patch by VictorStinner.

  • bpo-42218: Fixed a bug in the PEG parser that was causing crashes in debugmode. Now errors are checked in left-recursive rules to avoid cases wheresuch errors do not get handled in time and appear as long-distance crashesin other places.

  • bpo-42214: Fixed a possible crash in the PEG parser when checking for the'!=' token in thebarry_as_flufl rule. Patch by Pablo Galindo.

  • bpo-42206: Propagate and raise the errors caused byPyAST_Validate() in the parser.

  • bpo-41796: Theast module internal state is now per interpreter.Patch by Victor Stinner.

  • bpo-42143: Fix handling of errors during creation ofPyFunctionObject,which resulted in operations on uninitialized memory. Patch by YonatanGoldschmidt.

  • bpo-41659: Fix a bug in the parser, where a curly brace following aprimary didn't fail immediately. This led to invalid expressions likea{b} to throw aSyntaxError with a wrong offset, or invalidexpressions ending with a curly brace likea{ to not fail immediatelyin the REPL.

  • bpo-42150: Fix possible buffer overflow in the new parser when checkingfor continuation lines. Patch by Pablo Galindo.

  • bpo-42123: Run the parser two times. On the first run, disable all therules that only generate better error messages to gain performance. Ifthere's a parse failure, run the parser a second time with those enabled.

  • bpo-42093: TheLOAD_ATTR instruction now uses new "per opcode cache"mechanism and it is about 36% faster now. Patch by Pablo Galindo and YurySelivanov.

  • bpo-42030: Support for the legacy AIX-specific shared library loadingsupport has been removed. All versions of AIX since 4.3 have supported anddefaulted to using the common Unix mechanism instead.

  • bpo-41984: The garbage collector now tracks all user-defined classes.Patch by Brandt Bucher.

  • bpo-41993: Fixed potential issues with removing not completely initializedmodule fromsys.modules when import fails.

  • bpo-41979: Star-unpacking is now allowed for with item's targets in thePEG parser.

  • bpo-41974: Removed special methods__int__,__float__,__floordiv__,__mod__,__divmod__,__rfloordiv__,__rmod__ and__rdivmod__ of thecomplex class. Theyalways raised aTypeError.

  • bpo-41902: Micro optimization when computesq_item andmp_subscript ofrange. Patch byDonghee Na.

  • bpo-41894: When loading a native module and a load failure occurs, preventa possible UnicodeDecodeError when not running in a UTF-8 locale bydecoding the load error message using the current locale's encoding.

  • bpo-41902: Micro optimization for range.index if step is 1. Patch byDonghee Na.

  • bpo-41435: Addsys._current_exceptions() function to retrieve adictionary mapping each thread's identifier to the topmost exceptioncurrently active in that thread at the time the function is called.

  • bpo-38605: Enablefrom__future__importannotations (PEP 563) bydefault. The values found in__annotations__ dicts are nowstrings, for example{"x":"int"} instead of{"x":int}.

Library

  • bpo-35455: On Solaris,thread_time() is now implemented withgethrvtime() becauseclock_gettime(CLOCK_THREAD_CPUTIME_ID) is notalways available. Patch by Jakub Kulik.

  • bpo-42233: Therepr() oftyping types containingGeneric Alias Types previously did not showthe parameterized types in theGenericAlias. They have now beenchanged to do so.

  • bpo-29566:binhex.binhex() consistently writes macOS 9 line endings.

  • bpo-26789: Thelogging.FileHandler class now keeps a reference tothe builtinopen() function to be able to open or reopen the fileduring Python finalization. Fix errors like:NameError:name'open'isnotdefined. Patch by Victor Stinner.

  • bpo-42157: Removed theunicodedata.ucnhash_CAPI attribute which was aninternal PyCapsule object. The related private_PyUnicode_Name_CAPIstructure was moved to the internal C API. Patch by Victor Stinner.

  • bpo-42157: Convert theunicodedata extension module to themultiphase initialization API (PEP 489) and convert theunicodedata.UCD static type to a heap type. Patch by Mohamed Koubaaand Victor Stinner.

  • bpo-42146: Fix memory leak insubprocess.Popen() in case an uid(gid) specified inuser (group,extra_groups) overflowsuid_t (gid_t).

  • bpo-42103:InvalidFileException andRecursionErrorare now the only errors caused by loading malformed binary Plist file(previously ValueError and TypeError could be raised in some specificcases).

  • bpo-41490: Inimportlib.resources,.path method is more aggressiveabout releasing handles to zipfile objects early, enabling use-cases likecertifi to leave the context open but delete the underlying zip file.

  • bpo-41052: Pickling heap types implemented in C with protocols 0 and 1raises now an error instead of producing incorrect data.

  • bpo-42089: Inimportlib.metadata.PackageNotFoundError, make referenceto the package metadata being missing to improve the user experience.

  • bpo-41491: plistlib: fix parsing XML plists with hexadecimal integervalues

  • bpo-42065: Fix an incorrectly formatted error from_codecs.charmap_decode() when called with a mapped value outsidethe range of valid Unicode code points. PR by Max Bernstein.

  • bpo-41966: Fix pickling pure Pythondatetime.time subclasses.Patch by Dean Inwood.

  • bpo-19270:sched.scheduler.cancel() will now cancel the correctevent, if two events with same priority are scheduled for the same time.Patch by Bar Harel.

  • bpo-28660:textwrap.wrap() now attempts to break long words afterhyphens whenbreak_long_words=True andbreak_on_hyphens=True.

  • bpo-35823: Usevfork() instead offork() forsubprocess.Popen() on Linux to improve performance in cases where itis deemed safe.

  • bpo-42043: Add support forzipfile.Path inheritance.zipfile.Path.is_file() now returns False for non-existent names.zipfile.Path objects now expose a.filename attribute and rely onthat to resolve.name and.parent when thePath object is atthe root of the zipfile.

  • bpo-42021: Fix possible ref leaks insqlite3 module init.

  • bpo-39101: Fixed tests using IsolatedAsyncioTestCase from hanging onBaseExceptions.

  • bpo-41976: Fixed a bug that was causingctypes.util.find_library()to returnNone when triying to locate a library in an environment whengcc>=9 is available andldconfig is not. Patch by Pablo Galindo

  • bpo-41943: Fix bug where TestCase.assertLogs doesn't correctly filtermessages by level.

  • bpo-41923: ImplementPEP 613, introducingtyping.TypeAliasannotation.

  • bpo-41905: A new function in abc:update_abstractmethods to re-calculatean abstract class's abstract status. In addition,dataclass has beenchanged to call this function.

  • bpo-23706: Addednewline parameter topathlib.Path.write_text().

  • bpo-41876: Tkinter font class repr uses font name

  • bpo-41831:str() for thetype attribute of thetkinter.Eventobject always returns now the numeric code returned by Tk instead of thename of the event type.

  • bpo-39337:encodings.normalize_encoding() now ignores non-ASCIIcharacters.

  • bpo-41747: Ensure all methods that generated fromdataclasses.dataclass() objects now have the proper__qualname__attribute referring to the class they belong to. Patch by Batuhan Taskaya.

  • bpo-30681: Handle exceptions caused by unparsable date headers when usingemail "default" policy. Patch by Tim Bell, Georges Toth

  • bpo-41586: Add F_SETPIPE_SZ and F_GETPIPE_SZ to fcntl module. Allowsetting pipesize on subprocess.Popen.

  • bpo-41229: Addcontextlib.aclosing for deterministic cleanup of asyncgenerators which is analogous tocontextlib.closing for non-asyncgenerators. Patch by Joongi Kim and John Belmonte.

  • bpo-16396: Allowctypes.wintypes to be imported on non-Windowssystems.

  • bpo-4356: Add a key function to the bisect module.

  • bpo-40592:shutil.which() now ignores empty entries inPATHEXT instead of treating them as a match.

  • bpo-40492: Fix--outfile forcProfile /profile notwriting the output file in the original directory when the program beingprofiled changes the working directory. PR by Anthony Sottile.

  • bpo-34204: Theshelve module now usespickle.DEFAULT_PROTOCOL by default instead ofpickleprotocol3.

  • bpo-27321: Fixed KeyError exception when flattening an email to a stringattempts to replace a non-existent Content-Transfer-Encoding header.

  • bpo-38976: Thehttp.cookiejar module now supports the parsing ofcookies in CURL-style cookiejar files through MozillaCookieJar on allplatforms. Previously, such cookie entries would be silently ignored whenloading a cookiejar with such entries.

    Additionally, the HTTP Only attribute is persisted in the object, and willbe correctly written to file if the MozillaCookieJar object issubsequently dumped.

Documentation

  • bpo-42061: Document __format__ functionality for IP addresses.

  • bpo-41910: Document the default implementation ofobject.__eq__.

  • bpo-42010: Clarify that subscription expressions are also valid forcertainclasses andtypes in the standardlibrary, and for user-defined classes and types if the classmethod__class_getitem__() is provided.

  • bpo-41805: Documentedgeneric alias type andtypes.GenericAlias. Also added an entry in glossary forgeneric types.

  • bpo-39693: Fix tarfile's extractfile documentation

  • bpo-39416: Document some restrictions on the default stringrepresentations of numeric classes.

Tests

  • bpo-41739: Fix test_logging.test_race_between_set_target_and_flush(): thetest now waits until all threads complete to avoid leaking runningthreads.

  • bpo-41970: Avoid a test failure intest_lib2to3 if the module hasalready imported at the time the test executes. Patch by Pablo Galindo.

  • bpo-41944: Tests for CJK codecs no longer calleval() on contentreceived via HTTP.

  • bpo-41306: Fixed a failure intest_tk.test_widgets.ScaleTest happeningwhen executing the test with Tk 8.6.10.

Build

  • bpo-38980: Add-fno-semantic-interposition to both the compile andlink line when building with--enable-optimizations. Patch by VictorStinner and Pablo Galindo.

Windows

  • bpo-38439: Updates the icons for IDLE in the Windows Store package.

  • bpo-38252: Use 8-byte step to detect ASCII sequence in 64-bit Windowsbuild.

  • bpo-39107: Update Tcl and Tk to 8.6.10 in Windows installer.

  • bpo-41557: Update Windows installer to use SQLite 3.33.0.

  • bpo-38324: Avoid Unicode errors when accessing certain locale data onWindows.

macOS

  • bpo-41471: Ignore invalid prefix lengths in system proxy excludes.

IDLE

  • bpo-33987: Mostly finish using ttk widgets, mainly for editor, settings,and searches. Some patches by Mark Roseman.

  • bpo-40511: Typing opening and closing parentheses inside the parenthesesof a function call will no longer cause unnecessary "flashing" off and onof an existing open call-tip, e.g. when typed in a string literal.

  • bpo-38439: Add a 256×256 pixel IDLE icon to the Windows .ico file. Createdby Andrew Clover. Remove the low-color gif variations from the .ico file.

C API

  • bpo-42157: The private_PyUnicode_Name_CAPI structure of the PyCapsuleAPIunicodedata.ucnhash_CAPI has been moved to the internal C API.Patch by Victor Stinner.

  • bpo-42015: Fix potential crash in deallocating method objects whendynamically allocatedPyMethodDef's lifetime is managed throughtheself argument of aPyCFunction.

  • bpo-40423: Thesubprocess module andos.closerange will now usetheclose_range(low,high,flags) syscall when it is available formore efficient closing of ranges of descriptors.

  • bpo-41845:PyObject_GenericGetDict() is available again in thelimited API when targeting 3.10 or later.

  • bpo-40422: Add_Py_closerange function to provide performant closingof a range of file descriptors.

  • bpo-41986:Py_FileSystemDefaultEncodeErrors andPy_UTF8Mode are available again in limited API.

  • bpo-41756: AddPyIter_Send function to allow sending value intogenerator/coroutine/iterator without raising StopIteration exception tosignal return.

  • bpo-41784: AddedPyUnicode_AsUTF8AndSize to the limited C API.

Python 3.10.0 alpha 1

Release date: 2020-10-05

Security

  • bpo-41304: Fixespython3x._pth being ignored on Windows, caused by thefix forbpo-29778 (CVE 2020-15801).

  • bpo-41162: Audit hooks are now cleared later during finalization to avoidmissing events.

  • bpo-29778: Ensurepython3.dll is loaded from correct locationswhen Python is embedded (CVE 2020-15523).

  • bpo-41004: The __hash__() methods of ipaddress.IPv4Interface andipaddress.IPv6Interface incorrectly generated constant hash values of 32and 128 respectively. This resulted in always causing hash collisions. Thefix uses hash() to generate hash values for the tuple of (address, masklength, network address).

  • bpo-39603: Prevent http header injection by rejecting control charactersin http.client.putrequest(...).

Core and Builtins

  • bpo-41909: Fixed stack overflow inissubclass() andisinstance() when getting the__bases__ attribute leads toinfinite recursion.

  • bpo-41922: Speed up calls toreversed() by using thePEP 590vectorcall calling convention. Patch by Donghee Na.

  • bpo-41873: Calls tofloat() are now faster due to thevectorcallcalling convention. Patch by Dennis Sweeney.

  • bpo-41870: Speed up calls tobool() by using thePEP 590vectorcall calling convention. Patch by Donghee Na.

  • bpo-1635741: Port the_bisect module to the multi-phaseinitialization API (PEP 489).

  • bpo-39934: Correctly count control blocks in 'except' in compiler. Ensuresthat a syntax error, rather a fatal error, occurs for deeply nested, namedexception handlers.

  • bpo-41780: Fix__dir__() oftypes.GenericAlias. Patch byBatuhan Taskaya.

  • bpo-1635741: Port the_lsprof extension module to multi-phaseinitialization (PEP 489).

  • bpo-1635741: Port thecmath extension module to multi-phaseinitialization (PEP 489).

  • bpo-1635741: Port the_scproxy extension module to multi-phaseinitialization (PEP 489).

  • bpo-1635741: Port thetermios extension module to multi-phaseinitialization (PEP 489).

  • bpo-1635741: Convert the_sha256 extension module types to heaptypes.

  • bpo-41690: Fix a possible stack overflow in the parser when parsingfunctions and classes with a huge amount of arguments. Patch by PabloGalindo.

  • bpo-1635741: Port the_overlapped extension module to multi-phaseinitialization (PEP 489).

  • bpo-1635741: Port the_curses_panel extension module tomulti-phase initialization (PEP 489).

  • bpo-1635741: Port the_opcode extension module to multi-phaseinitialization (PEP 489).

  • bpo-41681: Fixes the wrong error description in the error raised by using2, in format string in f-string andstr.format().

  • bpo-41675: The implementation ofsignal.siginterrupt() now usessigaction() (if it is available in the system) instead of thedeprecatedsiginterrupt(). Patch by Pablo Galindo.

  • bpo-41670: Prevent line trace being skipped on platforms not compiled withUSE_COMPUTED_GOTOS. Fixes issue where some lines nested within atry-except block were not being traced on Windows.

  • bpo-41654: Fix a crash that occurred when destroying subclasses ofMemoryError. Patch by Pablo Galindo.

  • bpo-1635741: Port thezlib extension module to multi-phaseinitialization (PEP 489).

  • bpo-41631: The_ast module uses again a global state. Using a modulestate per module instance is causing subtle practical problems. Forexample, the Mercurial project replaces the__import__() function toimplement lazy import, whereas Python expected thatimport_ast alwaysreturn a fully initialized_ast module.

  • bpo-40077: Convert_operator to usePyType_FromSpec().

  • bpo-1653741: Port_sha3 to multi-phase init. Convert static typesto heap types.

  • bpo-1635741: Port the_blake2 extension module to the multi-phaseinitialization API (PEP 489).

  • bpo-41533: Free the stack allocated inva_build_stack ifdo_mkstack fails and the stack is not asmall_stack.

  • bpo-41531: Fix a bug that was dropping keys when compiling dict literalswith more than 0xFFFF elements. Patch by Pablo Galindo.

  • bpo-41525: The output ofpython--help contains now only ASCIIcharacters.

  • bpo-1635741: Port the_sha1,_sha512, and_md5extension modules to multi-phase initialization API (PEP 489).

  • bpo-41431: Optimizedict_merge() for copying dict (e.g.dict(d)and{}.update(d)).

  • bpo-41428: Implement PEP 604. This supports (int | str) etc. in place ofUnion[str, int].

  • bpo-41340: Removed fallback implementation forstrdup.

  • bpo-38156: Handle interrupts that come after EOF correctly inPyOS_StdioReadline.

  • bpo-41342:round() with integer argument is now faster (9--60%).

  • bpo-41334: Constructorsstr(),bytes() andbytearray()are now faster (around 30--40% for small objects).

  • bpo-41295: Resolve a regression in CPython 3.8.4 where defining"__setattr__" in a multi-inheritance setup and calling up the hierarchychain could fail if builtins/extension types were involved in the basetypes.

  • bpo-41323: Bytecode optimizations are performed directly on the controlflow graph. This will result in slightly more compact code objects in somecircumstances.

  • bpo-41247: Always cache the running loop holder when runningasyncio.set_running_loop.

  • bpo-41252: Fix incorrect refcounting in _ssl.c's_servername_callback().

  • bpo-1635741: Portmultiprocessing to multi-phase initialization

  • bpo-1635741: Portwinapi to multiphase initialization

  • bpo-41215: Use non-NULL default values in the PEG parser keyword list toovercome a bug that was preventing Python from being properly compiledwhen using the XLC compiler. Patch by Pablo Galindo.

  • bpo-41218: Python 3.8.3 had a regression where compiling withast.PyCF_ALLOW_TOP_LEVEL_AWAIT would aggressively mark list comprehensionwith CO_COROUTINE. Now only list comprehension making use of async/awaitwill tagged as so.

  • bpo-1635741: Portfaulthandler to multiphase initialization.

  • bpo-1635741: Portsha256 to multiphase initialization

  • bpo-41175: Guard against a NULL pointer dereference within bytearrayobjecttriggered by thebytearray()+bytearray() operation.

  • bpo-41100: add arm64 to the allowable Mac OS arches in mpdecimal.h

  • bpo-41094: Fix decoding errors with audit when open files with non-ASCIInames on non-UTF-8 locale.

  • bpo-39960: The "hackcheck" that prevents sneaking around a type's__setattr__() by calling the superclass method was rewritten to allow Cimplemented heap types.

  • bpo-41084: Prefix the error message with 'f-string: ', when parsing anf-string expression which throws aSyntaxError.

  • bpo-40521: Empty frozensets are no longer singletons.

  • bpo-41076: Pre-feed the parser with the location of the f-stringexpression, not the f-string itself, which allows us to skip the shiftingof the AST node locations after the parsing is completed.

  • bpo-41056: Fixes a reference to deallocated stack space during startupwhen constructing sys.path involving a relative symlink when code wassupplied via -c. (discovered via Coverity)

  • bpo-41061: Fix incorrect expressions and asserts in hashtable code andtests.

  • bpo-41052: Opt out serialization/deserialization for _random.Random

  • bpo-40939: RenamePyPegen* functions toPyParser*, so that we canremove the old set ofPyParser* functions that were using the oldparser, but keep everything backwards-compatible.

  • bpo-35975: Stefan Behnel reported that cf_feature_version is used evenwhen PyCF_ONLY_AST is not set. This is against the intention and againstthe documented behavior, so it's been fixed.

  • bpo-40939: Remove the remaining files from the old parser and thesymbol module.

  • bpo-40077: Convert_bz2 to usePyType_FromSpec().

  • bpo-41006: Theencodings.latin_1 module is no longer imported atstartup. Now it is only imported when it is the filesystem encoding or thestdio encoding.

  • bpo-40636:zip() now supportsPEP 618'sstrict parameter,which raises aValueError if the arguments are exhausted atdifferent lengths. Patch by Brandt Bucher.

  • bpo-1635741: Port_gdbm to multiphase initialization.

  • bpo-40985: Fix a bug that caused theSyntaxError text to be emptywhen a file ends with a line ending in a line continuation character (i.e.backslash). The error text should contain the text of the last line.

  • bpo-40958: Fix a possible buffer overflow in the PEG parser when gatheringinformation for emitting syntax errors. Patch by Pablo Galindo.

  • bpo-1635741: Port_dbm to multiphase initialization.

  • bpo-40957: Fix refleak in _Py_fopen_obj() when PySys_Audit() fails

  • bpo-40950: Add a state to thenis module (PEP 3121) and applythe multiphase initialization. Patch by Donghee Na.

  • bpo-40947: The PythonPath Configuration nowtakesPyConfig.platlibdir in account.

  • bpo-40939: Remove the old parser, theparser module and allassociated support code, command-line options and environment variables.Patch by Pablo Galindo.

  • bpo-40847: Fix a bug where a line with only a line continuation characteris not considered a blank line at tokenizer level. In such cases, morethan a singleNEWLINE token was emitted. The old parser was workingaround the issue, but the new parser threw aSyntaxError for validinput due to this. For example, an empty line following a linecontinuation character was interpreted as aSyntaxError.

  • bpo-40890: Each dictionary view now has amapping attribute thatprovides atypes.MappingProxyType wrapping the originaldictionary. Patch contributed by Dennis Sweeney.

  • bpo-40889: Improved the performance of symmetric difference operations ondictionary item views. Patch by Dennis Sweeney.

  • bpo-40904: Fix possible segfault in the new PEG parser when parsingf-string containing yield statements with no value (f"{yield}").Patch by Pablo Galindo

  • bpo-40903: Fixed a possible segfault in the new PEG parser when producingerror messages for invalid assignments of the formp=p=. Patch byPablo Galindo

  • bpo-40880: Fix invalid memory read in the new parser when checkingnewlines in string literals. Patch by Pablo Galindo.

  • bpo-40883: Fix memory leak in when parsing f-strings in the new parser.Patch by Pablo Galindo

  • bpo-40870: RaiseValueError when validating custom AST's where theconstantsTrue,False andNone are used within aast.Name node.

  • bpo-40854: Allow overridingsys.platlibdir via a newPYTHONPLATLIBDIR environment variable.

  • bpo-40826: Fix GIL usage inPyOS_Readline(): lock the GIL to setan exception and pass the Python thread state when checking if there is apending signal.

  • bpo-1635741: Portfcntl to multiphase initialization.

  • bpo-19468: Delete unnecessary instance check in importlib.reload(). Patchby Furkan Önder.

  • bpo-40824: Unexpected errors in calling the__iter__ method are nolonger masked byTypeError in thein operator and functionscontains(),indexOf() andcountOf() of theoperator module.

  • bpo-40792: Attributesstart,stop andstep of therange object now always has exact typeint. Previously,they could have been an instance of a subclass ofint.

  • bpo-40780: Fix a corner case where g-style string formatting of a floatfailed to remove trailing zeros.

  • bpo-38964: When there's aSyntaxError in the expression part of anfstring, the filename attribute of theSyntaxError gets correctlyset to the name of the file the fstring resides in.

  • bpo-40750: Support the "-d" debug flag in the new PEG parser. Patch byPablo Galindo

  • bpo-40217: Instances of types created withPyType_FromSpecWithBases() will no longer automatically visittheir class object when traversing references in the garbage collector.The user is expected to manually visit the object's class. Patch by PabloGalindo.

  • bpo-39573:Py_TYPE() is changed to the inline static function.Patch by Donghee Na.

  • bpo-40696: Fix a hang that can arise aftergenerator.throw() due toa cycle in the exception context chain.

  • bpo-40521: Each interpreter now its has own free lists, singletons andcaches:

    • Free lists: float, tuple, list, dict, frame, context,asynchronous generator, MemoryError.

    • Singletons: empty tuple, empty bytes string, empty Unicode string,single byte character, single Unicode (latin1) character.

    • Slice cache.

    They are no longer shared by all interpreters.

  • bpo-40679: CertainTypeError messages about missing or extraarguments now include the function'squalified name. Patch byDennis Sweeney.

  • bpo-29590: Make the stack trace correct after callinggenerator.throw() on a generator that has yielded from ayieldfrom.

  • bpo-4022: Improve performance of generators by not raising internalStopIteration.

  • bpo-1635741: Portmmap to multiphase initialization.

  • bpo-1635741: Port_lzma to multiphase initialization.

  • bpo-37999: Builtin and extension functions that take integer arguments nolonger acceptDecimals,Fractions and other objects that can be converted to integers only with a loss(e.g. that have the__int__() method but do not have the__index__() method).

  • bpo-29882: Addint.bit_count(), counting the number of ones in thebinary representation of an integer. Patch by Niklas Fiekas.

  • bpo-36982: Use ncurses extended color functions when available to supportterminals with 256 colors, and add the new functioncurses.has_extended_color_support() to indicate whether extendedcolor support is provided by the underlying ncurses library.

  • bpo-19569: Add the private macros_Py_COMP_DIAG_PUSH,_Py_COMP_DIAG_IGNORE_DEPR_DECLS, and_Py_COMP_DIAG_POP.

  • bpo-26680: The int type now supports the x.is_integer() method forcompatibility with float.

Library

  • bpo-41900: C14N 2.0 serialisation in xml.etree.ElementTree failed forunprefixed attributes when a default namespace was defined.

  • bpo-41887: Strip leading spaces and tabs onast.literal_eval(). Alsodocument stripping of spaces and tabs foreval().

  • bpo-41773: Note in documentation thatrandom.choices() doesn'tsupport non-finite weights, raiseValueError when given non-finiteweights.

  • bpo-41840: Fix a bug in thesymtable module that was causingmodule-scope global variables to not be reported as both local and global.Patch by Pablo Galindo.

  • bpo-41842: Addcodecs.unregister() function to unregister a codecsearch function.

  • bpo-40564: Inzipfile.Path, mutate the passed ZipFile object typeinstead of making a copy. Prevents issues when both the local copy and thecaller’s copy attempt to close the same file handle.

  • bpo-40670: More reliable validation of statements intimeit.Timer. It now accepts "empty" statements (only whitespacesand comments) and rejects misindentent statements.

  • bpo-41833: Thethreading.Thread constructor now uses the targetname if thetarget argument is specified but thename argument isomitted.

  • bpo-41817: fixtkinter.EventType Enum so all members are strings, andnone are tuples

  • bpo-41810:types.EllipsisType,types.NotImplementedTypeandtypes.NoneType have been reintroduced, providing a new set oftypes readily interpretable by static type checkers.

  • bpo-41815: Fix SQLite3 segfault when backing up closed database. Patchcontributed by Peter David McCormick.

  • bpo-41816: StrEnum added: it ensures that all members are already stringsor string candidates

  • bpo-41517: fix bug allowing Enums to be extended via multiple inheritance

  • bpo-39587: use the correct mix-in data type when constructing Enums

  • bpo-41792: Add is_typeddict function to typing.py to check if a type is aTypedDict class

    Previously there was no way to check that without using private API. Seetherelevant issue in python/typing.

  • bpo-41789: Honorobject overrides inEnum class creation(specifically,__str__,__repr__,__format__, and__reduce_ex__).

  • bpo-32218:enum.Flag andenum.IntFlag members are now iterable.

  • bpo-39651: Fix a race condition in thecall_soon_threadsafe() methodofasyncio.ProactorEventLoop: do nothing if the self-pipe socket hasbeen closed.

  • bpo-1635741: Port themashal extension module to the multi-phaseinitialization API (PEP 489).

  • bpo-1635741: Port the_string extension module to the multi-phaseinitialization API (PEP 489).

  • bpo-41732: Added aniterator tomemoryview.

  • bpo-41720: Fixedturtle.Vec2D.__rmul__() for arguments which are notint or float.

  • bpo-41696: Fix handling of debug mode inasyncio.run(). This allowssettingPYTHONASYNCIODEBUG or-Xdev to enable asyncio debug modewhen usingasyncio.run().

  • bpo-41687: Fix implementation of sendfile to be compatible with Solaris.

  • bpo-41662: No longer override exceptions raised in__len__() of asequence of parameters insqlite3 withProgrammingError.

  • bpo-39010: Restarting aProactorEventLoop on Windows no longer logsspuriousConnectionResetErrors.

  • bpo-41638:ProgrammingError message for absent parameterinsqlite3 contains now the name of the parameter instead of itsindex when parameters are supplied as a dict.

  • bpo-41662: Fixed crash when mutate list of parameters during iteration insqlite3.

  • bpo-41513: Improved the accuracy of math.hypot(). Internally, each stepis computed with extra precision so that the result is now almost alwayscorrectly rounded.

  • bpo-41609: The pdb whatis command correctly reports instance methods as'Method' rather than 'Function'.

  • bpo-39994: Fixed pprint's handling of dict subclasses that override__repr__.

  • bpo-32751: When cancelling the task due to a timeout,asyncio.wait_for() will now wait until the cancellation is completealso in the case whentimeout is <= 0, like it does with positivetimeouts.

  • bpo-37658:asyncio.wait_for() now properly handles races betweencancellation of itself and the completion of the wrapped awaitable.

  • bpo-40782: Change the method asyncio.AbstractEventLoop.run_in_executor tonot be a coroutine.

  • bpo-41520: Fixcodeop regression that prevented turning compilewarnings into errors.

  • bpo-41528: turtle uses math module functions to convert degrees to radiansand vice versa and to calculate vector norm

  • bpo-41513: Minor algorithmic improvement to math.hypot() and math.dist()giving small gains in speed and accuracy.

  • bpo-41503: Fixed a race between setTarget and flush inlogging.handlers.MemoryHandler.

  • bpo-41497: Fix potential UnicodeDecodeError in dis module.

  • bpo-41467: On Windows, fix asynciorecv_into() return value when thesocket/pipe is closed (BrokenPipeError): return0 rather thanan empty byte string (b'').

  • bpo-41425: Make tkinter doc example runnable.

  • bpo-41421: Make an algebraic simplification to random.paretovariate(). Itnow is slightly less subject to round-off error and is slightly faster.Inputs that used to cause ZeroDivisionError now cause an OverflowErrorinstead.

  • bpo-41440: Addos.cpu_count() support for VxWorks RTOS.

  • bpo-41316: Fix thetarfile module to write only basename of TARfile to GZIP compression header.

  • bpo-41384: Raise TclError instead of TypeError when an unknown option ispassed to tkinter.OptionMenu.

  • bpo-41317: Use add_done_callback() in asyncio.loop.sock_accept() tounsubscribe reader early on cancellation.

  • bpo-41364: Reduce import overhead ofuuid.

  • bpo-35328: Set the environment variableVIRTUAL_ENV_PROMPT atvenv activation.

  • bpo-41341: Recursive evaluation oftyping.ForwardRef inget_type_hints.

  • bpo-41344: Prevent creatingshared_memory.SharedMemory objectswithsize=0.

  • bpo-41333:collections.OrderedDict.pop() is now 2 times faster.

  • bpo-41288: Unpickling invalid NEWOBJ_EX opcode with the C implementationraises now UnpicklingError instead of crashing.

  • bpo-39017: Avoid infinite loop when reading specially crafted TAR filesusing the tarfile module (CVE 2019-20907).

  • bpo-41273: Speed up any transport using_ProactorReadPipeTransport bycallingrecv_into instead ofrecv, thus not creating a new bufferfor eachrecv call in the transport's read loop.

  • bpo-41235: Fix the error handling inssl.SSLContext.load_dh_params().

  • bpo-41207: In distutils.spawn, restore expectation that DistutilsExecErroris raised when the command is not found.

  • bpo-29727: Registerarray.array as aMutableSequence. Patch by Pablo Galindo.

  • bpo-39168: Remove the__new__ method oftyping.Generic.

  • bpo-41194: Fix a crash in the_ast module: it can no longer be loadedmore than once. It now uses a global state rather than a module state.

  • bpo-41195: Add read-only ssl.SSLContext.security_level attribute toretrieve the context's security level.

  • bpo-41193: Thewrite_history() atexit function of the readlinecompleter now ignores anyOSError to ignore error if the filesystemis read-only, instead of only ignoringFileNotFoundError andPermissionError.

  • bpo-41182: selector: use DefaultSelector based upon implementation

  • bpo-41161: The decimal module now requires libmpdec-2.5.0. Users of--with-system-libmpdec should update their system library.

  • bpo-40874: The decimal module now requires libmpdec-2.5.0.

  • bpo-41138: Fixed thetrace module CLI for Python source files withnon-UTF-8 encoding.

  • bpo-31082: Use the term "iterable" in the docstring forfunctools.reduce().

  • bpo-40521: Remove freelist from collections.deque().

  • bpo-31938: Fix default-value signatures of several functions in theselect module - by Anthony Sottile.

  • bpo-41068: Fixed reading files with non-ASCII names from ZIP archivedirectly after writing them.

  • bpo-41058:pdb.find_function() now correctly determines the sourcefile encoding.

  • bpo-41056: Invalid file descriptor values are now prevented from beingpassed to os.fpathconf. (discovered by Coverity)

  • bpo-41056: Fix a NULL pointer dereference within the ssl module during aMemoryError in the keylog callback. (discovered by Coverity)

  • bpo-41056: Fixed an instance where a MemoryError within the zoneinfomodule might not be reported or not reported at its source. (found byCoverity)

  • bpo-41048:mimetypes.read_mime_types() function reads the rule fileusing UTF-8 encoding, not the locale encoding. Patch by Srinivas ReddyThatiparthy.

  • bpo-41043: Fixed the use ofglob() in the stdlib: literal partof the path is now always correctly escaped.

  • bpo-41025: Fixed an issue preventing the C implementation ofzoneinfo.ZoneInfo from being subclassed.

  • bpo-35018: Add thexml.sax.handler.LexicalHandler class that ispresent in other SAX XML implementations.

  • bpo-41002: Improve performance of HTTPResponse.read with a given amount.Patch by Bruce Merry.

  • bpo-40448:ensurepip now disables the use ofpip cache wheninstalling the bundled versions ofpip andsetuptools. Patch byKrzysztof Konopko.

  • bpo-40967: Removedasyncio.Task.current_task() andasyncio.Task.all_tasks(). Patch contributed by Rémi Lapeyre.

  • bpo-40924: Ensureimportlib.resources.path returns an extant path forthe SourceFileLoader's resource reader. Avoids the regression identifiedin master while a long-term solution is devised.

  • bpo-40955: Fix a minor memory leak insubprocess module whenextra_groups was specified.

  • bpo-40855: The standard deviation and variance functions in the statisticsmodule were ignoring their mu and xbar arguments.

  • bpo-40939: Use the new PEG parser when generating the stdlibkeyword module.

  • bpo-23427: Addsys.orig_argv attribute: the list of the originalcommand line arguments passed to the Python executable.

  • bpo-33689: Ignore empty or whitespace-only lines in .pth files. Thismatches the documentated behavior. Before, empty lines caused thesite-packages dir to appear multiple times in sys.path. By Ido Michael,contributors Malcolm Smith and Tal Einat.

  • bpo-40884: Added adefaults parameter tologging.Formatter,to allow specifying default values for custom fields. Patch by Asaf Alonand Bar Harel.

  • bpo-40876: Clarify error message in thecsv module.

  • bpo-39791: Refresh importlib.metadata from importlib_metadata 1.6.1.

  • bpo-40807: Stop codeop._maybe_compile, used by code.InteractiveInterpreter(and IDLE). from emitting each warning three times.

  • bpo-32604: Fix reference leak in theselect module when the moduleis imported in a subinterpreter.

  • bpo-39791: Built-in loaders (SourceFileLoader and ZipImporter) now supplyTraversableResources implementations forResourceReader, and thefallback function has been removed.

  • bpo-39314:rlcompleter.Completer and the standard Python shellnow close the parenthesis for functions that take no arguments. Patchcontributed by Rémi Lapeyre.

  • bpo-17005: The topological sort functionality that was introducedinitially in thefunctools module has been moved to a newgraphlib module to better accommodate the new tools and keep theoriginal scope of thefunctools module. Patch by Pablo Galindo

  • bpo-40834: Fix truncate when sending str objectwith_xxsubinterpreters.channel_send.

  • bpo-40755: Add rich comparisons to collections.Counter().

  • bpo-26407: Unexpected errors in calling the__iter__ method are nolonger masked byTypeError incsv.reader(),csv.writer.writerow() andcsv.writer.writerows().

  • bpo-39384: Fixed email.contentmanager to allow set_content() to set a nullstring.

  • bpo-40744: Thesqlite3 module uses SQLite API functions thatrequire SQLite v3.7.3 or higher. This patch removes support for olderSQLite versions, and explicitly requires SQLite 3.7.3 both at build,compile and runtime. Patch by Sergey Fedoseev and Erlend E. Aasland.

  • bpo-40777: Initialize PyDateTime_IsoCalendarDateType.tp_base at run-timeto avoid errors on some compilers.

  • bpo-38488: Update ensurepip to install pip 20.1.1 and setuptools 47.1.0.

  • bpo-40792: The result ofoperator.index() now always has exact typeint. Previously, the result could have been an instance of asubclass ofint.

  • bpo-40767:webbrowser now properly finds the default browser inpure Wayland systems by checking the WAYLAND_DISPLAY environment variable.Patch contributed by Jérémy Attali.

  • bpo-40791:hashlib.compare_digest() uses OpenSSL'sCRYPTO_memcmp() function when OpenSSL is available.

  • bpo-40795:ctypes module: If ctypes fails to convert the result ofa callback or if a ctypes callback function raises an exception,sys.unraisablehook is now called with an exception set. Previously, theerror was logged into stderr byPyErr_Print().

  • bpo-16995: Addbase64.b32hexencode() andbase64.b32hexdecode()to support the Base32 Encoding with Extended Hex Alphabet.

  • bpo-30008: Fixssl code to be compatible with OpenSSL 1.1.x buildsthat useno-deprecated and--api=1.1.0.

  • bpo-30064: Fix asyncioloop.sock_* race condition issue

  • bpo-40759: Deprecate thesymbol module.

  • bpo-40756: The second argument (extra) ofLoggerAdapter.__init__ nowdefaults to None.

  • bpo-37129: Add a newos.RWF_APPEND flag foros.pwritev().

  • bpo-40737: Fix possible reference leak forsqlite3 initialization.

  • bpo-40726: Handle cases where theend_lineno isNone onast.increment_lineno().

  • bpo-40698:distutils upload creates SHA2-256 and Blake2b-256 digests.MD5 digests is skipped if platform blocks MD5.

  • bpo-40695:hashlib no longer falls back to builtin hashimplementations when OpenSSL provides a hash digest and the algorithm isblocked by security policy.

  • bpo-9216:hashlib.new() passedusedforsecurity to OpenSSL EVPconstructor_hashlib.new(). test_hashlib and test_smtplib handlestrict security policy better.

  • bpo-40614:ast.parse() will not parse self documenting expressionsin f-strings when passedfeature_version is less than(3,8).

  • bpo-40626: Add h5 file extension as MIME Type application/x-hdf5, as perHDF Group recommendation for HDF5 formatted data files. Patch contributedby Mark Schwab.

  • bpo-25920: On macOS, when building Python for macOS 10.4 and older, whichwasn't the case for python.org macOS installer,socket.getaddrinfo()no longer uses an internal lock to prevent race conditions when callinggetaddrinfo() which is thread-safe since macOS 10.5. Python 3.9requires macOS 10.6 or newer. The internal lock caused random hang on forkwhen another thread was callingsocket.getaddrinfo(). The lock wasalso used on FreeBSD older than 5.3, OpenBSD older than 201311 and NetBSDolder than 4.

  • bpo-40671: Prepare_hashlib forPEP 489 and usePyModule_AddType().

  • bpo-32309: Added a newcoroutineasyncio.to_thread(). It ismainly used for running IO-bound functions in a separate thread to avoidblocking the event loop, and essentially works as a high-level version ofrun_in_executor() that can directly take keywordarguments.

  • bpo-36543: Restored the deprecatedxml.etree.cElementTree module.

  • bpo-40611:MAP_POPULATE constant has now been added to thelist of exportedmmap module flags.

  • bpo-39881: PEP 554 for use in the test suite. (Patch By Joannah Nanjekye)

  • bpo-13097:ctypes now raises anArgumentError when a callback isinvoked with more than 1024 arguments.

  • bpo-39385: A new test assertion context-manager,unittest.assertNoLogs() will ensure a given block of code emits nolog messages using the logging module. Contributed by Kit Yan Choi.

  • bpo-23082: Updated the error message and docs of PurePath.relative_to() tobetter reflect the function behaviour.

  • bpo-40318: Use SQLite3 trace v2 API, if it is available.

  • bpo-40105: ZipFile truncates files to avoid corruption when a shortercomment is provided in append ("a") mode. Patch by Jan Mazur.

  • bpo-40084: FixEnum.__dir__: dir(Enum.member) now includes attributesas well as methods.

  • bpo-31122: ssl.wrap_socket() now raises ssl.SSLEOFError rather thanOSError when peer closes connection during TLS negotiation

  • bpo-39728: fix default_missing_ so a duplicateValueError is notset as the__context__ of the originalValueError.

  • bpo-39244: Fixedmultiprocessing.context.get_all_start_methods toproperly return the default method first on macOS.

  • bpo-39040: Fix parsing of invalid mime headers parameters by collapsingwhitespace between encoded words in a bare-quote-string.

  • bpo-38731: Add--quiet option to command-line interface ofpy_compile. Patch by Gregory Schevchenko.

  • bpo-35714:struct.error is now raised if there is a null characterin astruct format string.

  • bpo-38144: Added theroot_dir anddir_fd parameters inglob.glob().

  • bpo-26543: FixIMAP4.noop() when debug mode is enabled (ex:imaplib.Debug=3).

  • bpo-12178:csv.writer() now correctly escapesescapechar wheninput containsescapechar. Patch by Catalin Iacob, Berker Peksag, andItay Elbirt.

  • bpo-36290: AST nodes are now raisingTypeError on conflictingkeyword arguments. Patch contributed by Rémi Lapeyre.

  • bpo-33944: Added site.py site-packages tracing in verbose mode.

  • bpo-35078: Refactor formatweekday, formatmonthname methods inLocaleHTMLCalendar and LocaleTextCalendar classes in calendar module tocall the base class methods.This enables customizable CSS classes forLocaleHTMLCalendar. Patch by Srinivas Reddy Thatiparthy

  • bpo-29620:assertWarns() no longer raises aRuntimeException when accessing a module's__warningregistry__causes importation of a new module, or when a new module is imported inanother thread. Patch by Kernc.

  • bpo-31844: RemoveParserBase.error() method from the private andundocumented_markupbase module.html.parser.HTMLParser isthe only subclass ofParserBase and itserror() implementation wasdeprecated in Python 3.4 and removed in Python 3.5.

  • bpo-34226: Fixcgi.parse_multipart without content_length. Patch byRoger Duran

  • bpo-33660: Fix pathlib.PosixPath to resolve a relative path located on theroot directory properly.

  • bpo-28557: Improve the error message for a misbehavingrawio.readinto

  • bpo-26680: The d.is_integer() method is added to the Decimal type, forcompatibility with other number types.

  • bpo-26680: The x.is_integer() method is incorporated into the abstracttypes of the numeric tower, Real, Rational and Integral, with appropriatedefault implementations.

Documentation

  • bpo-41428: Add documentation forPEP 604 (Allow writing union types asX|Y).

  • bpo-41774: In Programming FAQ "Sequences (Tuples/Lists)" section, add "Howdo you remove multiple items from a list".

  • bpo-35293: Fix RemovedInSphinx40Warning when building the documentation.Patch by Donghee Na.

  • bpo-37149: Change Shipman tkinter doc link from archive.org to TkDocs.(The doc has been removed from the NMT server.) The new link respondsmuch faster and includes a short explanatory note.

  • bpo-41726: Update the refcounts info ofPyType_FromModuleAndSpec.

  • bpo-41624: Fix the signature oftyping.Coroutine.

  • bpo-40204: Enable Sphinx 3.2c_allow_pre_v3 option and disablec_warn_on_allowed_pre_v3 option to make the documentation compatiblewith Sphinx 2 and Sphinx 3.

  • bpo-41045: Add documentation for debug feature of f-strings.

  • bpo-41314: Changed the release whenfrom__future__importannotationsbecomes the default from4.0 to3.10 (following a change in PEP563).

  • bpo-40979: Refactored typing.rst, arranging more than 70 classes,functions, and decorators into new sub-sections.

  • bpo-40552: Fix in tutorial section 4.2. Code snippet is now correct.

  • bpo-39883: Make code, examples, and recipes in the Python documentation belicensed under the more permissive BSD0 license in addition to theexisting Python 2.0 license.

  • bpo-37703: Updated Documentation to comprehensively elaborate on thebehaviour of gather.cancel()

Tests

  • bpo-41939: Fix test_site.test_license_exists_at_url(): callurllib.request.urlcleanup() to reset the globalurllib.request._opener. Patch by Victor Stinner.

  • bpo-41731: Make test_cmd_line_script pass with option '-vv'.

  • bpo-41602: Add tests for SIGINT handling in the runpy module.

  • bpo-41521:test.support: Renameblacklist parameter ofcheck__all__() tonot_exported.

  • bpo-41477: Make ctypes optional in test_genericalias.

  • bpo-41085: Fix integer overflow in thearray.array.index() method on64-bit Windows for index larger than2**31.

  • bpo-41069:test.support.TESTFN and the current directory for testswhen run viatest.regrtest contain now non-ascii characters ifpossible.

  • bpo-38377: On Linux, skip tests using multiprocessing if the current usercannot create a file in/dev/shm/ directory. Add theskip_if_broken_multiprocessing_synchronize() functionto thetest.support module.

  • bpo-41009: Fix use ofsupport.require_{linux|mac|freebsd}_version()decorators as class decorator.

  • bpo-41003: Fixtest_copyreg whennumpy is installed:test.pickletester now saves/restores warnings filters when importingnumpy, to ignore filters installed bynumpy.

  • bpo-40964: Disable remoteimaplib tests, host cyrus.andrew.cmu.eduis blocking incoming connections.

  • bpo-40927: Fix test_binhex when run twice: it now usesimport_fresh_module() to ensure that it raises DeprecationWarning eachtime.

  • bpo-17258: Skip somemultiprocessing tests when MD5 hash digest isblocked.

  • bpo-31904: Increase LOOPBACK_TIMEOUT to 10 for VxWorks RTOS.

  • bpo-38169: Increase code coverage for SharedMemory and ShareableList

  • bpo-34401: Make test_gdb properly run on HP-UX. Patch by Michael Osipov.

Build

  • bpo-38249: UpdatePy_UNREACHABLE to use __builtin_unreachable()if only the compiler is able to use it. Patch by Donghee Na.

  • bpo-41617: Fixpycore_bitutils.h header file to support old clangversions:__builtin_bswap16() is not available in LLVM clang 3.0.

  • bpo-40204: Pin Sphinx version to 2.3.1 inDoc/Makefile.

  • bpo-36020: The C99 functionssnprintf() andvsnprintf()are now required to build Python.

  • bpo-40684:makeinstall now uses thePLATLIBDIR variable for thedestinationlib-dynload/ directory when./configure--with-platlibdir is used.

  • bpo-40683: Fixed an issue where thezoneinfo module and its testswere not included when Python is installed withmake.

Windows

  • bpo-41744: Fixes automatic import of props file when using the Nugetpackage.

  • bpo-41627: The user site directory for 32-bit now includes a-32suffix to distinguish it from the 64-bit interpreter's directory.

  • bpo-41526: Fixed layout of final page of the installer by removing thespecial thanks to Mark Hammond (with his permission).

  • bpo-41492: Fixes the description that appears in UAC prompts.

  • bpo-40948: Improve post-install message to direct people to the "py"command.

  • bpo-41412: The installer will now fail to install on Windows 7 and Windows8. Further, the UCRT dependency is now always downloaded on demand.

  • bpo-40741: Update Windows release to include SQLite 3.32.3.

  • bpo-41142:msilib now supports creating CAB files with non-ASCIIfile path and adding files with non-ASCII file path to them.

  • bpo-41074: Fixed support of non-ASCII names in functionsmsilib.OpenDatabase() andmsilib.init_database() andnon-ASCII SQL in methodmsilib.Database.OpenView().

  • bpo-41039: Stable ABI redirection DLL (python3.dll) now uses#pragmacomment(linker) for re-exporting.

  • bpo-40164: Updates Windows OpenSSL to 1.1.1g

  • bpo-39631: Changes the registered MIME type for.py files on Windowstotext/x-python instead oftext/plain.

  • bpo-40677: Manually define IO_REPARSE_TAG_APPEXECLINK in case some oldWindows SDK doesn't have it.

  • bpo-37556: Extend py.exe help to mention overrides via venv, shebang,environmental variables & ini files.

macOS

  • bpo-41557: Update macOS installer to use SQLite 3.33.0.

  • bpo-39580: Avoid opening Finder window if running installer from thecommand line. Patch contributed by Rick Heil.

  • bpo-41100: Fix configure error when building on macOS 11. Note that thecurrent Python release was released shortly after the first developerpreview of macOS 11 (Big Sur); there are other known issues with buildingand running on the developer preview. Big Sur is expected to be fullysupported in a future bugfix release of Python 3.8.x and with 3.9.0.

  • bpo-40741: Update macOS installer to use SQLite 3.32.3.

  • bpo-41005: fixed an XDG settings issue not allowing macos to open browserin webbrowser.py

  • bpo-40741: Update macOS installer to use SQLite 3.32.2.

IDLE

  • bpo-41775: Use 'IDLE Shell' as shell title

  • bpo-35764: Rewrite the Calltips doc section.

  • bpo-40181: In calltips, stop reminding that '/' marks the end ofpositional-only arguments.

  • bpo-41468: Improve IDLE run crash error message (which users should neversee).

  • bpo-41373: Save files loaded with no line ending, as when blank, ordifferent line endings, by setting its line ending to the system default.Fix regression in 3.8.4 and 3.9.0b4.

  • bpo-41300: Save files with non-ascii chars. Fix regression released in3.9.0b4 and 3.8.4.

  • bpo-37765: Add keywords to module name completion list. RewriteCompletions section of IDLE doc.

  • bpo-41152: The encoding ofstdin,stdout andstderr in IDLE isnow always UTF-8.

  • bpo-41144: Make Open Module open a special module such as os.path.

  • bpo-39885: Make context menu Cut and Copy work again when right-clickingwithin a selection.

  • bpo-40723: Make test_idle pass when run after import.

C API

Python 3.9.0 beta 1

Release date: 2020-05-19

Security

Core and Builtins

  • bpo-40663: Correctly generate annotations where parentheses are omittedbut required (e.g:Type[(str,int,*other))].

  • bpo-40596: Fixedstr.isidentifier() for non-canonicalized stringscontaining non-BMP characters on Windows.

  • bpo-40593: Improved syntax errors for invalid characters in source code.

  • bpo-40585: Fixed a bug when usingcodeop.compile_command() that wascausing exceptions to be swallowed with the new parser. Patch by PabloGalindo

  • bpo-40566: ApplyPEP 573 toabc.

  • bpo-40502: Initializen->n_col_offset. (Patch by Joannah Nanjekye)

  • bpo-40527: Fix command line argument parsing: no longer write errorsmultiple times into stderr.

  • bpo-1635741: Porterrno to multiphase initialization (PEP 489).

  • bpo-40523: Add pass-throughs forhash() andreversed() toweakref.proxy objects. Patch by Pablo Galindo.

  • bpo-1635741: Portsyslog to multiphase initialization (PEP 489).

  • bpo-40246: Reporting a specialised error message for invalid stringprefixes, which was introduced inbpo-40246, is being reverted due tobackwards compatibility concerns for strings that immediately follow areserved keyword without whitespace between them. Constructs likebg="#d00"ifclearelse"#fca" were failing to parse, which is not anacceptable breakage on such short notice.

  • bpo-40417: Fix imp module deprecation warning when PyImport_ReloadModuleis called. Patch by Robert Rouhani.

  • bpo-40408: Fixed support of nested type variables in GenericAlias (e.g.list[list[T]]).

  • bpo-1635741: Port _stat module to multiphase initialization (PEP 489).

  • bpo-29587: Enable implicit exception chaining when callinggenerator.throw().

  • bpo-40328: Add tools for generating mappings headers for CJKCodecs.

  • bpo-40228: Setting frame.f_lineno is now robust w.r.t. changes in thesource-to-bytecode compiler

  • bpo-38880: Added the ability to list interpreters associated with channelends in the internal subinterpreters module.

  • bpo-37986: Improve performance ofPyLong_FromDouble() for valuesthat fit intolong.

Library

  • bpo-40662: Fixedast.get_source_segment() for ast nodes that haveincomplete location information. Patch by Irit Katriel.

  • bpo-40665: Convertbisect to use Argument Clinic.

  • bpo-40536: Added theavailable_timezones() function to thezoneinfo module. Patch by Paul Ganssle.

  • bpo-40645: Thehmac.HMAC exposes internal implementation details.The attributesdigest_cons,inner, andouter are deprecatedand will be removed in the future.

  • bpo-40645: The internal module_hashlib wraps and exposes OpenSSL'sHMAC API. The new code will be used in Python 3.10 after the internalimplementation details of the pure Python HMAC module are no longer partof the public API.

  • bpo-40637: Builtin hash modules can now be disabled or selectively enabledwithconfigure--with-builtin-hashlib-hashes=sha3,blake1 or--without-builtin-hashlib-hashes.

  • bpo-37630: Thehashlib module can now use SHA3 hashes and SHAKE XOFfrom OpenSSL when available.

  • bpo-40479: Thehashlib now compiles with OpenSSL 3.0.0-alpha2.

  • bpo-40257: Revert changes toinspect.getdoc().

  • bpo-40607: When cancelling a task due to timeout,asyncio.wait_for()will now propagate the exception if an error happens during cancellation.Patch by Roman Skurikhin.

  • bpo-40612: Fix edge cases in SyntaxError formatting. If the offset is <=0, no caret is printed. If the offset is > line length, the caret isprinted pointing just after the last character.

  • bpo-40597: If text content lines are longer than policy.max_line_length,always use a content-encoding to make sure they are wrapped.

  • bpo-40571: Added functools.cache() as a simpler, more discoverable way toaccess the unbounded cache variant of lru_cache(maxsize=None).

  • bpo-40503:PEP 615, thezoneinfo module. Adds support for theIANA time zone database.

  • bpo-40397: Removed attributes__args__ and__parameters__ fromspecial generic aliases liketyping.List (not subscripted).

  • bpo-40549: Convert posixmodule.c ("posix" or "nt" module) to themultiphase initialization (PEP 489).

  • bpo-31033: Add amsg argument toFuture.cancel() andTask.cancel().

  • bpo-40541: Added an optionalcounts parameter to random.sample().

  • bpo-40515: Thessl andhashlib modules now actively checkthat OpenSSL is build with thread support. Python 3.7.0 made threadsupport mandatory and no longer works safely with a no-thread builds.

  • bpo-31033: When aasyncio.Task is cancelled, the exceptiontraceback now chains all the way back to where the task was firstinterrupted.

  • bpo-40504:functools.lru_cache() objects can now be the targets ofweakrefs.

  • bpo-40559: Fix possible memory leak in the C implementation ofasyncio.Task.

  • bpo-40480:fnmatch.fnmatch() could take exponential time in thepresence of multiple* pattern characters. This was repaired bygenerating more elaborate regular expressions to avoid futilebacktracking.

  • bpo-40495:compileall is now able to use hardlinks to preventduplicates in a case when.pyc files for different optimization levelshave the same content.

  • bpo-40457: The ssl module now support OpenSSL builds without TLS 1.0 and1.1 methods.

  • bpo-40355: Improve error reporting inast.literal_eval() in thepresence of malformedast.Dict nodes instead of silently ignoringany non-conforming elements. Patch by Curtis Bucher.

  • bpo-40465: Deprecated the optionalrandom argument torandom.shuffle().

  • bpo-40459:platform.win32_ver() now produces correctptype stringsinstead of empty strings.

  • bpo-39435: The first argument ofpickle.loads() is nowpositional-only.

  • bpo-39305: Updatenntplib to mergenntplib.NNTP andnntplib._NNTPBase. Patch by Donghee Na.

  • bpo-32494: Updatedbm.gnu to use gdbm_count if possible whencallinglen(). Patch by Donghee Na.

  • bpo-40453: Addisolated=True keyword-only parameter to_xxsubinterpreters.create(). An isolated subinterpreter cannot spawnthreads, spawn a child process or callos.fork().

  • bpo-40286: Remove_random.Random.randbytes(): the C implementation ofrandbytes(). Implement the method in Python to ease subclassing:randbytes() now directly reusesgetrandbits().

  • bpo-40394: Added default arguments todifflib.SequenceMatcher.find_longest_match().

  • bpo-39995: Fix a race condition in concurrent.futures._ThreadWakeup:access to _ThreadWakeup is now protected with the shutdown lock.

  • bpo-30966:Process.shutdown(wait=True) ofconcurrent.futuresnow closes explicitly the result queue.

  • bpo-30966: Add a newclose() method totheSimpleQueue class to explicitly close thequeue.

  • bpo-39966: Revertbpo-25597.unittest.mock.MagicMock with wraps'set uses default return values for magic methods.

  • bpo-39791: Addedfiles() function to importlib.resources with supportfor subdirectories in package data, matching backport inimportlib_resources 1.5.

  • bpo-40375:imaplib.IMAP4.unselect() is added. Patch by Donghee Na.

  • bpo-40389:repr() now returnstyping.Optional[T] when called fortyping.Union of two types, one of which isNoneType.

  • bpo-40291: Add support for CAN_J1939 sockets (available on Linux 5.4+)

  • bpo-40273:types.MappingProxyType is now reversible.

  • bpo-39075: The repr fortypes.SimpleNamespace is now insertionordered rather than alphabetical.

  • bpo-40192: On AIX,thread_time() is now implemented withthread_cputime() which has nanosecond resolution, rather thanclock_gettime(CLOCK_THREAD_CPUTIME_ID) which has a resolution of 10milliseconds. Patch by Batuhan Taskaya.

  • bpo-40025: Raise TypeError when _generate_next_value_ is defined aftermembers. Patch by Ethan Onstott.

  • bpo-39058: In the argparse module, the repr for Namespace() and otherargument holders now displayed in the order attributes were added.Formerly, it displayed in alphabetical order even though argument order ispreserved the user visible parts of the module.

  • bpo-24416: Theisocalendar() methods ofdatetime.date anddatetime.datetime now return anamed tuple instead of atuple.

Documentation

  • bpo-34790: Add version of removal for explicit passing of coros toasyncio.wait()'s documentation

  • bpo-40561: Provide docstrings for webbrowser open functions.

  • bpo-40499: Mention thatasyncio.wait() requires a non-empty set ofawaitables.

  • bpo-39705: Tutorial example for sorted() in the Loop Techniques section isgiven a better explanation. Also a new example is included to explainsorted()'s basic behavior.

  • bpo-39435: Fix an incorrect signature forpickle.loads() in the docs

Tests

  • bpo-40055: distutils.tests now saves/restores warnings filters to leavethem unchanged. Importing tests imports docutils which importspkg_resources which adds a warnings filter.

  • bpo-40436: test_gdb and test.pythoninfo now check gdb command exit code.

Build

  • bpo-40653: Move _dirnameW out of HAVE_SYMLINK to fix a potential compilingissue.

  • bpo-40514: Add--with-experimental-isolated-subinterpreters buildoption toconfigure: better isolate subinterpreters, experimentalbuild mode.

Windows

  • bpo-40650: Include winsock2.h in pytime.c for timeval.

  • bpo-40458: Increase reserved stack space to prevent overflow crash onWindows.

  • bpo-39148: Add IPv6 support toasyncio datagram endpoints inProactorEventLoop. Change the raised exception for unknown addressfamilies to ValueError as it's not coming from Windows API.

macOS

  • bpo-34956: When building Python on macOS from source,_tkinter nowlinks with non-system Tcl and Tk frameworks if they are installed in/Library/Frameworks, as had been the case on older releases of macOS.If a macOS SDK is explicitly configured, by using--enable-universalsdk= or-isysroot, only the SDK itself issearched. The default behavior can still be overridden with--with-tcltk-includes and--with-tcltk-libs.

  • bpo-35569: Expose RFC 3542 IPv6 socket options.

Tools/Demos

  • bpo-40479: Update multissltest helper to test with latest OpenSSL 1.0.2,1.1.0, 1.1.1, and 3.0.0-alpha.

  • bpo-40431: Fix a syntax typo inturtledemo that now raises aSyntaxError.

  • bpo-40163: Fix multissltest tool. OpenSSL has changed download URL for oldreleases. The multissltest tool now tries to download from current and olddownload URLs.

C API

  • bpo-39465: Remove the_PyUnicode_ClearStaticStrings() function fromthe C API.

  • bpo-38787: Add PyCFunction_CheckExact() macro for exact type checks nowthat we allow subtypes of PyCFunction, as well as PyCMethod_CheckExact()and PyCMethod_Check() for the new PyCMethod subtype.

  • bpo-40545: Declare_PyErr_GetTopmostException() withPyAPI_FUNC()to properly export the function in the C API. The function remains private(_Py) prefix.

  • bpo-40412: Nullify inittab_copy during finalization, preventing futureinterpreter initializations in an embedded situation from crashing. Patchby Gregory Szorc.

  • bpo-40429: ThePyThreadState_GetFrame() function now returns astrong reference to the frame.

  • bpo-40428: Remove the following functions from the C API. CallPyGC_Collect() explicitly to free all free lists.

    • PyAsyncGen_ClearFreeLists()

    • PyContext_ClearFreeList()

    • PyDict_ClearFreeList()

    • PyFloat_ClearFreeList()

    • PyFrame_ClearFreeList()

    • PyList_ClearFreeList()

    • PySet_ClearFreeList()

    • PyTuple_ClearFreeList()

  • bpo-40421: NewPyFrame_GetBack() function: get the frame nextouter frame.

  • bpo-40421: NewPyFrame_GetCode() function: return a borrowedreference to the frame code.

  • bpo-40217: Ensure that instances of types created withPyType_FromSpecWithBases() will visit its class object whentraversing references in the garbage collector (implemented as anextension of the providedtp_traverse). Patch byPablo Galindo.

  • bpo-38787: Module C state is now accessible from C-defined heap typemethods (PEP 573). Patch by Marcel Plch and Petr Viktorin.

Python 3.9.0 alpha 6

Release date: 2020-04-27

Security

  • bpo-40121: Fixes audit events raised on creating a new socket.

  • bpo-39073: Disallow CR or LF in email.headerregistry.Address arguments toguard against header injection attacks.

  • bpo-39503:CVE 2020-8492: TheAbstractBasicAuthHandler class of theurllib.request module uses an inefficient regular expression whichcan be exploited by an attacker to cause a denial of service. Fix theregex to prevent the catastrophic backtracking. Vulnerability reported byBen Caller and Matt Schwager.

Core and Builtins

  • bpo-40313: Improve the performance of bytes.hex().

  • bpo-40334: Switch to a new parser, based on PEG. For more details see PEP617. To temporarily switch back to the old parser, use-Xoldparser orPYTHONOLDPARSER=1. In Python 3.10 we will remove the old parsercompletely, including theparser module (already deprecated) andanything that depends on it.

  • bpo-40267: Fix the tokenizer to display the correct error message, whenthere is aSyntaxError on the last input character and no newlinefollows. It used to beunexpectedEOFwhileparsing, while it shouldbeinvalidsyntax.

  • bpo-39522: Correctly unparse explicitu prefix for strings whenpostponed evaluation for annotations activated. Patch by Batuhan Taskaya.

  • bpo-40246: Report a specialized error message,invalidstringprefix,when the tokenizer encounters a string with an invalid prefix.

  • bpo-40082: Fix the signal handler: it now always uses the maininterpreter, rather than trying to get the current Python thread state.

  • bpo-37388: str.encode() and str.decode() no longer check the encoding anderrors in development mode or in debug mode during Python finalization.The codecs machinery can no longer work on very late calls to str.encode()and str.decode().

  • bpo-40077: Fix possible refleaks in_json, memo of PyScannerObjectshould be traversed.

  • bpo-37207: Speed up calls todict() by using thePEP 590vectorcall calling convention.

  • bpo-40141: Add column and line information toast.keyword nodes. Patchby Pablo Galindo.

  • bpo-1635741: Portresource to multiphase initialization(PEP 489).

  • bpo-1635741: Portmath to multiphase initialization (PEP 489).

  • bpo-1635741: Port _uuid module to multiphase initialization (PEP 489).

  • bpo-40077: Convert json module to usePyType_FromSpec().

  • bpo-40067: Improve the error message for multiple star expressions in anassignment. Patch by Furkan Onder

  • bpo-1635741: Port _functools module to multiphase initialization (PEP489). Patch by Paulo Henrique Silva.

  • bpo-1635741: Port operator module to multiphase initialization (PEP 489).Patch by Paulo Henrique Silva.

  • bpo-20526: FixPyThreadState_Clear().PyThreadState.frame isa borrowed reference, not a strong reference:PyThreadState_Clear()must not callPy_CLEAR(tstate->frame).

  • bpo-1635741: Port time module to multiphase initialization (PEP 489).Patch by Paulo Henrique Silva.

  • bpo-1635741: Port _weakref extension module to multiphase initialization(PEP 489).

  • bpo-40020: Fix a leak and subsequent crash in parsetok.c caused by reallocmisuse on a rare codepath.

  • bpo-39939: Added str.removeprefix and str.removesuffix methods andcorresponding bytes, bytearray, and collections.UserString methods toremove affixes from a string if present. SeePEP 616 for a fulldescription. Patch by Dennis Sweeney.

  • bpo-39481: Implement PEP 585. This supports list[int], tuple[str, ...]etc.

  • bpo-32894: Support unparsing of infinity numbers in postponed annotations.Patch by Batuhan Taşkaya.

  • bpo-37207: Speed up calls tolist() by using thePEP 590vectorcall calling convention. Patch by Mark Shannon.

Library

  • bpo-40398:typing.get_args() now always returns an empty tuple forspecial generic aliases.

  • bpo-40396: Functionstyping.get_origin(),typing.get_args()andtyping.get_type_hints() support now generic aliases likelist[int].

  • bpo-38061: Optimize thesubprocess module on FreeBSD usingclosefrom(). A singleclose(fd) syscall is cheap, but whensysconf(_SC_OPEN_MAX) is high, the loop callingclose(fd) on eachfile descriptor can take several milliseconds.

    The workaround on FreeBSD to improve performance was to load and mount thefdescfs kernel module, but this is not enabled by default.

    Initial patch by Ed Maste (emaste), Conrad Meyer (cem), Kyle Evans(kevans) and Kubilay Kocak (koobs):https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=242274

  • bpo-38061: On FreeBSD,os.closerange(fd_low,fd_high) now callsclosefrom(fd_low) iffd_high is greater than or equal tosysconf(_SC_OPEN_MAX).

    Initial patch by Ed Maste (emaste), Conrad Meyer (cem), Kyle Evans(kevans) and Kubilay Kocak (koobs):https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=242274

  • bpo-40360: Thelib2to3 module is pending deprecation due toPEP 617.

  • bpo-40138: Fix the Windows implementation ofos.waitpid() for exitcode larger thanINT_MAX>>8. The exit status is now interpreted asan unsigned number.

  • bpo-39942: Set "__main__" as the default module name when "__name__" ismissing intyping.TypeVar. Patch by Weipeng Hong.

  • bpo-40275: Thelogging package is now imported lazily inunittest only when theassertLogs()assertion is used.

  • bpo-40275: Theasyncio package is now imported lazily inunittest only when theIsolatedAsyncioTestCaseclass is used.

  • bpo-40330: InShareableList.__setitem__(), check the size of a newstring item after encoding it to utf-8, not before.

  • bpo-40148: Addedpathlib.Path.with_stem() to create a new Path withthe stem replaced.

  • bpo-40325: Deprecated support for set objects in random.sample().

  • bpo-40257: Improved help for thetyping module. Docstrings are nowshown for all special forms and special generic aliases (likeUnionandList). Usinghelp() with generic alias likeList[int] willshow the help for the correspondent concrete type (list in this case).

  • bpo-40257:inspect.getdoc() no longer returns docstring inheritedfrom the type of the object or from parent class if it is a class if it isnot defined in the object itself. Inpydoc the documentation stringis now shown not only for class, function, method etc, but for any objectthat has its own__doc__ attribute.

  • bpo-40287: FixedSpooledTemporaryFile.seek() to return the position.

  • bpo-40290: Added zscore() to statistics.NormalDist().

  • bpo-40282: Allowrandom.getrandbits(0) to succeed and to return 0.

  • bpo-40286: Addrandom.randbytes() function andrandom.Random.randbytes() method to generate random bytes.

  • bpo-40277:collections.namedtuple() now provides a human-readablerepr for its field accessors.

  • bpo-40270: The included copy of sqlite3 on Windows is now compiled withthe json extension. This allows the use of functions such asjson_object.

  • bpo-29255: Wait inKqueueSelector.select when no fds are registered

  • bpo-40260: Ensuremodulefinder usesio.open_code() andrespects coding comments.

  • bpo-40234: Allow again to spawn daemon threads in subinterpreters (revertchange which denied them).

  • bpo-39207: Workers inProcessPoolExecutor arenow spawned on demand, only when there are no available idle workers toreuse. This optimizes startup overhead and reduces the amount of lost CPUtime to idle workers. Patch by Kyle Stanley.

  • bpo-40091: Fix a hang at fork in the logging module: the new private_at_fork_reinit() method is now used to reinitialize locks at fork in thechild process.

  • bpo-40149: Implement traverse and clear slots in _abc._abc_data type.

  • bpo-40208: Remove deprecatedsymtable.SymbolTable.has_exec().

  • bpo-40196: Fix a bug in thesymtable module that was causingincorrectly report global variables as local. Patch by Pablo Galindo.

  • bpo-40190: Add support for_SC_AIX_REALMEM toposix.sysconf().

  • bpo-40182: Removed the_field_types attribute of thetyping.NamedTuple class.

  • bpo-36517: Multiple inheritance withtyping.NamedTuple now raisesan error instead of silently ignoring other types.

  • bpo-40126: Fixed reverting multiple patches in unittest.mock. Patcher's__exit__() is now never called if its__enter__() is failed.Returning true from__exit__() silences now the exception.

  • bpo-40094: CGIHTTPRequestHandler of http.server now logs the CGI scriptexit code, rather than the CGI script exit status of os.waitpid(). Forexample, if the script is killed by signal 11, it now logs: "CGI scriptexit code -11."

  • bpo-40108: Improve the error message when triying to import a module usingrunpy and incorrectly using the ".py" extension at the end of themodule name. Patch by Pablo Galindo.

  • bpo-40094: Addos.waitstatus_to_exitcode() function: convert a waitstatus to an exit code.

  • bpo-40089: Fix threading._after_fork(): if fork was not called by a threadspawned by threading.Thread, threading._after_fork() now creates a_MainThread instance for _main_thread, instead of a _DummyThread instance.

  • bpo-40089: Add a private_at_fork_reinit() method to_thread.Lock,_thread.RLock,threading.RLockandthreading.Condition classes: reinitialize the lock at fork inthe child process, reset the lock to the unlocked state. Rename also theprivate_reset_internal_locks() method ofthreading.Event to_at_fork_reinit().

  • bpo-25780: ExposeCAN_RAW_JOIN_FILTERS in thesocket module.

  • bpo-39503:AbstractBasicAuthHandler ofurllib.request now parses all WWW-Authenticate HTTP headers andaccepts multiple challenges per header: use the realm of the first Basicchallenge.

  • bpo-39812: Removed daemon threads fromconcurrent.futures by addingan internalthreading._register_atexit(), which calls registeredfunctions prior to joining all non-daemon threads. This allows forcompatibility with subinterpreters, which don't support daemon threads.

  • bpo-40050: Fiximportlib._bootstrap_external: avoid creating a newwinreg builtin module if it's already available insys.modules, and remove redundant imports.

  • bpo-40014: Fixos.getgrouplist(): ifgetgrouplist() function failsbecause the group list is too small, retry with a larger group list. Onfailure, the glibc implementation ofgetgrouplist() setsngroupsto the total number of groups. For other implementations, double the grouplist size.

  • bpo-40017: Addtime.CLOCK_TAI constant if the operating systemsupport it.

  • bpo-40016: In re docstring, clarify the relationship between inline andargument compile flags.

  • bpo-39953: Update internal table of OpenSSL error codes in thesslmodule.

  • bpo-36144: AddedPEP 584 operators toweakref.WeakValueDictionary.

  • bpo-36144: AddedPEP 584 operators toweakref.WeakKeyDictionary.

  • bpo-38891: Fix linear runtime behaviour of the__getitem__ and__setitem__ methods inmultiprocessing.shared_memory.ShareableList. This avoidsquadratic performance when iterating aShareableList. Patch by ThomasKrennwallner.

  • bpo-39682: Remove undocumented support forclosing apathlib.Pathobject via its context manager. The context manager magic methods remain,but they are now a no-op, makingPath objects immutable.

  • bpo-36144: AddedPEP 584 operators (| and|=) tocollections.ChainMap.

  • bpo-39011: Normalization of line endings in ElementTree attributes wasremoved, as line endings which were replaced by entity numbers should bepreserved in original form.

  • bpo-38410: Properly handlesys.audit() failures insys.set_asyncgen_hooks().

  • bpo-36541: lib2to3 now recognizes named assignment expressions (the walrusoperator,:=)

  • bpo-35967: In platform, delay the invocation of 'uname -p' until theprocessor attribute is requested.

  • bpo-35113:inspect.getsource() now returns correct source code forinner class with same name as module level class. Decorators are alsoreturned as part of source of the class. Patch by KarthikeyanSingaravelan.

  • bpo-33262: Deprecate passing None as an argument forshlex.split()'ss parameter. Patch by Zackery Spytz.

  • bpo-31758: Prevent crashes when using an uninitialized_elementtree.XMLParser object. Patch by Oren Milman.

Documentation

  • bpo-27635: The pickle documentation incorrectly claimed that__new__isn't called by default when unpickling.

  • bpo-39879: Updated資料模型 docs to includedict() insertionorder preservation. Patch by Furkan Onder and Samy Lahfa.

  • bpo-38387: DocumentPyDoc_STRVAR macro in the C-API reference.

  • bpo-13743: Some methods within xml.dom.minidom.Element class are nowbetter documented.

Tests

  • bpo-31904: Set expected default encoding in test_c_locale_coercion.py forVxWorks RTOS.

  • bpo-40162: Update Travis CI configuration to OpenSSL 1.1.1f.

  • bpo-40146: Update OpenSSL to 1.1.1f in Azure Pipelines.

  • bpo-40094: Addtest.support.wait_process() function.

  • bpo-40003:test.bisect_cmd now copies Python command line options like-O or-W. Moreover, emit a warning iftest.bisect_cmd is usedwith-w/--verbose2 option.

  • bpo-39380: Add the encoding inftplib.FTP andftplib.FTP_TLS to the constructor as keyword-only and change thedefault fromlatin-1 toutf-8 to followRFC 2640.

  • bpo-39793: Use the same domain when testingmake_msgid. Patch byBatuhan Taskaya.

  • bpo-1812: Fix newline handling in doctest.testfile when loading from apackage whose loader has a get_data method. Patch by Peter Donis.

Build

  • bpo-38360: Support single-argument form of macOS -isysroot flag.

  • bpo-40158: Fix CPython MSBuild Properties in NuGet Package(build/native/python.props)

  • bpo-38527: Fix configure check on Solaris for "float word ordering":sometimes, the correct "grep" command was not being used. Patch by ArnonYaari.

Windows

  • bpo-40164: Updates Windows to OpenSSL 1.1.1f

  • bpo-8901: Ignore the Windows registry when the-E option is used.

macOS

  • bpo-38329: python.org macOS installers now update the Current versionsymlink of /Library/Frameworks/Python.framework/Versions for 3.9 installs.Previously, Current was only updated for Python 2.x installs. This shouldmake it easier to embed Python 3 into other macOS applications.

  • bpo-40164: Update macOS installer builds to use OpenSSL 1.1.1g.

IDLE

  • bpo-38439: Add a 256×256 pixel IDLE icon to support more modernenvironments. Created by Andrew Clover. Delete the unused macOS idle.icnsicon file.

  • bpo-38689: IDLE will no longer freeze when inspect.signature fails whenfetching a calltip.

Tools/Demos

C API

Python 3.9.0 alpha 5

Release date: 2020-03-23

Security

  • bpo-38576: Disallow control characters in hostnames in http.client,addressingCVE 2019-18348. Such potentially malicious header injectionURLs now cause a InvalidURL to be raised.

Core and Builtins

  • bpo-40010: Optimize pending calls in multithreaded applications. If athread different than the main thread schedules a pending call(Py_AddPendingCall()), the bytecode evaluation loop is no longerinterrupted at each bytecode instruction to check for pending calls whichcannot be executed. Only the main thread can execute pending calls.

    Previously, the bytecode evaluation loop was interrupted at eachinstruction until the main thread executes pending calls.

  • bpo-1635741: Port _weakref extension module to multiphase initialization(PEP 489).

  • bpo-1635741: Port _collections module to multiphase initialization(PEP 489).

  • bpo-40010: Optimize signal handling in multithreaded applications. If athread different than the main thread gets a signal, the bytecodeevaluation loop is no longer interrupted at each bytecode instruction tocheck for pending signals which cannot be handled. Only the main thread ofthe main interpreter can handle signals.

    Previously, the bytecode evaluation loop was interrupted at eachinstruction until the main thread handles signals.

  • bpo-39984: IfPy_AddPendingCall() is called in a subinterpreter,the function is now scheduled to be called from the subinterpreter, ratherthan being called from the main interpreter. Each subinterpreter now hasits own list of scheduled calls.

  • bpo-1635741: Port _heapq module to multiphase initialization.

  • bpo-1635741: Port itertools module to multiphase initialization(PEP 489).

  • bpo-37207: Speed up calls tofrozenset() by using thePEP 590vectorcall calling convention. Patch by Donghee Na.

  • bpo-39984: subinterpreters: Move_PyRuntimeState.ceval.tracing_possible toPyInterpreterState.ceval.tracing_possible: each interpreter now hasits own variable.

  • bpo-37207: Speed up calls toset() by using thePEP 590vectorcall calling convention. Patch by Donghee Na.

  • bpo-1635741: Port _statistics module to multiphase initialization(PEP 489).

  • bpo-39968: Use inline function to replace extension modules'get_module_state macros.

  • bpo-39965: Correctly raiseSyntaxError ifawait is used insidenon-async functions andPyCF_ALLOW_TOP_LEVEL_AWAIT is set (like in theasyncio REPL). Patch by Pablo Galindo.

  • bpo-39562: Allow executing asynchronous comprehensions on the top levelwhen thePyCF_ALLOW_TOP_LEVEL_AWAIT flag is given. Patch by BatuhanTaskaya.

  • bpo-37207: Speed up calls totuple() by using thePEP 590vectorcall calling convention. Patch by Donghee Na.

  • bpo-38373: Changed list overallocation strategy. It no longeroverallocates if the new size is closer to overallocated size than to theold size and adds padding.

  • bpo-39926: Update Unicode database to Unicode version 13.0.0.

  • bpo-19466: Clear the frames of daemon threads earlier during the Pythonshutdown to call objects destructors. So "unclosed file" resource warningsare now emitted for daemon threads in a more reliable way.

  • bpo-38894: Fix a bug that was causing incomplete results when callingpathlib.Path.glob in the presence of symlinks that point to fileswhere the user does not have read access. Patch by Pablo Galindo and MattWozniski.

  • bpo-39877: FixPyEval_RestoreThread() random crash at exit withdaemon threads. It now accesses the_PyRuntime variable directlyinstead of usingtstate->interp->runtime, sincetstate can be adangling pointer afterPy_Finalize() has been called. Moreover,the daemon thread now exits before trying to take the GIL.

  • bpo-39871: Fix a possibleSystemError inmath.{atan2,copysign,remainder}() when the first argument cannot beconverted to afloat. Patch by Zackery Spytz.

  • bpo-39776: Fix race condition where threads created by PyGILState_Ensure()could get a duplicate id.

    This affects consumers of tstate->id like the contextvar cachingmachinery, which could return invalid cached objects under heavy threadload (observed in embedded scenarios).

  • bpo-39778: Fixed a crash due to incorrect handling of weak references incollections.OrderedDict classes. Patch by Pablo Galindo.

  • bpo-1635741: Port audioop extension module to multiphase initialization(PEP 489).

  • bpo-39702: Relaxdecorator grammar restrictions to allow any validexpression (PEP 614).

  • bpo-38091: Tweak import deadlock detection code to not deadlock itself.

  • bpo-1635741: Port _locale extension module to multiphase initialization(PEP 489).

  • bpo-39087: OptimizePyUnicode_AsUTF8() andPyUnicode_AsUTF8AndSize() slightly when they need to createinternal UTF-8 cache.

  • bpo-39520: Fix unparsing of ext slices with no items (foo[:,]). Patchby Batuhan Taskaya.

  • bpo-39220: Do not optimize annotations if 'from __future__ importannotations' is used. Patch by Pablo Galindo.

  • bpo-35712: UsingNotImplemented in a boolean context has beendeprecated. Patch contributed by Josh Rosenberg.

  • bpo-22490: Don't leak environment variable__PYVENV_LAUNCHER__ intothe interpreter session on macOS.

Library

  • bpo-39830: Addzipfile.Path to__all__ in thezipfilemodule.

  • bpo-40000: Improved error messages for validation ofast.Constantnodes. Patch by Batuhan Taskaya.

  • bpo-39999:__module__ of the AST node classes is now set to "ast"instead of "_ast". Added docstrings for dummy AST node classes anddeprecated attributes.

  • bpo-39991:uuid.getnode() now skips IPv6 addresses with the samestring length than a MAC address (17 characters): only use MAC addresses.

  • bpo-39988: Deprecatedast.AugLoad andast.AugStore node classesbecause they are no longer used.

  • bpo-39656: Ensurebin/python3.# is always present in virtualenvironments on POSIX platforms - by Anthony Sottile.

  • bpo-39969: Deprecatedast.Param node class because it's no longerused. Patch by Batuhan Taskaya.

  • bpo-39360: Ensure all workers exit when finalizing amultiprocessing.Pool implicitly via the module finalizationhandlers of multiprocessing. This fixes a deadlock situation that can beexperienced when the Pool is not properly finalized via the contextmanager or a call tomultiprocessing.Pool.terminate. Patch by BatuhanTaskaya and Pablo Galindo.

  • bpo-35370: sys.settrace(), sys.setprofile() and _lsprof.Profiler.enable()now properly reportPySys_Audit() error if "sys.setprofile" or"sys.settrace" audit event is denied.

  • bpo-39936: AIX: Fix _aix_support module when the subprocess is notavailable, when building Python from scratch. It now uses new private_bootsubprocess module, rather than having two implementations dependingif subprocess is available or not. So _aix_support.aix_platform() resultis now the same if subprocess is available or not.

  • bpo-36144:collections.OrderedDict now implements| and|= (PEP 584).

  • bpo-39652: The column name found insqlite3.Cursor.description is nowtruncated on the first '[' only if the PARSE_COLNAMES option is set.

  • bpo-39915: Ensureunittest.mock.AsyncMock.await_args_list has callobjects in the order of awaited arguments instead of usingunittest.mock.Mock.call_args which has the last value of the call.Patch by Karthikeyan Singaravelan.

  • bpo-36144: Updatedos.environ andos.environb to supportPEP 584's merge (|) and update (|=) operators.

  • bpo-38662: Theensurepip module now invokespip via therunpymodule. Hence it is no longer tightly coupled with the internal API of thebundledpip version, allowing easier updates to a newerpipversion both internally and for distributors.

  • bpo-38075: Fix therandom.Random.seed() method when aboolis passed as the seed.

  • bpo-39916: More reliable use ofos.scandir() inPath.glob(). It nolonger emits a ResourceWarning when interrupted.

  • bpo-39850:multiprocessing now supports abstract socket addresses(if abstract sockets are supported in the running platform). When creatingarbitrary addresses (like when default-constructingmultiprocessing.connection.Listener objects) abstract sockets arepreferred to avoid the case when the temporary-file-generated address istoo large for an AF_UNIX socket address. Patch by Pablo Galindo.

  • bpo-36287:ast.dump() no longer outputs optional fields andattributes with default values. The default values for optional fields andattributes of AST nodes are now set as class attributes (e.g.Constant.kind is set toNone).

  • bpo-39889: Fixedast.unparse() for extended slices containing asingle element (e.g.a[i:j,]). Remove redundant tuples when index witha tuple (e.g.a[i,j]).

  • bpo-39828: Fixjson.tool to catchBrokenPipeError. Patch byDonghee Na.

  • bpo-13487: Avoid a possible"RuntimeError: dictionary changed size duringiteration" frominspect.getmodule() when it tried to loop throughsys.modules.

  • bpo-39674: Revert "bpo-37330: open() no longer accept 'U' in file mode".The "U" mode of open() is kept in Python 3.9 to ease transition fromPython 2.7, but will be removed in Python 3.10.

  • bpo-28577: The hosts method on 32-bit prefix length IPv4Networks and128-bit prefix IPv6Networks now returns a list containing the singleAddress instead of an empty list.

  • bpo-39826: Add getConnection method to logging HTTPHandler to enablecustom connections.

  • bpo-39763: Reimplementdistutils.spawn.spawn function with thesubprocess module.

  • bpo-39794: Add --without-decimal-contextvar build option. This enables athread-local rather than a coroutine local context.

  • bpo-36144:collections.defaultdict now implements|(PEP 584).

  • bpo-39517: Fix runpy.run_path() when using pathlike objects

  • bpo-39775: Changeinspect.Signature.parameters back tocollections.OrderedDict. This was changed todict in Python3.9.0a4.

  • bpo-39678: Refactor queue_manager inconcurrent.futures.ProcessPoolExecutor to make it easier tomaintain.

  • bpo-39764: Fix AttributeError when calling get_stack on a PyAsyncGenObjectTask

  • bpo-39769: Thecompileall.compile_dir() function'sddir parameterand the compileall command line flag-d no longer write the wrongpathname to the generated pyc file for submodules beneath the root of thedirectory tree being compiled. This fixes a regression introduced withPython 3.5.

  • bpo-36144:types.MappingProxyType objects now support the merge(|) operator fromPEP 584.

  • bpo-38691: Theimportlib module now ignores thePYTHONCASEOK environment variable when the-E or-I command line options are being used.

  • bpo-39719: Removetempfile.SpooledTemporaryFile.softspace() as filesno longer have thesoftspace attribute in Python 3. Patch by Shantanu.

  • bpo-39667: Improve pathlib.Path compatibility on zipfile.Path and correctperformance degradation as found in zipp 3.0.

  • bpo-39638: Keep ASDL signatures in the docstrings forAST nodes. Patchby Batuhan Taskaya

  • bpo-39639: Deprecatedast.Suite node class because it's no longerused. Patch by Batuhan Taskaya.

  • bpo-39609: Add thread_name_prefix to default asyncio executor

  • bpo-39548: Fix handling of header inurllib.request.AbstractDigestAuthHandler when the optionalqop parameter is not present.

  • bpo-39509: HTTP status codes103EARLY_HINTS and425TOO_EARLY areadded tohttp.HTTPStatus. Patch by Donghee Na.

  • bpo-39507: Adding HTTP status 418 "I'm a Teapot" to HTTPStatus in httplibrary. Patch by Ross Rhodes.

  • bpo-39495: Remove default value fromattrs parameter ofxml.etree.ElementTree.TreeBuilder.start() for consistency betweenPython and C implementations.

  • bpo-38971: Open issue in the BPO indicated a desire to make theimplementation of codecs.open() at parity with io.open(), which implementsa try/except to assure file stream gets closed before an exception israised.

  • bpo-38641: Added starred expressions support toreturn andyieldstatements forlib2to3. Patch by Vlad Emelianov.

  • bpo-37534: When using minidom module to generate XML documents the abilityto add Standalone Document Declaration is added. All the changes are madeto generate a document in compliance with Extensible Markup Language (XML)1.0 (Fifth Edition) W3C Recommendation (available here:https://www.w3.org/TR/xml/#sec-prolog-dtd).

  • bpo-34788: Add support for scoped IPv6 addresses toipaddress.Patch by Oleksandr Pavliuk.

  • bpo-34822: Simplified AST for subscription. Simple indices are nowrepresented by their value, extended slices are represented as tuples.ast classesIndex andExtSlice are considered deprecatedand will be removed in future Python versions. In the meantime,Index(value) now returns avalue itself,ExtSlice(slices)returnsTuple(slices,Load()).

Documentation

  • bpo-39868: Updated the Language Reference forPEP 572.

  • bpo-13790: Change 'string' to 'specification' in format doc.

  • bpo-17422: The language reference no longer restricts default classnamespaces to dicts only.

  • bpo-39530: Fix misleading documentation about mixed-type numericcomparisons.

  • bpo-39718: Updatetoken documentation to reflect additions inPython 3.8

  • bpo-39677: Changed operand name ofMAKE_FUNCTION fromargc toflags for moduledis

Tests

  • bpo-40019: test_gdb now skips tests if it detects that gdb failed to readdebug information because the Python binary is optimized.

  • bpo-27807:test_site.test_startup_imports() is now skipped if a pathofsys.path contains a.pth file.

  • bpo-26067: Do not fail test_shutil test_chown test when uid or gid of usercannot be resolved to a name.

  • bpo-39855: test_subprocess.test_user() now skips the test on an user nameif the user name doesn't exist. For example, skip the test if the user"nobody" doesn't exist on Linux.

Build

  • bpo-39761: Fix build with DTrace but without additional DFLAGS.

  • bpo-39763: setup.py now uses a basic implementation of thesubprocess module if thesubprocess module is not available:before required C extension modules are built.

  • bpo-1294959: Add--with-platlibdir option to the configure script:name of the platform-specific library directory, stored in the newsys.platlibdir attribute. It is used to build the path ofplatform-specific extension modules and the path of the standard library.It is equal to"lib" on most platforms. On Fedora and SuSE, it isequal to"lib64" on 64-bit platforms. Patch by Jan Matějek, MatějCepl, Charalampos Stratakis and Victor Stinner.

Windows

  • bpo-39930: Ensures the requiredvcruntime140.dll is included ininstall packages.

  • bpo-39847: Avoid hang when computer is hibernated whilst waiting for amutex (for lock-related objects fromthreading) around 49-dayuptime.

  • bpo-38597:distutils will no longer statically linkvcruntime140.dll when a redistributable version is unavailable.All future releases of CPython will include a copy of this DLL to ensuredistributed extensions can continue to load.

  • bpo-38380: Update Windows builds to use SQLite 3.31.1

  • bpo-39789: Update Windows release build machines to Visual Studio 2019(MSVC 14.2).

  • bpo-34803: Package for nuget.org now includes repository reference andbundled icon image.

macOS

  • bpo-38380: Update macOS builds to use SQLite 3.31.1

IDLE

  • bpo-27115: For 'Go to Line', use a Query box subclass with IDLE standardbehavior and improved error checking.

  • bpo-39885: Since clicking to get an IDLE context menu moves the cursor,any text selection should be and now is cleared.

  • bpo-39852: Edit "Go to line" now clears any selection, preventingaccidental deletion. It also updates Ln and Col on the status bar.

  • bpo-39781: Selecting code context lines no longer causes a jump.

Tools/Demos

  • bpo-36184: Port python-gdb.py to FreeBSD. python-gdb.py now checks for"take_gil" function name to check if a frame tries to acquire the GIL,instead of checking for "pthread_cond_timedwait" which is specific toLinux and can be a different condition than the GIL.

  • bpo-38080: Added support to fixgetproxies in thelib2to3.fixes.fix_urllib module. Patch by José Roberto MezaCabrera.

C API

Python 3.9.0 alpha 4

Release date: 2020-02-25

Security

  • bpo-39184: Add audit events to functions infcntl,msvcrt,os,resource,shutil,signal andsyslog.

  • bpo-39401: Avoid unsafe DLL load at startup on Windows 7 and earlier.

  • bpo-39184: Add audit events to command execution functions in os and ptymodules.

Core and Builtins

  • bpo-39382: Fix a use-after-free in the single inheritance path ofissubclass(), when the__bases__ of an object has a singlereference, and so does its first item. Patch by Yonatan Goldschmidt.

  • bpo-39573: Update clinic tool to usePy_IS_TYPE(). Patch byDonghee Na.

  • bpo-39619: Enable use ofos.chroot() on HP-UX systems.

  • bpo-39573: AddPy_IS_TYPE() static inline function to checkwhether the objecto type istype.

  • bpo-39606: Fix regression caused by fix forbpo-39386, that preventedcallingaclose on an async generator that had already been closed orexhausted.

  • bpo-39579: Change the ending column offset ofAttribute nodesconstructed inast_for_dotted_name to point at the end of the currentnode and not at the end of the lastNAME node.

  • bpo-1635741: Port _crypt extension module to multiphase initialization(PEP 489).

  • bpo-1635741: Port _contextvars extension module to multiphaseinitialization (PEP 489).

  • bpo-39510: Fix segfault inreadinto() method on closed BufferedReader.

  • bpo-39502: Fixtime.localtime() on 64-bit AIX to support yearsbefore 1902 and after 2038. Patch by M Felt.

  • bpo-39492: Fix a reference cycle in the C Pickler that was preventing thegarbage collection of deleted, pickled objects.

  • bpo-39453: Fixed a possible crash inlist.__contains__() when a listis changed during comparing items. Patch by Donghee Na.

  • bpo-39434:floor division of float operation now has a betterperformance. Also the message ofZeroDivisionError for thisoperation is updated. Patch by Donghee Na.

  • bpo-1635741: Port _codecs extension module to multiphase initialization(PEP 489).

  • bpo-1635741: Port _bz2 extension module to multiphase initialization(PEP 489).

  • bpo-1635741: Port _abc extension module to multiphase initialization(PEP 489).

  • bpo-39320: Replace two complex bytecodes for building dicts with twosimpler ones. The new bytecodesDICT_MERGE andDICT_UPDATE havebeen added The old bytecodesBUILD_MAP_UNPACK andBUILD_MAP_UNPACK_WITH_CALL have been removed.

  • bpo-39219: Syntax errors raised in the tokenizer now always set correct"text" and "offset" attributes.

  • bpo-36051: Drop the GIL during largebytes.join operations. Patch byBruce Merry.

  • bpo-38960: Fix DTrace build issues on FreeBSD. Patch by David Carlier.

  • bpo-37207: Speed up calls torange() by about 30%, by using the PEP590vectorcall calling convention. Patch by Mark Shannon.

  • bpo-36144:dict (andcollections.UserDict) objects nowsupport PEP 584's merge (|) and update (|=) operators. Patch byBrandt Bucher.

  • bpo-32856: Optimized the idiom for assignment a temporary variable incomprehensions. Nowforyin[expr] in comprehensions is as fast as asimple assignmenty=expr.

Library

  • bpo-30566: FixIndexError when trying to decode an invalid stringwith punycode codec.

  • bpo-39649: Remove obsolete check for__args__ inbdb.Bdb.format_stack_entry.

  • bpo-39648: Expandedmath.gcd() andmath.lcm() to handlemultiple arguments.

  • bpo-39681: Fix a regression where the C pickle module wouldn't allowunpickling from a file-like object that doesn't expose a readinto()method.

  • bpo-35950: Raiseio.UnsupportedOperation inio.BufferedReader.truncate() when it is called on a read-onlyio.BufferedReader instance.

  • bpo-39479: Addmath.lcm() function: least common multiple.

  • bpo-39674: Revert "Do not expose abstract collection classes in thecollections module" change (bpo-25988). Aliases to ABC likecollections.Mapping are kept in Python 3.9 to ease transition from Python2.7, but will be removed in Python 3.10.

  • bpo-39104: Fix hanging ProcessPoolExcutor onshutdown(wait=False) whena task has failed pickling.

  • bpo-39627: Fixed TypedDict totality check for inherited keys.

  • bpo-39474: Fixed starting position of AST for expressions like(a)(b),(a)[b] and(a).b.

  • bpo-21016: Thepydoc andtrace modules now use thesysconfig module to get the path to the Python standard library, tosupport uncommon installation path like/usr/lib64/python3.9/ onFedora. Patch by Jan Matějek.

  • bpo-39590: Collections.deque now holds strong references duringdeque.__contains__ and deque.count, fixing crashes.

  • bpo-39586: The distutilsbdist_msi command is deprecated in Python3.9, usebdist_wheel (wheel packages) instead.

  • bpo-39595: Improved performance of zipfile.Path for files with a largenumber of entries. Also improved performance and fixed minor issue aspublished withimportlib_metadata 1.5.

  • bpo-39350: Fix regression infractions.Fraction if the numeratorand/or the denominator is anint subclass. Themath.gcd()function is now used to normalize thenumerator anddenominator.math.gcd() always return aint type. Previously, the GCDtype depended onnumerator anddenominator.

  • bpo-39567: Added audit foros.walk(),os.fwalk(),pathlib.Path.glob() andpathlib.Path.rglob().

  • bpo-39559: Remove unused, undocumented argumentgetters fromuuid.getnode()

  • bpo-38149:sys.audit() is now called only once per call ofglob.glob() andglob.iglob().

  • bpo-39546: Fix a regression inArgumentParser whereallow_abbrev=False was ignored for long options that used a prefixcharacter other than "-".

  • bpo-39450: Striped whitespace from docstring before returning it fromunittest.case.shortDescription().

  • bpo-12915: A new functionresolve_name has been added to thepkgutil module. This resolves a string of the form'a.b.c.d' or'a.b:c.d' to an object. In the example,a.b is a package/moduleandc.d is an object within that package/module reached via recursiveattribute access.

  • bpo-39353: Thebinascii.crc_hqx() function is no longer deprecated.

  • bpo-39493: Marktyping.IO.closed as a property

  • bpo-39491: Addtyping.Annotated andinclude_extras parametertotyping.get_type_hints() as part ofPEP 593. Patch by TillVaroquaux, documentation by Till Varoquaux and Konstantin Kashin.

  • bpo-39485: Fix a bug inunittest.mock.create_autospec() that wouldcomplain about the wrong number of arguments for custom descriptorsdefined in an extension module returning functions.

  • bpo-38932: Mock fully resets child objects on reset_mock(). Patch byVegard Stikbakke

  • bpo-39082: Allow AsyncMock to correctly patch static/class methods

  • bpo-39432: Implement PEP-489 algorithm for non-ascii "PyInit_..." symbolnames in distutils to make it export the correct init symbol also onWindows.

  • bpo-18819: Omitdevmajor anddevminor fields for non-device filesintarfile archives, enabling bit-for-bit compatibility with GNUtar(1).

  • bpo-39349: Added a newcancel_futures parameter toconcurrent.futures.Executor.shutdown() that cancels all pendingfutures which have not started running, instead of waiting for them tocomplete before shutting down the executor.

  • bpo-39274:bool(fraction.Fraction) now returns a boolean even if(numerator != 0) does not return a boolean (ex: numpy number).

  • bpo-34793: Remove support forwith(awaitasyncio.lock): andwith(yieldfromasyncio.lock):. The same is correct forasyncio.Condition andasyncio.Semaphore.

  • bpo-25597: Ensure, ifwraps is supplied tounittest.mock.MagicMock, it is used to calculate return valuesfor the magic methods instead of using the default return values. Patch byKarthikeyan Singaravelan.

  • bpo-36350:inspect.Signature.parameters andinspect.BoundArguments.arguments are now dicts instead ofOrderedDicts. Patch contributed by Rémi Lapeyre.

  • bpo-35727: Fix sys.exit() and sys.exit(None) exit code propagation whenused in multiprocessing.Process.

  • bpo-32173: * Addlazycache function to__all__. * Usedict.clear to clear the cache. * Refactoringgetline function andcheckcache function.

Documentation

  • bpo-17422: The language reference now specifies restrictions on classnamespaces. Adapted from a patch by Ethan Furman.

  • bpo-39572: Updated documentation oftotal flag ofTypedDict.

  • bpo-39654: In pyclbr doc, update 'class' to 'module' where appropriate andadd readmodule comment. Patch by Hakan Çelik.

  • bpo-39153: Clarify refcounting semantics for the following functions: -PyObject_SetItem - PyMapping_SetItemString - PyDict_SetItem -PyDict_SetItemString

  • bpo-39392: Explain that when filling with turtle, overlap regions may beleft unfilled.

  • bpo-39369: Update mmap readline method description. The fact that thereadline method does update the file position should not be ignored sincethis might give the impression for the programmer that it doesn't updateit.

  • bpo-9056: Include subsection in TOC for PDF version of docs.

Tests

Build

Windows

  • bpo-39553: Delete unused code related to SxS manifests.

  • bpo-39439: Honor the Python path when a virtualenv is active on Windows.

  • bpo-39393: Improve the error message when attempting to load a DLL withunresolved dependencies.

  • bpo-38883:home() andexpanduser()on Windows now preferUSERPROFILE and no longer useHOME, which is not normally set for regular user accounts. Thismakes them again behave likeos.path.expanduser(), which was changedto ignoreHOME in 3.8, seebpo-36264.

  • bpo-39185: The build.bat script has additional options for very-quietoutput (-q) and very-verbose output (-vv)

IDLE

  • bpo-39663: Add tests for pyparse find_good_parse_start().

  • bpo-39600: In the font configuration window, remove duplicated font names.

  • bpo-30780: Add remaining configdialog tests for buttons and highlights andkeys tabs.

  • bpo-39388: IDLE Settings Cancel button now cancels pending changes

  • bpo-38792: Close an IDLE shell calltip if aKeyboardInterrupt orshell restart occurs. Patch by Zackery Spytz.

C API

  • bpo-35081: Move thebytes_methods.h header file to the internal C APIaspycore_bytes_methods.h: it only contains private symbols (prefixedby_Py), except of thePyDoc_STRVAR_shared() macro.

  • bpo-35081: Move thedtoa.h header file to the internal C API aspycore_dtoa.h: it only contains private functions (prefixed by_Py). Themath andcmath modules must now be compiledwith thePy_BUILD_CORE macro defined.

  • bpo-39573: AddPy_SET_SIZE() function to set the size of anobject.

  • bpo-39500:PyUnicode_IsIdentifier() does not callPy_FatalError() anymore if the string is not ready.

  • bpo-39573: AddPy_SET_TYPE() function to set the type of anobject.

  • bpo-39573: Add aPy_SET_REFCNT() function to set the referencecounter of an object.

  • bpo-39542: ConvertPyType_HasFeature(),PyType_Check() andPyType_CheckExact() macros to static inline functions.

  • bpo-39542: In the limited C API,PyObject_INIT() andPyObject_INIT_VAR() are now defined as aliases toPyObject_Init() andPyObject_InitVar() to make theirimplementation opaque. It avoids to leak implementation details in thelimited C API. Exclude the following functions from the limited C API:_Py_NewReference(),_Py_ForgetReference(),_PyTraceMalloc_NewReference() and_Py_GetRefTotal().

  • bpo-39542: Exclude trashcan mechanism from the limited C API: it requiresaccess to PyTypeObject and PyThreadState structure fields, whereas thesestructures are opaque in the limited C API.

  • bpo-39511: ThePyThreadState_Clear() function now calls thePyThreadState.on_delete callback. Previously, that happened inPyThreadState_Delete().

  • bpo-38076: Fix to clear the interpreter state only after clearing moduleglobals to guarantee module state access from C Extensions during runtimedestruction

  • bpo-39245: The Vectorcall API (PEP 590) was made public, adding thefunctionsPyObject_Vectorcall,PyObject_VectorcallMethod,PyVectorcall_Function,PyObject_CallOneArg,PyObject_CallMethodNoArgs,PyObject_CallMethodOneArg,PyObject_FastCallDict, and the flagPy_TPFLAGS_HAVE_VECTORCALL.

Python 3.9.0 alpha 3

Release date: 2020-01-24

Core and Builtins

  • bpo-39427: Document all possibilities for the-X options in thecommand line help section. Patch by Pablo Galindo.

  • bpo-39421: Fix possible crashes when operating with the functions in theheapq module and custom comparison operators.

  • bpo-39386: Prevent double awaiting of async iterator.

  • bpo-17005: Addfunctools.TopologicalSorter to thefunctools module to offers functionality to perform topologicalsorting of graphs. Patch by Pablo Galindo, Tim Peters and Larry Hastings.

  • bpo-39320: Replace four complex bytecodes for building sequences withthree simpler ones.

    The following four bytecodes have been removed:

    • BUILD_LIST_UNPACK

    • BUILD_TUPLE_UNPACK

    • BUILD_SET_UNPACK

    • BUILD_TUPLE_UNPACK_WITH_CALL

    The following three bytecodes have been added:

    • LIST_TO_TUPLE

    • LIST_EXTEND

    • SET_UPDATE

  • bpo-39336: Import loaders which publish immutable module objects can nowpublish immutable packages in addition to individual modules.

  • bpo-39322: Added a new functiongc.is_finalized() to check if anobject has been finalized by the garbage collector. Patch by PabloGalindo.

  • bpo-39048: Improve the displayed error message when incorrect types arepassed toasyncwith statements by looking up the__aenter__()special method before the__aexit__() special method when enteringan asynchronous context manager. Patch by Géry Ogam.

  • bpo-39235: Fix AST end location for lone generator expression in functioncall, e.g. f(i for i in a).

  • bpo-39209: Correctly handle multi-line tokens in interactive mode. Patchby Pablo Galindo.

  • bpo-1635741: Port _json extension module to multiphase initialization(PEP 489).

  • bpo-39216: Fix constant folding optimization for positional only arguments- by Anthony Sottile.

  • bpo-39215: FixSystemError when nested function has annotation onpositional-only argument - by Anthony Sottile.

  • bpo-39200: Correct the error message when calling themin() ormax() with no arguments. Patch by Donghee Na.

  • bpo-39200: Correct the error message when trying to constructrange objects with no arguments. Patch by Pablo Galindo.

  • bpo-39166: Fix incorrect line execution reporting in trace functions whentracing the last iteration of asynchronous for loops. Patch by PabloGalindo.

  • bpo-39114: Fix incorrect line execution reporting in trace functions whentracing exception handlers with name binding. Patch by Pablo Galindo.

  • bpo-39156: Split the COMPARE_OP bytecode instruction into four distinctinstructions.

    • COMPARE_OP for rich comparisons

    • IS_OP for 'is' and 'is not' tests

    • CONTAINS_OP for 'in' and 'is not' tests

    • JUMP_IF_NOT_EXC_MATCH for checking exceptions in 'try-except' statements.

    This improves the clarity of the interpreter and should provide a modestspeedup.

  • bpo-38588: Fix possible crashes in dict and list when callingPyObject_RichCompareBool().

  • bpo-13601: By default,sys.stderr is line-buffered now, even ifstderr is redirected to a file. You can still makesys.stderrunbuffered by passing the-u command-line option or setting thePYTHONUNBUFFERED environment variable.

    (Contributed by Jendrik Seipp inbpo-13601.)

  • bpo-38610: Fix possible crashes in several list methods by holding strongreferences to list elements when callingPyObject_RichCompareBool().

  • bpo-32021: Include brotli .br encoding in mimetypes encodings_map

Library

  • bpo-39430: Fixed race condition in lazy imports intarfile.

  • bpo-39413: Theos.unsetenv() function is now also available onWindows.

  • bpo-39390: Fixed a regression with theignore callback ofshutil.copytree(). The argument types are nowstr andList[str] again.

  • bpo-39395: Theos.putenv() andos.unsetenv() functions are nowalways available.

  • bpo-39406: Ifsetenv() C function is available,os.putenv() isnow implemented withsetenv() instead ofputenv(), so Pythondoesn't have to handle the environment variable memory.

  • bpo-39396: Fixmath.nextafter(-0.0,+0.0) on AIX 7.1.

  • bpo-29435: Allowtarfile.is_tarfile() to be used with file andfile-like objects, likezipfile.is_zipfile(). Patch by WilliamWoodruff.

  • bpo-39377: Removedencoding option fromjson.loads(). It hasbeen deprecated since Python 3.1.

  • bpo-39389: Write accurate compression level metadata ingziparchives, rather than always signaling maximum compression.

  • bpo-39366: The previously deprecatedxpath() andxgtitle() methodsofnntplib.NNTP have been removed.

  • bpo-39357: Remove thebuffering parameter ofbz2.BZ2File. SincePython 3.0, it was ignored and using it was emittingDeprecationWarning. Pass an open file object, to control how thefile is opened. Thecompresslevel parameter becomes keyword-only.

  • bpo-39353: Deprecate binhex4 and hexbin4 standards. Deprecate thebinhex module and the followingbinascii functions:b2a_hqx(),a2b_hqx(),rlecode_hqx(),rledecode_hqx(),crc_hqx().

  • bpo-39351: Removebase64.encodestring() andbase64.decodestring(),aliases deprecated since Python 3.1: usebase64.encodebytes() andbase64.decodebytes() instead.

  • bpo-39350: Removefractions.gcd() function, deprecated since Python3.5 (bpo-22486): usemath.gcd() instead.

  • bpo-39329:LMTP constructor now has an optionaltimeout parameter. Patch by Donghee Na.

  • bpo-39313: Add a newexec_function option (--exec-function in theCLI) toRefactoringTool for makingexec a function. Patch byBatuhan Taskaya.

  • bpo-39259:FTP_TLS andFTP_TLS now raiseaValueError if the given timeout for their constructor is zeroto prevent the creation of a non-blocking socket. Patch by Donghee Na.

  • bpo-39259:SMTP andSMTP_SSL now raiseaValueError if the given timeout for their constructor is zeroto prevent the creation of a non-blocking socket. Patch by Donghee Na.

  • bpo-39310: Addmath.ulp(): return the value of the least significantbit of a float.

  • bpo-39297: Improved performance of importlib.metadata distributiondiscovery and resilients to inaccessible sys.path entries(importlib_metadata v1.4.0).

  • bpo-39259:NNTP andNNTP_SSL now raise aValueError if the given timeout for their constructor is zero toprevent the creation of a non-blocking socket. Patch by Donghee Na.

  • bpo-38901: When you specify prompt='.' or equivalently python -m venv--prompt . ... the basename of the current directory is used to set thecreated venv's prompt when it's activated.

  • bpo-39288: Addmath.nextafter(): return the next floating-pointvalue afterx towardsy.

  • bpo-39259:POP3 andPOP3_SSL now raise aValueError if the given timeout for their constructor is zero toprevent the creation of a non-blocking socket. Patch by Donghee Na.

  • bpo-39242: Updated the Gmane domain from news.gmane.org to news.gmane.iowhich is used for examples ofNNTP news reader server andnntplib tests.

  • bpo-35292: Proxy theSimpleHTTPRequestHandler.guess_type tomimetypes.guess_type so themimetypes.init is called lazily toavoid unnecessary costs whenhttp.server module is imported.

  • bpo-39239: Theselect.epoll.unregister() method no longer ignorestheEBADF error.

  • bpo-38907: In http.server script, restore binding to IPv4 on Windows.

  • bpo-39152: Fix ttk.Scale.configure([name]) to return configuration tuplefor name or all options. Giovanni Lombardo contributed part of the patch.

  • bpo-39198: If an exception were to be thrown inLogger.isEnabledFor(say, by asyncio timeouts or stopit) , thelogging global lock may notbe released appropriately, resulting in deadlock. This change wraps thatblock of code withtry...finally to ensure the lock is released.

  • bpo-39191: Perform a check for running loop before starting a new task inloop.run_until_complete() to fail fast; it prevents the side effect ofnew task spawning before exception raising.

  • bpo-38871: Correctly parenthesize filter-based statements that containlambda expressions inlib2to3. Patch by Donghee Na.

  • bpo-39142: A change was made to logging.config.dictConfig to avoidconverting instances of named tuples to ConvertingTuple. It's assumed thatnamed tuples are too specialised to be treated like ordinary tuples; if auser of named tuples requires ConvertingTuple functionality, they willhave to implement that themselves in their named tuple class.

  • bpo-39158: ast.literal_eval() now supports empty sets.

  • bpo-39129: Fix import path forasyncio.TimeoutError

  • bpo-39057:urllib.request.proxy_bypass_environment() now ignoresleading dots and no longer ignores a trailing newline.

  • bpo-39056: Fixed handling invalid warning category in the -W option. Nolonger import the re module if it is not needed.

  • bpo-39055:base64.b64decode() withvalidate=True raises now abinascii.Error if the input ends with a single\n.

  • bpo-21600: Fixmock.patch.stopall() to stop active patches that werecreated withmock.patch.dict().

  • bpo-39019: Implement dummy__class_getitem__ fortempfile.SpooledTemporaryFile.

  • bpo-39019: Implement dummy__class_getitem__ forsubprocess.Popen,subprocess.CompletedProcess

  • bpo-38914: Adjusted the wording of the warning issued by distutils'check command when theauthor andmaintainer fields aresupplied but no corresponding e-mail field (author_email ormaintainer_email) is found. The wording now reflects the fact thatthese fields are suggested, but not required. Patch by Juergen Gmach.

  • bpo-38878: Fixed __subclasshook__ ofos.PathLike to return acorrect result upon inheritance. Patch by Bar Harel.

  • bpo-38615:IMAP4 andIMAP4_SSL nowhave an optionaltimeout parameter for their constructors. Also, theopen() method now has an optionaltimeout parameterwith this change. The overridden methods ofIMAP4_SSLandIMAP4_stream were applied to this change. Patch byDonghee Na.

  • bpo-35182: FixedPopen.communicate() subsequent call crash when thechild process has already closed any piped standard stream, but stillcontinues to be running. Patch by Andriy Maletsky.

  • bpo-38630: On Unix,subprocess.Popen.send_signal() now polls theprocess status. Polling reduces the risk of sending a signal to the wrongprocess if the process completed, thesubprocess.Popen.returncodeattribute is stillNone, and the pid has been reassigned (recycled) toa new different process.

  • bpo-38536: Removes trailing space in formatted currency withinternational=True and a locale with symbol following value. E.g.locale.currency(12.34,international=True) returned'12,34EUR'instead of'12,34EUR'.

  • bpo-38473: Use signature from inner mock for autospecced methods attachedwithunittest.mock.attach_mock(). Patch by Karthikeyan Singaravelan.

  • bpo-38361: Fixed an issue whereident could include a leading pathseparator whensyslog.openlog() was called without arguments.

  • bpo-38293: Addcopy.copy() andcopy.deepcopy() support toproperty() objects.

  • bpo-37958: Added the pstats.Stats.get_profile_dict() method to return theprofile data as a StatsProfile instance.

  • bpo-28367: Termios magic constants for the following baud rates: -B500000 - B576000 - B921600 - B1000000 - B1152000 - B1500000 -B2000000 - B2500000 - B3000000 - B3500000 - B4000000 Patch byAndrey Smirnov

Documentation

  • bpo-39381: Mention in docs thatasyncio.get_event_loop() implicitlycreates new event loop only if called from the main thread.

  • bpo-38918: Add an entry for__module__ in the "function" & "method"sections of theinspect docs'Types and members table.

  • bpo-3530: In theast module documentation, fix a misleadingNodeTransformer example and add advice on when to use thefix_missing_locations function.

Build

  • bpo-39395: On non-Windows platforms, thesetenv() andunsetenv() functions are now required to build Python.

  • bpo-39160: Updated the documentation in./configure--help to showdefault values, reference documentation where required and add additionalexplanation where needed.

  • bpo-39144: The ctags and etags build targets both include Modules/_ctypesand Python standard library source files.

IDLE

  • bpo-39050: Make IDLE Settings dialog Help button work again.

  • bpo-34118: Tag memoryview, range, and tuple as classes, the same as list,etcetera, in the library manual built-in functions list.

  • bpo-32989: Add tests for editor newline_and_indent_event method. Removedead code from pyparse find_good_parse_start method.

C API

  • bpo-39372: Clean header files of interfaces defined but with noimplementation. The public API symbols being removed are:_PyBytes_InsertThousandsGroupingLocale,_PyBytes_InsertThousandsGrouping,_Py_InitializeFromArgs,_Py_InitializeFromWideArgs,_PyFloat_Repr,_PyFloat_Digits,_PyFloat_DigitsInit,PyFrame_ExtendStack,_PyAIterWrapper_Type,PyNullImporter_Type,PyCmpWrapper_Type,PySortWrapper_Type,PyNoArgsFunction.

  • bpo-39164: Add a private_PyErr_GetExcInfo() function to retrieveexception information of the specified Python thread state.

Python 3.9.0 alpha 2

Release date: 2019-12-18

Security

  • bpo-38945: Newline characters have been escaped when performing uuencoding to prevent them from overflowing into to content section of theencoded file. This prevents malicious or accidental modification of dataduring the decoding process.

  • bpo-37228: Due to significant security concerns, thereuse_addressparameter ofasyncio.loop.create_datagram_endpoint() is no longersupported. This is because of the behavior ofSO_REUSEADDR in UDP. Formore details, see the documentation forloop.create_datagram_endpoint(). (Contributed by Kyle Stanley, AntoinePitrou, and Yury Selivanov inbpo-37228.)

  • bpo-38804: Fixes a ReDoS vulnerability inhttp.cookiejar. Patch byBen Caller.

Core and Builtins

  • bpo-39028: Slightly improve the speed of keyword argument parsing withmany kwargs by strengthening the assumption that kwargs are internedstrings.

  • bpo-39080: Fix the value ofend_col_offset for Starred Expression ASTnodes when they are among the elements in theargs attribute of Call ASTnodes.

  • bpo-39031: When parsing an "elif" node, lineno and col_offset of the nodenow point to the "elif" keyword and not to its condition, making itconsistent with the "if" node. Patch by Lysandros Nikolaou.

  • bpo-20443: In Python 3.9.0a1, sys.argv[0] was made an absolute path if afilename was specified on the command line. Revert this change, since mostusers expect sys.argv to be unmodified.

  • bpo-39008:PySys_Audit() now requiresPy_ssize_t to be usedfor size arguments in the format string, regardless of whetherPY_SSIZE_T_CLEAN was defined at include time.

  • bpo-38673: In REPL mode, don't switch to PS2 if the line starts withcomment or whitespace. Based on work by Batuhan Taşkaya.

  • bpo-38922: Callingreplace on a code object now raises thecode.__new__ audit event.

  • bpo-38920: Add audit hooks for whensys.excepthook() andsys.unraisablehook() are invoked.

  • bpo-38892: Improve documentation for audit events table and functions.

  • bpo-38852: Set the thread stack size to 8 Mb for debug builds on androidplatforms.

  • bpo-38858: Each Python subinterpreter now has its own "small integersingletons": numbers in [-5; 257] range. It is no longer possible tochange the number of small integers at build time by overridingNSMALLNEGINTS andNSMALLPOSINTS macros: macros should now bemodified manually inpycore_pystate.h header file.

  • bpo-36854: The garbage collector state becomes per interpreter(PyInterpreterState.gc), rather than being global(_PyRuntimeState.gc).

  • bpo-38835: ThePyFPE_START_PROTECT() andPyFPE_END_PROTECT()macros are empty: they have been doing nothing for the last year, so stopusing them.

  • bpo-38328: Sped up the creation time of constantlist andset displays. Patch by Brandt Bucher.

  • bpo-38707:MainThread.native_id is now correctly reset in childprocesses spawned usingmultiprocessing.Process, instead ofretaining the parent's value.

  • bpo-38629: Added__floor__ and__ceil__ methods to float object.Patch by Batuhan Taşkaya.

  • bpo-27145: int + int and int - int operators can now return small integersingletons. Patch by hongweipeng.

  • bpo-38021: Provide a platform tag for AIX that is sufficient for PEP425binary distribution identification. Patch by Michael Felt.

  • bpo-35409: Ignore GeneratorExit exceptions when throwing an exception intothe aclose coroutine of an asynchronous generator.

  • bpo-33387: Removed WITH_CLEANUP_START, WITH_CLEANUP_FINISH, BEGIN_FINALLY,END_FINALLY, CALL_FINALLY and POP_FINALLY bytecodes. Replaced with RERAISEand WITH_EXCEPT_START bytecodes. The compiler now generates different codefor exceptional and non-exceptional branches for 'with' and 'try-except'statements. For 'try-finally' statements the 'finally' block is replicatedfor each exit from the 'try' body.

Library

  • bpo-39033: FixNameError inzipimport. Patch by KarthikeyanSingaravelan.

  • bpo-39022: Update importlib.metadata to include improvements fromimportlib_metadata 1.3 including better serialization of EntryPoints andimproved documentation for custom finders.

  • bpo-39006: Fix asyncio when the ssl module is missing: only check forssl.SSLSocket instance if the ssl module is available.

  • bpo-38708: Fix a potential IndexError in email parser when parsing anempty msg-id.

  • bpo-38698: Add a newInvalidMessageID token to email parser torepresent invalid Message-ID headers. Also, add defects when there isremaining value after parsing the header.

  • bpo-38994: Implement__class_getitem__ foros.PathLike,pathlib.Path.

  • bpo-38979: Return class fromContextVar.__class_getitem__ to simplifysubclassing.

  • bpo-38978: Implement__class_getitem__ on asyncio objects (Future,Task, Queue). Patch by Batuhan Taskaya.

  • bpo-38916:array.array: Removetostring() andfromstring() methods. They were aliases totobytes() andfrombytes(), deprecated since Python 3.2.

  • bpo-38986: Make repr of C accelerated TaskWakeupMethWrapper the same as ofpure Python version.

  • bpo-38982: Fix asyncioPidfdChildWatcher: handlewaitpid() error.Ifwaitpid() is called elsewhere,waitpid() call fails withChildProcessError: use return code 255 in this case, and log awarning. It ensures that the pidfd file descriptor is closed if this erroroccurs.

  • bpo-38529: Drop too noisy asyncio warning about deletion of a streamwithout explicit.close() call.

  • bpo-27413: Added ability to pass throughensure_ascii options tojson.dumps in thejson.tool command-line interface.

  • bpo-38634: Thereadline module now detects if Python is linked tolibedit at runtime on all platforms. Previously, the check was only doneon macOS.

  • bpo-33684: Fixjson.tool failed to read a JSON file with non-ASCIIcharacters when locale encoding is not UTF-8.

  • bpo-38698: Prevent UnboundLocalError to pop up in parse_message_id.

    parse_message_id() was improperly using a token defined inside anexception handler, which was raisingUnboundLocalError on parsing aninvalid value. Patch by Claudiu Popa.

  • bpo-38927: Usepython-mpip instead ofpip to upgradedependencies in venv.

  • bpo-26730: FixSpooledTemporaryFile.rollover() might corrupt the filewhen it is in text mode. Patch by Serhiy Storchaka.

  • bpo-38881: random.choices() now raises a ValueError when all the weightsare zero.

  • bpo-38876: Raise pickle.UnpicklingError when loading an item from memo forinvalid input.

    The previous code was raising aKeyError for both the Python and Cimplementation. This was caused by the specified index of an invalid inputwhich did not exist in the memo structure, where the pickle stores whatobjects it has seen. The malformed input would have caused either aBINGET orLONG_BINGET load from the memo, leading to aKeyError as the determined index was bogus. Patch by Claudiu Popa.

  • bpo-38688: Calling func:shutil.copytree to copy a directory tree fromone directory to another subdirectory resulted in an endless loop and aRecursionError. A fix was added to consume an iterator and create the listof the entries to be copied, avoiding the recursion for newly createddirectories. Patch by Bruno P. Kinoshita.

  • bpo-38863: Improveis_cgi() function inhttp.server, whichenables processing the case that cgi directory is a child of anotherdirectory other than root.

  • bpo-37838:typing.get_type_hints() properly handles functionsdecorated withfunctools.wraps().

  • bpo-38870: Exposeast.unparse() as a function of theastmodule that can be used to unparse anast.AST object and producea string with code that would produce an equivalentast.ASTobject when parsed. Patch by Pablo Galindo and Batuhan Taskaya.

  • bpo-38859: AsyncMock now returns StopAsyncIteration on the exhaustion of aside_effects iterable. Since PEP-479 its Impossible to raise aStopIteration exception from a coroutine.

  • bpo-38857: AsyncMock fix for return values that are awaitable types. Thisalso covers side_effect iterable values that happened to be awaitable, andwraps callables that return an awaitable type. Before these awaitableswere being awaited instead of being returned as is.

  • bpo-38834:typing.TypedDict subclasses now track which keys areoptional using the__required_keys__ and__optional_keys__attributes, to enable runtime validation by downstream projects. Patch byZac Hatfield-Dodds.

  • bpo-38821: Fix unhandled exceptions inargparse wheninternationalizing error messages for arguments withnargs set tospecial (non-integer) values. Patch by Federico Bond.

  • bpo-38820: Make Python compatible with OpenSSL 3.0.0.ssl.SSLSocket.getpeercert() no longer returns IPv6 addresses with atrailing new line.

  • bpo-38811: Fix an unhandled exception inpathlib whenos.link() is missing. Patch by Toke Høiland-Jørgensen.

  • bpo-38686: Added support for multipleqop values inurllib.request.AbstractDigestAuthHandler.

  • bpo-38712: Add the Linux-specificsignal.pidfd_send_signal()function, which allows sending a signal to a process identified by a filedescriptor rather than a pid.

  • bpo-38348: Add-i and--indent (indentation level), and--no-type-comments (type comments) command line options to ast parsingtool.

  • bpo-37523: Changezipfile.ZipExtFile to raiseValueError whentrying to access the underlying file object after it has been closed. Thisnew behavior is consistent with how accessing closed files is handled inother parts of Python.

  • bpo-38045: Improve the performance ofenum._decompose() inenum. Patch by hongweipeng.

  • bpo-36820: Break cycle generated when saving an exception in socket.py,codeop.py and dyld.py as they keep alive not only the exception but userobjects through the__traceback__ attribute. Patch by Mario Corchero.

  • bpo-36406: Handle namespace packages indoctest. Patch byKarthikeyan Singaravelan.

  • bpo-34776: Fix dataclasses to support forward references in typeannotations

  • bpo-20928: ElementTree supports recursive XInclude processing. Patch byStefan Behnel.

  • bpo-29636: Add whitespace options for formatting JSON with thejson.tool CLI. The following mutually exclusive options are nowsupported:--indent for setting the indent level in spaces;--tabfor indenting with tabs;--no-indent for suppressing newlines; and--compact for suppressing all whitespace. The default behavior remainsthe same as--indent=4.

Documentation

Tests

  • bpo-38546: Fix test_ressources_gced_in_workers() oftest_concurrent_futures: explicitly stop the manager to prevent leaking achild process running in the background after the test completes.

  • bpo-38546: Multiprocessing and concurrent.futures tests now stop theresource tracker process when tests complete.

  • bpo-38614: Replace hardcoded timeout constants in tests with newtest.support constants:LOOPBACK_TIMEOUT,INTERNET_TIMEOUT,SHORT_TIMEOUT andLONG_TIMEOUT. It becomes easier to adjust these fourtimeout constants for all tests at once, rather than having to adjustevery single test file.

  • bpo-38547: Fix test_pty: if the process is the session leader, closing themaster file descriptor raises a SIGHUP signal: simply ignore SIGHUP whenrunning the tests.

  • bpo-38992: Fix a test formath.fsum() that was failing due toconstant folding.

  • bpo-38991:test.support:run_python_until_end(),assert_python_ok() andassert_python_failure() functions no longer stripwhitespaces from stderr. Removetest.support.strip_python_stderr()function.

  • bpo-38965: Fix test_faulthandler on GCC 10. Use the "volatile" keyword infaulthandler._stack_overflow() to prevent tail call optimization onany compiler, rather than relying on compiler specific pragma.

  • bpo-38875: test_capi: trashcan tests now require the test "cpu" resource.

  • bpo-38841: Skip asyncio test_create_datagram_endpoint_existing_sock_unixon platforms lacking a functional bind() for named unix domain sockets.

  • bpo-38692: Skip the test_posix.test_pidfd_open() test ifos.pidfd_open() fails with aPermissionError. This situationcan happen in a Linux sandbox using a syscall whitelist which doesn'tallow thepidfd_open() syscall yet.

  • bpo-38839: Fix some unused functions in tests. Patch by Adam Johnson.

  • bpo-38669: RaiseTypeError when passing target as a string withunittest.mock.patch.object().

  • bpo-37957: test.regrtest now can receive a list of test patterns to ignore(using the -i/--ignore argument) or a file with a list of patterns toignore (using the --ignore-file argument). Patch by Pablo Galindo.

Build

  • bpo-37404:asyncio now raisesTypeError when callingincompatible methods with anssl.SSLSocket socket. Patch by IdoMichael.

  • bpo-36500: Added an optional "regen" project to the Visual Studio solutionthat will regenerate all grammar, tokens, and opcodes.

Windows

  • bpo-39007: Add auditing events to functions inwinreg.

  • bpo-33125: Add support for building and releasing Windows ARM64 packages.

macOS

  • bpo-37931: Fixed a crash on OSX dynamic builds that occurred whenre-initializing the posix module after a Py_Finalize if the environmenthad changed since the previousimportposix. Patch by Benoît Hudson.

IDLE

  • bpo-38944: Escape key now closes IDLE completion windows. Patch by JohnnyNajera.

  • bpo-38943: Fix IDLE autocomplete windows not always appearing on somesystems. Patch by Johnny Najera.

  • bpo-38862: 'Strip Trailing Whitespace' on the Format menu removes extranewlines at the end of non-shell files.

  • bpo-38636: Fix IDLE Format menu tab toggle and file indent width. Thesefunctions (default shortcuts Alt-T and Alt-U) were mistakenly disabled in3.7.5 and 3.8.0.

C API

  • bpo-38896: RemovePyUnicode_ClearFreeList() function: the Unicode freelist has been removed in Python 3.3.

  • bpo-37340: RemovePyMethod_ClearFreeList() andPyCFunction_ClearFreeList() functions: the free lists of bound methodobjects have been removed.

  • bpo-38835: ExcludePyFPE_START_PROTECT() andPyFPE_END_PROTECT()macros ofpyfpe.h fromPy_LIMITED_API (stable API).

Python 3.9.0 alpha 1

Release date: 2019-11-19

Security

Core and Builtins

  • bpo-38631: ReplacePy_FatalError() call with a regularRuntimeError exception infloat.__getformat__().

  • bpo-38639: Optimizedmath.floor(),math.ceil() andmath.trunc() for floats.

  • bpo-38640: Fixed a bug in the compiler that was causing to raise in thepresence of break statements and continue statements inside always falsewhile loops. Patch by Pablo Galindo.

  • bpo-38613: Optimized some set operations (e.g.|,^, and-) ofdict_keys.d.keys()|other was slower thanset(d)|other butthey are almost same performance for now.

  • bpo-28029:"".replace("",s,n) now returnss instead of an emptystring for all non-zeron. There are similar changes forbytes andbytearray objects.

  • bpo-38535: Fixed line numbers and column offsets for AST nodes for callswithout arguments in decorators.

  • bpo-38525: Fix a segmentation fault when using reverse iterators of emptydict objects. Patch by Donghee Na and Inada Naoki.

  • bpo-38465:bytearray,array andmmap objects allow now to export more than2**31buffers at a time.

  • bpo-38469: Fixed a bug where the scope of named expressions was not beingresolved correctly in the presence of theglobal keyword. Patch by PabloGalindo.

  • bpo-38437: Activate theGC_DEBUG macro for debug builds of theinterpreter (whenPy_DEBUG is set). Patch by Pablo Galindo.

  • bpo-38379: When the garbage collector makes a collection in which someobjects resurrect (they are reachable from outside the isolated cyclesafter the finalizers have been executed), do not block the collection ofall objects that are still unreachable. Patch by Pablo Galindo and TimPeters.

  • bpo-38379: When cyclic garbage collection (gc) runs finalizers thatresurrect unreachable objects, the current gc run ends, without collectingany cyclic trash. However, the statistics reported bycollect() andget_stats() claimed that all cyclic trash found was collected, andthat the resurrected objects were collected. Changed the stats to reportthat none were collected.

  • bpo-38392: In debug mode,PyObject_GC_Track() now callstp_traverse() of the object type to ensure that the object is valid:test that objects visited bytp_traverse() are valid.

  • bpo-38210: Remove unnecessary intersection and update set operation indictview with empty set. (Contributed by Donghee Na inbpo-38210.)

  • bpo-38402: Check the error from the system's underlyingcrypt orcrypt_r.

  • bpo-37474: On FreeBSD, Python no longer callsfedisableexcept() atstartup to control the floating-point control mode. The call becameuseless since FreeBSD 6: it became the default mode.

  • bpo-38006: Fix a bug due to the interaction of weakrefs and the cyclicgarbage collector. We must clear any weakrefs in garbage in order toprevent their callbacks from executing and causing a crash.

  • bpo-38317: Fix warnings options priority:PyConfig.warnoptions has thehighest priority, as stated in thePEP 587.

  • bpo-38310: PredictBUILD_MAP_UNPACK_WITH_CALL ->CALL_FUNCTION_EXopcode pairs in the main interpreter loop. Patch by Brandt Bucher.

  • bpo-36871: Improve error handling for the assert_has_calls andassert_has_awaits methods of mocks. Fixed a bug where any errorsencountered while binding the expected calls to the mock's spec weresilently swallowed, leading to misleading error output.

  • bpo-11410: Better control over symbol visibility is provided through useof the visibility attributes available in gcc >= 4.0, provided in auniform way across POSIX and Windows. The POSIX build files have beenupdated to compile with -fvisibility=hidden, minimising exported symbols.

  • bpo-38219: Optimized thedict constructor and theupdate() method for the case when the argument is a dict.

  • bpo-38236: Python now dumps path configuration if it fails to import thePython codecs of the filesystem and stdio encodings.

  • bpo-38013: Allow to callasync_generator_athrow().throw(...) even fornon-started async generator helper. It fixes annoying warning at the endofasyncio.run() call.

  • bpo-38124: Fix an off-by-one error in PyState_AddModule that could causeout-of-bounds memory access.

  • bpo-38116: The select module is now PEP-384 compliant and no longer hasstatic state

  • bpo-38113: ast module updated to PEP-384 and all statics removed

  • bpo-38076: The struct module is now PEP-384 compatible

  • bpo-38075: The random module is now PEP-384 compatible

  • bpo-38074: zlib module made PEP-384 compatible

  • bpo-38073: Make pwd extension module PEP-384 compatible

  • bpo-38072: grp module made PEP-384 compatible

  • bpo-38069: Make _posixsubprocess PEP-384 compatible

  • bpo-38071: Make termios extension module PEP-384 compatible

  • bpo-38005: Fixed comparing and creating of InterpreterID and ChannelID.

  • bpo-36946: Fix possible signed integer overflow when handling slices.Patch by hongweipeng.

  • bpo-37994: Fixed silencing arbitrary errors if an attribute lookup failsin several sites. Only AttributeError should be silenced.

  • bpo-8425: Optimize set difference_update for the case when the other setis much larger than the base set. (Suggested by Evgeny Kapun with codecontributed by Michele Orrù).

  • bpo-37966: The implementation ofis_normalized() hasbeen greatly sped up on strings that aren't normalized, by implementingthe full normalization-quick-check algorithm from the Unicode standard.

  • bpo-37947: Adjust correctly the recursion level in the symtable generationfor named expressions. Patch by Pablo Galindo.

  • bpo-37812: TheCHECK_SMALL_INT macro used insideObject/longobject.c has been replaced with an explicitreturnat each call site.

  • bpo-37751: Fixcodecs.lookup() to normalize the encoding name thesame way thanencodings.normalize_encoding(), except thatcodecs.lookup() also converts the name to lower case.

  • bpo-37830: Fixed compilation ofbreak andcontinuein thefinally block when the correspondingtryblock containsreturn with a non-constant value.

  • bpo-20490: Improve import error message for partially initialized moduleon circularfrom imports - by Anthony Sottile.

  • bpo-37840: Fix handling of negative indices insq_item ofbytearray. Patch bySergey Fedoseev.

  • bpo-37802: Slightly improve performance ofPyLong_FromUnsignedLong(),PyLong_FromUnsignedLongLong()andPyLong_FromSize_t(). Patch by Sergey Fedoseev.

  • bpo-37409: Ensure explicit relative imports from interactive sessions andscripts (having no parent package) always raise ImportError, rather thantreating the current module as the package. Patch by Ben Lewis.

  • bpo-32912: Revertedbpo-32912: emittingSyntaxWarning insteadofDeprecationWarning for invalid escape sequences in string andbytes literals.

  • bpo-37757:PEP 572: As described in the PEP, assignment expressions nowraiseSyntaxError when their interaction with comprehension scopingresults in an ambiguous target scope.

    TheTargetScopeError subclass originally proposed by the PEP has beenremoved in favour of just raising regular syntax errors for the disallowedcases.

  • bpo-36279: Fix potential use of uninitialized memory inos.wait3().

  • bpo-36311: Decoding bytes objects larger than 2GiB is faster and no longerfails when a multibyte characters spans a chunk boundary.

  • bpo-34880: Theassert statement now works properly if theAssertionError exception is being shadowed. Patch by Zackery Spytz.

  • bpo-37340: Removed object cache (free_list) for bound method objects.Temporary bound method objects are less used than before thanks to theLOAD_METHOD opcode and the_PyObject_VectorcallMethod C API.

  • bpo-37648: Fixed minor inconsistency inlist.__contains__(),tuple.__contains__() and a few other places. The collection's itemis now always at the left and the needle is on the right of==.

  • bpo-37444: Update differing exception betweenbuiltins.__import__()andimportlib.__import__().

  • bpo-37619: When adding a wrapper descriptor from one class to a differentclass (for example, setting__add__=str.__add__ on anintsubclass), an exception is correctly raised when the operator is called.

  • bpo-37593: Swap the positions of theposonlyargs andargs parametersin the constructor ofast.parameters nodes.

  • bpo-37543: Optimized pymalloc for non PGO build.

  • bpo-37537: Compute allocated pymalloc blocks inside_Py_GetAllocatedBlocks(). This slows down _Py_GetAllocatedBlocks() butgives a small speedup to _PyObject_Malloc() and _PyObject_Free().

  • bpo-37467: Fixsys.excepthook() andPyErr_Display() if afilename is a bytes string. For example, for a SyntaxError exception wherethe filename attribute is a bytes string.

  • bpo-37433: FixSyntaxError indicator printing too many spaces formulti-line strings - by Anthony Sottile.

  • bpo-37417:bytearray.extend() now correctly handles errors thatarise during iteration. Patch by Brandt Bucher.

  • bpo-37414: The undocumentedsys.callstats() function has been removed.Since Python 3.7, it was deprecated and always returnedNone. Itrequired a special build optionCALL_PROFILE which was already removedin Python 3.7.

  • bpo-37392: Removesys.getcheckinterval() andsys.setcheckinterval() functions. They were deprecated since Python3.2. Usesys.getswitchinterval() andsys.setswitchinterval()instead. Remove alsocheck_interval field of thePyInterpreterState structure.

  • bpo-37388: In development mode and in debug build,encoding anderrorsarguments are now checked on string encoding and decoding operations.Examples:open(),str.encode() andbytes.decode().

    By default, for best performances, theerrors argument is only checkedat the first encoding/decoding error, and theencoding argument issometimes ignored for empty strings.

  • bpo-37348: Optimized decoding short ASCII string with UTF-8 and asciicodecs.b"foo".decode() is about 15% faster. Patch by Inada Naoki.

  • bpo-24214: Improved support of the surrogatepass error handler in theUTF-8 and UTF-16 incremental decoders.

  • bpo-37330:open(),io.open(),codecs.open() andfileinput.FileInput no longer accept'U' ("universalnewline") in the file mode. This flag was deprecated since Python 3.3.

  • bpo-35224: Reverse evaluation order of key: value in dict comprehensionsas proposed in PEP 572. I.e. in{k:vfor...},k will beevaluated beforev.

  • bpo-37316: Fix thePySys_Audit() call inmmap.mmap.

  • bpo-37300: Remove an unnecessary Py_XINCREF in classobject.c.

  • bpo-37269: Fix a bug in the peephole optimizer that was not treatingcorrectly constant conditions with binary operators. Patch by PabloGalindo.

  • bpo-20443: Python now gets the absolute path of the script filenamespecified on the command line (ex: "python3 script.py"): the __file__attribute of the __main__ module and sys.path[0] become an absolute path,rather than a relative path.

  • bpo-37257: Python's small object allocator (obmalloc.c) now allows (nomore than) one empty arena to remain available for immediate reuse,without returning it to the OS. This prevents thrashing in simple loopswhere an arena could be created and destroyed anew on each iteration.

  • bpo-37231: The dispatching of type slots to special methods (for examplecalling__mul__ when doingx*y) has been made faster.

  • bpo-36974: Implemented separate vectorcall functions for every callingconvention of builtin functions and methods. This improves performance forcalls.

  • bpo-37213: Handle correctly negative line offsets in the peepholeoptimizer. Patch by Pablo Galindo.

  • bpo-37219: Remove erroneous optimization for empty set differences.

  • bpo-15913: ImplementPyBuffer_SizeFromFormat() function(previously documented but not implemented): callstruct.calcsize().Patch by Joannah Nanjekye.

  • bpo-36922: Slot functions optimize any callable withPy_TPFLAGS_METHOD_DESCRIPTOR instead of only instances offunction.

  • bpo-36974: The slottp_vectorcall_offset is inherited unconditionallyto supportsuper().__call__() when the base class uses vectorcall.

  • bpo-37160:threading.get_native_id() now also supports NetBSD.

  • bpo-37077: Addthreading.get_native_id() support for AIX. Patch byM. Felt

  • bpo-36781:sum() has been optimized for boolean values.

  • bpo-34556: Add--upgrade-deps to venv module. Patch by Cooper Ry Lees

  • bpo-20523:pdb.Pdb supports ~/.pdbrc in Windows 7. Patch by Tim Hopperand Dan Lidral-Porter.

  • bpo-35551: Updated encodings: - Removed the "tis260" encoding, which wasan alias for the nonexistent "tactis" codec. - Added "mac_centeuro" as analias for the mac_latin2 encoding.

  • bpo-19072: Theclassmethod decorator can now wrap otherdescriptors such as property objects. Adapted from a patch written byGraham Dumpleton.

  • bpo-27575: Improve speed of dictview intersection by directly using setintersection logic. Patch by David Su.

  • bpo-30773: Prohibit parallel running of aclose() / asend() / athrow(). Fixag_running to reflect the actual running status of the AG.

Library

  • bpo-36589: Thecurses.update_lines_cols() function now returnsNone instead of1 on success.

  • bpo-38807: UpdateTypeError messages foros.path.join() toincludeos.PathLike objects as acceptable input types.

  • bpo-38724: Add a repr forsubprocess.Popen objects. Patch by AndreyDoroschenko.

  • bpo-38786: pydoc now recognizes and parses HTTPS URLs. Patch by python273.

  • bpo-38785: Prevent asyncio from crashing if parent__init__ is notcalled from a constructor of object derived fromasyncio.Future.

  • bpo-38723:pdb now usesio.open_code() to trigger auditingevents.

  • bpo-27805: Allow opening pipes and other non-seekable files in append modewithopen().

  • bpo-38438: Simplify theargparse usage message fornargs="*".

  • bpo-38761: WeakSet is now registered as a collections.abc.MutableSet.

  • bpo-38716: logging: change RotatingHandler namer and rotator toclass-level attributes. This stops __init__ from setting them to None inthe case where a subclass defines them with eponymous methods.

  • bpo-38713: Addos.P_PIDFD constant, which may be passed toos.waitid() to wait on a Linux process file descriptor.

  • bpo-38692: Addasyncio.PidfdChildWatcher, a Linux-specific childwatcher implementation that polls process file descriptors.

  • bpo-38692: Expose the Linuxpidfd_open syscall asos.pidfd_open().

  • bpo-38602: Added constantsF_OFD_GETLK,F_OFD_SETLK andF_OFD_SETLKW to thefcntl module. Patch by Donghee Na.

  • bpo-38334: Fixed seeking backward on an encryptedzipfile.ZipExtFile.

  • bpo-38312: Addcurses.get_escdelay(),curses.set_escdelay(),curses.get_tabsize(), andcurses.set_tabsize() functions - byAnthony Sottile.

  • bpo-38586: NowfileConfig() correctly sets the .nameof handlers loaded.

  • bpo-38565: Add new cache_parameters() method for functools.lru_cache() tobetter support pickling.

  • bpo-34679: asynci.ProactorEventLoop.close() now only callssignal.set_wakeup_fd() in the main thread.

  • bpo-31202: The case the result ofpathlib.WindowsPath.glob() matchesnow the case of the pattern for literal parts.

  • bpo-36321: Remove misspelled attribute. The 3.8 changelog noted that thiswould be removed in 3.9.

  • bpo-38521: Fixed erroneous equality comparison in statistics.NormalDist().

  • bpo-38493: AddedCLD_KILLED andCLD_STOPPED forsi_code. Patch by Donghee Na.

  • bpo-38478: Fixed a bug ininspect.signature.bind() that was causingit to fail when handling a keyword argument with same name aspositional-only parameter. Patch by Pablo Galindo.

  • bpo-33604: Fixedhmac.new andhmac.HMAC to raise TypeError insteadof ValueError when the digestmod parameter, now required in 3.8, isomitted. Also clarified the hmac module documentation and docstrings.

  • bpo-38378: Parametersout andin ofos.sendfile() was renamed toout_fd andin_fd.

  • bpo-38417: Added support for setting the umask in the child process to thesubprocess module on POSIX systems.

  • bpo-38449: Revert PR 15522, which introduces a regression inmimetypes.guess_type() due to improper handling of filenames asurls.

  • bpo-38431: Fix__repr__ method fordataclasses.InitVar tosupport typing objects, patch by Samuel Colvin.

  • bpo-38109: Add missingstat.S_IFDOOR,stat.S_IFPORT,stat.S_IFWHT,stat.S_ISDOOR(),stat.S_ISPORT(), andstat.S_ISWHT() values to the Python implementation ofstat.

  • bpo-38422: Clarify docstrings of pathlib suffix(es)

  • bpo-38405: Nested subclasses oftyping.NamedTuple are nowpickleable.

  • bpo-38332: PreventKeyError thrown by_encoded_words.decode() when given an encoded-word with invalidcontent-type encoding from propagating all the way toemail.message.get().

  • bpo-38371: Deprecated thesplit() method in_tkinter.TkappType in favour of thesplitlist() method whichhas more consistent and predictable behavior.

  • bpo-38341: Addsmtplib.SMTPNotSupportedError to thesmtplibexported names.

  • bpo-38319: sendfile() used in socket and shutil modules was raisingOverflowError for files >= 2GiB on 32-bit architectures. (patch byGiampaolo Rodola)

  • bpo-38242: Revert the new asyncio Streams API

  • bpo-13153: OS native encoding is now used for converting between Pythonstrings and Tcl objects. This allows to display, copy and paste toclipboard emoji and other non-BMP characters. Converting strings from Tclto Python and back now never fails (except MemoryError).

  • bpo-38019: Correctly handle pause/resume reading of closed asyncio unixpipe.

  • bpo-38163: Child mocks will now detect their type as either synchronous orasynchronous, asynchronous child mocks will be AsyncMocks and synchronouschild mocks will be either MagicMock or Mock (depending on their parenttype).

  • bpo-38161: Removes _AwaitEvent from AsyncMock.

  • bpo-38216: Allow the rare code that wants to send invalid http requestsfrom thehttp.client library a way to do so. The fixes forbpo-30458led to breakage for some projects that were relying on this ability totest their own behavior in the face of bad requests.

  • bpo-28286: Deprecate openingGzipFile for writingimplicitly. Always specify themode argument for writing.

  • bpo-38108: Any synchronous magic methods on an AsyncMock now return aMagicMock. Any asynchronous magic methods on a MagicMock now return anAsyncMock.

  • bpo-38265: Update thelength parameter ofos.pread() to acceptPy_ssize_t instead ofint.

  • bpo-38112:compileall has a higher default recursion limit and newcommand-line arguments for path manipulation, symlinks handling, andmultiple optimization levels.

  • bpo-38248: asyncio: Fix inconsistent immediate Task cancellation

  • bpo-38237: The arguments for the builtin pow function are moredescriptive. They can now also be passed in as keywords.

  • bpo-34002: Improve efficiency in parts of email package by changingwhile-pop to a for loop, using isdisjoint instead of set intersections.

  • bpo-38191: Constructors ofNamedTuple andTypedDict types now accept arbitrary keyword argumentnames, including "cls", "self", "typename", "_typename", "fields" and"_fields".

  • bpo-38155: Add__all__ todatetime. Patch by Tahia Khan.

  • bpo-38185: Fixed case-insensitive string comparison insqlite3.Row indexing.

  • bpo-38136: Changes AsyncMock call count and await count to be twodifferent counters. Now await count only counts when a coroutine has beenawaited, not when it has been called, and vice-versa. Update thedocumentation around this.

  • bpo-37828: Fix default mock name inunittest.mock.Mock.assert_called() exceptions. Patch by AbrahamToriz Cruz.

  • bpo-38175: Fix a memory leak in comparison ofsqlite3.Rowobjects.

  • bpo-33936: _hashlib no longer calls obsolete OpenSSL initializationfunction with OpenSSL 1.1.0+.

  • bpo-34706: Preserve subclassing in inspect.Signature.from_callable.

  • bpo-38153: Names of hashing algorithms from OpenSSL are now normalized tofollow Python's naming conventions. For example OpenSSL uses sha3-512instead of sha3_512 or blake2b512 instead of blake2b.

  • bpo-38115: Fix a bug in dis.findlinestarts() where it would return invalidbytecode offsets. Document that a code object's co_lnotab can containinvalid bytecode offsets.

  • bpo-38148: Add slots toasyncio transport classes, which can reducememory usage.

  • bpo-38142: The _hashlib OpenSSL wrapper extension module is now PEP-384compliant.

  • bpo-9216: hashlib constructors now support usedforsecurity flag to signalthat a hashing algorithm is not used in a security context.

  • bpo-36991: Fixes a potential incorrect AttributeError exception escapingZipFile.extract() in some unsupported input error situations.

  • bpo-38134: Remove obsolete copy of PBKDF2_HMAC_fast. All supported OpenSSLversions contain a fast implementation.

  • bpo-38132: The OpenSSL hashlib wrapper uses a simpler implementation.Several Macros and pointless caches are gone. The hash name now comes fromOpenSSL's EVP. The algorithm name stays the same, except it is now alwayslower case.

  • bpo-38008: Fix parent class check in protocols to correctly identify themodule that provides a builtin protocol, instead of assuming they all comefrom thecollections.abc module

  • bpo-34037: Forasyncio, add a new coroutineloop.shutdown_default_executor(). The new coroutine provides an APIto schedule an executor shutdown that waits on the threadpool to finishclosing. Also,asyncio.run() has been updated to utilize the newcoroutine. Patch by Kyle Stanley.

  • bpo-37405: Fixed regression bug for socket.getsockname() for non-CAN_ISOTPAF_CAN address family sockets by returning a 1-tuple instead of string.

  • bpo-38121: Update parameter names on functions in importlib.metadatamatching the changes in the 0.22 release of importlib_metadata.

  • bpo-38110: The os.closewalk() implementation now uses the libc fdwalk()API on platforms where it is available.

  • bpo-38093: Fixes AsyncMock so it doesn't crash when used withAsyncContextManagers or AsyncIterators.

  • bpo-37488: Add warning todatetime.utctimetuple(),datetime.utcnow() anddatetime.utcfromtimestamp() .

  • bpo-35640: Allow passing apath-like object asdirectoryargument to thehttp.server.SimpleHTTPRequestHandler class. Patchby Géry Ogam.

  • bpo-38086: Update importlib.metadata with changes fromimportlib_metadata0.21.

  • bpo-37251: Remove__code__ check in AsyncMock that incorrectlyevaluated function specs as async objects but failed to evaluate classeswith__await__ but no__code__ attribute defined as async objects.

  • bpo-38037: Fix reference counters in thesignal module.

  • bpo-38066: Hide internal asyncio.Stream methods: feed_eof(), feed_data(),set_exception() and set_transport().

  • bpo-38059: inspect.py now uses sys.exit() instead of exit()

  • bpo-38049: Added command-line interface for theast module.

  • bpo-37953: Intyping, improved the__hash__ and__eq__methods forForwardReferences.

  • bpo-38026: Fixedinspect.getattr_static() usedisinstance whileit should avoid dynamic lookup.

  • bpo-35923: Updateimportlib.machinery.BuiltinImporter to useloader._ORIGIN instead of a hardcoded value. Patch by Donghee Na.

  • bpo-38010: Inimportlib.metadata sync withimportlib_metadata0.20, clarifying behavior offiles() and fixing issue where only onerequirement was returned forrequires() ondist-info packages.

  • bpo-38006: weakref.WeakValueDictionary defines a local remove() functionused as callback for weak references. This function was created with aclosure. Modify the implementation to avoid the closure.

  • bpo-37995: Added theindent option toast.dump() which allows itto produce a multiline indented output.

  • bpo-34410: Fixed a crash in thetee() iterator when re-enter it.RuntimeError is now raised in this case.

  • bpo-37140: Fix a ctypes regression of Python 3.8. When a ctypes.Structureis passed by copy to a function, ctypes internals created a temporaryobject which had the side effect of calling the structure finalizer(__del__) twice. The Python semantics requires a finalizer to be calledexactly once. Fix ctypes internals to no longer call the finalizer twice.

  • bpo-37587:_json.scanstring is now up to 3x faster when there are manybackslash escaped characters in the JSON string.

  • bpo-37834: Prevent shutil.rmtree exception when built on non-Windowssystem without fd system call support, like older versions of macOS.

  • bpo-10978: Semaphores and BoundedSemaphores can now release more than onewaiting thread at a time.

  • bpo-37972: Subscripts to theunittest.mock.call objects now receivethe same chaining mechanism as any other custom attributes, so that thefollowing usage no longer raises aTypeError:

    call().foo().__getitem__('bar')

    Patch by blhsing

  • bpo-37965: Fix C compiler warning caused bydistutils.ccompiler.CCompiler.has_function.

  • bpo-37964: AddF_GETPATH command tofcntl.

  • bpo-37960:repr() of buffered and text streams now silences onlyexpected exceptions when get the value of "name" and "mode" attributes.

  • bpo-37961: Add atotal_nframe field to the traces collected by thetracemalloc module. This field indicates the original number of framesbefore it was truncated.

  • bpo-37951: Most features of the subprocess module now work again insubinterpreters. Onlypreexec_fn is restricted in subinterpreters.

  • bpo-36205: Fix the rusage implementation of time.process_time() tocorrectly report the sum of the system and user CPU time.

  • bpo-37950: Fixast.dump() when call with incompletely initializednode.

  • bpo-34679: Restores instantiation of Windows IOCP event loops from thenon-main thread.

  • bpo-36917: Add default implementation of theast.NodeVisitor.visit_Constant() method which emits a deprecationwarning and calls corresponding methodsvisit_Num(),visit_Str(),etc.

  • bpo-37798: Update test_statistics.py to verify that the statistics moduleworks well for both C and Python implementations. Patch by Donghee Na

  • bpo-26589: Added a new status code to the http module: 451UNAVAILABLE_FOR_LEGAL_REASONS

  • bpo-37915: Fix a segmentation fault that appeared when comparing instancesofdatetime.timezone anddatetime.tzinfo objects. Patch by PabloGalindo.

  • bpo-32554: Deprecate having random.seed() call hash on arbitrary types.

  • bpo-9938: Add optional keyword argumentexit_on_error forArgumentParser.

  • bpo-37851: Thefaulthandler module no longer allocates itsalternative stack at Python startup. Now the stack is only allocated atthe first faulthandler usage.

  • bpo-32793: Fix a duplicated debug message whensmtplib.SMTP.connect() is called.

  • bpo-37885: venv: Don't generate unset variable warning on deactivate.

  • bpo-37868: Fix dataclasses.is_dataclass when given an instance that neverraises AttributeError in __getattr__. That is, an object that returnssomething for __dataclass_fields__ even if it's not a dataclass.

  • bpo-37811: Fixsocket module'ssocket.connect(address) functionbeing unable to establish connection in case of interrupted system call.The problem was observed on all OSes whichpoll(2) system call cantake only non-negative integers and -1 as a timeout value.

  • bpo-37863: Optimizations for Fraction.__hash__ suggested by Tim Peters.

  • bpo-21131: Fixfaulthandler.register(chain=True) stack. faulthandlernow allocates a dedicated stack ofSIGSTKSZ*2 bytes, instead of justSIGSTKSZ bytes. Calling the previous signal handler in faulthandlersignal handler uses more thanSIGSTKSZ bytes of stack memory on someplatforms.

  • bpo-37798: Add C fastpath for statistics.NormalDist.inv_cdf() Patch byDonghee Na

  • bpo-37804: Remove the deprecated methodthreading.Thread.isAlive().Patch by Donghee Na.

  • bpo-37819: Add Fraction.as_integer_ratio() to match the correspondingmethods in bool, int, float, and decimal.

  • bpo-14465: Add an xml.etree.ElementTree.indent() function forpretty-printing XML trees. Contributed by Stefan Behnel.

  • bpo-37810: Fixdifflib? hint in diff output when dealing withtabs. Patch by Anthony Sottile.

  • bpo-37772: Inzipfile.Path, when adding implicit dirs, ensure thatancestral directories are added and that duplicates are excluded.

  • bpo-18578: Renamed and documentedtest.bytecode_helper astest.support.bytecode_helper. Patch by Joannah Nanjekye.

  • bpo-37785: Fix xgettext warnings inargparse.

  • bpo-34488:writelines() method ofio.BytesIO is nowslightly faster when many small lines are passed. Patch by SergeyFedoseev.

  • bpo-37449:ensurepip now usesimportlib.resources.read_binary() toread data instead ofpkgutil.get_data(). Patch by Joannah Nanjekye.

  • bpo-28292: Mark calendar.py helper functions as being private. Thefollows PEP 8 guidance to maintain the style conventions in the module andit addresses a known case of user confusion.

  • bpo-18049: Add definition of THREAD_STACK_SIZE for AIX inPython/thread_pthread.h The default thread stacksize caused crashes withthe default recursion limit Patch by M Felt

  • bpo-37742: The logging.getLogger() API now returns the root logger whenpassed the name 'root', whereas previously it returned a non-root loggernamed 'root'. This could affect cases where user code explicitly wants anon-root logger named 'root', or instantiates a logger usinglogging.getLogger(__name__) in some top-level module called 'root.py'.

  • bpo-37738: Fix the implementation of cursesaddch(str,color_pair):pass the color pair tosetcchar(), instead of always passing 0 as thecolor pair.

  • bpo-37723: Fix performance regression on regular expression parsing withhuge character sets. Patch by Yann Vaginay.

  • bpo-35943: The functionPyImport_GetModule() now ensures anymodule it returns is fully initialized. Patch by Joannah Nanjekye.

  • bpo-32178: Fix IndexError inemail package when trying to parseinvalid address fields starting with:.

  • bpo-37268: Theparser module is deprecated and will be removed infuture versions of Python.

  • bpo-11953: Completing WSA* error codes insocket.

  • bpo-37685: Fixed comparisons ofdatetime.timedelta anddatetime.timezone.

  • bpo-37697: Synchronizeimportlib.metadata withimportlib_metadata0.19,improving handling of EGG-INFO files and fixing a crash when entry pointnames contained colons.

  • bpo-37695: Correctcurses.unget_wch() error message. Patch byAnthony Sottile.

  • bpo-37689: Addis_relative_to() inPurePath to determinewhether or not one path is relative to another.

  • bpo-29553: Fixedargparse.ArgumentParser.format_usage() for mutuallyexclusive groups. Patch by Andrew Nester.

  • bpo-37691: Let math.dist() accept coordinates as sequences (or iterables)rather than just tuples.

  • bpo-37685: Fixed__eq__,__lt__ etc implementations in someclasses. They now returnNotImplemented for unsupported type ofthe other operand. This allows the other operand to play role (for examplethe equality comparison withANY will returnTrue).

  • bpo-37354: Make Activate.ps1 Powershell script static to allow for signingit.

  • bpo-37664: Update wheels bundled with ensurepip (pip 19.2.3 and setuptools41.2.0)

  • bpo-37663: Bring consistency to venv shell activation scripts by alwaysusing __VENV_PROMPT__.

  • bpo-37642: Allowed the pure Python implementation ofdatetime.timezone to represent sub-minute offsets close tominimum and maximum boundaries, specifically in the ranges (23:59, 24:00)and (-23:59, 24:00). Patch by Ngalim Siregar

  • bpo-36161: Inposix, usettyname_r instead ofttyname forthread safety.

  • bpo-36324: Make internal attributes for statistics.NormalDist() private.

  • bpo-37555: FixNonCallableMock._call_matcher returning tuple insteadof_Call object whenself._spec_signature exists. Patch byElizabeth Uselton

  • bpo-29446: Makefromtkinterimport* import only the expectedobjects.

  • bpo-16970: Adding a value error when an invalid value in passed to nargsPatch by Robert Leenders

  • bpo-34443: Exceptions fromenum now use the__qualname of theenum class in the exception message instead of the__name__.

  • bpo-37491: FixIndexError when parsing email headers with unexpectedlyending bare-quoted string value. Patch by Abhilash Raj.

  • bpo-37587: Make json.loads faster for long strings. (Patch by MarcoPaolini)

  • bpo-18378: Recognize "UTF-8" as a valid value for LC_CTYPE inlocale._parse_localename.

  • bpo-37579: ReturnNotImplemented in Python implementation of__eq__ fortimedelta andtimewhen the other object being compared is not of the same type to match Cimplementation. Patch by Karthikeyan Singaravelan.

  • bpo-21478: Record calls to parent when autospecced object is attached to amock usingunittest.mock.attach_mock(). Patch by KarthikeyanSingaravelan.

  • bpo-37531: "python3 -m test -jN --timeout=TIMEOUT" now kills a workerprocess if it runs longer thanTIMEOUT seconds.

  • bpo-37482: Fix serialization of display name in originator or destinationaddress fields with both encoded words and special chars.

  • bpo-36993: Improve error reporting for corrupt zip files with bad zip64extra data. Patch by Daniel Hillier.

  • bpo-37502: pickle.loads() no longer raises TypeError when the buffersargument is set to None

  • bpo-37520: Correct behavior for zipfile.Path.parent when the path objectidentifies a subdirectory.

  • bpo-18374: Fix the.col_offset attribute of nestedast.BinOpinstances which had a too large value in some situations.

  • bpo-37424: Fixes a possible hang when using a timeout onsubprocess.run() while capturing output. If the child process spawnedits own children or otherwise connected its stdout or stderr handles withanother process, we could hang after the timeout was reached and our childwas killed when attempting to read final output from the pipes.

  • bpo-37421: Fixmultiprocessing.util.get_temp_dir() finalizer: clearalso the 'tempdir' configuration of the current process, so next call toget_temp_dir() will create a new temporary directory, rather thanreusing the removed temporary directory.

  • bpo-37481: The distutilsbdist_wininst command is deprecated in Python3.8, usebdist_wheel (wheel packages) instead.

  • bpo-37479: WhenEnum.__str__ is overridden in a derived class, theoverride will be used byEnum.__format__ regardless of whether mixinclasses are present.

  • bpo-37440: http.client now enables TLS 1.3 post-handshake authenticationfor default context or if a cert_file is passed to HTTPSConnection.

  • bpo-37437: Update vendorized expat version to 2.2.7.

  • bpo-37428: SSLContext.post_handshake_auth = True no longer setsSSL_VERIFY_POST_HANDSHAKE verify flag for client connections. Although theoption is documented as ignored for clients, OpenSSL implicitly enablescert chain validation when the flag is set.

  • bpo-37420:os.sched_setaffinity() now correctly handles errors thatarise during iteration over itsmask argument. Patch by Brandt Bucher.

  • bpo-37412: Theos.getcwdb() function now uses the UTF-8 encoding onWindows, rather than the ANSI code page: seePEP 529 for the rationale.The function is no longer deprecated on Windows.

  • bpo-37406: The sqlite3 module now raises TypeError, rather thanValueError, if operation argument type is not str: execute(),executemany() and calling a connection.

  • bpo-29412: Fix IndexError in parsing a header value ending unexpectedly.Patch by Abhilash Raj.

  • bpo-36546: Thedist argument for statistics.quantiles() is nowpositional only. The current name doesn't reflect that the argument can beeither a dataset or a distribution. Marking the parameter as positionalavoids confusion and makes it possible to change the name later.

  • bpo-37394: Fix a bug that was causing thequeue module to fail ifthe accelerator module was not available. Patch by Pablo Galindo.

  • bpo-37376:pprint now has support fortypes.SimpleNamespace. Patch by Carl Bordum Hansen.

  • bpo-26967: AnArgumentParser withallow_abbrev=False no longer disables grouping of short flags, such as-vv, but only disables abbreviation of long flags as documented. Patchby Zac Hatfield-Dodds.

  • bpo-37212:unittest.mock.call() now preserves the order of keywordarguments in repr output. Patch by Karthikeyan Singaravelan.

  • bpo-37372: Fix error unpickling datetime.time objects from Python 2 withseconds>=24. Patch by Justin Blanchard.

  • bpo-37345: Add formal support for UDPLITE sockets. Support was presentbefore, but it is now easier to detect support withhasattr(socket,'IPPROTO_UDPLITE') and there are constants defined for each of thevalues needed:socket.IPPROTO_UDPLITE,UDPLITE_SEND_CSCOV, andUDPLITE_RECV_CSCOV. Patch by Gabe Appleton.

  • bpo-37358: Optimizedfunctools.partial by using vectorcall.

  • bpo-37347:sqlite3.Connection.create_aggregate(),sqlite3.Connection.create_function(),sqlite3.Connection.set_authorizer(),sqlite3.Connection.set_progress_handler()sqlite3.Connection.set_trace_callback() methods lead to segfaults ifsome of these methods are called twice with an equal object but not thesame. Now callbacks are stored more carefully. Patch by Aleksandr Balezin.

  • bpo-37163: Theobj argument ofdataclasses.replace() ispositional-only now.

  • bpo-37085: Add the optional Linux SocketCAN Broadcast Manager constants,used as flags to configure the BCM behaviour, in the socket module. Patchby Karl Ding.

  • bpo-37328:HTMLParser.unescape is removed. It was undocumented anddeprecated since Python 3.4.

  • bpo-37305: Add .webmanifest -> application/manifest+json to list ofrecognized file types and content type headers

  • bpo-37320:aifc.openfp() alias toaifc.open(),sunau.openfp()alias tosunau.open(), andwave.openfp() alias towave.open()have been removed. They were deprecated since Python 3.7.

  • bpo-37315: Deprecated accepting floats with integral value (like5.0)inmath.factorial().

  • bpo-37312:_dummy_thread anddummy_threading modules have beenremoved. These modules were deprecated since Python 3.7 which requiresthreading support.

  • bpo-33972: Email with single part but content-type set tomultipart/*doesn't raise AttributeError anymore.

  • bpo-37280: Use threadpool for reading from file for sendfile fallbackmode.

  • bpo-37279: Fix asyncio sendfile support when sendfile sends extra data infallback mode.

  • bpo-19865:ctypes.create_unicode_buffer() now also supports non-BMPcharacters on platforms with 16-bitwchar_t (for example,Windows and AIX).

  • bpo-37266: In a subinterpreter, spawning a daemon thread now raises anexception. Daemon threads were never supported in subinterpreters.Previously, the subinterpreter finalization crashed with a Python fatalerror if a daemon thread was still running.

  • bpo-37210: Allow pure Python implementation ofpickle to work evenwhen the C_pickle module is unavailable.

  • bpo-21872: Fixlzma: module decompresses data incompletely. Whendecompressing a FORMAT_ALONE format file, and it doesn't have the endmarker, sometimes the last one to dozens bytes can't be output. Patch byMa Lin.

  • bpo-35922: FixRobotFileParser.crawl_delay() andRobotFileParser.request_rate() to returnNone rather than raiseAttributeError when no relevant rule is defined in the robots.txtfile. Patch by Rémi Lapeyre.

  • bpo-35766: Change the format of feature_version to be a (major, minor)tuple.

  • bpo-36607: EliminateRuntimeError raised byasyncio.all_tasks() if internal tasks weak set is changed by anotherthread during iteration.

  • bpo-18748:_pyio.IOBase destructor now does nothing if gettingtheclosed attribute fails to better mimic_io.IOBasefinalizer.

  • bpo-36402: Fix a race condition at Python shutdown when waiting forthreads. Wait until the Python thread state of all non-daemon threads getdeleted (join all non-daemon threads), rather than just wait untilnon-daemon Python threads complete.

  • bpo-37206: Default values which cannot be represented as Python objects nolonger improperly represented asNone in function signatures.

  • bpo-37111: Addedencoding anderrors keyword parameters tologging.basicConfig.

  • bpo-12144: Ensure cookies withexpires attribute are handled inCookieJar.make_cookies().

  • bpo-34886: Fix an unintended ValueError fromsubprocess.run() whenchecking for conflictinginput andstdin orcapture_output andstdout orstderr args when they were explicitly provided but withNone values within a passed in**kwargs dict rather than as passeddirectly by name. Patch contributed by Rémi Lapeyre.

  • bpo-37173: The exception message forinspect.getfile() now correctlyreports the passed class rather than the builtins module.

  • bpo-37178: Give math.perm() a one argument form that means the same asmath.factorial().

  • bpo-37178: For math.perm(n, k), let k default to n, giving the same resultas factorial.

  • bpo-37165: Converted _collections._count_elements to use the ArgumentClinic.

  • bpo-34767: Do not always create acollections.deque inasyncio.Lock.

  • bpo-37158: Speed-up statistics.fmean() by switching from a function to agenerator.

  • bpo-34282: RemoveEnum._convert method, deprecated in 3.8.

  • bpo-37150:argparse._ActionsContainer.add_argument now throws error,if someone accidentally pass FileType class object instead of instance ofFileType astype argument.

  • bpo-28724: The socket module now has thesocket.send_fds() andsocket.recv.fds() methods. Contributed by Joannah Nanjekye, ShinyaOkano and Victor Stinner.

  • bpo-35621: Support running asyncio subprocesses when execution event loopin a thread on UNIX.

  • bpo-36520: Lengthy email headers with UTF-8 characters are now properlyencoded when they are folded. Patch by Jeffrey Kintscher.

  • bpo-30835: Fixed a bug in email parsing where a message with invalid bytesin content-transfer-encoding of a multipart message can cause anAttributeError. Patch by Andrew Donnellan.

  • bpo-31163: pathlib.Path instance's rename and replace methods now returnthe new Path instance.

  • bpo-25068:urllib.request.ProxyHandler now lowercases the keys ofthe passed dictionary.

  • bpo-26185: Fixrepr() on emptyZipInfo object. Patch byMickaël Schoentgen.

  • bpo-21315: Email headers containing RFC2047 encoded words are parseddespite the missing whitespace, and a defect registered. Also missingtrailing whitespace after encoded words is now registered as a defect.

  • bpo-31904: Port test_datetime to VxWorks: skip zoneinfo tests on VxWorks

  • bpo-35805: Add parser for Message-ID header and add it to defaultHeaderRegistry. This should prevent folding of Message-ID using RFC 2048encoded words.

  • bpo-36871: Ensure method signature is used instead of constructorsignature of a class while asserting mock object against method calls.Patch by Karthikeyan Singaravelan.

  • bpo-35070: posix.getgrouplist() now works correctly when the user belongsto NGROUPS_MAX supplemental groups. Patch by Jeffrey Kintscher.

  • bpo-31783: Fix race condition in ThreadPoolExecutor when worker threadsare created during interpreter shutdown.

  • bpo-36582: FixUserString.encode() to correctly returnbytesrather than aUserString instance.

  • bpo-32424: Deprecate xml.etree.ElementTree.Element.copy() in favor ofcopy.copy().

    Patch by Gordon P. Hemsley

  • bpo-36564: Fix infinite loop in email header folding logic that would betriggered when an email policy's max_line_length is not long enough toinclude the required markup and any values in the message. Patch by PaulGanssle

  • bpo-36543: Removed methods Element.getchildren(), Element.getiterator()and ElementTree.getiterator() and the xml.etree.cElementTree module.

  • bpo-36409: Remove the old plistlib API deprecated in Python 3.4

  • bpo-36302: distutils sorts source file lists so that Extension .so filesbuild more reproducibly by default

  • bpo-36250: IgnoreValueError fromsignal withinteraction innon-main thread.

  • bpo-36046: Addeduser,group andextra_groups parameters tothe subprocess.Popen constructor. Patch by Patrick McLean.

  • bpo-32627: Fix compile error when_uuid headers conflicting included.

  • bpo-35800: Deprecatesmtpd.MailmanProxy ready for future removal.

  • bpo-35168:shlex.shlex.punctuation_chars is now a read-onlyproperty.

  • bpo-8538: Add support for boolean actions like--foo and--no-footo argparse. Patch contributed by Rémi Lapeyre.

  • bpo-20504: Fixes a bug incgi module when a multipart/form-datarequest has noContent-Length header.

  • bpo-25988: The abstract base classes incollections.abc no longerare exposed in the regularcollections module.

  • bpo-11122: Distutils won't check for rpmbuild in specified paths only.

  • bpo-34775: Division handling of PurePath now returns NotImplementedinstead of raising a TypeError when passed something other than aninstance of str or PurePath. Patch by Roger Aiudi.

  • bpo-34749:binascii.a2b_base64() is now up to 2 times faster. Patchby Sergey Fedoseev.

  • bpo-34519: Add additional aliases for HP Roman 8. Patch by Michael Osipov.

  • bpo-28009: Fix uuid.getnode() on platforms with '.' as MAC Addr delimiteras well fix for MAC Addr format that omits a leading 0 in MAC Addr values.Currently, AIX is the only know platform with these settings. Patch byMichael Felt.

  • bpo-30618: Addreadlink(). Patch by Girts Folkmanis.

  • bpo-32498: Madeurllib.parse.unquote() accept bytes in addition tostrings. Patch by Stein Karlsen.

  • bpo-33348: lib2to3 now recognizes expressions after* and** likeinf(*[]or[]).

  • bpo-32689: Updateshutil.move() function to allow for Path objectsto be used as source argument. Patch by Emily Morehouse and Maxwell"5.13b" McKinnon.

  • bpo-32820: Added__format__ to IPv4 and IPv6 classes. Always outputsa fully zero-padded string. Supports b/x/n modifiers (bin/hex/nativeformat). Native format for IPv4 is bin, native format for IPv6 is hex.Also supports '#' and '_' modifiers.

  • bpo-27657: Fix urllib.parse.urlparse() with numeric paths. A string like"path:80" is no longer parsed as a path but as a scheme ("path") and apath ("80").

  • bpo-4963: Fixed non-deterministic behavior related to mimetypes extensionmapping and module reinitialization.

Documentation

  • bpo-21767: Explicitly mention abc support in functools.singledispatch

  • bpo-38816: Provides more details about the interaction betweenfork() and CPython's runtime, focusing just on the C-API. Thisincludes cautions about wherefork() should and shouldn't becalled.

  • bpo-38351: Modernizeemail examples from %-formatting to f-strings.

  • bpo-38778: Document the fact thatRuntimeError is raised ifos.fork() is called in a subinterpreter.

  • bpo-38592: Add Brazilian Portuguese to the language switcher at PythonDocumentation website.

  • bpo-38294: Add list of no-longer-escaped chars to re.escape documentation

  • bpo-38053: Modernized the plistlib documentation

  • bpo-26868: Fix example usage ofPyModule_AddObject() to properlyhandle errors.

  • bpo-36797: Fix a dead link in the distutils API Reference.

  • bpo-37977: Warn more strongly and clearly about pickle insecurity

  • bpo-37979: Added a link to dateutil.parser.isoparse in thedatetime.fromisoformat documentation. Patch by Paul Ganssle

  • bpo-12707: Deprecate info(), geturl(), getcode() methods in favor of theheaders, url, and status properties, respectively, for HTTPResponse andaddinfourl. Also deprecate the code attribute of addinfourl in favor ofthe status attribute. Patch by Ashwin Ramaswami

  • bpo-37937: Mentionframe.f_trace insys.settrace() docs.

  • bpo-37878: MakePyThreadState_DeleteCurrent() Internal.

  • bpo-37759: Beginning edits to Whatsnew 3.8

  • bpo-37726: Stop recommending getopt in the tutorial for command lineargument parsing and promote argparse.

  • bpo-32910: Remove implementation-specific behaviour of how venv'sDeactivate works.

  • bpo-37256: Fix wording of arguments forRequest inurllib.request

  • bpo-37284: Add a brief note to indicate that any newsys.implementation required attributes must go through the PEPprocess.

  • bpo-30088: Documented thatmailbox.Maildir constructor doesn'tattempt to verify the maildir folder layout correctness. Patch bySviatoslav Sydorenko.

  • bpo-37521: Fiximportlib examples to insert any newly created modulesvia importlib.util.module_from_spec() immediately into sys.modules insteadof after calling loader.exec_module().

    Thanks to Benjamin Mintz for finding the bug.

  • bpo-37456: Slash ('/') is now part of syntax.

  • bpo-37487: Fix PyList_GetItem index description to include 0.

  • bpo-37149: Replace the dead link to the Tkinter 8.5 reference by JohnShipman, New Mexico Tech, with a link to the archive.org copy.

  • bpo-37478: Added possible exceptions to the description of os.chdir().

  • bpo-34903: Documented that indatetime.datetime.strptime(), theleading zero in some two-digit formats is optional. Patch by Mike Gleen.

  • bpo-36260: Add decompression pitfalls to zipfile module documentation.

  • bpo-37004: In the documentation for difflib, a note was added explicitlywarning that the results of SequenceMatcher's ratio method may depend onthe order of the input strings.

  • bpo-36960: Restructured thedatetime docs in the interest of makingthem more user-friendly and improving readability. Patch by Brad Solomon.

  • bpo-36487: Make C-API docs clear about what the "main" interpreter is.

  • bpo-23460: The documentation for decimal string formatting using the:g specifier has been updated to reflect the correct exponentialnotation cutoff point. Original patch contributed by Tuomas Suutari.

  • bpo-35803: Document and test thattempfile functions may accept apath-like object for thedir argument. Patch by AnthonySottile.

  • bpo-33944: Added a note about the intended use of code in .pth files.

  • bpo-34293: Fix the Doc/Makefile regarding PAPER environment variable andPDF builds

  • bpo-25237: Add documentation for tkinter modules

Tests

  • bpo-38614: Fix test_communicate() of test_asyncio.test_subprocess: usesupport.LONG_TIMEOUT (5 minutes), instead of just 1 minute.

  • bpo-38614: Add timeout constants totest.support:LOOPBACK_TIMEOUT,INTERNET_TIMEOUT,SHORT_TIMEOUT andLONG_TIMEOUT.

  • bpo-38502: test.regrtest now uses process groups in the multiprocessingmode (-jN command line option) if process groups are available: ifos.setsid() andos.killpg() functions are available.

  • bpo-35998: Fix a race condition in test_asyncio.test_start_tls_server_1().Previously, there was a race condition between the test main() functionwhich replaces the protocol and the test ServerProto protocol which sendsANSWER once it gets HELLO. Now, only the test main() function isresponsible to send data, ServerProto no longer sends data.

  • bpo-38470: Fixtest_compileall.test_compile_dir_maxlevels() on Windowswithout long path support: only create 3 subdirectories instead of between20 and 100 subdirectories.

  • bpo-37531: On timeout, regrtest no longer attempts to callpopen.communicate() again: it can hang until all child processes usingstdout and stderr pipes completes. Kill the worker process and ignores itsoutput. Change also the faulthandler timeout of the main process from 1minute to 5 minutes, for Python slowest buildbots.

  • bpo-38239: Fix test_gdb for Link Time Optimization (LTO) builds.

  • bpo-38275: test_ssl now handles disabled TLS/SSL versions better.OpenSSL's crypto policy and run-time settings are recognized and tests fordisabled versions are skipped. Tests also accept more TLS minimum_versionsfor platforms that override OpenSSL's default with strict settings.

  • bpo-38271: The private keys for test_ssl were encrypted with 3DES intraditional PKCS#5 format. 3DES and the digest algorithm of PKCS#5 areblocked by some strict crypto policies. Use PKCS#8 format with AES256encryption instead.

  • bpo-38270: test.support now has a helper function to check foravailability of a hash digest function. Several tests are refactored avoidMD5 and use SHA256 instead. Other tests are marked to use MD5 and skippedwhen MD5 is disabled.

  • bpo-37123: Multiprocessing test test_mymanager() now also expects-SIGTERM, not only exitcode 0. BaseManager._finalize_manager() sendsSIGTERM to the manager process if it takes longer than 1 second to stop,which happens on slow buildbots.

  • bpo-38212: Multiprocessing tests: increasetest_queue_feeder_donot_stop_onexc() timeout from 1 to 60 seconds.

  • bpo-38117: Test with OpenSSL 1.1.1d

  • bpo-38018: Increase code coverage for multiprocessing.shared_memory.

  • bpo-37805: Add tests for json.dump(..., skipkeys=True). Patch by DongheeNa.

  • bpo-37531: Enhance regrtest multiprocess timeout: write a message whenkilling a worker process, catch popen.kill() and popen.wait() exceptions,put a timeout on the second call to popen.communicate().

  • bpo-37876: Add tests for ROT-13 codec.

  • bpo-36833: Added tests forPyDateTime_xxx_GET_xxx() macros ofthe C API of thedatetime module. Patch by Joannah Nanjekye.

  • bpo-37558: Fix test_shared_memory_cleaned_after_process_termination namehandling

  • bpo-37526: Addtest.support.catch_threading_exception(): contextmanager catchingthreading.Thread exception usingthreading.excepthook().

  • bpo-37421: test_concurrent_futures now explicitly stops the ForkServerinstance if it's running.

  • bpo-37421: multiprocessing tests now stop the ForkServer instance if it'srunning: close the "alive" file descriptor to ask the server to stop andthen remove its UNIX address.

  • bpo-37421: test_distutils.test_build_ext() is now able to remove thetemporary directory on Windows: don't import the newly built C extension("xx") in the current process, but test it in a separated process.

  • bpo-37421: test_concurrent_futures now cleans up multiprocessing to removeimmediately temporary directories created bymultiprocessing.util.get_temp_dir().

  • bpo-37421: test_winconsoleio doesn't leak a temporary file anymore: usetempfile.TemporaryFile() to remove it when the test completes.

  • bpo-37421: multiprocessing tests now explicitly call_run_finalizers()to immediately remove temporary directories created by tests.

  • bpo-37421: urllib.request tests now callurlcleanup() to remove temporary files created byurlretrieve() tests and to clear the_opener global variable setbyurlopen() and functions calling indirectlyurlopen().

  • bpo-37472: RemoveLib/test/outstanding_bugs.py.

  • bpo-37199: Fix test failures when IPv6 is unavailable or disabled.

  • bpo-19696: Replace deprecated method "random.choose" with "random.choice"in "test_pkg_import.py".

  • bpo-37335: Remove no longer necessary code from c locale coercion tests

  • bpo-37421: Fix test_shutil to no longer leak temporary files.

  • bpo-37411: Fix test_wsgiref.testEnviron() to no longer depend on theenvironment variables (don't fail if "X" variable is set).

  • bpo-37400: Fix test_os.test_chown(): use os.getgroups() rather thangrp.getgrall() to get groups. Rename also the test to test_chown_gid().

  • bpo-37359: Add --cleanup option to python3 -m test to removetest_python_* directories of previous failed jobs. Add "makecleantest" to runpython3-mtest--cleanup.

  • bpo-37362: test_gdb no longer fails if it gets an "unexpected" message onstderr: it now ignores stderr. The purpose of test_gdb is to test thatpython-gdb.py commands work as expected, not to test gdb.

  • bpo-35998: Avoid TimeoutError in test_asyncio: test_start_tls_server_1()

  • bpo-37278: Fix test_asyncio ProactorLoopCtrlC: join the thread to preventleaking a running thread and leaking a reference.

  • bpo-37261: Fixtest.support.catch_unraisable_exception(): its__exit__() method now ignores unraisable exception raised when clearingitsunraisable attribute.

  • bpo-37069: regrtest now usessys.unraisablehook() to mark a test as"environment altered" (ENV_CHANGED) if it emits an "unraisable exception".Moreover, regrtest logs a warning in this case.

    Usepython3-mtest--fail-env-changed to catch unraisable exceptionsin tests.

  • bpo-37252: Fix assertions intest_close andtest_events_mask_overflow devpoll tests.

  • bpo-37169: Rewrite_PyObject_IsFreed() unit tests.

  • bpo-37153:test_venv.test_multiprocessing() now explicitly callspool.terminate() to wait until the pool completes.

  • bpo-34001: Make test_ssl pass with LibreSSL. LibreSSL handles minimum andmaximum TLS version differently than OpenSSL.

  • bpo-36919: Maketest_source_encoding.test_issue2301 implementationindependent. The test will work now for both CPython and IronPython.

  • bpo-30202: Updatetest.test_importlib.test_abc to testfind_spec().

  • bpo-28009: Modify the test_uuid logic to test when a program is availableAND can be used to obtain a MACADDR as basis for an UUID. Patch by M. Felt

  • bpo-34596: Fallback to a default reason whenunittest.skip() isuncalled. Patch by Naitree Zhu.

Build

  • bpo-38809: On Windows, build scripts will now recognize and use python.exefrom an active virtual env.

  • bpo-38684: Fix _hashlib build when Blake2 is disabled, but OpenSSLsupports it.

  • bpo-38468: Misc/python-config.in now usesgetvar() for all stillexistingsysconfig.get_config_var() calls. Patch by Joannah Nanjekye.

  • bpo-37415: Fix stdatomic.h header check for ICC compiler: the ICCimplementation lacks atomic_uintptr_t type which is needed by Python.

  • bpo-38301: In Solaris family, we must be sure to use-D_REENTRANT.Patch by Jesús Cea Avión.

  • bpo-36002: Locatellvm-profdata andllvm-ar binaries usingAC_PATH_TOOL rather thanAC_PATH_TARGET_TOOL.

  • bpo-37936: The.gitignore file systematically keeps "rooted", witha non-trailing slash, all the rules that are meant to apply to files in aspecific place in the repo. Previously, when the intended file to ignorehappened to be at the root of the repo, we'd most often accidentally alsoignore files and directories with the same name anywhere in the tree.

  • bpo-37760: TheTools/unicode/makeunicodedata.py script, which isused for converting information from the Unicode Character Database intogenerated code and data used by the methods ofstr and by theunicodedata module, now handles each character's data as adataclass with named attributes, rather than a length-18 list ofdifferent fields.

  • bpo-37936: The.gitignore file no longer applies to any files thatare in fact tracked in the Git repository. Patch by Greg Price.

  • bpo-37725: Change "clean" makefile target to also clean the program guidedoptimization (PGO) data. Previously you would have to use "make clean"and "make profile-removal", or "make clobber".

  • bpo-37707: Mark some individual tests to skip when --pgo is used. Thetests marked increase the PGO task time significantly and likely don'thelp improve optimization of the final executable.

  • bpo-36044: Reduce the number of unit tests run for the PGO generationtask. This speeds up the task by a factor of about 15x. Running the fullunit test suite is slow. This change may result in a slightly lessoptimized build since not as many code branches will be executed. If youare willing to wait for the much slower build, the old behavior can berestored using './configure [..] PROFILE_TASK="-m test --pgo-extended"'.We make no guarantees as to which PGO task set produces a faster build.Users who care should run their own relevant benchmarks as results candepend on the environment, workload, and compiler tool chain.

  • bpo-37468:makeinstall no longer installswininst-*.exe filesused by distutils bdist_wininst: bdist_wininst only works on Windows.

  • bpo-37189: ManyPyRun_XXX() functions likePyRun_String() were no longer exported inlibpython38.dll bymistake. Export them again to fix the ABI compatibility.

  • bpo-25361: Enables use of SSE2 instructions in Windows 32-bit build.

  • bpo-36210: Update optional extension module detection for AIX. ossaudiodevand spwd are not applicable for AIX, and are no longer reported asmissing. 3rd-party packaging of ncurses (with ASIS support) conflicts withofficially supported AIX curses library, so configure AIX to uselibcurses.a. However, skip trying to build _curses_panel.

    patch by M Felt

Windows

  • bpo-38589: Fixes HTML Help shortcut when Windows is not installed to Cdrive

  • bpo-38453: Ensure ntpath.realpath() correctly resolves relative paths.

  • bpo-38519: Restores the internal C headers that were missing from thenuget.org and Microsoft Store packages.

  • bpo-38492: Removepythonw.exe dependency on the Microsoft C++ runtime.

  • bpo-38344: Fix error message in activate.bat

  • bpo-38359: Ensurespyw.exe launcher reads correct registry key.

  • bpo-38355: Fixesntpath.realpath failing onsys.executable.

  • bpo-38117: Update bundled OpenSSL to 1.1.1d

  • bpo-38092: Reduce overhead when using multiprocessing in a Windows virtualenvironment.

  • bpo-38133: Allow py.exe launcher to locate installations from theMicrosoft Store and improve display of active virtual environments.

  • bpo-38114: Thepip.ini is no longer included in the Nuget package.

  • bpo-32592: Set Windows 8 as the minimum required version for API support

  • bpo-36634:os.cpu_count() now returns active processors rather thanmaximum processors.

  • bpo-36634: venv activate.bat now works when the existing variables containdouble quote characters.

  • bpo-38081: Prevent error callingos.path.realpath() on'NUL'.

  • bpo-38087: Fix case sensitivity in test_pathlib and test_ntpath.

  • bpo-38088: Fixes distutils not finding vcruntime140.dll with only the v142toolset installed.

  • bpo-37283: Ensure command-line and unattend.xml setting overridepreviously detected states in Windows installer.

  • bpo-38030: Fixesos.stat() failing for block devices on Windows

  • bpo-38020: Fixes potential crash when callingos.readlink() (orindirectly throughrealpath()) on a file that is not asupported link.

  • bpo-37705: Improve the implementation ofwinerror_to_errno().

  • bpo-37549:os.dup() no longer fails for standard streams on Windows7.

  • bpo-1311: Thenul file on Windows now returns True fromexists() and a valid result fromos.stat() withS_IFCHR set.

  • bpo-9949: Enable support for following symlinks inos.realpath().

  • bpo-37834: Treat all name surrogate reparse points on Windows inos.lstat() and other reparse points as regular files inos.stat().

  • bpo-36266: Add the module name in the formatted error message when DLLload fail happens during module import in_PyImport_FindSharedFuncptrWindows(). Patch by Srinivas Nyayapati.

  • bpo-25172: Trying to import thecrypt module on Windows willresult in anImportError with a message explaining that the moduleisn't supported on Windows. On other platforms, if the underlying_crypt module is not available, the ImportError will include a messageexplaining the problem.

  • bpo-37778: Fixes the icons used for file associations to the MicrosoftStore package.

  • bpo-37734: Fix use of registry values to launch Python from MicrosoftStore app.

  • bpo-37702: Fix memory leak on Windows in creating an SSLContext object orrunningurllib.request.urlopen('https://...').

  • bpo-37672: Switch Windows Store package's pip to use bundledpip.ini instead ofPIP_USER variable.

  • bpo-10945: Officially drop support for creating bdist_wininst installerson non-Windows systems.

  • bpo-37445: Include theFORMAT_MESSAGE_IGNORE_INSERTS flag inFormatMessageW() calls.

  • bpo-37369: Fixes path forsys.executable when running from theMicrosoft Store.

  • bpo-37380: Don't collect unfinished processes withsubprocess._activeon Windows to cleanup later. Patch by Ruslan Kuprieiev.

  • bpo-37351: Removes libpython38.a from standard Windows distribution.

  • bpo-35360: Update Windows builds to use SQLite 3.28.0.

  • bpo-37267: On Windows,os.dup() no longer creates an inheritable fdwhen handling a character file.

  • bpo-36779: Ensuretime.tzname is correct on Windows when the activecode page is set to CP_UTF7 or CP_UTF8.

  • bpo-32587: Makewinreg.REG_MULTI_SZ support zero-length strings.

  • bpo-28269: Replace use ofstrcasecmp() for the system function_stricmp(). Patch by Minmin Gong.

  • bpo-36590: Add native Bluetooth RFCOMM support to socket module.

macOS

  • bpo-38117: Updated OpenSSL to 1.1.1d in macOS installer.

  • bpo-38089: Move Azure Pipelines to latest VM versions and make macOS testsoptional

  • bpo-18049: Increase the default stack size of threads from 5MB to 16MB onmacOS, to match the stack size of the main thread. This avoids crashes ondeep recursion in threads.

  • bpo-34602: Avoid test suite failures on macOS by no longer callingresource.setrlimit to increase the process stack size limit at runtime.The runtime change is no longer needed since the interpreter is beingbuilt with a larger default stack size.

  • bpo-35360: Update macOS installer to use SQLite 3.28.0.

  • bpo-34631: Updated OpenSSL to 1.1.1c in macOS installer.

IDLE

  • bpo-26353: Stop adding newline when saving an IDLE shell window.

  • bpo-4630: Add an option to toggle IDLE's cursor blink for shell, editor,and output windows. See Settings, General, Window Preferences, CursorBlink. Patch by Zackery Spytz.

  • bpo-38598: Do not try to compile IDLE shell or output windows

  • bpo-36698: IDLE no longer fails when write non-encodable characters tostderr. It now escapes them with a backslash, as the regular Pythoninterpreter. Added theerrors field to the standard streams.

  • bpo-35379: When exiting IDLE, catch any AttributeError. One happens whenEditorWindow.close is called twice. Printing a traceback, when IDLE isrun from a terminal, is useless and annoying.

  • bpo-38183: To avoid problems, test_idle ignores the user config directory.It no longer tries to create or access .idlerc or any files within. Usersmust run IDLE to discover problems with saving settings.

  • bpo-38077: IDLE no longer adds 'argv' to the user namespace wheninitializing it. This bug only affected 3.7.4 and 3.8.0b2 to 3.8.0b4.

  • bpo-38041: Shell restart lines now fill the window width, always startwith '=', and avoid wrapping unnecessarily. The line will still wrap ifthe included file name is long relative to the width.

  • bpo-35771: To avoid occasional spurious test_idle failures on slowermachines, increase thehover_delay in test_tooltip.

  • bpo-37824: Properly handle user input warnings in IDLE shell. Ceaseturning SyntaxWarnings into SyntaxErrors.

  • bpo-37929: IDLE Settings dialog now closes properly when there is no shellwindow.

  • bpo-37902: Add mousewheel scrolling for IDLE module, path, and stackbrowsers. Patch by George Zhang.

  • bpo-37849: Fixed completions list appearing too high or low when shownabove the current line.

  • bpo-36419: Refactor IDLE autocomplete and improve testing.

  • bpo-37748: Reorder the Run menu. Put the most common choice, Run Module,at the top.

  • bpo-37692: Improve highlight config sample with example shell interactionand better labels for shell elements.

  • bpo-37628: Settings dialog no longer expands with font size.

  • bpo-37627: Initialize the Customize Run dialog with the command linearguments most recently entered before. The user can optionally editbefore submitting them.

  • bpo-33610: Fix code context not showing the correct context when firsttoggled on.

  • bpo-37530: Optimize code context to reduce unneeded background activity.Font and highlight changes now occur along with text changes instead ofafter a random delay.

  • bpo-27452: Cleanupconfig.py by inliningRemoveFile andsimplifying the handling offile inCreateConfigHandlers.

  • bpo-37325: Fix tab focus traversal order for help source and custom rundialogs.

  • bpo-37321: Both subprocess connection error messages now refer to the'Startup failure' section of the IDLE doc.

  • bpo-17535: Add optional line numbers for IDLE editor windows. Windowsopen without line numbers unless set otherwise in the General tab of theconfiguration dialog.

  • bpo-26806: To compensate for stack frames added by IDLE and avoid possibleproblems with low recursion limits, add 30 to limits in the user codeexecution process. Subtract 30 when reporting recursion limits to makethis addition mostly transparent.

  • bpo-37177: Properly 'attach' search dialogs to their main window so thatthey behave like other dialogs and do not get hidden behind their mainwindow.

  • bpo-37039: Adjust "Zoom Height" to individual screens by momentarilymaximizing the window on first use with a particular screen. Changingscreen settings may invalidate the saved height. While a window ismaximized, "Zoom Height" has no effect.

  • bpo-35763: Make calltip reminder about '/' meaning positional-only lessobtrusive by only adding it when there is room on the first line.

  • bpo-5680: Add 'Run... Customized' to the Run menu to run a module withcustomized settings. Any 'command line arguments' entered are added tosys.argv. One can suppress the normal Shell main module restart.

  • bpo-36390: Gather Format menu functions into format.py. Combineparagraph.py, rstrip.py, and format methods from editor.py.

Tools/Demos

  • bpo-38118: Update Valgrind suppression file to ignore a false alarm inPyUnicode_Decode() when using GCC builtin strcmp().

  • bpo-38347: pathfix.py: Assume all files that end on '.py' are Pythonscripts when working recursively.

  • bpo-37803: pdb's--help and--version long options now work.

  • bpo-37942: Improve ArgumentClinic converter for floats.

  • bpo-37704: RemoveTools/scripts/h2py.py: use cffi to access a C API inPython.

  • bpo-37675: 2to3 now works when run from a zipped standard library.

  • bpo-37034: Argument Clinic now uses the argument name on errors withkeyword-only argument instead of their position. Patch contributed by RémiLapeyre.

  • bpo-37064: Add option -k to pathscript.py script: preserve shebang flags.Add option -a to pathscript.py script: add flags.

C API

  • bpo-37633: Re-export some function compatibility wrappers for macros inpythonrun.h.

  • bpo-38644: ProvidePy_EnterRecursiveCall() andPy_LeaveRecursiveCall() as regular functions for the limited API.Previously, there were defined as macros, but these macros didn't workwith the limited API which cannot accessPyThreadState.recursion_depthfield. Remove_Py_CheckRecursionLimit from the stable ABI.

  • bpo-38650: The global variablePyStructSequence_UnnamedField isnow a constant and refers to a constant string.

  • bpo-38540: Fixed possible leak inPyArg_Parse() and similarfunctions for format units"es#" and"et#" when the macroPY_SSIZE_T_CLEAN is not defined.

  • bpo-38395: Fix a crash inweakref.proxy objects due to incorrectlifetime management when calling some associated methods that may deletethe last reference to object being referenced by the proxy. Patch by PabloGalindo.

  • bpo-36389: The_PyObject_CheckConsistency() function is now alsoavailable in release mode. For example, it can be used to debug a crash inthevisit_decref() function of the GC.

  • bpo-38266: Revert the removal of PyThreadState_DeleteCurrent() withdocumentation.

  • bpo-38303: Update audioop extension module to use the stable ABI(PEP-384). Patch by Tyler Kieft.

  • bpo-38234:Py_SetPath() now setssys.executable to theprogram full path (Py_GetProgramFullPath()) rather than to theprogram name (Py_GetProgramName()).

  • bpo-38234: Python ignored arguments passed toPy_SetPath(),Py_SetPythonHome() andPy_SetProgramName(): fix Pythoninitialization to use specified arguments.

  • bpo-38205: ThePy_UNREACHABLE() macro now callsPy_FatalError().

  • bpo-38140: Make dict and weakref offsets opaque for C heap types bypassing the offsets through PyMemberDef

  • bpo-15088: The C functionPyGen_NeedsFinalizing has been removed. Itwas not documented, tested or used anywhere within CPython after theimplementation ofPEP 442. Patch by Joannah Nanjekye. (Patch by JoannahNanjekye)

  • bpo-36763: Options added byPySys_AddXOption() are now handled thesame way thanPyConfig.xoptions and command line-X options.

  • bpo-37926: Fix a crash inPySys_SetArgvEx(0,NULL,0).

  • bpo-37879: Fix subtype_dealloc to suppress the type decref when the basetype is a C heap type

  • bpo-37645: Add_PyObject_FunctionStr() to get a user-friendlystring representation of a function-like object. Patch by Jeroen Demeyer.

  • bpo-29548: The functionsPyEval_CallObject,PyEval_CallFunction,PyEval_CallMethod andPyEval_CallObjectWithKeywords aredeprecated. UsePyObject_Call() and its variants instead.

  • bpo-37151:PyCFunction_Call is now a deprecated alias ofPyObject_Call().

  • bpo-37540: The vectorcall protocol now requires that the caller passesonly strings as keyword names.

  • bpo-37207: The vectorcall protocol is now enabled fortype objects:settp_vectorcall to a vectorcall function to be used instead oftp_new andtp_init when calling the class itself.

  • bpo-21120: Exclude Python-ast.h, ast.h and asdl.h from the limited API.

  • bpo-37483: Add new function_PyObject_CallOneArg for calling an objectwith one positional argument.

  • bpo-36763: AddPyConfig_SetWideStringList() function.

  • bpo-37337: Add fast functions for calling methods:_PyObject_VectorcallMethod(),_PyObject_CallMethodNoArgs() and_PyObject_CallMethodOneArg().

  • bpo-28805: TheMETH_FASTCALL calling convention has beendocumented.

  • bpo-37221: The new functionPyCode_NewWithPosOnlyArgs() allows tocreate code objects likePyCode_New(), but with an extraposonlyargcount parameter for indicating the number of positonal-onlyarguments.

  • bpo-37215: Fix dtrace issue introduce bybpo-36842

  • bpo-37194: Add a new publicPyObject_CallNoArgs() function to theC API: call a callable Python object without any arguments. It is the mostefficient way to call a callback without any argument. On x86-64, forexample,PyObject_CallFunctionObjArgs(func,NULL) allocates 960 byteson the stack per call, whereasPyObject_CallNoArgs(func) onlyallocates 624 bytes per call.

  • bpo-37170: Fix the cast on error inPyLong_AsUnsignedLongLongMask().

  • bpo-35381: Convert posixmodule.c statically allocated typesDirEntryType andScandirIteratorType to heap-allocated types.

  • bpo-34331: Use singular/plural noun in error message when instantiating anabstract class with non-overridden abstract method(s).

Python 3.8.0 beta 1

Release date: 2019-06-04

Security

  • bpo-35907:CVE 2019-9948: Avoid file reading by disallowinglocal-file:// andlocal_file:// URL schemes inURLopener().open() andURLopener().retrieve() ofurllib.request.

  • bpo-33529: Prevent fold function used in email header encoding fromentering infinite loop when there are too many non-ASCII characters in aheader.

  • bpo-33164: Updated blake2 implementation which uses secure memsetimplementation provided by platform.

Core and Builtins

  • bpo-35814: Allow unpacking in the right hand side of annotatedassignments. In particular,t:Tuple[int,...]=x,y,*z is nowallowed.

  • bpo-37126: All structseq objects are now tracked by the garbage collector.Patch by Pablo Galindo.

  • bpo-37122: Make theco_argcount attribute of code objects represent thetotal number of positional arguments (including positional-onlyarguments). The value ofco_posonlyargcount can be used to distinguishwhich arguments are positional only, and the difference (co_argcount -co_posonlyargcount) is the number of positional-or-keyword arguments.Patch by Pablo Galindo.

  • bpo-20092: Constructors ofint,float andcomplex will now use the__index__() specialmethod, if available and the corresponding method__int__(),__float__() or__complex__() is not available.

  • bpo-37087: Add native thread ID (TID) support to OpenBSD.

  • bpo-26219: Implemented per opcode cache mechanism andLOAD_GLOBALinstruction use it.LOAD_GLOBAL is now about 40% faster. Contributedby Yury Selivanov, and Inada Naoki.

  • bpo-37072: Fix crash in PyAST_FromNodeObject() when flags is NULL.

  • bpo-37029: Freeing a great many small objects could take time quadratic inthe number of arenas, due to using linear search to keepobmalloc.c'slist of usable arenas sorted by order of number of free memory pools.This is accomplished without search now, leaving the worst-case timelinear in the number of arenas. For programs where this quite visiblymatters (typically with more than 100 thousand small objects alivesimultaneously), this can greatly reduce the time needed to release theirmemory.

  • bpo-26423: Fix possible overflow inwrap_lenfunc() whensizeof(long)<sizeof(Py_ssize_t) (e.g., 64-bit Windows).

  • bpo-37050: Improve the AST for "debug" f-strings, which use '=' to printout the source of the expression being evaluated. Delete expr_text fromthe FormattedValue node, and instead use a Constant string node (possiblymerged with adjacent constant expressions inside the f-string).

  • bpo-22385: Thebytes.hex,bytearray.hex, andmemoryview.hexmethods as well as thebinascii.hexlify andb2a_hex functions nowhave the ability to include an optional separator between hex bytes. Thisfunctionality was inspired by MicroPython's hexlify implementation.

  • bpo-26836: Addos.memfd_create().

  • bpo-37032: Added newreplace() method to the code type(types.CodeType).

  • bpo-37007: Implementsocket.if_nameindex(),socket.if_nametoindex(), andsocket.if_indextoname() onWindows.

  • bpo-36829:PyErr_WriteUnraisable() now creates a traceback objectif there is no current traceback. Moreover, callPyErr_NormalizeException() andPyException_SetTraceback()to normalize the exception value. Ignore any error.

  • bpo-36878: Only accept text after#type:ignore if the firstcharacter is ASCII. This is to disallow things like#type:ignoreé.

  • bpo-36878: Store text appearing after a#type:ignore comment in theAST. For example a type ignore like#type:ignore[E1000] will havethe string"[E1000]" stored in its AST node.

  • bpo-2180: Treat line continuation at EOF as aSyntaxError by AnthonySottile.

  • bpo-36907: Fix a crash when calling a C function with a keyword dict(f(**kwargs)) and changing the dictkwargs while that function isrunning.

  • bpo-36946: Fix possible signed integer overflow when handling slices.

  • bpo-36826: Add NamedExpression kind support to ast_unparse.c

  • bpo-1875: ASyntaxError is now raised if a code blocks that will beoptimized away (e.g. if conditions that are always false) contains syntaxerrors. Patch by Pablo Galindo.

  • bpo-36027: Allow computation of modular inverses via three-argumentpow: the second argument is now permitted to be negative in the casewhere the first and third arguments are relatively prime.

  • bpo-36861: Update the Unicode database to version 12.1.0.

  • bpo-28866: Avoid caching attributes of classes which type defines mro() toavoid a hard cache invalidation problem.

  • bpo-36851: TheFrameType stack is now correctly cleaned up if theexecution ends with a return and the stack is not empty.

  • bpo-34616: Thecompile() builtin functions now support theast.PyCF_ALLOW_TOP_LEVEL_AWAIT flag, which allow to compile sourcesthat contains top-levelawait,asyncwith orasyncfor. Thisis useful to evaluate async-code from with an already async functions; forexample in a custom REPL.

  • bpo-36842: Implement PEP 578, adding sys.audit, io.open_code and relatedAPIs.

  • bpo-27639: Correct return type for UserList slicing operations. Patch byMichael Blahay, Erick Cervantes, and vaultah

  • bpo-36737: Move PyRuntimeState.warnings into per-interpreter state (via"module state").

  • bpo-36793: Removed__str__ implementations from builtin typesbool,int,float,complex and fewclasses from the standard library. They now inherit__str__() fromobject.

  • bpo-36817: Add a= feature f-strings for debugging. This can precede!s,!r, or!a. It produces the text of the expression,followed by an equal sign, followed by the repr of the value of theexpression. Sof'{3*9+15=}' would be equal to the string'3*9+15=42'. If= is specified, the default conversion is set to!r, unless a format spec is given, in which case the formattingbehavior is unchanged, and __format__ will be used.

  • bpo-24048: Save the live exception during import.c'sremove_module().

  • bpo-27987: pymalloc returns memory blocks aligned by 16 bytes, instead of8 bytes, on 64-bit platforms to conform x86-64 ABI. Recent compilersassume this alignment more often. Patch by Inada Naoki.

  • bpo-36601: A long-since-meaningless check forgetpid()==main_pid wasremoved from Python's internal C signal handler.

  • bpo-36594: Fix incorrect use of%p in format strings. Patch by ZackerySpytz.

  • bpo-36045:builtins.help() now prefixesasync for async functions.

  • bpo-36084: Add native thread ID (TID) to threading.Thread objects(supported platforms: Windows, FreeBSD, Linux, macOS)

  • bpo-36035: Added fix for broken symlinks in combination with pathlib

  • bpo-35983: Added new trashcan macros to deal with a double deallocationthat could occur when thetp_dealloc of a subclass calls thetp_dealloc of a base class and that base class uses the trashcanmechanism. Patch by Jeroen Demeyer.

  • bpo-20602: Do not clearsys.flags andsys.float_infoduring shutdown. Patch by Zackery Spytz.

  • bpo-26826: Exposecopy_file_range() as a low level API in theos module.

  • bpo-32388: Remove cross-version binary compatibility requirement intp_flags.

  • bpo-31862: Port binascii to PEP 489 multiphase initialization. Patch byMarcel Plch.

Library

  • bpo-37128: Addedmath.perm().

  • bpo-37120: Add SSLContext.num_tickets to control the number of TLSv1.3session tickets.

  • bpo-12202: Fix the error handling inmsilib.SummaryInformation.GetProperty(). Patch by Zackery Spytz.

  • bpo-26835: The fcntl module now contains file sealing constants forsealing of memfds.

  • bpo-29262: Addget_origin() andget_args() introspection helperstotyping module.

  • bpo-12639:msilib.Directory.start_component() no longer fails ifkeyfile is notNone.

  • bpo-36999: Add theasyncio.Task.get_coro() method to publicly exposethe tasks's coroutine object.

  • bpo-35246: Makeasyncio.create_subprocess_exec() accept path-likearguments.

  • bpo-35279: Change defaultmax_workers ofThreadPoolExecutor fromcpu_count()*5 tomin(32,cpu_count()+4). Previous value wasunreasonably large on many cores machines.

  • bpo-37076:_thread.start_new_thread() now logs uncaught exceptionraised by the function usingsys.unraisablehook(), rather thansys.excepthook(), so the hook gets access to the function whichraised the exception.

  • bpo-33725: On macOS, themultiprocessing module now usesspawnstart method by default.

  • bpo-37054: Fix destructor_pyio.BytesIO and_pyio.TextIOWrapper: initialize their_buffer attribute assoon as possible (in the class body), because it's used by__del__()which callsclose().

  • bpo-37058: PEP 544: AddProtocol and@runtime_checkable to thetyping module.

  • bpo-36933: The functionssys.set_coroutine_wrapper andsys.get_coroutine_wrapper that were deprecated and marked for removalin 3.8 have been removed.

  • bpo-37047: Handle late binding and attribute access inunittest.mock.AsyncMock setup for autospeccing. Document newlyimplemented async methods inunittest.mock.MagicMock.

  • bpo-37049: PEP 589: AddTypedDict to thetyping module.

  • bpo-37046: PEP 586: AddLiteral to thetyping module.

  • bpo-37045: PEP 591: AddFinal qualifier and@final decorator tothetyping module.

  • bpo-37035: Don't log OSError based exceptions if a fatal error hasoccurred in asyncio transport. Peer can generate almost any OSError, usercannot avoid these exceptions by fixing own code. Errors are stillpropagated to user code, it's just logging them is pointless and polluteasyncio logs.

  • bpo-37001:symtable.symtable() now accepts the same input types forsource code as the built-incompile() function. Patch by DinoViehland.

  • bpo-37028: Implement asyncio REPL

  • bpo-37027: Return safe to use proxy socket object fromtransport.get_extra_info('socket')

  • bpo-32528: Make asyncio.CancelledError a BaseException.

    This will address the common mistake many asyncio users make: an "exceptException" clause breaking Tasks cancellation.

    In addition to this change, we stop inheriting asyncio.TimeoutError andasyncio.InvalidStateError from their concurrent.futures.* counterparts.There's no point for these exceptions to share the inheritance chain.

  • bpo-1230540: Add a newthreading.excepthook() function which handlesuncaughtthreading.Thread.run() exception. It can be overridden tocontrol how uncaughtthreading.Thread.run() exceptions are handled.

  • bpo-36996: Handleunittest.mock.patch() used as a decorator on asyncfunctions.

  • bpo-37008: Add support for callingnext() with the mock resultingfromunittest.mock.mock_open()

  • bpo-27737: Allow whitespace only header encoding inemail.header - byBatuhan Taskaya

  • bpo-36969: PDB commandargs now display positional only arguments.Patch contributed by Rémi Lapeyre.

  • bpo-36969: PDB commandargs now display keyword only arguments. Patchcontributed by Rémi Lapeyre.

  • bpo-36983: Add missing names totyping.__all__:ChainMap,ForwardRef,OrderedDict - by Anthony Sottile.

  • bpo-36972: Add SupportsIndex protocol to the typing module to allow typechecking to detect classes that can be passed tohex(),oct() andbin().

  • bpo-32972: Implementunittest.IsolatedAsyncioTestCase to help testingasyncio-based code.

  • bpo-36952:fileinput.input() andfileinput.FileInputbufsize argument has been removed (was deprecated and ignored sincePython 3.6), and as a result themode andopenhook arguments havebeen made keyword-only.

  • bpo-36952: Starting with Python 3.3, importing ABCs fromcollections is deprecated, and import should be done fromcollections.abc. Still being able to import fromcollectionswas marked for removal in 3.8, but has been delayed to 3.9; documentationandDeprecationWarning clarified.

  • bpo-36949: Implement __repr__ for WeakSet objects.

  • bpo-36948: FixNameError inurllib.request.URLopener.retrieve(). Patch by KarthikeyanSingaravelan.

  • bpo-33524: Fix the folding of email header when the max_line_length is 0or None and the header contains non-ascii characters. Contributed byLicht Takeuchi (@Licht-T).

  • bpo-24564:shutil.copystat() now ignoreserrno.EINVAL onos.setxattr() which may occur when copying files on filesystemswithout extended attributes support.

    Original patch by Giampaolo Rodola, updated by Ying Wang.

  • bpo-36888: Python child processes can now access the status of theirparent process using multiprocessing.process.parent_process

  • bpo-36921: Deprecate@coroutine for sake ofasyncdef.

  • bpo-25652: Fix bug in__rmod__ ofUserString - by Batuhan Taskaya.

  • bpo-36916: Remove a message about an unhandled exception in a task whenwriter.write() is used without await and writer.drain() fails with anexception.

  • bpo-36889: Introduceasyncio.Stream class that mergesasyncio.StreamReader andasyncio.StreamWriterfunctionality.asyncio.Stream can work in readonly, writeonly andreadwrite modes. Provideasyncio.connect(),asyncio.connect_unix(),asyncio.connect_read_pipe() andasyncio.connect_write_pipe() factories to openasyncio.Stream connections. Provideasyncio.StreamServerandUnixStreamServer to serve servers with asyncio.Stream API.Modifyasyncio.create_subprocess_shell() andasyncio.create_subprocess_exec() to useasyncio.Streaminstead of deprecatedStreamReader andStreamWriter.Deprecateasyncio.StreamReader andasyncio.StreamWriter.Deprecate usage of private classes, e.g.asyncio.FlowControlMixing andasyncio.StreamReaderProtocol outside of asyncio package.

  • bpo-36845: Added validation of integer prefixes to the construction of IPnetworks and interfaces in the ipaddress module.

  • bpo-23378: Add an extend action to argparser.

  • bpo-36867: Fix a bug making a SharedMemoryManager instance and its parentprocess use two separate resource_tracker processes.

  • bpo-23896: Adds a grammar to lib2to3.pygram that contains exec as afunction not as statement.

  • bpo-36895: The functiontime.clock() was deprecated in 3.3 in favor oftime.perf_counter() and marked for removal in 3.8, it has removed.

  • bpo-35545: Fix asyncio discarding IPv6 scopes when ensuring hostnameresolutions internally

  • bpo-36887: Add new functionmath.isqrt() to compute integer squareroots.

  • bpo-34632: Introduce theimportlib.metadata module with (provisional)support for reading metadata from third-party packages.

  • bpo-36878: When usingtype_comments=True inast.parse, treat#type:ignore followed by a non-alphanumeric character and then arbitrarytext as a type ignore, instead of requiring nothing but whitespace oranother comment. This is to permit formations such as#type:ignore[E1000].

  • bpo-36778:cp65001 encoding (Windows code page 65001) becomes an aliastoutf_8 encoding.

  • bpo-36867: The multiprocessing.resource_tracker replaces themultiprocessing.semaphore_tracker module. Other than semaphores,resource_tracker also tracks shared_memory segments.

  • bpo-30262: TheCache andStatement objects of thesqlite3module are not exposed to the user. Patch by Aviv Palivoda.

  • bpo-24538: Inshutil.copystat(), first copy extended file attributesand then file permissions, since extended attributes can only be set onthe destination while it is still writeable.

  • bpo-36829: Add newsys.unraisablehook() function which can beoverridden to control how "unraisable exceptions" are handled. It iscalled when an exception has occurred but there is no way for Python tohandle it. For example, when a destructor raises an exception or duringgarbage collection (gc.collect()).

  • bpo-36832: Introducingzipfile.Path, a pathlib-compatible wrapper fortraversing zip files.

  • bpo-36814: Fix an issue where os.posix_spawnp() would incorrectly raise aTypeError when file_actions is None.

  • bpo-33110: Handle exceptions raised by functions added byconcurrent.futures add_done_callback correctly when the Future has alreadycompleted.

  • bpo-26903: Limitmax_workers inProcessPoolExecutor to 61 to workaround a WaitForMultipleObjects limitation.

  • bpo-36813: FixQueueListener to callqueue.task_done() upon stopping. Patch by Bar Harel.

  • bpo-36806: Forbid creation of asyncio stream objects like StreamReader,StreamWriter, Process, and their protocols outside of asyncio package.

  • bpo-36802: Provide both sync and async calls for StreamWriter.write() andStreamWriter.close()

  • bpo-36801: Properly handle SSL connection closing in asyncioStreamWriter.drain() call.

  • bpo-36785: Implement PEP 574 (pickle protocol 5 with out-of-band buffers).

  • bpo-36772: functools.lru_cache() can now be used as a straight decoratorin addition to its existing usage as a function that returns a decorator.

  • bpo-6584: Add aBadGzipFile exception to thegzipmodule.

  • bpo-36748: Optimized write buffering in C implementation ofTextIOWrapper. Writing ASCII string toTextIOWrapper with ascii,latin1, or utf-8 encoding is about 20% faster. Patch by Inada Naoki.

  • bpo-8138: Don't markwsgiref.simple_server.SimpleServer asmulti-threaded sincewsgiref.simple_server.WSGIServer issingle-threaded.

  • bpo-22640:py_compile.compile() now supports silent mode. Patch byJoannah Nanjekye

  • bpo-29183: Fix double exceptions inwsgiref.handlers.BaseHandlerby calling itsclose() method onlywhen no exception is raised.

  • bpo-36548: Improved the repr of regular expression flags.

  • bpo-36542: The signature of Python functions can now be overridden byspecifying the__text_signature__ attribute.

  • bpo-36533: Reinitialize logging.Handler locks in forked child processesinstead of attempting to acquire them all in the parent before forkingonly to be released in the child process. The acquire/release pattern wasleading to deadlocks in code that has implemented any form of chainedlogging handlers that depend upon one another as the lock acquisitionorder cannot be guaranteed.

  • bpo-35252: Throw a TypeError instead of an AssertionError when using aninvalid type annotation with singledispatch.

  • bpo-35900: Allow reduction methods to return a 6-item tuple where the 6thitem specifies a custom state-setting method that's called instead of theregular__setstate__ method.

  • bpo-35900: enable custom reduction callback registration for functions andclasses in _pickle.c, using the new Pickler's attributereducer_override

  • bpo-36368: Fix a bug crashing SharedMemoryManager instances in interactivesessions after a ctrl-c (KeyboardInterrupt) was sent

  • bpo-31904: Fix mmap fail for VxWorks

  • bpo-27497:csv.DictWriter.writeheader() now returns the return valueof the underlyingcsv.Writer.writerow() method. Patch contributed byAshish Nitin Patil.

  • bpo-36239: Parsing .mo files now ignores comments starting and ending with#-#-#-#-#.

  • bpo-26707: Enable plistlib to read and write binary plist files that werecreated as a KeyedArchive file. Specifically, this allows the plistlib toprocess 0x80 tokens as UID objects.

  • bpo-31904: Add posix module support for VxWorks.

  • bpo-35125: Asyncio: Remove inner callback on outer cancellation in shield

  • bpo-35721: Fixasyncio.SelectorEventLoop.subprocess_exec() leaksfile descriptors ifPopen fails and called withstdin=subprocess.PIPE. Patch by Niklas Fiekas.

  • bpo-31855:unittest.mock.mock_open() results now respects theargument of read([size]). Patch contributed by Rémi Lapeyre.

  • bpo-35431: Implementmath.comb() that returns binomial coefficient,that computes the number of ways to choose k items from n items withoutrepetition and without order. Patch by Yash Aggarwal and Keller Fuchs.

  • bpo-26660: Fixed permission errors inTemporaryDirectory clean up. PreviouslyTemporaryDirectory.cleanup() failed when non-writeable ornon-searchable files or directories were created inside a temporarydirectory.

  • bpo-34271: Add debugging helpers to ssl module. It's now possible to dumpkey material and to trace TLS protocol. The default and stdlib contextsalso support SSLKEYLOGFILE env var.

  • bpo-26467: Added AsyncMock to support using unittest to mock asynciocoroutines. Patch by Lisa Roach.

  • bpo-33569: dataclasses.InitVar: Exposes the type used to create the initvar.

  • bpo-34424: Fix serialization of messages containing encoded strings whenthe policy.linesep is set to a multi-character string. Patch by JensTroeger.

  • bpo-34303: Performance offunctools.reduce() is slightly improved.Patch by Sergey Fedoseev.

  • bpo-33361: Fix a bug incodecs.StreamRecoder where seeking mightleave old data in a buffer and break subsequent read calls. Patch by AmmarAskar.

  • bpo-22454: Theshlex module now exposesshlex.join(), theinverse ofshlex.split(). Patch by Bo Bayles.

  • bpo-31922:asyncio.AbstractEventLoop.create_datagram_endpoint(): Donot connect UDP socket when broadcast is allowed. This allows to receivereplies after a UDP broadcast.

  • bpo-24882: Change ThreadPoolExecutor to use existing idle threads beforespinning up new ones.

  • bpo-31961: Added support for bytes and path-like objects insubprocess.Popen() on Windows. Theargs parameter now accepts apath-like object ifshell isFalse and a sequence containingbytes and path-like objects. Theexecutable parameter now accepts abytes andpath-like object. Thecwd parameter now accepts abytes object. Based on patch by Anders Lorentsen.

  • bpo-33123:pathlib.Path.unlink now accepts amissing_okparameter to avoid aFileNotFoundError from being raised. Patch byRobert Buchholz.

  • bpo-32941: Allowmmap.mmap objects to access the madvise() systemcall (throughmmap.mmap.madvise()).

  • bpo-22102: Added support for ZIP files with disks set to 0. Such files arecommonly created by builtin tools on Windows when use ZIP64 extension.Patch by Francisco Facioni.

  • bpo-32515: trace.py can now run modules via python3 -m trace -t --modulemodule_name

  • bpo-32299: Changedunittest.mock.patch.dict() to return the patcheddictionary when used as context manager. Patch by Vadim Tsander.

  • bpo-27141: Added a__copy__() tocollections.UserList andcollections.UserDict in order to correctly implement shallow copyingof the objects. Patch by Bar Harel.

  • bpo-31829:\r,\0 and\x1a (end-of-file on Windows) are nowescaped in protocol 0 pickles of Unicode strings. This allows to load themwithout loss from files open in text mode in Python 2.

  • bpo-23395:_thread.interrupt_main() now avoids setting the Pythonerror status if theSIGINT signal is ignored or not handled by Python.

Documentation

  • bpo-36896: Clarify that some types have unstable constructor signaturebetween Python versions.

  • bpo-36686: Improve documentation of the stdin, stdout, and stderrarguments of theasyncio.subprocess_exec function to specify whichvalues are supported. Also mention that decoding as text is not supported.

    Add a few tests to verify that the various values passed to the std*arguments actually work.

  • bpo-36984: Improve version added references intyping module - byAnthony Sottile.

  • bpo-36868: What's new now mentions SSLContext.hostname_checks_common_nameinstead of SSLContext.host_flags.

  • bpo-35924: Add a note to thecurses.addstr() documentation to warnthat multiline strings can cause segfaults because of an ncurses bug.

  • bpo-36783: Added C API Documentation for Time_FromTimeAndFold andPyDateTime_FromDateAndTimeAndFold as per PEP 495. Patch by EdisonAbahurire.

  • bpo-36797: More of the legacy distutils documentation has been eitherpruned, or else more clearly marked as being retained solely until thesetuptools documentation covers it independently.

  • bpo-22865: Add detail to the documentation on thepty.spawn function.

  • bpo-35397: Remove deprecation and document urllib.parse.unwrap(). Patchcontributed by Rémi Lapeyre.

  • bpo-32995: Added the context variable in glossary.

  • bpo-33519: Clarify thatcopy() is not part of theMutableSequenceABC.

  • bpo-33482: Makecodecs.StreamRecoder.writelines take a list of bytes.

  • bpo-25735: Added documentation for func factorial to indicate that returnsinteger values

  • bpo-20285: Expand object.__doc__ (docstring) to make it clearer. Modifypydoc.py so that help(object) lists object methods (for other classes,help omits methods of the object base class.)

Tests

  • bpo-37069: Modify test_coroutines, test_cprofile, test_generators,test_raise, test_ssl and test_yield_from to usetest.support.catch_unraisable_exception() rather thantest.support.captured_stderr().

  • bpo-37098: Fix test_memfd_create on older Linux Kernels.

  • bpo-37081: Test with OpenSSL 1.1.1c

  • bpo-36829: Addtest.support.catch_unraisable_exception(): contextmanager catching unraisable exception usingsys.unraisablehook().

  • bpo-36915: The main regrtest process now always removes all temporarydirectories of worker processes even if they crash or if they are killedon KeyboardInterrupt (CTRL+c).

  • bpo-36719: "python3 -m test -jN ..." now continues the execution of nexttests when a worker process crash (CHILD_ERROR state). Previously, thetest suite stopped immediately. Use --failfast to stop at the first error.

  • bpo-36816: Update Lib/test/selfsigned_pythontestdotnet.pem to matchself-signed.pythontest.net's new TLS certificate.

  • bpo-35925: Skip httplib and nntplib networking tests when they wouldotherwise fail due to a modern OS or distro with a default OpenSSL policyof rejecting connections to servers with weak certificates.

  • bpo-36782: Add tests for several C API functions in thedatetimemodule. Patch by Edison Abahurire.

  • bpo-36342: Fix test_multiprocessing in test_venv if platform lacksfunctioning sem_open.

Build

  • bpo-36721: To embed Python into an application, a new--embed optionmust be passed topython3-config--libs--embed to get-lpython3.8(link the application to libpython). To support both 3.8 and older, trypython3-config--libs--embed first and fallback topython3-config--libs (without--embed) if the previous command fails.

    Add a pkg-configpython-3.8-embed module to embed Python into anapplication:pkg-configpython-3.8-embed--libs includes-lpython3.8. To support both 3.8 and older, trypkg-configpython-X.Y-embed--libs first and fallback topkg-configpython-X.Y--libs (without--embed) if the previous command fails (replaceX.Y with the Python version).

    On the other hand,pkg-configpython3.8--libs no longer contains-lpython3.8. C extensions must not be linked to libpython (except onAndroid, case handled by the script); this change is backward incompatibleon purpose.

  • bpo-36786: "make install" now runs compileall in parallel.

Windows

  • bpo-36965: include of STATUS_CONTROL_C_EXIT without depending on MSCcompiler

  • bpo-35926: Update to OpenSSL 1.1.1b for Windows.

  • bpo-29883: Add Windows support for UDP transports for the Proactor EventLoop. Patch by Adam Meily.

  • bpo-33407: ThePy_DEPRECATED() macro has been implemented forMSVC.

macOS

  • bpo-36231: Support building Python on macOS without /usr/includeinstalled. As of macOS 10.14, system header files are only availablewithin an SDK provided by either the Command Line Tools or the Xcode app.

IDLE

  • bpo-35610: Replace now redundant .context_use_ps1 with .prompt_last_line.This finishes change started inbpo-31858.

  • bpo-37038: Make idlelib.run runnable; add test clause.

  • bpo-36958: Print any argument other than None or int passed to SystemExitor sys.exit().

  • bpo-36807: When saving a file, call os.fsync() so bits are flushed to e.g.USB drive.

  • bpo-32411: In browser.py, remove extraneous sorting by line number sincedictionary was created in line number order.

Tools/Demos

  • bpo-37053: Handle strings like u"bar" correctly inTools/parser/unparse.py. Patch by Chih-Hsuan Yen.

C API

  • bpo-36763: Implement thePEP 587 "Python Initialization Configuration".

  • bpo-36379: Fix crashes when attempting to use themodulo parameter when__ipow__ is implemented in C.

  • bpo-37107: UpdatePyObject_CallMethodObjArgs() and_PyObject_CallMethodIdObjArgs to use_PyObject_GetMethod to avoidcreating a bound method object in many cases. Patch by Michael J.Sullivan.

  • bpo-36974: ImplementPEP 590: Vectorcall: a fast calling protocol forCPython. This is a new protocol to optimize calls of custom callableobjects.

  • bpo-36763:Py_Main() now returns the exitcode rather than callingPy_Exit(exitcode) when callingPyErr_Print() if the currentexception type isSystemExit.

  • bpo-36922: Add new type flagPy_TPFLAGS_METHOD_DESCRIPTOR for objectsbehaving like unbound methods. These are objects supporting theoptimization given by theLOAD_METHOD/CALL_METHOD opcodes. See PEP590.

  • bpo-36728: ThePyEval_ReInitThreads() function has been removedfrom the C API. It should not be called explicitly: usePyOS_AfterFork_Child() instead.

Python 3.8.0 alpha 4

Release date: 2019-05-06

Security

  • bpo-36742: Fixes mishandling of pre-normalization characters inurlsplit().

  • bpo-30458: AddressCVE 2019-9740 by disallowing URL paths with embeddedwhitespace or control characters through into the underlying http clientrequest. Such potentially malicious header injection URLs now cause anhttp.client.InvalidURL exception to be raised.

  • bpo-35755:shutil.which() now usesos.confstr("CS_PATH") ifavailable and if thePATH environment variable is not set.Remove also the current directory fromposixpath.defpath. On Unix,shutil.which() and thesubprocess module no longer search theexecutable in the current directory if thePATH environmentvariable is not set.

Core and Builtins

  • bpo-36722: In debug build, import now also looks for C extensions compiledin release mode and for C extensions compiled in the stable ABI.

  • bpo-32849: Fix Python Initialization code on FreeBSD to detect properlywhen stdin file descriptor (fd 0) is invalid.

  • bpo-36623: Remove parser headers and related function declarations thatlack implementations after the removal of pgen.

  • bpo-20180:dict.pop() is now up to 33% faster thanks to ArgumentClinic. Patch by Inada Naoki.

  • bpo-36611: Debug memory allocators: disable serialno field by default fromdebug hooks on Python memory allocators to reduce the memory footprint by5%. Enabletracemalloc to get the traceback where a memory blockhas been allocated when a fatal memory error is logged to decide where toput a breakpoint. Compile Python withPYMEM_DEBUG_SERIALNO defined toget back the field.

  • bpo-36588: On AIX,sys.platform doesn't contain the major versionanymore. Always return'aix', instead of'aix3' ..'aix7'.Since older Python versions include the version number, it is recommendedto always usesys.platform.startswith('aix'). Contributed by M. Felt.

  • bpo-36549: Change str.capitalize to use titlecase for the first characterinstead of uppercase.

  • bpo-36540: ImplementPEP 570 (Python positional-only parameters). Patchby Pablo Galindo.

  • bpo-36475:PyEval_AcquireLock() andPyEval_AcquireThread() now terminate the current thread if calledwhile the interpreter is finalizing, making them consistent withPyEval_RestoreThread(),Py_END_ALLOW_THREADS(), andPyGILState_Ensure().

  • bpo-36504: Fix signed integer overflow in _ctypes.c'sPyCArrayType_new().

  • bpo-20844: Fix running script with encoding cookie and LF line ending mayfail on Windows.

  • bpo-24214: Fixed support of the surrogatepass error handler in the UTF-8incremental decoder.

  • bpo-36452: Changingdict keys during iteration of the dict itself,keys(),values(), oritems() will now be detected in certaincorner cases where keys are deleted/added so that the number of keys isn'tchanged. ARuntimeError will be raised afterlen(dict) iterations.Contributed by Thomas Perl.

  • bpo-36459: Fix a possible doublePyMem_FREE() due to tokenizer.c'stok_nextc().

  • bpo-36433: Fixed TypeError message in classmethoddescr_call.

  • bpo-36430: Fix a possible reference leak initertools.count().

  • bpo-36440: Include node names inParserError messages, instead ofnumeric IDs. Patch by A. Skrobov.

  • bpo-36143: Regeneratekeyword from the Grammar and Tokens fileusing pgen. Patch by Pablo Galindo.

  • bpo-18372: Add missingPyObject_GC_Track() calls in thepickle module. Patch by Zackery Spytz.

Library

  • bpo-35952: Fix pythoninfo when the compiler is missing.

  • bpo-28238: The.find*() methods of xml.etree.ElementTree can nowsearch for wildcards like{*}tag and{ns}* that match a tag in anynamespace or all tags in a namespace. Patch by Stefan Behnel.

  • bpo-26978:pathlib.path.link_to() is now implemented. It creates ahard link pointing to a path.

  • bpo-1613500:fileinput.FileInput now uses the input file mode tocorrectly set the output file mode (previously it was hardcoded to'w') wheninplace=True is passed to its constructor.

  • bpo-36734: Fix compilation offaulthandler.c on HP-UX. Initializestack_tcurrent_stack to zero usingmemset().

  • bpo-13611: The xml.etree.ElementTree packages gained support for C14N 2.0serialisation. Patch by Stefan Behnel.

  • bpo-36669: Add missing matrix multiplication operator support toweakref.proxy.

  • bpo-36676: The XMLParser() in xml.etree.ElementTree provides namespaceprefix context to the parser target if it defines the callback methods"start_ns()" and/or "end_ns()". Patch by Stefan Behnel.

  • bpo-36673: The TreeBuilder and XMLPullParser in xml.etree.ElementTreegained support for parsing comments and processing instructions. Patch byStefan Behnel.

  • bpo-36650: The C version of functools.lru_cache() was treating calls withan empty**kwargs dictionary as being distinct from calls with nokeywords at all. This did not result in an incorrect answer, but it didtrigger an unexpected cache miss.

  • bpo-28552: Fixdistutils.sysconfig ifsys.executable isNone or an empty string: useos.getcwd() to initializeproject_base. Fix also the distutils build command: don't usesys.executable if it isNone or an empty string.

  • bpo-35755:shutil.which() anddistutils.spawn.find_executablenow useos.confstr("CS_PATH") if available instead ofos.defpath, if thePATH environment variable is not set.Moreover, don't useos.confstr("CS_PATH") noros.defpath ifthePATH environment variable is set to an empty string.

  • bpo-25430: improve performance ofIPNetwork.__contains__()

  • bpo-30485: Path expressions in xml.etree.ElementTree can now avoidexplicit namespace prefixes for tags (or the "{namespace}tag" notation) bypassing a default namespace with an empty string prefix.

  • bpo-36613: Fixasyncio wait() not removing callback if exception

  • bpo-36598: Fixisinstance check for Mock objects with spec when thecode is executed under tracing. Patch by Karthikeyan Singaravelan.

  • bpo-18748: In development mode (-Xdev) and in debug build,theio.IOBase destructor now logsclose() exceptions. Theseexceptions are silent by default in release mode.

  • bpo-36575: The_lsprof module now uses internal timer same totime.perf_counter() by default.gettimeofday(2) was used on Unix.New timer has better resolution on most Unix platforms and timings are nolonger impacted by system clock updates sinceperf_counter() ismonotonic. Patch by Inada Naoki.

  • bpo-33461:json.loads now emitsDeprecationWarning whenencoding option is specified. Patch by Matthias Bussonnier.

  • bpo-36559: The random module now prefers the lean internal _sha512 moduleover hashlib for seed(version=2) to optimize import time.

  • bpo-17561: Set backlog=None as the default for socket.create_server.

  • bpo-34373: Fixtime.mktime() error handling on AIX for year before1970.

  • bpo-36232: Improve error message when trying to open existing DBM databasethat actually doesn't exist. Patch by Marco Rougeth.

  • bpo-36546: Add statistics.quantiles()

  • bpo-36050: Optimizedhttp.client.HTTPResponse.read() for largeresponse. Patch by Inada Naoki.

  • bpo-36522: Ifdebuglevel is set to >0 inhttp.client, print allvalues for headers with multiple values for the same header name. Patch byMatt Houglum.

  • bpo-36492: Deprecated passing required arguments likefunc as keywordarguments in functions which should accept arbitrary keyword arguments andpass them to other function. Arbitrary keyword arguments (even with names"self" and "func") can now be passed to these functions if the requiredarguments are passed as positional arguments.

  • bpo-27181: Add statistics.geometric_mean().

  • bpo-30427:os.path.normcase() relies onos.fspath() to check thetype of its argument. Redundant checks have been removed from itsposixpath.normcase() andntpath.normcase() implementations. Patchby Wolfgang Maier.

  • bpo-36385: Stop rejecting IPv4 octets for being ambiguously octal. Leadingzeros are ignored, and no longer are assumed to specify octal octets.Octets are always decimal numbers. Octets must still be no more than threedigits, including leading zeroes.

  • bpo-36434: Errors during writing to a ZIP file no longer prevent toproperly close it.

  • bpo-36407: Fixed wrong indentation writing for CDATA section inxml.dom.minidom. Patch by Vladimir Surjaninov.

  • bpo-36326: inspect.getdoc() can now find docstrings for member objectswhen __slots__ is a dictionary.

  • bpo-36366: Callingstop() on an unstarted or stoppedunittest.mock.patch() object will now returnNone instead ofraisingRuntimeError, making the method idempotent. Patch byKarthikeyan Singaravelan.

  • bpo-36348: Theimap.IMAP4.logout() method no longer ignores silentlyarbitrary exceptions.

  • bpo-31904: Add time module support and fix test_time failures for VxWorks.

  • bpo-36227: Added support for keyword argumentsdefault_namespace andxml_declaration in functionsElementTree.tostring() andElementTree.tostringlist().

  • bpo-36004: Added new alternate constructorsdatetime.date.fromisocalendar() anddatetime.datetime.fromisocalendar(), which construct date objectsfrom ISO year, week number and weekday; these are the inverse of eachclass'sisocalendar method. Patch by Paul Ganssle.

  • bpo-35936:modulefinder no longer depends on the deprecatedimp module, and the initializer formodulefinder.ModuleFinder now has immutable default arguments.Patch by Brandt Bucher.

  • bpo-35376:modulefinder correctly handles modules that have thesame name as a bad package. Patch by Brandt Bucher.

  • bpo-17396:modulefinder no longer crashes when encountering syntaxerrors in followed imports. Patch by Brandt Bucher.

  • bpo-35934: Addedcreate_server() andhas_dualstack_ipv6() convenience functions to automate thenecessary tasks usually involved when creating a server socket, includingaccepting both IPv4 and IPv6 connections on the same socket. (Contributedby Giampaolo Rodola inbpo-17561.)

  • bpo-23078: Add support forclassmethod() andstaticmethod() tounittest.mock.create_autospec(). Initial patch by Felipe Ochoa.

  • bpo-35416: Fix potential resource warnings in distutils. Patch by MickaëlSchoentgen.

  • bpo-25451: Add transparency methods totkinter.PhotoImage. Patchby Zackery Spytz.

  • bpo-35082: Don't return deleted attributes when calling dir on aunittest.mock.Mock.

  • bpo-34547:wsgiref.handlers.BaseHandler now handles abrupt clientconnection terminations gracefully. Patch by Petter Strandmark.

  • bpo-31658:xml.sax.parse() now supportspath-like. Patch by Mickaël Schoentgen.

  • bpo-34139: Remove stale unix datagram socket before binding

  • bpo-33530: Implemented Happy Eyeballs inasyncio.create_connection().Added two new arguments,happy_eyeballs_delay andinterleave, tospecify Happy Eyeballs behavior.

  • bpo-33291: Do not raise AttributeError when calling the inspect functionsisgeneratorfunction, iscoroutinefunction, isasyncgenfunction on a methodcreated from an arbitrary callable. Instead, return False.

  • bpo-31310: Fix the multiprocessing.semaphore_tracker so it is reused bychild processes

  • bpo-31292: Fixsetup.pycheck--restructuredtext for files containinginclude directives.

Documentation

  • bpo-36625: Remove obsolete comments from docstrings in fractions.Fraction

  • bpo-30840: Document relative imports

  • bpo-36523: Add docstring for io.IOBase.writelines().

  • bpo-36425: New documentation translation:Simplified Chinese.

  • bpo-36345: Avoid the duplication of code fromTools/scripts/serve.pyin using theliteralinclude directive for the basicwsgiref-based web server in the documentation ofwsgiref.Contributed by Stéphane Wirtel.

  • bpo-36345: Using the code of theTools/scripts/serve.py script as anexample in thewsgiref documentation. Contributed by StéphaneWirtel.

  • bpo-36157: Added documentation for PyInterpreterState_Main().

  • bpo-33043: Updates the docs.python.org page with the addition of a'Contributing to Docs' link at the end of the page (between 'ReportingBugs' and 'About Documentation'). Updates the 'Found a Bug' page withadditional links and information in the Documentation Bugs section.

  • bpo-35581: @typing.type_check_only now allows type stubs to mark functionsand classes not available during runtime.

  • bpo-33832: Add glossary entry for 'magic method'.

  • bpo-32913: Added re.Match.groupdict example to regex HOWTO.

Tests

  • bpo-36719: regrtest now always detects uncollectable objects. Previously,the check was only enabled by--findleaks. The check now also workswith-jN/--multiprocessN.--findleaks becomes a deprecated aliasto--fail-env-changed.

  • bpo-36725: When using multiprocessing mode (-jN), regrtest now betterreports errors if a worker process fails, and it exits immediately on aworker thread failure or when interrupted.

  • bpo-36454: Change test_time.test_monotonic() to test only the lower boundof elapsed time after a sleep command rather than the upper bound. Thisprevents unnecessary test failures on slow buildbots. Patch by VictorStinner.

  • bpo-32424: Improve test coverage for xml.etree.ElementTree. Patch byGordon P. Hemsley.

  • bpo-32424: Fix typo in test_cyclic_gc() test for xml.etree.ElementTree.Patch by Gordon P. Hemsley.

  • bpo-36635: Add a new_testinternalcapi module to test the internalC API.

  • bpo-36629: Fixtest_imap4_host_default_value() oftest_imaplib:catch alsoerrno.ENETUNREACH error.

  • bpo-36611: Fixtest_sys.test_getallocatedblocks() whentracemalloc is enabled.

  • bpo-36560: Fix reference leak hunting in regrtest: compute also deltas (ofreference count, allocated memory blocks, file descriptor count) duringwarmup, to ensure that everything is initialized before starting to huntreference leaks.

  • bpo-36565: Fix reference hunting (python3-mtest-R3:3) when Pythonhas no built-in abc module.

  • bpo-31904: Port test_resource to VxWorks: skip tests cases settingRLIMIT_FSIZE and RLIMIT_CPU.

  • bpo-31904: Fix test_tabnanny on VxWorks: adjust ENOENT error message.

  • bpo-36436: Fix_testcapi.pymem_buffer_overflow(): handle memoryallocation failure.

  • bpo-31904: Fix test_utf8_mode on VxWorks: Python always use UTF-8 onVxWorks.

  • bpo-36341: Fix tests that may fail with PermissionError upon callingbind() on AF_UNIX sockets.

Build

  • bpo-36747: Remove the stale scriptsinstall Makefile target.

  • bpo-21536: On Unix, C extensions are no longer linked to libpython excepton Android and Cygwin.

    It is now possible for a statically linked Python to load a C extensionbuilt using a shared library Python.

    When Python is embedded,libpython must not be loaded withRTLD_LOCAL, butRTLD_GLOBAL instead. Previously, usingRTLD_LOCAL, it was already not possible to load C extensions whichwere not linked tolibpython, such as C extensions of the standardlibrary built by the*shared* section ofModules/Setup.

    distutils, python-config and python-config.py have been modified.

  • bpo-36707:./configure--with-pymalloc no longer adds them flagto SOABI (sys.implementation.cache_tag). Enabling or disabling pymallochas no impact on the ABI.

  • bpo-36635: ChangePyAPI_FUNC(type),PyAPI_DATA(type) andPyMODINIT_FUNC macros ofpyport.h whenPy_BUILD_CORE_MODULE isdefined. ThePy_BUILD_CORE_MODULE define must be now be used to builda C extension as a dynamic library accessing Python internals: export thePyInit_xxx() function in DLL exports on Windows.

  • bpo-31904: Don't build the_crypt extension on VxWorks.

  • bpo-36618: Add-fmax-type-align=8 to CFLAGS when clang compiler isdetected. The pymalloc memory allocator aligns memory on 8 bytes. Onx86-64, clang expects alignment on 16 bytes by default and so uses MOVAPSinstruction which can lead to segmentation fault. Instruct clang thatPython is limited to alignment on 8 bytes to use MOVUPS instructioninstead: slower but don't trigger a SIGSEGV if the memory is not alignedon 16 bytes. Sadly, the flag must be added toCFLAGS and not justCFLAGS_NODIST, since third party C extensions can have the same issue.

  • bpo-36605:maketags andmakeTAGS now also parseModules/_io/*.c andModules/_io/*.h.

  • bpo-36465: Release builds and debug builds are now ABI compatible:defining thePy_DEBUG macro no longer implies thePy_TRACE_REFSmacro, which introduces the only ABI incompatibility. ThePy_TRACE_REFS macro, which adds thesys.getobjects() functionand thePYTHONDUMPREFS environment variable, can be set usingthe new./configure--with-trace-refs build option.

  • bpo-36577: setup.py now correctly reports missing OpenSSL headers andlibraries again.

  • bpo-36544: Fix regression introduced inbpo-36146 refactoring setup.py

  • bpo-36508:python-config--ldflags no longer includes flags of theLINKFORSHARED variable. TheLINKFORSHARED variable must only beused to build executables.

  • bpo-36503: Remove references to "aix3" and "aix4". Patch by M. Felt.

Windows

  • bpo-35920: Added platform.win32_edition() and platform.win32_is_iot().Added support for cross-compiling packages for Windows ARM32. Skip teststhat are not expected to work on Windows IoT Core ARM32.

  • bpo-36649: Remove trailing spaces for registry keys when installed via theStore.

  • bpo-34144: Fixed activate.bat to correctly update codepage when chcp.comreturns dots in output. Patch by Lorenz Mende.

  • bpo-36509: Added preset-iot layout for Windows IoT ARM containers. Thislayout doesn't contain UI components like tkinter or IDLE. It also doesn'tcontain files to support on-target builds since Windows ARM32 builds mustbe cross-compiled when using MSVC.

  • bpo-35941: enum_certificates function of the ssl module now returnscertificates from all available certificate stores inside windows in aquery instead of returning only certificates from the system widecertificate store. This includes certificates from these certificatestores: local machine, local machine enterprise, local machine grouppolicy, current user, current user group policy, services, users.ssl.enum_crls() function is changed in the same way to return allcertificate revocation lists inside the windows certificate revocationlist stores.

  • bpo-36441: Fixes creating a venv when debug binaries are installed.

  • bpo-36085: Enable better DLL resolution on Windows by using safe DLLsearch paths and addingos.add_dll_directory().

  • bpo-36010: Add the venv standard library module to the nuget distributionfor Windows.

  • bpo-29515: Add the following socket module constants on Windows:IPPROTO_AH IPPROTO_CBT IPPROTO_DSTOPTS IPPROTO_EGP IPPROTO_ESPIPPROTO_FRAGMENT IPPROTO_GGP IPPROTO_HOPOPTS IPPROTO_ICLFXBMIPPROTO_ICMPV6 IPPROTO_IDP IPPROTO_IGMP IPPROTO_IGP IPPROTO_IPV4IPPROTO_IPV6 IPPROTO_L2TP IPPROTO_MAX IPPROTO_ND IPPROTO_NONE IPPROTO_PGMIPPROTO_PIM IPPROTO_PUP IPPROTO_RDP IPPROTO_ROUTING IPPROTO_SCTPIPPROTO_ST

  • bpo-35947: Added current version of libffi to cpython-source-deps. Change_ctypes to use current version of libffi on Windows.

  • bpo-34060: Report system load when running test suite on Windows. Patch byAmmar Askar. Based on prior work by Jeremy Kloth.

  • bpo-31512: With the Windows 10 Creators Update, non-elevated users can nowcreate symlinks as long as the computer has Developer Mode enabled.

macOS

  • bpo-34602: Avoid failures setting macOS stack resource limit withresource.setrlimit. This reverts an earlier fix forbpo-18075 which forceda non-default stack size when building the interpreter executable onmacOS.

IDLE

  • bpo-36429: Fix starting IDLE with pyshell. Add idlelib.pyshell alias attop; remove pyshell alias at bottom. Remove obsolete __name__=='__main__'command.

Tools/Demos

  • bpo-14546: Fix the argument handling in Tools/scripts/lll.py.

C API

  • bpo-36763: Fix memory leak inPy_SetStandardStreamEncoding():release memory if the function is called twice.

  • bpo-36641:PyDoc_VAR(name) andPyDoc_STRVAR(name,str)now createstaticconstcharname[] instead ofstaticcharname[].Patch by Inada Naoki.

  • bpo-36389: Change the value ofCLEANBYTE,DEADDYTE andFORBIDDENBYTE internal constants used by debug hooks on Python memoryallocators (PyMem_SetupDebugHooks() function). Byte patterns0xCB,0xDB and0xFB have been replaced with0xCD,0xDDand0xFD to use the same values than Windows CRT debugmalloc()andfree().

  • bpo-36443: Since Python 3.7.0, callingPy_DecodeLocale() beforePy_Initialize() produces mojibake if theLC_CTYPE locale iscoerced and/or if the UTF-8 Mode is enabled by the user configuration. TheLC_CTYPE coercion and UTF-8 Mode are now disabled by default to fix themojibake issue. They must now be enabled explicitly (opt-in) using the new_Py_PreInitialize() API with_PyPreConfig.

  • bpo-36025: Fixed an accidental change to the datetime C API where thearguments to thePyDate_FromTimestamp() function were incorrectlyinterpreted as a single timestamp rather than an arguments tuple, whichcauses existing code to start raisingTypeError. Thebackwards-incompatible change was only present in alpha releases of Python3.8. Patch by Paul Ganssle.

  • bpo-35810: ModifyPyObject_Init to correctly increase the refcount ofheap-allocated Type objects. Also fix the refcounts of the heap-allocatedtypes that were either doing this manually or not decreasing the type'srefcount in tp_dealloc

Python 3.8.0 alpha 3

Release date: 2019-03-25

Security

  • bpo-36216: Changes urlsplit() to raise ValueError when the URL containscharacters that decompose under IDNA encoding (NFKC-normalization) intocharacters that affect how the URL is parsed.

  • bpo-35121: Don't send cookies of domain A without Domain attribute todomain B when domain A is a suffix match of domain B while using acookiejar withhttp.cookiejar.DefaultCookiePolicy policy. Patchby Karthikeyan Singaravelan.

Core and Builtins

  • bpo-36421: Fix a possible double decref in _ctypes.c'sPyCArrayType_new().

  • bpo-36412: Fix a possible crash when creating a new dictionary.

  • bpo-36398: Fix a possible crash instructseq_repr().

  • bpo-36256: Fix bug in parsermodule when parsing a state in a DFA that hastwo or more arcs with labels of the same type. Patch by Pablo Galindo.

  • bpo-36365: repr(structseq) is no longer limited to 512 bytes.

  • bpo-36374: Fix a possible null pointer dereference inmerge_consts_recursive(). Patch by Zackery Spytz.

  • bpo-36236: At Python initialization, the current directory is no longerprepended tosys.path if it has been removed.

  • bpo-36352: Python initialization now fails with an error, rather thansilently truncating paths, if a path is too long.

  • bpo-36301: Python initialization now fails if decodingpybuilddir.txtconfiguration file fails at startup.

  • bpo-36333: Fix leak in _PyRuntimeState_Fini. Contributed by StéphaneWirtel.

  • bpo-36332: The builtincompile() can now handle AST objects thatcontain assignment expressions. Patch by Pablo Galindo.

  • bpo-36282: Improved error message for too much positional arguments insome builtin functions.

  • bpo-30040: New empty dict uses fewer memory for now. It used more memorythan empty dict created bydict.clear(). And empty dict creation anddeletion is about 2x faster. Patch by Inada Naoki.

  • bpo-36262: Fix an unlikely memory leak on conversion from string to floatin the function_Py_dg_strtod() used byfloat(str),complex(str),pickle.load(),marshal.load(), etc.

  • bpo-36252: Update Unicode databases to version 12.0.0.

  • bpo-36218: Fix a segfault occurring when sorting a list of heterogeneousvalues. Patch contributed by Rémi Lapeyre and Elliot Gorokhovsky.

  • bpo-36188: Cleaned up left-over vestiges of Python 2 unbound methodhandling in method objects and documentation. Patch by Martijn Pieters

  • bpo-36124: Add a new interpreter-specific dict and expose it in the C-APIvia PyInterpreterState_GetDict(). This parallels PyThreadState_GetDict().However, extension modules should continue using PyModule_GetState() fortheir own internal per-interpreter state.

  • bpo-35975: Add afeature_version flag toast.parse() (documented)andcompile() (hidden) that allows tweaking the parser to supportolder versions of the grammar. In particular, iffeature_version is 5or 6, the hacks for theasync andawait keyword from PEP 492 arereinstated. (For 7 or higher, these are unconditionally treated askeywords, but they are still special tokens rather thanNAME tokensthat the parser driver recognizes.)

  • bpo-31904: Use UTF-8 as the system encoding on VxWorks.

  • bpo-36048: The__index__() special method will be usedinstead of__int__() for implicit conversion of Pythonnumbers to C integers. Using the__int__() method in implicitconversions has been deprecated.

  • bpo-35808: Retire pgen and use a modified version of pgen2 to generate theparser. Patch by Pablo Galindo.

Library

  • bpo-36401: The class documentation created by pydoc now has a separatesection for readonly properties.

  • bpo-36320: The typing.NamedTuple() class has deprecated the _field_typesattribute in favor of the __annotations__ attribute which carried the sameinformation. Also, both attributes were converted from OrderedDict to aregular dict.

  • bpo-34745: Fixasyncio ssl memory issues caused by circularreferences

  • bpo-36324: Add method to statistics.NormalDist for computing the inversecumulative normal distribution.

  • bpo-36321: collections.namedtuple() misspelled the name of an attribute.To be consistent with typing.NamedTuple, the attribute name should havebeen "_field_defaults" instead of "_fields_defaults". For backwardscompatibility, both spellings are now created. The misspelled version maybe removed in the future.

  • bpo-36297: "unicode_internal" codec is removed. It was deprecated sincePython 3.3. Patch by Inada Naoki.

  • bpo-36298: Raise ModuleNotFoundError in pyclbr when a module can't befound. Thanks to 'mental' for the bug report.

  • bpo-36268: Switch the default format used for writing tars withtarfile to the modern POSIX.1-2001 pax standard, from thevendor-specific GNU. Contributed by C.A.M. Gerlach.

  • bpo-36285: Fix integer overflows in the array module. Patch by StephanHohe.

  • bpo-31904: Add _signal module support for VxWorks.

  • bpo-36272:logging does not silently ignore RecursionError anymore.Patch contributed by Rémi Lapeyre.

  • bpo-36280: Add a kind field to ast.Constant. It is 'u' if the literal hasa 'u' prefix (i.e. a Python 2 style unicode literal), else None.

  • bpo-35931: Thepdbdebug command now gracefully handles allexceptions.

  • bpo-36251: Fix format strings used for stderrprinter and re.Match reprs.Patch by Stephan Hohe.

  • bpo-36235: FixCFLAGS incustomize_compiler() ofdistutils.sysconfig: when theCFLAGS environment variable isdefined, don't overrideCFLAGS variable with theOPT variableanymore. Initial patch written by David Malcolm.

  • bpo-35807: Update ensurepip to install pip 19.0.3 and setuptools 40.8.0.

  • bpo-36139: Release GIL when closingmmap objects.

  • bpo-36179: Fix two unlikely reference leaks in _hashopenssl. The leaksonly occur in out-of-memory cases.

  • bpo-36169: Add overlap() method to statistics.NormalDist. Computes theoverlapping coefficient for two normal distributions.

  • bpo-36103: Default buffer size used byshutil.copyfileobj() is changedfrom 16 KiB to 64 KiB on non-Windows platform to reduce system calloverhead. Contributed by Inada Naoki.

  • bpo-36130: Fixpdb withskip=... when stepping into a framewithout a__name__ global. Patch by Anthony Sottile.

  • bpo-35652: shutil.copytree(copy_function=...) erroneously pass DirEntryinstead of a path string.

  • bpo-35178: Ensure customwarnings.formatwarning() function canreceiveline as positional argument. Based on patch by Tashrif Billah.

  • bpo-36106: Resolve potential name clash with libm's sinpi(). Patch byDmitrii Pasechnik.

  • bpo-36091: Clean up reference to async generator in Lib/types. Patch byHenry Chen.

  • bpo-36043:FileCookieJar supportspath-like object.Contributed by Stéphane Wirtel

  • bpo-35899: Enum has been fixed to correctly handle empty strings andstrings with non-Latin characters (ie. 'α', 'א') without crashing.Original patch contributed by Maxwell. Assisted by Stéphane Wirtel.

  • bpo-21269: Addargs andkwargs properties to mock call objects.Contributed by Kumar Akshay.

  • bpo-30670:pprint.pp has been added to pretty-print objects withdictionary keys being sorted with their insertion order by default.Parametersort_dicts has been added topprint.pprint,pprint.pformat andpprint.PrettyPrinter. Contributed by RémiLapeyre.

  • bpo-35843: Implement__getitem__ for_NamespacePath. Patch byAnthony Sottile.

  • bpo-35802: Clean up code which checked presence ofos.stat /os.lstat /os.chmod which are always present. Patch by AnthonySottile.

  • bpo-35715: Librates the return value of a ProcessPoolExecutor_process_worker after it's no longer needed to free memory

  • bpo-35493: Usemultiprocessing.connection.wait() instead of pollingeach 0.2 seconds for worker updates inmultiprocessing.Pool.Patch by Pablo Galindo.

  • bpo-35661: Store the venv prompt in pyvenv.cfg.

  • bpo-35121: Don't set cookie for a request when the request path is aprefix match of the cookie's path attribute but doesn't end with "/".Patch by Karthikeyan Singaravelan.

  • bpo-21478: Calls to a child function created withunittest.mock.create_autospec() should propagate to the parent.Patch by Karthikeyan Singaravelan.

  • bpo-35198: Fix C++ extension compilation on AIX

Documentation

  • bpo-36329: Declare the path of the Python binary for the usage ofTools/scripts/serve.py when executingmake-CDoc/serve.Contributed by Stéphane Wirtel

  • bpo-36138: Improve documentation about converting datetime.timedelta toscalars.

  • bpo-21314: A new entry was added to the Core Language Section of theProgramming FAQ, which explaines the usage of slash(/) in the signature ofa function. Patch by Lysandros Nikolaou

Tests

  • bpo-36234: test_posix.PosixUidGidTests: add tests for invalid uid/gid type(str). Initial patch written by David Malcolm.

  • bpo-29571: Fixtest_re.test_locale_flag(): uselocale.getpreferredencoding() rather thanlocale.getlocale() toget the locale encoding. With some locales,locale.getlocale() returnsthe wrong encoding.

  • bpo-36123: Fix race condition in test_socket.

Build

  • bpo-36356: Fix leaks that led to build failure when configured withaddress sanitizer.

  • bpo-36146: AddTEST_EXTENSIONS constant tosetup.py to allow tonot build test extensions like_testcapi.

  • bpo-36146: Fix setup.py on macOS: only add/usr/include/ffi to includedirectories of _ctypes, not for all extensions.

  • bpo-31904: Enable build system to cross-build for VxWorks RTOS.

Windows

  • bpo-36312: Fixed decoders for the following code pages: 50220, 50221,50222, 50225, 50227, 50229, 57002 through 57011, 65000 and 42.

  • bpo-36264: Don't honor POSIXHOME inos.path.expanduser onwindows. Patch by Anthony Sottile.

  • bpo-24643: Fix name collisions due to#definetimezone_timezone inPC/pyconfig.h.

IDLE

  • bpo-36405: Use dict unpacking in idlelib.

  • bpo-36396: Remove fgBg param of idlelib.config.GetHighlight(). This paramwas only used twice and changed the return type.

  • bpo-36176: Fix IDLE autocomplete & calltip popup colors. Prevent conflictswith Linux dark themes (and slightly darken calltip background).

  • bpo-23205: For the grep module, add tests for findfiles, refactorfindfiles to be a module-level function, and refactor findfiles to useos.walk.

  • bpo-23216: Add docstrings to IDLE search modules.

  • bpo-36152: Remove colorizer.ColorDelegator.close_when_done and thecorresponding argument of .close(). In IDLE, both have always been Noneor False since 2007.

  • bpo-32129: Avoid blurry IDLE application icon on macOS with Tk 8.6. Patchby Kevin Walzer.

  • bpo-36096: Refactor class variables to instance variables in colorizer.

  • bpo-30348: Increase test coverage of idlelib.autocomplete by 30%. Patch byLouie Lu

Tools/Demos

  • bpo-35132: Fix py-list and py-bt commands of python-gdb.py on gdb7.

  • bpo-32217: Fix freeze script on Windows.

C API

  • bpo-36381: RaiseDeprecationWarning when '#' formats are used forbuilding or parsing values withoutPY_SSIZE_T_CLEAN.

  • bpo-36142: The whole coreconfig.h header is now excluded fromPy_LIMITED_API. Move functions definitions into a new internalpycore_coreconfig.h header.

Python 3.8.0 alpha 2

Release date: 2019-02-25

Core and Builtins

  • bpo-36052: Raise aSyntaxError when assigning a value to__debug__ with the Assignment Operator. Contributed by Stéphane Wirteland Pablo Galindo.

  • bpo-36012: Doubled the speed of class variable writes. When a non-dunderattribute was updated, there was an unnecessary call to update slots.

  • bpo-35942: The error message emitted when returning invalid types from__fspath__ in interfaces that allow passingPathLikeobjects has been improved and now it does explain the origin of the error.

  • bpo-36016:gc.get_objects can now receive an optional parameterindicating a generation to get objects from. Patch by Pablo Galindo.

  • bpo-1054041: When the main interpreter exits due to an uncaughtKeyboardInterrupt, the process now exits in the appropriate manner for itsparent process to detect that a SIGINT or ^C terminated the process. Thisallows shells and batch scripts to understand that the user has asked themto stop.

  • bpo-35992: Fix__class_getitem__() not being called on a class with acustom non-subscriptable metaclass.

  • bpo-35993: Fix a crash on fork when using subinterpreters. Contributed byStéphane Wirtel

  • bpo-35991: Fix a potential double free in Modules/_randommodule.c.

  • bpo-35961: Fix a crash in slice_richcompare(): use strong referencesrather than stolen references for the two temporary internal tuples.

  • bpo-35911: Enable the creation of cell objects by adding acell.__new__ method, and expose the typecell inLib/types.pyunder the name CellType. Patch by Pierre Glaser.

  • bpo-12822: Use monotonic clock forpthread_cond_timedwait whenpthread_condattr_setclock andCLOCK_MONOTONIC are available.

  • bpo-15248: The compiler emits now syntax warnings in the case when a commais likely missed before tuple or list.

  • bpo-35886: The implementation of PyInterpreterState has been moved intothe internal header files (guarded by Py_BUILD_CORE).

  • bpo-31506: Clarify the errors reported whenobject.__new__ andobject.__init__ receive more than one argument. Contributed by SanyamKhurana.

  • bpo-35724: Signal-handling is now guaranteed to happen relative to themain interpreter.

  • bpo-33608: We added a new internal _Py_AddPendingCall() that operatesrelative to the provided interpreter. This allows us to use the existingimplementation to ask another interpreter to do work that cannot be donein the current interpreter, like decref an object the other interpreterowns. The existing Py_AddPendingCall() only operates relative to the maininterpreter.

  • bpo-33989: Fix a possible crash inlist.sort() when sorting objectswithob_type->tp_richcompare==NULL. Patch by Zackery Spytz.

Library

  • bpo-35512:unittest.mock.patch.dict() used as a decorator withstring target resolves the target during function call instead of duringdecorator construction. Patch by Karthikeyan Singaravelan.

  • bpo-36018: Add statistics.NormalDist, a tool for creating and manipulatingnormal distributions of random variable. Features a composite class thattreats the mean and standard deviation of measurement data as singleentity.

  • bpo-35904: Added statistics.fmean() as a faster, floating-point variant ofthe existing mean() function.

  • bpo-35918: Removed brokenhas_key method frommultiprocessing.managers.SyncManager.dict. Contributed by Rémi Lapeyre.

  • bpo-18283: Add support for bytes toshutil.which().

  • bpo-35960: Fixdataclasses.field() throwing away empty mappingobjects passed as metadata.

  • bpo-35500: Write expected and actual call parameters on separate lines inunittest.mock.Mock.assert_called_with() assertion errors.Contributed by Susan Su.

  • bpo-35931: Thepdbdebug command now gracefully handles syntaxerrors.

  • bpo-24209: In http.server script, rely on getaddrinfo to bind to preferredaddress based on the bind parameter. Now default bind or binding to a namemay bind to IPv6 or dual-stack, depending on the environment.

  • bpo-35321: Set__spec__.origin of_frozen_importlib to frozen sothat it matches the behavior of_frozen_importlib_external. Patch byNina Zakharenko.

  • bpo-35378: Fix a reference issue insidemultiprocessing.Pool thatcaused the pool to remain alive if it was deleted without being closed orterminated explicitly. A new strong reference is added to the pooliterators to link the lifetime of the pool to the lifetime of itsiterators so the pool does not get destroyed if a pool iterator is stillalive.

  • bpo-34294: re module, fix wrong capturing groups in rare cases.re.search(),re.findall(),re.sub() and other functionsthat scan through string looking for a match, should reset capturinggroups between two match attempts. Patch by Ma Lin.

  • bpo-35615:weakref: Fix a RuntimeError when copying aWeakKeyDictionary or a WeakValueDictionary, due to some keys or valuesdisappearing while iterating.

  • bpo-35606: Implementmath.prod() as analogous function tosum() that returns the product of a 'start' value (default: 1) timesan iterable of numbers. Patch by Pablo Galindo.

  • bpo-32417: Performing arithmetic betweendatetime.datetimesubclasses anddatetime.timedelta now returns an object of thesame type as thedatetime.datetime subclass. As a result,datetime.datetime.astimezone() and alternate constructors likedatetime.datetime.now() anddatetime.fromtimestamp() calledwith atz argument nowalso retain their subclass.

  • bpo-35153: Addheaders optional keyword-only parameter toxmlrpc.client.ServerProxy,xmlrpc.client.Transport andxmlrpc.client.SafeTransport. Patch by Cédric Krier.

  • bpo-34572: Fix C implementation of pickle.loads to use importlib's lockingmechanisms, and thereby avoid using partially loaded modules. Patch by TimBurgess.

Documentation

  • bpo-36083: Fix formatting of --check-hash-based-pycs options in themanpage Synopsis.

  • bpo-36007: Bump minimum sphinx version to 1.8. Patch by Anthony Sottile.

  • bpo-22062: Update documentation and docstrings for pathlib. Original patchby Mike Short.

Tests

  • bpo-27313: Avoid test_ttk_guionly ComboboxTest failure with macOS CocoaTk.

  • bpo-36019: Add test.support.TEST_HTTP_URL and replace references ofhttp://www.example.com by this new constant. Contributed by StéphaneWirtel.

  • bpo-36037: Fix test_ssl for strict OpenSSL configuration like RHEL8 strictcrypto policy. Use older TLS version for minimum TLS version of the serverSSL context if needed, to test TLS version older than default minimum TLSversion.

  • bpo-35798: Addedtest.support.check_syntax_warning().

  • bpo-35505: Make test_imap4_host_default_value independent on whether thelocal IMAP server is running.

  • bpo-35917: multiprocessing: provide unit tests for SyncManager andSharedMemoryManager classes + all the shareable types which are supposedto be supported by them. (patch by Giampaolo Rodola)

  • bpo-35704: Skiptest_shutil.test_unpack_archive_xztar to prevent aMemoryError on 32-bit AIX when MAXDATA setting is less than 0x20000000.

    Patch by Michael Felt (aixtools)

  • bpo-34720: Assert m_state != NULL to mimic GC traversal functions that donot correctly handle module creation when the module state has not beencreated.

Windows

  • bpo-35976: Added ARM build support to Windows build files in PCBuild.

  • bpo-35692:pathlib no longer raises when checking file and directoryexistence on drives that are not ready

  • bpo-35872: Uses the base Python executable when invoking venv in a virtualenvironment

  • bpo-35873: Prevents venv paths being inherited by child processes

  • bpo-35299: Fix sysconfig detection of the source directory and distutilshandling of pyconfig.h during PGO profiling

IDLE

  • bpo-24310: IDLE -- Document settings dialog font tab sample.

  • bpo-35833: Revise IDLE doc for control codes sent to Shell. Add a codeexample block.

  • bpo-35689: Add docstrings and unittests for colorizer.py.

Python 3.8.0 alpha 1

Release date: 2019-02-03

Security

  • bpo-35746:CVE 2019-5010: Fix a NULL pointer deref in ssl module. Thecert parser did not handle CRL distribution points with empty DP or URIcorrectly. A malicious or buggy certificate can result into segfault.Vulnerability (TALOS-2018-0758) reported by Colin Read and Nicolas Edet ofCisco.

  • bpo-34812: The-I command line option (run Python in isolatedmode) is now also copied by themultiprocessing anddistutilsmodules when spawning child processes. Previously, only-E and-s options (enabled by-I) were copied.

  • bpo-34791: The xml.sax and xml.dom.domreg no longer use environmentvariables to override parser implementations whensys.flags.ignore_environment is set by -E or -I arguments.

  • bpo-17239: The xml.sax and xml.dom.minidom parsers no longer processesexternal entities by default. External DTD and ENTITY declarations nolonger load files or create network connections.

  • bpo-34623:CVE 2018-14647: The C accelerated _elementtree module nowinitializes hash randomization salt from _Py_HashSecret instead oflibexpat's default CSPRNG.

  • bpo-34405: Updated to OpenSSL 1.1.0i for Windows builds.

  • bpo-33871: Fixed sending the part of the file inos.sendfile() onmacOS. Using thetrailers argument could cause sending more bytes fromthe input file than was specified.

  • bpo-32533: Fixed thread-safety of error handling in _ssl.

  • bpo-33136: Harden ssl module against LibreSSLCVE 2018-8970.X509_VERIFY_PARAM_set1_host() is called with an explicit namelen. A newtest ensures that NULL bytes are not allowed.

  • bpo-33001: Minimal fix to prevent buffer overrun in os.symlink on Windows

  • bpo-32981: Regexes in difflib and poplib were vulnerable to catastrophicbacktracking. These regexes formed potential DOS vectors (REDOS). Theyhave been refactored. This resolvesCVE 2018-1060 andCVE 2018-1061.Patch by Jamie Davis.

  • bpo-28414: The ssl module now allows users to perform their own IDNen/decoding when using SNI.

Core and Builtins

  • bpo-35877: Make parenthesis optional for named expressions in whilestatement. Patch by Karthikeyan Singaravelan.

  • bpo-35814: Allow same right hand side expressions in annotated assignmentsas in normal ones. In particular,x:Tuple[int,int]=1,2 (withoutparentheses on the right) is now allowed.

  • bpo-35766: Add the option to parse PEP 484 type comments in the astmodule. (Off by default.) This is merging the key functionality of thethird party fork thereof,[typed_ast](https://github.com/python/typed_ast).

  • bpo-35713: Reorganize Python initialization to get working exceptions andsys.stderr earlier.

  • bpo-33416: Add end line and end column position information to the PythonAST nodes. This is a C-level backwards incompatible change.

  • bpo-35720: Fixed a minor memory leak in pymain_parse_cmdline_impl functionin Modules/main.c

  • bpo-35634:func(**kwargs) will now raise an error whenkwargs is amapping containing multiple entries with the same key. An error wasalready raised when other keyword arguments are passed before**kwargssince Python 3.6.

  • bpo-35623: Fix a crash when sorting very long lists. Patch by StephanHohe.

  • bpo-35214: clang Memory Sanitizer build instrumentation was added to workaround false positives from posix, socket, time, test_io, andtest_faulthandler.

  • bpo-35560: Fix an assertion error informat() in debug build forfloating-point formatting with "n" format, zero padding and small width.Release build is not impacted. Patch by Karthikeyan Singaravelan.

  • bpo-35552: Format characters%s and%V inPyUnicode_FromFormat() and%s inPyBytes_FromFormat()no longer read memory past the limit ifprecision is specified.

  • bpo-35504: Fix segfaults andSystemErrors when deleting certainattributes. Patch by Zackery Spytz.

  • bpo-35504: Fixed a SystemError when delete the characters_writtenattribute of an OSError.

  • bpo-35494: Improved syntax error messages for unbalanced parentheses inf-string.

  • bpo-35444: Fixed error handling in pickling methods when fail to look upbuiltin "getattr". Sped up pickling iterators.

  • bpo-35436: Fix various issues with memory allocation error handling.Patch by Zackery Spytz.

  • bpo-35423: Separate the signal handling trigger in the eval loop from the"pending calls" machinery. There is no semantic change and the differencein performance is insignificant.

  • bpo-35357: Internal attributes' names of unittest.mock._Call andunittest.mock.MagicProxy (name, parent & from_kall) are now prefixed with_mock_ in order to prevent clashes with widely used object attributes.Fixed minor typo in test function name.

  • bpo-35372: Fixed the code page decoder for input longer than 2 GiBcontaining undecodable bytes.

  • bpo-35336: Fix PYTHONCOERCECLOCALE=1 environment variable: only coerce theC locale if the LC_CTYPE locale is "C".

  • bpo-31241: Thelineno andcol_offset attributes of AST nodes for listcomprehensions, generator expressions and tuples are now point to theopening parenthesis or square brace. For tuples without parenthesis theypoint to the position of the first item.

  • bpo-33954: Forstr.format(),float.__format__() andcomplex.__format__() methods for non-ASCII decimal point when usingthe "n" formatter.

  • bpo-35269: Fix a possible segfault involving a newly created coroutine.Patch by Zackery Spytz.

  • bpo-35224: ImplementPEP 572 (assignment expressions). Patch by EmilyMorehouse.

  • bpo-32492: Speed upnamedtuple() attribute access by 1.6x using a Cfast-path for the name descriptors. Patch by Pablo Galindo.

  • bpo-35214: Fixed an out of bounds memory access when parsing a truncatedunicode escape sequence at the end of a string such as'\N'. It wouldread one byte beyond the end of the memory allocation.

  • bpo-35214: The interpreter and extension modules have had annotationsadded so that they work properly under clang's Memory Sanitizer. A newconfigure flag --with-memory-sanitizer has been added to make test buildsof this nature easier to perform.

  • bpo-35193: Fix an off by one error in the bytecode peephole optimizerwhere it could read bytes beyond the end of bounds of an array whenremoving unreachable code. This bug was present in every release of Python3.6 and 3.7 until now.

  • bpo-35169: Improved error messages for forbidden assignments.

  • bpo-34022: Fix handling of hash-based bytecode files inzipimport.Patch by Elvis Pranskevichus.

  • bpo-28401: Debug builds will no longer to attempt to import extensionmodules built for the ABI as they were never compatible to begin with.Patch by Stefano Rivera.

  • bpo-29341: Clarify in the docstrings ofos methods that path-likeobjects are also accepted as input parameters.

  • bpo-35050:socket: Fix off-by-one bug in length check forAF_ALG name and type.

  • bpo-29743: RaiseValueError instead ofOverflowError in caseof a negative_length_ in actypes.Array subclass. AlsoraiseTypeError instead ofAttributeError for non-integer_length_. Original patch by Oren Milman.

  • bpo-16806: Fixlineno andcol_offset for multi-line string tokens.

  • bpo-35029:SyntaxWarning raised as an exception at code generationtime will be now replaced with aSyntaxError for better errorreporting.

  • bpo-34983: Exposesymtable.Symbol.is_nonlocal() in the symtablemodule. Patch by Pablo Galindo.

  • bpo-34974:bytes andbytearray constructors no longerconvert unexpected exceptions (e.g.MemoryError andKeyboardInterrupt) toTypeError.

  • bpo-34939: Allow annotated names in module namespace that are declaredglobal before the annotation happens. Patch by Pablo Galindo.

  • bpo-34973: Fixed crash inbytes() when thelist argument ismutated while it is iterated.

  • bpo-34876: Thelineno andcol_offset attributes of the AST fordecorated function and class refer now to the position of thecorrespondingdef,asyncdef andclass instead of the positionof the first decorator. This leads to more correct line reporting intracing. This is the only case when the position of child AST nodes canprecede the position of the parent AST node.

  • bpo-34879: Fix a possible null pointer dereference in bytesobject.c.Patch by Zackery Spytz.

  • bpo-34784: Fix the implementation of PyStructSequence_NewType in order tocreate heap allocated StructSequences.

  • bpo-32912: ASyntaxWarning is now emitted instead of aDeprecationWarning for invalid escape sequences in string and bytesliterals.

  • bpo-34854: Fixed a crash in compiling string annotations containing alambda with a keyword-only argument that doesn't have a default value.

  • bpo-34850: The compiler now produces aSyntaxWarning when identitychecks (is andisnot) are used with certain types of literals(e.g. strings, ints). These can often work by accident in CPython, butare not guaranteed by the language spec. The warning advises users to useequality tests (== and!=) instead.

  • bpo-34824: Fix a possible null pointer dereference in Modules/_ssl.c.Patch by Zackery Spytz.

  • bpo-30156: The C functionproperty_descr_get() uses a "cached" tupleto optimize function calls. But this tuple can be discovered in debug modewithsys.getobjects(). Remove the optimization, it's not reallyworth it and it causes 3 different crashes last years.

  • bpo-34762: Fix contextvars C API to use PyObject* pointer types.

  • bpo-34751: The hash function for tuples is now based on xxHash which givesbetter collision results on (formerly) pathological cases. Additionally,on 64-bit systems it improves tuple hashes in general. Patch by JeroenDemeyer with substantial contributions by Tim Peters.

  • bpo-34735: Fix a memory leak in Modules/timemodule.c. Patch by ZackerySpytz.

  • bpo-34683: Fixed a bug where some SyntaxError error pointed to locationsthat were off-by-one.

  • bpo-34651: Only allow the main interpreter to fork. The avoids thepossibility of affecting the main interpreter, which is critical tooperation of the runtime.

  • bpo-34653: Remove unused function PyParser_SimpleParseStringFilename.

  • bpo-32236: Warn that line buffering is not supported ifopen() iscalled with binary mode andbuffering=1.

  • bpo-34641: Further restrict the syntax of the left-hand side of keywordarguments in function calls. In particular,f((keyword)=arg) is nowdisallowed.

  • bpo-34637: Make thestart argument tosum() visible as a keywordargument.

  • bpo-1621: Do not assume signed integer overflow behavior (C undefinedbehavior) when performing set hash table resizing.

  • bpo-34588: Fix an off-by-one in the recursive call pruning feature oftraceback formatting.

  • bpo-34485: On Windows, the LC_CTYPE is now set to the user preferredlocale at startup. Previously, the LC_CTYPE locale was "C" at startup, butchanged when calling setlocale(LC_CTYPE, "") or setlocale(LC_ALL, "").

  • bpo-34485: Standard streams like sys.stdout now use the "surrogateescape"error handler, instead of "strict", on the POSIX locale (when the C localeis not coerced and the UTF-8 Mode is disabled).

  • bpo-34485: Fix the error handler of standard streams like sys.stdout:PYTHONIOENCODING=":" is now ignored instead of setting the error handlerto "strict".

  • bpo-34485: Python now gets the locale encoding with C code to initializethe encoding of standard streams like sys.stdout. Moreover, the encodingis now initialized to the Python codec name to get a normalized encodingname and to ensure that the codec is loaded. The change avoids importing_bootlocale and _locale modules at startup by default.

  • bpo-34527: On FreeBSD, Py_DecodeLocale() and Py_EncodeLocale() now alsoforces the ASCII encoding if the LC_CTYPE locale is "POSIX", not only ifthe LC_CTYPE locale is "C".

  • bpo-34527: The UTF-8 Mode is now also enabled by the "POSIX" locale, notonly by the "C" locale.

  • bpo-34403: On HP-UX with C or POSIX locale, sys.getfilesystemencoding()now returns "ascii" instead of "roman8" (when the UTF-8 Mode is disabledand the C locale is not coerced).

  • bpo-34523: The Python filesystem encoding is now read earlier during thePython initialization.

  • bpo-12458: Tracebacks show now correct line number for subexpressions inmultiline expressions. Tracebacks show now the line number of the firstline for multiline expressions instead of the line number of the lastsubexpression.

  • bpo-34408: Prevent a null pointer dereference and resource leakage inPyInterpreterState_New().

  • bpo-34400: Fix undefined behavior in parsetok.c. Patch by Zackery Spytz.

  • bpo-33073: Added as_integer_ratio to ints to make them more interoperablewith floats.

  • bpo-34377: Update valgrind suppression list to use_PyObject_Free/_PyObject_Realloc instead ofPyObject_Free/PyObject_Realloc.

  • bpo-34353: Added the "socket" option in thestat.filemode() Pythonimplementation to match the C implementation.

  • bpo-34320: Fixdict(od) didn't copy iteration order of OrderedDict.

  • bpo-34113: Fixed crash on debug builds when opcode stack was adjusted withnegative numbers. Patch by Constantin Petrisor.

  • bpo-34100: Compiler now merges constants in tuples and frozensetsrecursively. Code attributes likeco_names are merged too.

  • bpo-34151: Performance of list concatenation, repetition and slicingoperations is slightly improved. Patch by Sergey Fedoseev.

  • bpo-34170: -X dev: it is now possible to override the memory allocatorusing PYTHONMALLOC even if the developer mode is enabled.

  • bpo-33237: ImprovedAttributeError message for partiallyinitialized module.

  • bpo-34149: Fix min and max functions to get default behavior when key isNone.

  • bpo-34125: Profiling of unbound built-in methods now works when**kwargs is given.

  • bpo-34141: Optimized pickling atomic types (None, bool, int, float, bytes,str).

  • bpo-34126: Fix crashes when profiling certain invalid calls of unboundmethods. Patch by Jeroen Demeyer.

  • bpo-24618: Fixed reading invalid memory when create the code object withtoo small varnames tuple or too large argument counts.

  • bpo-34068: Inio.IOBase.close(), ensure that theclosed attribute is not set with a live exception.Patch by Zackery Spytz and Serhiy Storchaka.

  • bpo-34087: Fix buffer overflow while converting unicode to numeric values.

  • bpo-34080: Fixed a memory leak in the compiler when it raised someuncommon errors during tokenizing.

  • bpo-34066: Disabled interruption by Ctrl-C between callingopen() andentering awith block inwithopen().

  • bpo-34042: Fix dict.copy() to maintain correct total refcount (as reportedby sys.gettotalrefcount()).

  • bpo-33418: Fix potential memory leak in function object when it createsreference cycle.

  • bpo-33985: Implement contextvars.ContextVar.name attribute.

  • bpo-33956: Update vendored Expat library copy to version 2.2.5.

  • bpo-24596: Decref the module object inPyRun_SimpleFileExFlags()before callingPyErr_Print(). Patch by Zackery Spytz.

  • bpo-33451: Close directly executed pyc files before callingPyEval_EvalCode().

  • bpo-1617161: The hash ofBuiltinMethodType instances (methods ofbuilt-in classes) now depends on the hash of the identity of__self__instead of its value. The hash and equality ofModuleType andMethodWrapperType instances (methods of user-defined classes andsome methods of built-in classes likestr.__add__) now depend on thehash and equality of the identity of__self__ instead of its value.MethodWrapperType instances no longer support ordering.

  • bpo-33824: Fix "LC_ALL=C python3.7 -V": reset properly the command lineparser when the encoding changes after reading the Python configuration.

  • bpo-33803: Fix a crash in hamt.c caused by enabling GC tracking for anobject that hadn't all of its fields set to NULL.

  • bpo-33738: Seven macro incompatibilities with the Limited API were fixed,and the macrosPyIter_Check(),PyIndex_Check() andPyExceptionClass_Name() were added as functions. A script forautomatic macro checks was added.

  • bpo-33786: Fix asynchronous generators to handle GeneratorExit in athrow()correctly

  • bpo-30167:PyRun_SimpleFileExFlags removes__cached__ from modulein addition to__file__.

  • bpo-33706: Fix a crash in Python initialization when parsing the commandline options. Thanks Christoph Gohlke for the bug report and the fix!

  • bpo-33597: ReducePyGC_Head size from 3 words to 2 words.

  • bpo-30654: Fixed reset of the SIGINT handler to SIG_DFL on interpretershutdown even when there was a custom handler set previously. Patch byPhilipp Kerling.

  • bpo-33622: Fixed a leak when the garbage collector fails to add an objectwith the__del__ method or referenced by it into thegc.garbage list.PyGC_Collect() can now be called when anexception is set and preserves it.

  • bpo-33462: Make dict and dict views reversible. Patch by Rémi Lapeyre.

  • bpo-23722: ARuntimeError is now raised when the custom metaclassdoesn't provide the__classcell__ entry in the namespace passed totype.__new__. ADeprecationWarning was emitted in Python3.6--3.7.

  • bpo-33499: AddPYTHONPYCACHEPREFIX environment variable and-Xpycache_prefix command-line option to set an alternateroot directory for writing module bytecode cache files.

  • bpo-25711: Thezipimport module has been rewritten in pure Python.

  • bpo-33509: Fix module_globals parameter of warnings.warn_explicit(): don'tcrash if module_globals is not a dict.

  • bpo-31849: Fix signed/unsigned comparison warning in pyhash.c.

  • bpo-33475: Fixed miscellaneous bugs in converting annotations to stringsand optimized parentheses in the string representation.

  • bpo-20104: Added support for thesetpgroup,resetids,setsigmask,setsigdef andscheduler parameters ofposix_spawn. Patch by Pablo Galindo.

  • bpo-33391: Fix a leak in set_symmetric_difference().

  • bpo-33363: Raise a SyntaxError forasyncwith andasyncforstatements outside of async functions.

  • bpo-28055: Fix unaligned accesses in siphash24(). Patch by Rolf Eike Beer.

  • bpo-33128: Fix a bug that causes PathFinder to appear twice onsys.meta_path. Patch by Pablo Galindo Salgado.

  • bpo-33331: Modules imported last are now cleared first at interpretershutdown.

  • bpo-33312: Fixed clang ubsan (undefined behavior sanitizer) warnings indictobject.c by adjusting how the internal struct _dictkeysobject sharedkeys structure is declared.

  • bpo-33305: Improved syntax error messages for invalid numerical literals.

  • bpo-33306: Improved syntax error messages for unbalanced parentheses.

  • bpo-33234: The list constructor will pre-size and not over-allocate whenthe input length is known.

  • bpo-33270: Intern the names for all anonymous code objects. Patch byZackery Spytz.

  • bpo-30455: The C and Python code and the documentation related to tokensare now generated from a single source fileGrammar/Tokens.

  • bpo-33176: Add atoreadonly() method to memoryviews.

  • bpo-33231: Fix potential memory leak innormalizestring().

  • bpo-33205: Change dict growth function fromround_up_to_power_2(used*2+hashtable_size/2) toround_up_to_power_2(used*3). Previously, dict is shrinked only whenused==0. Now dict has more chance to be shrinked.

  • bpo-29922: Improved error messages in 'async with' when__aenter__()or__aexit__() return non-awaitable object.

  • bpo-33199: Fixma_version_tag in dict implementation is uninitializedwhen copying from key-sharing dict.

  • bpo-33053: When using the -m switch, sys.path[0] is now explicitlyexpanded as thestarting working directory, rather than being left asthe empty path (which allows imports from the current working directory atthe time of the import)

  • bpo-33138: Changed standard error message for non-pickleable andnon-copyable types. It now says "cannot pickle" instead of "can't pickle"or "cannot serialize".

  • bpo-33018: Improve consistency of errors raised byissubclass() whencalled with a non-class and an abstract base class as the first and secondarguments, respectively. Patch by Josh Bronson.

  • bpo-33083:math.factorial no longer accepts arguments that are notint-like. Patch by Pablo Galindo.

  • bpo-33041: Added new opcodeEND_ASYNC_FOR and fixes thefollowing issues:

    • Setting globalStopAsyncIteration no longer breaksasyncforloops.

    • Jumping into anasyncfor loop is now disabled.

    • Jumping out of anasyncfor loop no longer corrupts the stack.

  • bpo-25750: Fix rare Python crash due to bad refcounting intype_getattro() if a descriptor deletes itself from the class. Patchby Jeroen Demeyer.

  • bpo-33041: Fixed bytecode generation for "async for" with a complextarget. A StopAsyncIteration raised on assigning or unpacking will be nowpropagated instead of stopping the iteration.

  • bpo-33026: Fixed jumping out of "with" block by setting f_lineno.

  • bpo-33005: Fix a crash on fork when using a custom memory allocator (ex:using PYTHONMALLOC env var). _PyGILState_Reinit() and_PyInterpreterState_Enable() now use the default RAW memory allocator toallocate a new interpreters mutex on fork.

  • bpo-32911: Due to unexpected compatibility issues discovered duringdownstream beta testing, revertedbpo-29463.docstring field isremoved from Module, ClassDef, FunctionDef, and AsyncFunctionDef ast nodeswhich was added in 3.7a1. Docstring expression is restored as a firststatement in their body. Based on patch by Inada Naoki.

  • bpo-17288: Prevent jumps from 'return' and 'exception' trace events.

  • bpo-32946: Importing names from already imported module with "from ...import ..." is now 30% faster if the module is not a package.

  • bpo-32932: Make error message more revealing when there are non-strobjects in__all__.

  • bpo-32925: Optimized iterating and containing test for literal listsconsisting of non-constants:xin[a,b] andforxin[a,b]. Thecase of all constant elements already was optimized.

  • bpo-32889: Update Valgrind suppression list to account for the rename ofPy_ADDRESS_IN_RANG toaddress_in_range.

  • bpo-32836: Don't use temporary variables in cases of list/dict/setcomprehensions

  • bpo-31356: Remove the new API added inbpo-31356 (gc.ensure_disabled()context manager).

  • bpo-32305: For namespace packages, ensure that both__file__ and__spec__.origin are set to None.

  • bpo-32303: Make sure__spec__.loader matches__loader__ fornamespace packages.

  • bpo-32711: Fix the warning messages for Python/ast_unparse.c. Patch byStéphane Wirtel

  • bpo-32583: Fix possible crashing in builtin Unicode decoders caused bywrite out-of-bound errors when using customized decode error handlers.

  • bpo-32489: Acontinue statement is now allowed in thefinally clause.

  • bpo-17611: Simplified the interpreter loop by moving the logic ofunrolling the stack of blocks into the compiler. The compiler emits nowexplicit instructions for adjusting the stack of values and calling thecleaning up code forbreak,continue andreturn.

    Removed opcodesBREAK_LOOP,CONTINUE_LOOP,SETUP_LOOP andSETUP_EXCEPT. Added new opcodesROT_FOUR,BEGIN_FINALLY andCALL_FINALLY andPOP_FINALLY. Changed the behavior ofEND_FINALLY andWITH_CLEANUP_START.

  • bpo-32285: New function unicodedata.is_normalized, which can check whethera string is in a specific normal form.

  • bpo-10544: Yield expressions are now disallowed in comprehensions andgenerator expressions except the expression for the outermost iterable.

  • bpo-32117: Iterable unpacking is now allowed without parentheses in yieldand return statements, e.g.yield1,2,3,*rest. Thanks to DavidCuthbert for the change and Jordan Chapman for added tests.

  • bpo-31902: Fix thecol_offset attribute for ast nodesast.AsyncFor,ast.AsyncFunctionDef, andast.AsyncWith.Previously,col_offset pointed to the keyword afterasync.

  • bpo-25862: Fix assertion failures in thetell() method ofio.TextIOWrapper. Patch by Zackery Spytz.

  • bpo-21983: Fix a crash inctypes.cast() in case the type argument is actypes structured data type. Patch by Eryk Sun and Oren Milman.

  • bpo-31577: Fix a crash inos.utime() in case of a bad ns argument.Patch by Oren Milman.

  • bpo-29832: Remove references to 'getsockaddrarg' from various socket errormessages. Patch by Oren Milman.

Library

  • bpo-35845: Add 'order' parameter to memoryview.tobytes().

  • bpo-35864: The _asdict() method for collections.namedtuple now returns aregular dict instead of an OrderedDict.

  • bpo-35537: An ExitStack is now used internally within subprocess.Popen toclean up pipe file handles. No behavior change in normal operation. But ifclosing one handle were ever to cause an exception, the others will now beclosed instead of leaked. (patch by Giampaolo Rodola)

  • bpo-35847: RISC-V needed the CTYPES_PASS_BY_REF_HACK. Fixes ctypesStructure test_pass_by_value.

  • bpo-35813: Shared memory submodule added to multiprocessing to avoid needfor serialization between processes

  • bpo-35780: Fix lru_cache() errors arising in recursive, reentrant, ormulti-threaded code. These errors could result in orphan links and in thecache being trapped in a state with fewer than the specified maximumnumber of links. Fix handling of negative maxsize which should have beentreated as zero. Fix errors in toggling the "full" status flag. Fixmisordering of links when errors are encountered. Sync-up the C code andpure Python code for the space saving path in functions with a singlepositional argument. In this common case, the space overhead of an lrucache entry is reduced by almost half. Fix counting of cache misses. Inerror cases, the miss count was out of sync with the actual number oftimes the underlying user function was called.

  • bpo-35537:os.posix_spawn() andos.posix_spawnp() now have asetsid parameter.

  • bpo-23846:asyncio.ProactorEventLoop now catches and logs senderrors when the self-pipe is full.

  • bpo-34323:asyncio: EnhanceIocpProactor.close() log: wait 1second before the first log, then log every second. Log also the number ofseconds sinceclose() was called.

  • bpo-35674: Add a newos.posix_spawnp() function. Patch by JoannahNanjekye.

  • bpo-35733:ast.Constant(boolean) no longer an instance ofast.Num. Patch by Anthony Sottile.

  • bpo-35726: QueueHandler.prepare() now makes a copy of the record beforemodifying and enqueueing it, to avoid affecting other handlers in thechain.

  • bpo-35719: Sped up multi-argumentmath functions atan2(),copysign(), remainder() and hypot() by 1.3--2.5 times.

  • bpo-35717: Fix KeyError exception raised when using enums and compile.Patch contributed by Rémi Lapeyre.

  • bpo-35699: Fixed detection of Visual Studio Build Tools 2017 in distutils

  • bpo-32710: Fix memory leaks in asyncio ProactorEventLoop on overlappedoperation failure.

  • bpo-35702: Thetime.CLOCK_UPTIME_RAW constant is now availablefor macOS 10.12.

  • bpo-32710: Fix a memory leak in asyncio in the ProactorEventLoop whenReadFile() orWSASend() overlapped operation fail immediately:release the internal buffer.

  • bpo-35682: Fixasyncio.ProactorEventLoop.sendfile(): don't attempt toset the result of an internal future if it's already done.

  • bpo-35283: Add a deprecated warning for thethreading.Thread.isAlive() method. Patch by Donghee Na.

  • bpo-35664: Improve operator.itemgetter() performance by 33% with optimizedargument handling and with adding a fast path for the common case of asingle non-negative integer index into a tuple (which is the typical usecase in the standard library).

  • bpo-35643: Fixed a SyntaxWarning: invalid escape sequence inModules/_sha3/cleanup.py. Patch by Mickaël Schoentgen.

  • bpo-35619: Improved support of custom data descriptors inhelp() andpydoc.

  • bpo-28503: Thecrypt module now internally uses thecrypt_r()library function instead ofcrypt() when available.

  • bpo-35614: Fixed help() on metaclasses. Patch by Sanyam Khurana.

  • bpo-35568: Exposeraise(signum) asraise_signal

  • bpo-35588: The floor division and modulo operations and thedivmod()function onfractions.Fraction types are 2--4x faster. Patch byStefan Behnel.

  • bpo-35585: Speed-up building enums by value, e.g. http.HTTPStatus(200).

  • bpo-30561: random.gammavariate(1.0, beta) now computes the same result asrandom.expovariate(1.0 / beta). This synchronizes the two algorithms andeliminates some idiosyncrasies in the old implementation. It does howeverproduce a difference stream of random variables than it used to.

  • bpo-35537: Thesubprocess module can now use theos.posix_spawn() function in some cases for better performance.

  • bpo-35526: Delaying the 'joke' of barry_as_FLUFL.mandatory to Pythonversion 4.0

  • bpo-35523: Removectypes callback workaround: no longer create acallback at startup. Avoid SELinux alert onimportctypes andimportuuid.

  • bpo-31784:uuid.uuid1() now callstime.time_ns() rather thanint(time.time()*1e9).

  • bpo-35513:TextTestRunner ofunittest.runner now usestime.perf_counter() rather thantime.time() to measure the execution time of a test:time.time() can go backwards, whereastime.perf_counter() ismonotonic.

  • bpo-35502: Fixed reference leaks inxml.etree.ElementTree.TreeBuilder in case of unfinished buildingof the tree (in particular when an error was raised during parsing XML).

  • bpo-35348: Makeplatform.architecture() parsing offile commandoutput more reliable: add the-b option to thefile command toomit the filename, force the usage of the C locale, and search also the"shared object" pattern.

  • bpo-35491:multiprocessing: AddPool.__repr__() and enhanceBaseProcess.__repr__() (add pid and parent pid) to ease debugging.Pool state constant values are now strings instead of integers, forexampleRUN value becomes'RUN' instead of0.

  • bpo-35477:multiprocessing.Pool.__enter__() now fails if the pool isnot running:withpool: fails if used more than once.

  • bpo-31446: Copy command line that was passed to CreateProcessW since thisfunction can change the content of the input buffer.

  • bpo-35471: Python 2.4 dropped MacOS 9 support. The macpath module wasdeprecated in Python 3.7. The module is now removed.

  • bpo-23057: Unblock Proactor event loop when keyboard interrupt is receivedon Windows

  • bpo-35052: Fix xml.dom.minidom cloneNode() on a document with an entity:pass the correct arguments to the user data handler of an entity.

  • bpo-20239: Allow repeated assignment deletion ofunittest.mock.Mock attributes. Patch by Pablo Galindo.

  • bpo-17185: Set__signature__ on mock forinspect to getsignature. Patch by Karthikeyan Singaravelan.

  • bpo-35445: Memory errors during creating posix.environ no longer ignored.

  • bpo-35415: Validate fileno= argument to socket.socket().

  • bpo-35424:multiprocessing.Pool destructor now emitsResourceWarning if the pool is still running.

  • bpo-35330: When aMock instance was used to wrap an object, ifside_effect is used in one of the mocks of it methods, don't call theoriginal implementation and return the result of using the side effect thesame way that it is done with return_value.

  • bpo-35346: Drop Mac OS 9 and Rhapsody support from theplatformmodule. Rhapsody last release was in 2000. Mac OS 9 last release was in2001.

  • bpo-10496:check_environ() ofdistutils.utilsnow catchesKeyError on callingpwd.getpwuid(): don't createtheHOME environment variable in this case.

  • bpo-10496:posixpath.expanduser() now returns the inputpathunchanged if theHOME environment variable is not set and the currentuser has no home directory (if the current user identifier doesn't existin the password database). This change fix thesite module if thecurrent user doesn't exist in the password database (if the user has nohome directory).

  • bpo-35389:platform.libc_ver() now usesos.confstr('CS_GNU_LIBC_VERSION') if available and theexecutableparameter is not set.

  • bpo-35394: Add empty slots to asyncio abstract protocols.

  • bpo-35310: Fix a bug inselect.select() where, in some cases, thefile descriptor sequences were returned unmodified after a signalinterruption, even though the file descriptors might not be ready yet.select.select() will now always return empty lists if a timeout hasoccurred. Patch by Oran Avraham.

  • bpo-35380: Enable TCP_NODELAY on Windows for proactor asyncio event loop.

  • bpo-35341: Add generic version ofcollections.OrderedDict to thetyping module. Patch by Ismo Toijala.

  • bpo-35371: Fixed possible crash inos.utime() on Windows when passincorrect arguments.

  • bpo-35346:platform.uname() now redirectsstderr toos.devnull when running external programs likecmd/cver.

  • bpo-35066: Previously, calling the strftime() method on a datetime objectwith a trailing '%' in the format string would result in an exception.However, this only occurred when the datetime C module was being used; thepython implementation did not match this behavior. Datetime is now PEP-399compliant, and will not throw an exception on a trailing '%'.

  • bpo-35345: The functionplatform.popen has been removed, it wasdeprecated since Python 3.3: useos.popen() instead.

  • bpo-35344: On macOS,platform.platform() now usesplatform.mac_ver(), if it returns a non-empty release string, to getthe macOS version rather than the darwin version.

  • bpo-35312: Makelib2to3.pgen2.parse.ParseError round-trip pickle-able.Patch by Anthony Sottile.

  • bpo-35308: Fix regression inwebbrowser where default browsers may bepreferred over browsers in theBROWSER environment variable.

  • bpo-24746: Avoid stripping trailing whitespace in doctest fancy diff.Original patch by R. David Murray & Jairo Trad. Enhanced by SanyamKhurana.

  • bpo-28604:locale.localeconv() now sets temporarily theLC_CTYPElocale to theLC_MONETARY locale if the two locales are different andmonetary strings are non-ASCII. This temporary change affects otherthreads.

  • bpo-35277: Update ensurepip to install pip 18.1 and setuptools 40.6.2.

  • bpo-24209: Adds IPv6 support when invoking http.server directly.

  • bpo-35226: Recursively check arguments when testing for equality ofunittest.mock.call objects and add note that tracking ofparameters used to create ancestors of mocks inmock_calls is notpossible.

  • bpo-29564: The warnings module now suggests to enable tracemalloc if thesource is specified, the tracemalloc module is available, but tracemallocis not tracing memory allocations.

  • bpo-35189: Modify the following fnctl function to retry if interrupted bya signal (EINTR): flock, lockf, fnctl

  • bpo-30064: Use add_done_callback() in sock_* asyncio API to unsubscribereader/writer early on calcellation.

  • bpo-35186: Removed the "built with" comment added whensetup.pyuploadis used with eitherbdist_rpm orbdist_dumb.

  • bpo-35152: Allow sending more than 2 GB at once on a multiprocessingconnection on non-Windows systems.

  • bpo-35062: Fix incorrect parsing ofio.IncrementalNewlineDecoder'stranslate argument.

  • bpo-35065: RemoveStreamReaderProtocol._untrack_reader. The call to_untrack_reader is currently performed too soon, causing the protocolto forget about the reader beforeconnection_lost can run and feed theEOF to the reader.

  • bpo-34160: ElementTree and minidom now preserve the attribute orderspecified by the user.

  • bpo-35079: Improve difflib.SequenceManager.get_matching_blocks doc byadding 'non-overlapping' and changing '!=' to '<'.

  • bpo-33710: Deprecatedl*gettext() functions and methods in thegettext module. They return encoded bytes instead of Unicodestrings and are artifacts from Python 2 times. Also deprecated functionsand methods related to setting the charset forl*gettext() functionsand methods.

  • bpo-35017:socketserver.BaseServer.serve_forever() now exitsimmediately if it'sshutdown() method iscalled while it is polling for new events.

  • bpo-35024:importlib no longer logswrote<bytecodepath>redundantly after(created|couldnotcreate)<bytecodepath> isalready logged. Patch by Quentin Agren.

  • bpo-35047:unittest.mock now includes mock calls in exception messagesifassert_not_called,assert_called_once, orassert_called_once_with fails. Patch by Petter Strandmark.

  • bpo-31047: Fixntpath.abspath regression where it didn't remove atrailing separator on Windows. Patch by Tim Graham.

  • bpo-35053: tracemalloc now tries to update the traceback when an object isreused from a "free list" (optimization for faster object creation, usedby the builtin list type for example).

  • bpo-31553: Add the --json-lines option to json.tool. Patch by hongweipeng.

  • bpo-34794: Fixed a leak in Tkinter when pass the Python wrapper aroundTcl_Obj back to Tcl/Tk.

  • bpo-34909: Enum: fix grandchildren subclassing when parent mixed withconcrete data types.

  • bpo-35022:unittest.mock.MagicMock now supports the__fspath__ method (fromos.PathLike).

  • bpo-35008: Fixed references leaks when call the__setstate__() methodofxml.etree.ElementTree.Element in the C implementation foralready initialized element.

  • bpo-23420: Verify the value for the parameter '-s' of the cProfile CLI.Patch by Robert Kuska

  • bpo-33947: dataclasses now handle recursive reprs without raisingRecursionError.

  • bpo-34890: Makeinspect.iscoroutinefunction(),inspect.isgeneratorfunction() andinspect.isasyncgenfunction()work withfunctools.partial(). Patch by Pablo Galindo.

  • bpo-34521: Usesocket.CMSG_SPACE() to calculate ancillary data sizeinstead ofsocket.CMSG_LEN() inmultiprocessing.reduction.recvfds() asRFC 3542 requires the useof the former for portable applications.

  • bpo-31522: Themailbox.mbox.get_string functionfrom_ parameter cannow successfully be set to a non-default value.

  • bpo-34970: Protect tasks weak set manipulation inasyncio.all_tasks()

  • bpo-34969: gzip: Add --fast, --best on the gzip CLI, these parameters willbe used for the fast compression method (quick) or the best methodcompress (slower, but smaller file). Also, change the default compressionlevel to 6 (tradeoff).

  • bpo-16965: The 2to3execfile fixer now opens the file with mode'rb'. Patch by Zackery Spytz.

  • bpo-34966:pydoc now supports aliases not only to methods definedin the end class, but also to inherited methods. The docstring is notduplicated for aliases.

  • bpo-34926:mimetypes.MimeTypes.guess_type() now acceptspath-like object in addition to url strings. Patch by MayankAsthana.

  • bpo-23831: Addmoveto() method to thetkinter.Canvas widget. Patchby Juliette Monsel.

  • bpo-34941: Methodsfind(),findtext() andfindall() of theElement class in thexml.etree.ElementTree module are now ableto find children which are instances ofElement subclasses.

  • bpo-32680:smtplib.SMTP objects now always have asockattribute present

  • bpo-34769: Fix for async generators not finalizing when event loop is indebug mode and garbage collector runs in another thread.

  • bpo-34936: FixTclError intkinter.Spinbox.selection_element().Patch by Juliette Monsel.

  • bpo-34829: Add methodsselection_from,selection_range,selection_present andselection_to to thetkinter.Spinbox forconsistency with thetkinter.Entry widget. Patch by Juliette Monsel.

  • bpo-34911: Addedsecure_protocols argument tohttp.cookiejar.DefaultCookiePolicy to allow for tweaking of protocolsand also to add support by default forwss, the secure websocketprotocol.

  • bpo-34922: Fixed integer overflow in thedigest() andhexdigest() methods for the SHAKE algorithm in thehashlib module.

  • bpo-34925: 25% speedup in argument parsing for the functions in the bisectmodule.

  • bpo-34900: Fixedunittest.TestCase.debug() when used to call testmethods with subtests. Patch by Bruno Oliveira.

  • bpo-34844: logging.Formatter enhancement - Ensure styles and fmt matchesin logging.Formatter - Added validate method in each format style class:StrFormatStyle, PercentStyle, StringTemplateStyle. - This method is calledin the constructor of logging.Formatter class - Also re-raise the KeyErrorin the format method of each style class, so it would a bit clear thatit's an error with the invalid format fields.

  • bpo-34897: Adjust test.support.missing_compiler_executable check so that anominal command name of "" is ignored. Patch by Michael Felt.

  • bpo-34871: Fix inspect module pollutedsys.modules when parsing__text_signature__ of callable.

  • bpo-34898: Addmtime argument togzip.compress for reproducibleoutput. Patch by Guo Ci Teo.

  • bpo-28441: On Cygwin and MinGW, ensure thatsys.executable alwaysincludes the full filename in the path, including the.exe suffix(unless it is a symbolic link).

  • bpo-34866: Addingmax_num_fields tocgi.FieldStorage to make DOSattacks harder by limiting the number ofMiniFieldStorage objectscreated byFieldStorage.

  • bpo-34711: http.server ensures it reports HTTPStatus.NOT_FOUND when thelocal path ends with "/" and is not a directory, even if the underlying OS(e.g. AIX) accepts such paths as a valid file reference. Patch by MichaelFelt.

  • bpo-34872: Fix self-cancellation in C implementation of asyncio.Task

  • bpo-34849: Don't log waiting forselector.select in asyncio loopiteration. The waiting is pretty normal for any asyncio program, loggingits time just adds a noise to logs without any useful informationprovided.

  • bpo-34022: TheSOURCE_DATE_EPOCH environment variable no longeroverrides the value of theinvalidation_mode argument topy_compile.compile(), and determines its default value instead.

  • bpo-34819: Use a monotonic clock to compute timeouts inExecutor.map() andas_completed(), in order to preventtimeouts from deviating when the system clock is adjusted.

  • bpo-34758: Add .wasm -> application/wasm to list of recognized file typesand content type headers

  • bpo-34789:xml.sax.make_parser() now accepts any iterable as itsparser_list argument. Patch by Andrés Delfino.

  • bpo-34334: InQueueHandler, clearexc_text fromLogRecord to prevent traceback from being written twice.

  • bpo-34687: On Windows, asyncio now uses ProactorEventLoop, instead ofSelectorEventLoop, by default.

  • bpo-5950: Support reading zip files with archive comments inzipimport.

  • bpo-32892: The parser now represents all constants asast.Constant instead of using specific constant AST types(Num,Str,Bytes,NameConstant andEllipsis). Theseclasses are considered deprecated and will be removed in future Pythonversions.

  • bpo-34728: Add deprecation warning whenloop is used in methods:asyncio.sleep,asyncio.wait andasyncio.wait_for.

  • bpo-34738: ZIP files created bydistutils will now include entries fordirectories.

  • bpo-34659: Add an optionalinitial argument to itertools.accumulate().

  • bpo-29577: Support multiple mixin classes when creating Enums.

  • bpo-34670: Add SSLContext.post_handshake_auth andSSLSocket.verify_client_post_handshake for TLS 1.3's post handshakeauthentication feature.

  • bpo-32718: The Activate.ps1 script from venv works with PowerShell Core6.1 and is now available under all operating systems.

  • bpo-31177: Fix bug that prevented usingreset_mock on mock instances with deleted attributes

  • bpo-34672: Add a workaround, so the'Z'time.strftime()specifier on the musl C library can work in some cases.

  • bpo-34666: Implementasyncio.StreamWriter.awrite andasyncio.StreamWriter.aclose() coroutines. Methods are needed forproviding a consistent stream API with control flow switched on bydefault.

  • bpo-6721: Acquire the logging module's commonly used internal locks whilefork()ing to avoid deadlocks in the child process.

  • bpo-34658: Fix a rare interpreter unhandled exception state SystemErroronly seen when using subprocess with a preexec_fn while an after_parenthandler has been registered with os.register_at_fork and the fork systemcall fails.

  • bpo-34652: Ensureos.lchmod() is never defined on Linux.

  • bpo-34638: Store a weak reference to stream reader to break strongreferences loop between reader and protocol. It allows to detect andclose the socket if the stream is deleted (garbage collected) withoutclose() call.

  • bpo-34536:Enum._missing_: raiseValueError if None returned andTypeError if non-member is returned.

  • bpo-34636: Speed up re scanning of many non-matching characters for s wand d within bytes objects. (microoptimization)

  • bpo-24412: AddaddModuleCleanup() andaddClassCleanup() to unittest to support cleanupsforsetUpModule() andsetUpClass(). Patch by Lisa Roach.

  • bpo-34630: Don't log SSL certificate errors in asyncio code (connectionerror logging is skipped already).

  • bpo-32490: Prevent filename duplication insubprocess exceptionmessages. Patch by Zackery Spytz.

  • bpo-34363: dataclasses.asdict() and .astuple() now handle namedtuplescorrectly.

  • bpo-34625: Update vendorized expat library version to 2.2.6.

  • bpo-32270: The subprocess module no longer mistakenly closes redirectedfds even when they were in pass_fds when outside of the default {0, 1, 2}set.

  • bpo-34622: Create a dedicatedasyncio.CancelledError,asyncio.InvalidStateError andasyncio.TimeoutError exceptionclasses. Inherit them from corresponding exceptions fromconcurrent.futures package. Extractasyncio exceptions into aseparate file.

  • bpo-34610: Fixed iterator ofmultiprocessing.managers.DictProxy.

  • bpo-34421: Fix distutils logging for non-ASCII strings. This causedinstallation issues on Windows.

  • bpo-34604: Fix possible mojibake in the error message ofpwd.getpwnamandgrp.getgrnam using string representation because of invisiblecharacters or trailing whitespaces. Patch by William Grzybowski.

  • bpo-30977: Make uuid.UUID use__slots__ to reduce its memoryfootprint. Based on original patch by Wouter Bolsterlee.

  • bpo-34574: OrderedDict iterators are not exhausted during picklinganymore. Patch by Sergey Fedoseev.

  • bpo-8110: Refactoredsubprocess to check for Windows-specificmodules rather thansys.platform=='win32'.

  • bpo-34530:distutils.spawn.find_executable() now falls back onos.defpath if thePATH environment variable is not set.

  • bpo-34563: On Windows, fix multiprocessing.Connection for very large read:fix _winapi.PeekNamedPipe() and _winapi.ReadFile() for read larger thanINT_MAX (usually2**31-1).

  • bpo-34558: Correct typo in Lib/ctypes/_aix.py

  • bpo-34282: MoveEnum._convert toEnumMeta._convert_ and fix enummembers getting shadowed by parent attributes.

  • bpo-22872: When the queue is closed,ValueError is now raised bymultiprocessing.Queue.put() andmultiprocessing.Queue.get()instead ofAssertionError andOSError, respectively. Patchby Zackery Spytz.

  • bpo-34515: Fix parsing non-ASCII identifiers inlib2to3.pgen2.tokenize (PEP 3131).

  • bpo-13312: Avoids a possible integer underflow (undefined behavior) in thetime module's year handling code when passed a very low negative yearvalue.

  • bpo-34472: Improved compatibility for streamed files inzipfile.Previously an optional signature was not being written and certain ZIPapplications were not supported. Patch by Silas Sewell.

  • bpo-34454: Fix the .fromisoformat() methods of datetime types crashingwhen given unicode with non-UTF-8-encodable code points. Specifically,datetime.fromisoformat() now accepts surrogate unicode code points used asthe separator. Report and tests by Alexey Izbyshev, patch by Paul Ganssle.

  • bpo-6700: Fix inspect.getsourcelines for module level frames/tracebacks.Patch by Vladimir Matveev.

  • bpo-34171: Running thetrace module no longer creates thetrace.cover file.

  • bpo-34441: Fix crash when anABC-derived class with invalid__subclasses__ is passed as the second argument toissubclass().Patch by Alexey Izbyshev.

  • bpo-34427: Fix infinite loop ina.extend(a) forMutableSequencesubclasses.

  • bpo-34412: Makesignal.strsignal() work on HP-UX. Patch by MichaelOsipov.

  • bpo-20849: shutil.copytree now accepts a newdirs_exist_ok keywordargument. Patch by Josh Bronson.

  • bpo-31715: Associate.mjs file extension withapplication/javascript MIME Type.

  • bpo-34384:os.readlink() now acceptspath-like andbytes objects on Windows.

  • bpo-22602: The UTF-7 decoder now raisesUnicodeDecodeError forill-formed sequences starting with "+" (as specified in RFC 2152). Patchby Zackery Spytz.

  • bpo-2122: Themmap.flush() method now returnsNone on success, raises an exception on error under all platforms.

  • bpo-34341: Appending to the ZIP archive with the ZIP64 extension no longergrows the size of extra fields of existing entries.

  • bpo-34333: Fix %-formatting inpathlib.PurePath.with_suffix() whenformatting an error message.

  • bpo-18540: Theimaplib.IMAP4 andimaplib.IMAP4_SSLclasses now resolve to the local host IP correctly when the default valueofhost parameter ('') is used.

  • bpo-26502: Implementtraceback.FrameSummary.__len__() method topreserve compatibility with the old tuple API.

  • bpo-34318:assertRaises(),assertRaisesRegex(),assertWarns() andassertWarnsRegex() no longer success if thepassed callable is None. They no longer ignore unknown keyword argumentsin the context manager mode. A DeprecationWarning was raised in thesecases since Python 3.5.

  • bpo-9372: Deprecate__getitem__() methods ofxml.dom.pulldom.DOMEventStream,wsgiref.util.FileWrapperandfileinput.FileInput.

  • bpo-33613: Fix a race condition inmultiprocessing.semaphore_trackerwhen the tracker receives SIGINT before it can register signal handlersfor ignoring it.

  • bpo-34248: Report filename in the exception raised when the database filecannot be opened bydbm.gnu.open() anddbm.ndbm.open() due toOS-related error. Patch by Zsolt Cserna.

  • bpo-33089: Add math.dist() to compute the Euclidean distance between twopoints.

  • bpo-34246:smtplib.SMTP.send_message() no longer modifies thecontent of themail_options argument. Patch by Pablo S. Blum de Aguiar.

  • bpo-31047: Fixntpath.abspath for invalid paths on windows. Patch byFranz Woellert.

  • bpo-32321: Add pure Python fallback for functools.reduce. Patch by RobertWright.

  • bpo-34270: The default asyncio task class now always has a name which canbe get or set using two new methods (get_name() andset_name()) and is visible in therepr() output.An initial name can also be set using the newname keyword argument toasyncio.create_task() or thecreate_task() method of the event loop.If no initial name is set, the default Task implementation generates aname likeTask-1 using a monotonic counter.

  • bpo-34263: asyncio's event loop will not pass timeouts longer than one dayto epoll/select etc.

  • bpo-34035: Fix several AttributeError in zipfile seek() methods. Patch byMickaël Schoentgen.

  • bpo-32215: Fix performance regression insqlite3 when a DMLstatement appeared in a different line than the rest of the SQL query.

  • bpo-34075: Deprecate passing non-ThreadPoolExecutor instances toAbstractEventLoop.set_default_executor().

  • bpo-34251: Restoremsilib.Win64 to preserve backwards compatibilitysince it's already used bydistutils'bdist_msi command.

  • bpo-19891: Ignore errors caused by missing / non-writable homedir whilewriting history during exit of an interactive session. Patch by AnthonySottile.

  • bpo-33089: Enhanced math.hypot() to support more than two dimensions.

  • bpo-34228: tracemalloc: PYTHONTRACEMALLOC=0 environment variable and -Xtracemalloc=0 command line option are now allowed to disable explicitlytracemalloc at startup.

  • bpo-13041: Useshutil.get_terminal_size() to calculate the terminalwidth correctly in theargparse.HelpFormatter class. Initial patch byZbyszek Jędrzejewski-Szmek.

  • bpo-34213: Allow frozen dataclasses to have a field named "object".Previously this conflicted with an internal use of "object".

  • bpo-34052:sqlite3.Connection.create_aggregate(),sqlite3.Connection.create_function(),sqlite3.Connection.set_authorizer(),sqlite3.Connection.set_progress_handler() methods raises TypeErrorwhen unhashable objects are passed as callable. These methods now don'tpass such objects to SQLite API. Previous behavior could lead tosegfaults. Patch by Sergey Fedoseev.

  • bpo-34197: Attributesskipinitialspace,doublequote andstrict ofthedialect attribute of thecsv reader are nowboolinstances instead of integers 0 or 1.

  • bpo-32788: Errors other thanTypeError raised in methods__adapt__() and__conform__() in thesqlite3 module are nowpropagated to the user.

  • bpo-21446: Thereload fixer now usesimportlib.reload() insteadof deprecatedimp.reload().

  • bpo-940286: pydoc'sHelper.showtopic() method now prints the crossreferences of a topic correctly.

  • bpo-34164:base64.b32decode() could raise UnboundLocalError orOverflowError for incorrect padding. Now it always raisesbase64.Error in these cases.

  • bpo-33729: Fixed issues with arguments parsing inhashlib.

  • bpo-34097: ZipFile can zip files older than 1980-01-01 and newer than2107-12-31 using a newstrict_timestamps parameter at the cost ofsetting the timestamp to the limit.

  • bpo-34108: Remove extraneous CR in 2to3 refactor.

  • bpo-34070: Make sure to only check if the handle is a tty, when opening afile withbuffering=-1.

  • bpo-27494: Revertedbpo-27494. 2to3 rejects now a trailing comma ingenerator expressions.

  • bpo-33967: functools.singledispatch now raises TypeError instead ofIndexError when no positional arguments are passed.

  • bpo-34041: Add the parameterdeterministic to thesqlite3.Connection.create_function() method. Patch by SergeyFedoseev.

  • bpo-34056: Ensure the loader shim created byimp.load_module alwaysreturns bytes from itsget_data() function. This fixes usingimp.load_module withPEP 552 hash-based pycs.

  • bpo-34054: The multiprocessing module now uses the monotonic clocktime.monotonic() instead of the system clocktime.time() toimplement timeout.

  • bpo-34043: Optimize tarfile uncompress performance about 15% when gzip isused.

  • bpo-34044:subprocess.Popen now copies thestartupinfo argument toleave it unchanged: it will modify the copy, so that the sameSTARTUPINFO object can be used multiple times.

  • bpo-34010: Fixed a performance regression for reading streams withtarfile. The buffered read should use a list, instead of appending to abytes object.

  • bpo-34019: webbrowser: Correct the arguments passed to Opera Browser whenopening a new URL using thewebbrowser module. Patch by Bumsik Kim.

  • bpo-34003: csv.DictReader now creates dicts instead of OrderedDicts. Patchby Michael Selik.

  • bpo-33978: Closed existing logging handlers before reconfiguration viafileConfig and dictConfig. Patch by Karthikeyan Singaravelan.

  • bpo-14117: Make minor tweaks to turtledemo. The 'wikipedia' example is now'rosette', describing what it draws. The 'penrose' print output isreduced. The'1024' output of 'tree' is eliminated.

  • bpo-33974: Fixed passing lists and tuples of strings containing specialcharacters",\,{,} and\n as options tottk widgets.

  • bpo-27500: Fix getaddrinfo to resolve IPv6 addresses correctly.

  • bpo-24567: Improve random.choices() to handle subnormal input weights thatcould occasionally trigger an IndexError.

  • bpo-33871: Fixed integer overflow inos.readv(),os.writev(),os.preadv() andos.pwritev() and inos.sendfile() withheaders ortrailers arguments (on BSD-based OSes and macOS).

  • bpo-25007: Addcopy.copy() andcopy.deepcopy() support to zlibcompressors and decompressors. Patch by Zackery Spytz.

  • bpo-33929: multiprocessing: Fix a race condition in Popen ofmultiprocessing.popen_spawn_win32. The child process now duplicates theread end of pipe instead of "stealing" it. Previously, the read end ofpipe was "stolen" by the child process, but it leaked a handle if thechild process had been terminated before it could steal the handle fromthe parent process.

  • bpo-33899: Tokenize module now implicitly emits a NEWLINE when providedwith input that does not have a trailing new line. This behavior nowmatches what the C tokenizer does internally. Contributed by Ammar Askar.

  • bpo-33897: Added a 'force' keyword argument to logging.basicConfig().

  • bpo-33695:shutil.copytree() usesos.scandir() function andall copy functions depending from it use cachedos.stat() values.The speedup for copying a directory with 8000 files is around +9% onLinux, +20% on Windows and + 30% on a Windows SMB share. Also the numberofos.stat() syscalls is reduced by 38% makingshutil.copytree() especially faster on network filesystems.(Contributed by Giampaolo Rodola' inbpo-33695.)

  • bpo-33916: bz2 and lzma: When Decompressor.__init__() is called twice,free the old lock to not leak memory.

  • bpo-32568: Make select.epoll() and its documentation consistent regardingsizehint andflags.

  • bpo-33833: Fixed bug in asyncio where ProactorSocketTransport logsAssertionError if force closed during write.

  • bpo-33663: Convert content length to string before putting to header.

  • bpo-33721:os.path functions that return a boolean result likeexists(),lexists(),isdir(),isfile(),islink(), andismount(), andpathlib.Path methods that return aboolean result likeexists(),is_dir(),is_file(),is_mount(),is_symlink(),is_block_device(),is_char_device(),is_fifo(),is_socket() now returnFalse instead of raisingValueError or its subclassesUnicodeEncodeError andUnicodeDecodeError for paths that contain characters or bytesunrepresentable at the OS level.

  • bpo-26544: Fixed implementation ofplatform.libc_ver(). It almostalways returned version '2.9' for glibc.

  • bpo-33843: Remove deprecatedcgi.escape,cgi.parse_qs andcgi.parse_qsl.

  • bpo-33842: Removetarfile.filemode which is deprecated since Python3.3.

  • bpo-30167: Prevent site.main() exception if PYTHONSTARTUP is set. Patch bySteve Weber.

  • bpo-33805: Improve error message of dataclasses.replace() when an InitVaris not specified

  • bpo-33687: Fix the call toos.chmod() foruu.decode() if a mode isgiven or decoded. Patch by Timo Furrer.

  • bpo-33812: Datetime instance d with non-None tzinfo, but withd.tzinfo.utcoffset(d) returning None is now treated as naive by theastimezone() method.

  • bpo-32108: In configparser, don't clear section when it is assigned toitself.

  • bpo-27397: Make email module properly handle invalid-length base64strings.

  • bpo-33578: Implement multibyte encoder/decoder state methods

  • bpo-30805: Avoid race condition with debug logging

  • bpo-33476: Fix _header_value_parser.py when address group is missing final';'. Contributed by Enrique Perez-Terron

  • bpo-33694: asyncio: Fix a race condition causing data loss onpause_reading()/resume_reading() when using the ProactorEventLoop.

  • bpo-32493: Correct test foruuid_enc_be availability inconfigure.ac. Patch by Michael Felt.

  • bpo-33792: Add asyncio.WindowsSelectorEventLoopPolicy andasyncio.WindowsProactorEventLoopPolicy.

  • bpo-33274: W3C DOM Level 1 specifies return value ofElement.removeAttributeNode() as "The Attr node that was removed."xml.dom.minidom now complies with this requirement.

  • bpo-33778: Updateunicodedata's database to Unicode version 11.0.0.

  • bpo-33165: Added a stacklevel parameter to logging calls to allow use ofwrapper/helper functions for logging APIs.

  • bpo-33770: improve base64 exception message for encoded inputs of invalidlength

  • bpo-33769: asyncio/start_tls: Fix error message; cancel callbacks in caseof an unhandled error; mark SSLTransport as closed if it is aborted.

  • bpo-33767: The concatenation (+) and repetition (*) sequenceoperations now raiseTypeError instead ofSystemError whenperformed onmmap.mmap objects. Patch by Zackery Spytz.

  • bpo-33734: asyncio/ssl: Fix AttributeError, increase default handshaketimeout

  • bpo-31014: Fixed creating a controller forwebbrowser when a userspecifies a path to an entry in the BROWSER environment variable. Basedon patch by John Still.

  • bpo-2504: Add gettext.pgettext() and variants.

  • bpo-33197: Add description property for _ParameterKind

  • bpo-32751: When cancelling the task due to a timeout,asyncio.wait_for() will now wait until the cancellation is complete.

  • bpo-32684: Fix gather to propagate cancellation of itself even withreturn_exceptions.

  • bpo-33654: Support protocol type switching in SSLTransport.set_protocol().

  • bpo-33674: Pause the transport as early as possible to further reduce therisk of data_received() being called before connection_made().

  • bpo-33671:shutil.copyfile(),shutil.copy(),shutil.copy2(),shutil.copytree() andshutil.move() useplatform-specific fast-copy syscalls on Linux and macOS in order to copythe file more efficiently. On Windowsshutil.copyfile() uses abigger default buffer size (1 MiB instead of 16 KiB) and amemoryview()-based variant ofshutil.copyfileobj() is used.The speedup for copying a 512MiB file is about +26% on Linux, +50% onmacOS and +40% on Windows. Also, much less CPU cycles are consumed.(Contributed by Giampaolo Rodola' inbpo-25427.)

  • bpo-33674: Fix a race condition in SSLProtocol.connection_made() ofasyncio.sslproto: start immediately the handshake instead of usingcall_soon(). Previously, data_received() could be called before thehandshake started, causing the handshake to hang or fail.

  • bpo-31647: Fixed bug where calling write_eof() on a_SelectorSocketTransport after it's already closed raises AttributeError.

  • bpo-32610: Make asyncio.all_tasks() return only pending tasks.

  • bpo-32410: Avoid blocking on file IO in sendfile fallback code

  • bpo-33469: Fix RuntimeError after closing loop that used run_in_executor

  • bpo-33672: Fix Task.__repr__ crash with Cython's bogus coroutines

  • bpo-33654: Fix transport.set_protocol() to support switching betweenasyncio.Protocol and asyncio.BufferedProtocol. Fix loop.start_tls() towork with asyncio.BufferedProtocols.

  • bpo-33652: Pickles of type variables and subscripted generics are nowfuture-proof and compatible with older Python versions.

  • bpo-32493: Fixeduuid.uuid1() on FreeBSD.

  • bpo-33238: AddInvalidStateError toconcurrent.futures.Future.set_result andFuture.set_exception now raiseInvalidStateError if the futures are not pending or running. Patch byJason Haydaman.

  • bpo-33618: Finalize and document preliminary and experimental TLS 1.3support with OpenSSL 1.1.1

  • bpo-33625: Release GIL ongrp.getgrnam,grp.getgrgid,pwd.getpwnam andpwd.getpwuid if reentrant variants of thesefunctions are available. Patch by William Grzybowski.

  • bpo-33623: Fix possible SIGSGV when asyncio.Future is created in __del__

  • bpo-11874: Use a better regex when breaking usage into wrappable parts.Avoids bogus assertion errors from custom metavar strings.

  • bpo-30877: Fixed a bug in the Python implementation of the JSON decoderthat prevented the cache of parsed strings from clearing after finishingthe decoding. Based on patch by c-fos.

  • bpo-33604: Remove HMAC default to md5 marked for removal in 3.8 (removaloriginally planned in 3.6, bump to 3.8 in PR 7062).

  • bpo-33582: Emit a deprecation warning for inspect.formatargspec

  • bpo-21145: Addfunctools.cached_property decorator, for computedproperties cached for the life of the instance.

  • bpo-33570: Change TLS 1.3 cipher suite settings for compatibility withOpenSSL 1.1.1-pre6 and newer. OpenSSL 1.1.1 will have TLS 1.3 ciphersenabled by default.

  • bpo-28556: Do not simplify arguments totyping.Union. NowUnion[Manager,Employee] is not simplified toEmployee at runtime.Such simplification previously caused several bugs and limitedpossibilities for introspection.

  • bpo-12486:tokenize.generate_tokens() is now documented as a publicAPI to tokenize unicode strings. It was previously present butundocumented.

  • bpo-33540: Add a newblock_on_close class attribute toForkingMixIn andThreadingMixIn classes ofsocketserver.

  • bpo-33548: tempfile._candidate_tempdir_list should consider common TEMPlocations

  • bpo-33109: argparse subparsers are once again not required by default,reverting the change in behavior introduced bybpo-26510 in 3.7.0a2.

  • bpo-33541: Remove unused private method_strptime.LocaleTime.__pad(a.k.a._LocaleTime__pad).

  • bpo-33536: dataclasses.make_dataclass now checks for invalid field namesand duplicate fields. Also, added a check for invalid fieldspecifications.

  • bpo-33542: Preventuuid.get_node from using a DUID instead of a MAC onWindows. Patch by Zvi Effron

  • bpo-26819: Fix race condition withReadTransport.resume_reading inWindows proactor event loop.

  • Fix failure intyping.get_type_hints() when ClassVar was provided as astring forward reference.

  • bpo-33516:unittest.mock.MagicMock now supports the__round__magic method.

  • bpo-28612: Added support for Site Maps to urllib'sRobotFileParser asRobotFileParser.site_maps(). Patch by Lady Red, basedon patch by Peter Wirtz.

  • bpo-28167: Remove platform.linux_distribution, which was deprecated since3.5.

  • bpo-33504: Switch the default dictionary implementation forconfigparser fromcollections.OrderedDict to the standarddict type.

  • bpo-33505: Optimize asyncio.ensure_future() by reordering if checks: 1.17xfaster.

  • bpo-33497: Add errors param to cgi.parse_multipart and make an encoding inFieldStorage use the given errors (needed for Twisted). Patch by AmberBrown.

  • bpo-29235: ThecProfile.Profile class can now be used as acontext manager. Patch by Scott Sanderson.

  • bpo-33495: Change dataclasses.Fields repr to use the repr of each of itsmembers, instead of str. This makes it more clear what each fieldactually represents. This is especially true for the 'type' member.

  • bpo-26103: Correctinspect.isdatadescriptor to look for__set__ or__delete__. Patch by Aaron Hall.

  • bpo-29209: Removed thedoctype() method and thehtml parameter ofthe constructor ofXMLParser. Thedoctype() method defined in a subclass will no longer be called.Deprecated methodsgetchildren() andgetiterator() in theElementTree module emit now aDeprecationWarninginstead ofPendingDeprecationWarning.

  • bpo-33453: Fix dataclasses to work if using literal string typeannotations or if using PEP 563 "Postponed Evaluation of Annotations".Only specific string prefixes are detected for both ClassVar ("ClassVar"and "typing.ClassVar") and InitVar ("InitVar" and "dataclasses.InitVar").

  • bpo-28556: Minor fixes in typing module: add annotations toNamedTuple.__new__, pass*args and**kwds inGeneric.__new__. Original PRs by Paulius Šarka and Chad Dombrova.

  • bpo-33365: Print the header values besides the header keys instead justthe header keys ifdebuglevel is set to >0 inhttp.client. Patchby Marco Strigl.

  • bpo-20087: Updated alias mapping with glibc 2.27 supported locales.

  • bpo-33422: Fix trailing quotation marks getting deleted when looking upbyte/string literals on pydoc. Patch by Andrés Delfino.

  • bpo-28167: The functionplatform.linux_distribution andplatform.dist now trigger aDeprecationWarning and have beenmarked for removal in Python 3.8

  • bpo-33281: Fix ctypes.util.find_library regression on macOS.

  • bpo-33311: Text and html output generated by cgitb does not displayparentheses if the current call is done directly in the module. Patch byStéphane Blondon.

  • bpo-27300: The file classes intempfile now accept anerrors parameterthat complements the already existingencoding. Patch by Stephan Hohe.

  • bpo-32933:unittest.mock.mock_open() now supports iteration over thefile contents. Patch by Tony Flury.

  • bpo-33217: RaiseTypeError when looking up non-Enum objects in Enumclasses and Enum members.

  • bpo-33197: Update error message when constructing invalidinspect.Parameters Patch by Donghee Na.

  • bpo-33383: Fixed crash in the get() method of thedbm.ndbm databaseobject when it is called with a single argument.

  • bpo-33375: The warnings module now finds the Python file associated with awarning from the code object, rather than the frame's global namespace.This is consistent with how tracebacks and pdb find filenames, and shouldwork better for dynamically executed code.

  • bpo-33336:imaplib now allowsMOVE command inIMAP4.uid() (RFC6851: IMAP MOVE Extension) and potentially as a name of supported methodofIMAP4 object.

  • bpo-32455: Addedjump parameter todis.stack_effect().

  • bpo-27485: Rename and deprecate undocumented functions inurllib.parse().

  • bpo-33332: Addsignal.valid_signals() to expose the POSIX sigfillset()functionality.

  • bpo-33251:ConfigParser.items() was fixed so that key-value pairspassed in viavars() are not included in the resulting output.

  • bpo-33329: Fix multiprocessing regression on newer glibcs

  • bpo-33334:dis.stack_effect() now supports all defined opcodesincluding NOP and EXTENDED_ARG.

  • bpo-991266: Fix quoting of theComment attribute ofhttp.cookies.SimpleCookie.

  • bpo-33131: Upgrade bundled version of pip to 10.0.1.

  • bpo-33308: Fixed a crash in theparser module when converting an STobject to a tree of tuples or lists withline_info=False andcol_info=True.

  • bpo-23403: lib2to3 now uses pickle protocol 4 for pre-computed grammars.

  • bpo-33266: lib2to3 now recognizesrf'...' strings.

  • bpo-11594: Ensure line-endings are respected when using lib2to3.

  • bpo-33254: Haveimportlib.resources.contents() andimportlib.abc.ResourceReader.contents() return aniterableinstead of aniterator.

  • bpo-33265:contextlib.ExitStack andcontextlib.AsyncExitStack nowuse a method instead of a wrapper function for exit callbacks.

  • bpo-33263: Fix FD leak in_SelectorSocketTransport Patch by VladStarostin.

  • bpo-33256: Fix display of<module> call in the html produced bycgitb.html(). Patch by Stéphane Blondon.

  • bpo-33144:random.Random() and its subclassing mechanism got optimizedto check only once at class/subclass instantiation time whether itsgetrandbits() method can be relied on by other methods, includingrandrange(), for the generation of arbitrarily large random integers.Patch by Wolfgang Maier.

  • bpo-33185: Fixed regression when running pydoc with the-mswitch. (The regression was introduced in 3.7.0b3 by the resolution ofbpo-33053)

    This fix also changed pydoc to addos.getcwd() tosys.pathwhen necessary, rather than adding".".

  • bpo-29613: Added support for theSameSite cookie flag to thehttp.cookies module.

  • bpo-33169: Delete entries ofNone insys.path_importer_cachewhenimportlib.machinery.invalidate_caches() is called.

  • bpo-33203:random.Random.choice() now raisesIndexError for emptysequences consistently even when called from subclasses without agetrandbits() implementation.

  • bpo-33224: Update difflib.mdiff() forPEP 479. Convert an uncaughtStopIteration in a generator into a return-statement.

  • bpo-33209: End framing at the end of C implementation ofpickle.Pickler.dump().

  • bpo-32861: The urllib.robotparser's__str__ representation nowincludes wildcard entries and the "Crawl-delay" and "Request-rate" fields.Also removes extra newlines that were being appended to the end of thestring. Patch by Michael Lazar.

  • bpo-23403:DEFAULT_PROTOCOL inpickle was bumped to 4. Protocol4 is described inPEP 3154 and available since Python 3.4. It offersbetter performance and smaller size compared to protocol 3 introduced inPython 3.0.

  • bpo-20104: Improved error handling and fixed a reference leak inos.posix_spawn().

  • bpo-33106: Deleting a key from a read-only dbm database raises modulespecific error instead of KeyError.

  • bpo-33175: In dataclasses, Field.__set_name__ now looks up the__set_name__ special method on the class, not the instance, of the defaultvalue.

  • bpo-32380: Create functools.singledispatchmethod to support generic singledispatch on descriptors and methods.

  • bpo-33141: Have Field objects pass through __set_name__ to their defaultvalues, if they have their own __set_name__.

  • bpo-33096: Allow ttk.Treeview.insert to insert iid that has a falseboolean value. Note iid=0 and iid=False would be same. Patch by GarvitKhatri.

  • bpo-32873: Treat type variables and special typing forms as immutable bycopy and pickle. This fixes several minor issues and inconsistencies, andimproves backwards compatibility with Python 3.6.

  • bpo-33134: When computing dataclass's __hash__, use the lookup table tocontain the function which returns the __hash__ value. This is animprovement over looking up a string, and then testing that string to seewhat to do.

  • bpo-33127: The ssl module now compiles with LibreSSL 2.7.1.

  • bpo-32505: Raise TypeError if a member variable of a dataclass is of typeField, but doesn't have a type annotation.

  • bpo-33078: Fix the failure on OSX caused by the tests relying onsem_getvalue

  • bpo-33116: Add 'Field' to dataclasses.__all__.

  • bpo-32896: Fix an error where subclassing a dataclass with a field thatuses a default_factory would generate an incorrect class.

  • bpo-33100: Dataclasses: If a field has a default value that's aMemberDescriptorType, then it's from that field being in __slots__, not anactual default value.

  • bpo-32953: If a non-dataclass inherits from a frozen dataclass, allowattributes to be added to the derived class. Only attributes from thefrozen dataclass cannot be assigned to. Require all dataclasses in ahierarchy to be either all frozen or all non-frozen.

  • bpo-33097: Raise RuntimeError whenexecutor.submit is called duringinterpreter shutdown.

  • bpo-32968: Modulo and floor division involving Fraction and float shouldreturn float.

  • bpo-33061: Add missingNoReturn to__all__ in typing.py

  • bpo-33078: Fix the size handling in multiprocessing.Queue when a picklingerror occurs.

  • bpo-33064: lib2to3 now properly supports trailing commas after*argsand**kwargs in function signatures.

  • bpo-33056: FIX properly close leaking fds inconcurrent.futures.ProcessPoolExecutor.

  • bpo-33021: Release the GIL during fstat() calls, avoiding hang of allthreads when calling mmap.mmap(), os.urandom(), and random.seed(). Patchby Nir Soffer.

  • bpo-31804: Avoid failing in multiprocessing.Process if the standardstreams are closed or None at exit.

  • bpo-33034: Providing an explicit error message when casting the portproperty to anything that is not an integer value usingurlparse() andurlsplit(). Patch by Matt Eaton.

  • bpo-30249: Improve struct.unpack_from() exception messages for problemswith the buffer size and offset.

  • bpo-33037: Skip sending/receiving data after SSL transport closing.

  • bpo-27683: Fix a regression inipaddress that result ofhosts() is empty when the network is constructed by a tuplecontaining an integer mask and only 1 bit left for addresses.

  • bpo-22674: Add the strsignal() function in the signal module that returnsthe system description of the given signal, as returned by strsignal(3).

  • bpo-32999: Fix C implementation ofABC.__subclasscheck__(cls,subclass) crashed whensubclass is not a type object.

  • bpo-33009: Fix inspect.signature() for single-parameter partialmethods.

  • bpo-32969: Expose several missing constants in zlib and fix correspondingdocumentation.

  • bpo-32056: Improved exceptions raised for invalid number of channels andsample width when read an audio file in modulesaifc,waveandsunau.

  • bpo-32970: Improved disassembly of the MAKE_FUNCTION instruction.

  • bpo-32844: Fix wrong redirection of a low descriptor (0 or 1) to stderr insubprocess if another low descriptor is closed.

  • bpo-32960: For dataclasses, disallow inheriting frozen from non-frozenclasses, and also disallow inheriting non-frozen from frozen classes. Thisrestriction will be relaxed at a future date.

  • bpo-32713: Fixed tarfile.itn handling of out-of-bounds float values. Patchby Joffrey Fuhrer.

  • bpo-32257: The ssl module now contains OP_NO_RENEGOTIATION constant,available with OpenSSL 1.1.0h or 1.1.1.

  • bpo-32951: Direct instantiation of SSLSocket and SSLObject objects is nowprohibited. The constructors were never documented, tested, or designed aspublic constructors. Users were suppose to use ssl.wrap_socket() orSSLContext.

  • bpo-32929: Remove the tri-state parameter "hash", and add the boolean"unsafe_hash". If unsafe_hash is True, add a __hash__ function, but if a__hash__ exists, raise TypeError. If unsafe_hash is False, add a __hash__based on the values of eq= and frozen=. The unsafe_hash=False behavior isthe same as the old hash=None behavior. unsafe_hash=False is the default,just as hash=None used to be.

  • bpo-32947: Add OP_ENABLE_MIDDLEBOX_COMPAT and test workaround for TLSv1.3for future compatibility with OpenSSL 1.1.1.

  • bpo-32146: Document the interaction between frozen executables and thespawn and forkserver start methods in multiprocessing.

  • bpo-30622: The ssl module now detects missing NPN support in LibreSSL.

  • bpo-32922: dbm.open() now encodes filename with the filesystem encodingrather than default encoding.

  • bpo-32759: Free unused arenas in multiprocessing.heap.

  • bpo-32859: Inos.dup2, don't check every call whether thedup3syscall exists or not.

  • bpo-32556: nt._getfinalpathname, nt._getvolumepathname andnt._getdiskusage now correctly convert from bytes.

  • bpo-21060: Rewrite confusing message from setup.py upload from "No distfile created in earlier command" to the more helpful "Must create andupload files in one command".

  • bpo-32857: Intkinter,after_cancel(None) now raises aValueError instead of canceling the first scheduled function.Patch by Cheryl Sabella.

  • bpo-32852: Make sure sys.argv remains as a list when running trace.

  • bpo-31333:_abc module is added. It is a speedup module with Cimplementations for various functions and methods inabc. Creating anABC subclass and callingisinstance orissubclass with an ABCsubclass are up to 1.5x faster. In addition, this makes Python start-up upto 10% faster.

    Note that the new implementation hides internal registry and caches,previously accessible via private attributes_abc_registry,_abc_cache, and_abc_negative_cache. There are three debugginghelper methods that can be used instead_dump_registry,_abc_registry_clear, and_abc_caches_clear.

  • bpo-32841: Fixedasyncio.Condition issue which silently ignoredcancellation after notifying and cancelling a conditional lock. Patch byBar Harel.

  • bpo-32819: ssl.match_hostname() has been simplified and no longer dependson re and ipaddress module for wildcard and IP addresses. Error reportingfor invalid wildcards has been improved.

  • bpo-19675:multiprocessing.Pool no longer leaks processes if itsinitialization fails.

  • bpo-32394: socket: RemoveTCP_FASTOPEN,TCP_KEEPCNT,TCP_KEEPIDLE,TCP_KEEPINTVL flags on older versionWindows during run-time.

  • bpo-31787: Fixed refleaks of__init__() methods in various modules.(Contributed by Oren Milman)

  • bpo-30157: Fixed guessing quote and delimiter in csv.Sniffer.sniff() whenonly the last field is quoted. Patch by Jake Davis.

  • bpo-30688: Added support of\N{name} escapes in regular expressions.Based on patch by Jonathan Eunice.

  • bpo-32792: collections.ChainMap() preserves the order of the underlyingmappings.

  • bpo-32775:fnmatch.translate() no longer produces patterns whichcontain set operations. Sets starting with '[' or containing '--', '&&','~~' or '||' will be interpreted differently in regular expressions infuture versions. Currently they emit warnings. fnmatch.translate() nowavoids producing patterns containing such sets by accident.

  • bpo-32622: Implement native fast sendfile for Windows proactor event loop.

  • bpo-32777: Fix a rare but potential pre-exec child process deadlock insubprocess on POSIX systems when marking file descriptors inheritable onexec in the child process. This bug appears to have been introduced in3.4.

  • bpo-32647: The ctypes module used to depend on indirect linking fordlopen. The shared extension is now explicitly linked against libdl onplatforms with dl.

  • bpo-32749: Adbm.dumb database opened with flags 'r' is nowread-only.dbm.dumb.open() with flags 'r' and 'w' no longer createsa database if it does not exist.

  • bpo-32741: Implementasyncio.TimerHandle.when() method.

  • bpo-32691: Use mod_spec.parent when running modules with pdb

  • bpo-32734: Fixedasyncio.Lock() safety issue which allowed acquiringand locking the same lock multiple times, without it being free. Patch byBar Harel.

  • bpo-32727: Do not include name field in SMTP envelope from address. Patchby Stéphane Wirtel

  • bpo-31453: Add TLSVersion constants and SSLContext.maximum_version /minimum_version attributes. The new API wraps OpenSSL 1.1https://web.archive.org/web/20180309043602/https://www.openssl.org/docs/man1.1.0/ssl/SSL_CTX_set_min_proto_version.htmlfeature.

  • bpo-24334: Internal implementation details of ssl module were cleaned up.The SSLSocket has one less layer of indirection. Owner and sessioninformation are now handled by the SSLSocket and SSLObject constructor.Channel binding implementation has been simplified.

  • bpo-31848: Fix the error handling in Aifc_read.initfp() when the SSNDchunk is not found. Patch by Zackery Spytz.

  • bpo-32585: Add Ttk spinbox widget totkinter.ttk. Patch by Alan DMoore.

  • bpo-32512:profile CLI accepts-mmodule_name as an alternativeto script path.

  • bpo-8525: help() on a type now displays builtin subclasses. This isintended primarily to help with notification of more specific exceptionsubclasses.

    Patch by Sanyam Khurana.

  • bpo-31639: http.server now exposes a ThreadingHTTPServer class and uses itwhen the module is run with-m to cope with web browsers pre-openingsockets.

  • bpo-29877: compileall: import ProcessPoolExecutor only when needed,preventing hangs on low resource platforms

  • bpo-32221: Various functions returning tuple containing IPv6 addresses nowomit%scope part since the same information is already encoded inscopeid tuple item. Especially this speeds upsocket.recvfrom()when it receives multicast packet since useless resolving of networkinterface name is omitted.

  • bpo-32147:binascii.unhexlify() is now up to 2 times faster. Patchby Sergey Fedoseev.

  • bpo-30693: The TarFile class now recurses directories in a reproducibleway.

  • bpo-30693: The ZipFile class now recurses directories in a reproducibleway.

  • bpo-31680: Addedcurses.ncurses_version.

  • bpo-31908: Fix output of cover files fortrace module command-linetool. Previously emitted cover files only when--missing option wasused. Patch by Michael Selik.

  • bpo-31608: Raise aTypeError instead of crashing if acollections.deque subclass returns a non-deque from__new__. Patchby Oren Milman.

  • bpo-31425: Add support for sockets of the AF_QIPCRTR address family,supported by the Linux kernel. This is used to communicate with services,such as GPS or radio, running on Qualcomm devices. Patch by BjornAndersson.

  • bpo-22005: Implemented unpickling instances ofdatetime,date andtime pickled by Python 2.encoding='latin1' shouldbe used for successful decoding.

  • bpo-27645:sqlite3.Connection now exposes abackup method, if the underlying SQLitelibrary is at version 3.6.11 or higher. Patch by Lele Gaifax.

  • bpo-16865: Support arrays >=2GiB inctypes. Patch by Segev Finer.

  • bpo-31508: Removed support of arguments intkinter.ttk.Treeview.selection. It was deprecated in 3.6. Usespecialized methods likeselection_set for changing the selection.

  • bpo-29456: Fix bugs in hangul normalization: u1176, u11a7 and u11c3

Documentation

  • bpo-21257: Documenthttp.client.parse_headers().

  • bpo-34764: Improve example of iter() with 2nd sentinel argument.

  • bpo-35564: Explicitly set master_doc variable in conf.py for compliancewith Sphinx 2.0

  • bpo-35511: Specified that profile.Profile class doesn't not support enableor disable methods. Also, elaborated that Profile object as a contextmanager is only supported in cProfile module.

  • bpo-10536: Enhance the gettext docs. Patch by Éric Araujo

  • bpo-35089: Remove mention oftyping.io andtyping.re. Their typesshould be imported fromtyping directly.

  • bpo-35038: Fix the documentation about an unexistingf_restrictedattribute in the frame object. Patch by Stéphane Wirtel

  • bpo-35042: Replace PEP XYZ by the pep role and allow to use the directlinks to the PEPs.

  • bpo-35044: Fix the documentation with the roleexc for theappropriated exception. Patch by Stéphane Wirtel

  • bpo-35035: Rename documentation foremail.utils toemail.utils.rst.

  • bpo-34967: Use app.add_object_type() instead of the deprecated Sphinxfunction app.description_unit()

  • bpo-34913: Add documentation about the new command line interface of thegzip module.

  • bpo-32174: chm document displays non-ASCII characters properly on someMBCS Windows systems.

  • bpo-11233: Create availability directive for documentation. Originalpatch by Georg Brandl.

  • bpo-34790: Document how passing coroutines to asyncio.wait() can beconfusing.

  • bpo-34552: Make clear that== operator sometimes is equivalent tois. The<,<=,> and>= operators are only definedwhere they make sense.

  • bpo-28617: Fixed info in the stdtypes docs concerning the types thatsupport membership tests.

  • bpo-20177: Migrate datetime.date.fromtimestamp to Argument Clinic. Patchby Tim Hoffmann.

  • bpo-34065: Fix wrongly written basicConfig documentation markup syntax

  • bpo-33460: replaced ellipsis with correct error codes in tutorial chapter3.

  • bpo-33847: Add '@' operator entry to index.

  • bpo-33409: Clarified the relationship betweenPEP 538'sPYTHONCOERCECLOCALE and PEP 540's PYTHONUTF8 mode.

  • bpo-33197: Add versionadded tag to the documentation ofParameterKind.description

  • bpo-17045: Improve the C-API doc for PyTypeObject. This includes addingseveral quick-reference tables and a lot of missing slot/typedef entries.The existing entries were also cleaned up with a slightly more consistentformat.

  • bpo-33736: Improve the documentation ofasyncio.open_connection(),asyncio.start_server() and their UNIX socket counterparts.

  • bpo-23859: Document thatasyncio.wait() does not cancel its futures ontimeout.

  • bpo-32436: DocumentPEP 567 changes to asyncio.

  • bpo-33604: Update HMAC md5 default to a DeprecationWarning, bump removalto 3.8.

  • bpo-33594: Documentgetargspec,from_function andfrom_builtinas deprecated in their respective docstring, and include version sincedeprecation in DeprecationWarning message.

  • bpo-33503: Fix broken pypi link

  • bpo-33421: Add missing documentation fortyping.AsyncContextManager.

  • bpo-33487: BZ2file now emit a DeprecationWarning when buffering=None ispassed, the deprecation message and documentation also now explicitlystate it is deprecated since 3.0.

  • bpo-33378: Add Korean language switcher forhttps://docs.python.org/3/

  • bpo-33276: Clarify that the__path__ attribute on modules cannot bejust any value.

  • bpo-33201: Modernize documentation for writing C extension types.

  • bpo-33195: DeprecatePy_UNICODE usage inc-api/arg document.Py_UNICODE related APIs are deprecated since Python 3.3, but it ismissed in the document.

  • bpo-33126: Document PyBuffer_ToContiguous().

  • bpo-27212: Modify documentation for theislice() recipe to consumeinitial values up to the start index.

  • bpo-28247: Updatezipapp documentation to describe how to makestandalone applications.

  • bpo-18802: Documentation changes for ipaddress. Patch by Jon Foster andBerker Peksag.

  • bpo-27428: Update documentation to clarify thatWindowsRegistryFinderimplementsMetaPathFinder. (Patch by Himanshu Lakhara)

  • bpo-28124: The ssl module function ssl.wrap_socket() has beende-emphasized and deprecated in favor of the more secure and efficientSSLContext.wrap_socket() method.

  • bpo-17232: Clarify docs for -O and -OO. Patch by Terry Reedy.

  • bpo-32436: Add documentation for the contextvars module (PEP 567).

  • bpo-32800: Update link to w3c doc for xml default namespaces.

  • bpo-11015: Updatetest.support documentation.

  • bpo-32613: Update the faq/windows.html to use the py command from PEP 397instead of python.

  • bpo-8722: Document__getattr__() behavior when propertyget()method raisesAttributeError.

  • bpo-32614: Modify RE examples in documentation to use raw strings topreventDeprecationWarning and add text to REGEX HOWTO to highlightthe deprecation.

  • bpo-20709: Remove the paragraph where we explain that os.utime() does notsupport a directory as path under Windows. Patch by Jan-Philip Gehrcke

  • bpo-32722: Remove the bad example in the tutorial of the GeneratorExpression. Patch by Stéphane Wirtel

  • bpo-31972: Improve docstrings forpathlib.PurePath subclasses.

  • bpo-30607: Use the externalizedpython-docs-theme package whenbuilding the documentation.

  • bpo-8243: Add a note about curses.addch and curses.addstr exceptionbehavior when writing outside a window, or pad.

  • bpo-32337: Update documentation related withdict order.

  • bpo-25041: DocumentAF_PACKET in thesocket module.

  • bpo-31432: Clarify meaning of CERT_NONE, CERT_OPTIONAL, and CERT_REQUIREDflags for ssl.SSLContext.verify_mode.

Tests

  • bpo-35772: Fix sparse file tests of test_tarfile on ppc64 with the tmpfsfilesystem. Fix the function testing if the filesystem supports sparsefiles: create a file which contains data and "holes", instead of creatinga file which contains no data. tmpfs effective block size is a page size(tmpfs lives in the page cache). RHEL uses 64 KiB pages on aarch64, ppc64,ppc64le, only s390x and x86_64 use 4 KiB pages, whereas the test punchholes of 4 KiB.

  • bpo-35045: Make ssl tests less strict and also accept TLSv1 as systemdefault. The changes unbreaks test_min_max_version on Fedora 29.

  • bpo-32710:test_asyncio/test_sendfile.py now resets the event looppolicy usingtearDownModule() as done in other tests, to prevent awarning when running tests on Windows.

  • bpo-33717: test.pythoninfo now logs information of all clocks, not onlytime.time() and time.perf_counter().

  • bpo-35488: Add a test to pathlib's Path.match() to verify it does notsupport glob-style ** recursive pattern matching.

  • bpo-31731: Fix a race condition incheck_interrupted_write() oftest_io: create directly the thread with SIGALRM signal blocked, ratherthan blocking the signal later from the thread. Previously, it waspossible that the thread gets the signal before the signal is blocked.

  • bpo-35424: Fix test_multiprocessing_main_handling: usemultiprocessing.Pool with a context manager and then explicitlyjoin the pool.

  • bpo-35519: Renametest.bisect module totest.bisect_cmd toavoid conflict withbisect module when running directly a test like./pythonLib/test/test_xmlrpc.py.

  • bpo-35513: Replacetime.time() withtime.monotonic() in teststo measure time delta.

  • bpo-34279:test.support.run_unittest() no longer raiseTestDidNotRun if the test result contains skipped tests. Theexception is now only raised if no test have been run and no test havebeen skipped.

  • bpo-35412: Add testcase totest_future4: check unicode literal.

  • bpo-26704: Added test demonstrating double-patching of an instance method.Patch by Anthony Sottile.

  • bpo-33725: test_multiprocessing_fork may crash on recent versions ofmacOS. Until the issue is resolved, skip the test on macOS.

  • bpo-35352: Modify test_asyncio to use the certificate set from the testdirectory.

  • bpo-35317: Fixmktime() overflow error intest_email: runtest_localtime_daylight_true_dst_true() andtest_localtime_daylight_false_dst_true() with a specific timezone.

  • bpo-21263: After several reports that test_gdb does not work properly onmacOS and since gdb is not shipped by default anymore, test_gdb is nowskipped on macOS when LLVM Clang has been used to compile Python. Patch byLysandros Nikolaou

  • bpo-34279: regrtest issue a warning when no tests have been executed in aparticular test file. Also, a new final result state is issued if no testhave been executed across all test files. Patch by Pablo Galindo.

  • bpo-34962: make docstest in Doc now passes., and is enforced in CI

  • bpo-23596: Use argparse for the command line of the gzip module. Patch byAntony Lee

  • bpo-34537: Fixtest_gdb.test_strings() whenLC_ALL=C and GDB wascompiled with Python 3.6 or earlier.

  • bpo-34587: test_socket: Remove RDSTest.testCongestion(). The test tries tofill the receiver's socket buffer and expects an error. But the RDSprotocol doesn't require that. Moreover, the Linux implementation of RDSexpects that the producer of the messages reduces its rate, it's not therole of the receiver to trigger an error. The test fails on Fedora 28 bydesign, so just remove it.

  • bpo-34661: Fix test_shutil if unzip doesn't support -t.

  • bpo-34200: Fixed non-deterministic flakiness of test_pkg by not using thescary test.support.module_cleanup() logic to save and restore sys.modulescontents between test cases.

  • bpo-34569: The experimental PEP 554 data channels now correctly passnegative PyLong objects between subinterpreters on 32-bit systems. Patchby Michael Felt.

  • bpo-34594: Fix usage of hardcodederrno values in the tests.

  • bpo-34579: Fix test_embed for AIX Patch by Michael Felt

  • bpo-34542: Use 3072 RSA keys and SHA-256 signature for test certs andkeys.

  • bpo-11193: Remove special condition for AIX intest_subprocess.test_undecodable_env

  • bpo-34347: Fixtest_utf8_mode.test_cmd_line for AIX

  • bpo-34490: On AIX with AF_UNIX family sockets getsockname() does notprovide 'sockname', so skip calls to transport.get_extra_info('sockname')

  • bpo-34391: Fix ftplib test for TLS 1.3 by reading from data socket.

  • bpo-11192: Fixtest_socket on AIX 6.1 and later IPv6 zone id supportsonly supported byinet_pton6_zone(). Switch to runtime-basedplatform.system() to establish current platform rather than build-timebasedsys.platform()

  • bpo-34399: Update all RSA keys and DH params to use at least 2048 bits.

  • bpo-34373: Fixtest_mktime andtest_pthread_getcpuclickid testsfor AIX Add range checking for_PyTime_localtime for AIX Patch byMichael Felt

  • bpo-11191: Skip the distutils test 'test_search_cpp' when using XLC ascompiler patch by aixtools (Michael Felt)

  • Improved an error message when mock assert_has_calls fails.

  • bpo-33746: Fix test_unittest when run in verbose mode.

  • bpo-33901: Fix test_dbm_gnu on macOS with gdbm 1.15: add a larger value tomake sure that the file size changes.

  • bpo-33873: Fix a bug inregrtest that caused an extra test to run if--huntrleaks/-R was used. Exit with error in case that invalid parametersare specified to --huntrleaks/-R (at least one warmup run and onerepetition must be used).

  • bpo-33562: Check that a global asyncio event loop policy is not leftbehind by any tests.

  • bpo-33655: Ignore test_posix_fallocate failures on BSD platforms thatmight be due to running on ZFS.

  • bpo-32962: Fixed test_gdb when Python is compiled with flags -mcet-fcf-protection -O0.

  • bpo-33358: Fixtest_embed.test_pre_initialization_sys_options() whenthe interpreter is built with--enable-shared.

  • bpo-32872: Avoid regrtest compatibility issue with namespace packages.

  • bpo-32517: Fix failingtest_asyncio on macOS 10.12.2+ due to transportofKqueueSelector loop was not being closed.

  • bpo-32663: Making sure theSMTPUTF8SimTests class of tests gets run intest_smtplib.py.

  • bpo-27643: Test_C test case needs "signed short" bitfields, but the IBMXLC compiler (on AIX) does not support this Skip the code and test whenAIX and XLC are used

    Applicable to Python2-2.7 and later

  • bpo-19417: Add test_bdb.py.

  • bpo-31809: Add tests to verify connection with secp ECDH curves.

Build

  • bpo-34691: The _contextvars module is now built into the core Pythonlibrary on Windows.

  • bpo-35683: Improved Azure Pipelines build steps and now verifying layoutscorrectly

  • bpo-35642: Remove asynciomodule.c from pythoncore.vcxproj

  • bpo-35550: Fix incorrect Solaris #ifdef checks to look for __sun && __SVR4instead of sun when compiling.

  • bpo-35499:makeprofile-opt no longer replacesCFLAGS_NODIST withCFLAGS. It now adds profile-guided optimization (PGO) flags toCFLAGS_NODIST: existingCFLAGS_NODIST flags are kept.

  • bpo-35257: Avoid leaking the linker flags from Link Time Optimizations(LTO) into distutils when compiling C extensions.

  • bpo-35351: When building Python with clang and LTO, LTO flags are nolonger passed into CFLAGS to build third-party C extensions throughdistutils.

  • bpo-35139: Fix a compiler error when statically linkingpyexpat inModules/Setup.

  • bpo-35059: PCbuild: Set InlineFunctionExpansion to OnlyExplicitInline("/Ob1" option) in pyproject.props in Debug mode to expand functionsmarked as inline. This change should make Python compiled in Debug mode alittle bit faster on Windows.

  • bpo-35011: Restores the use of pyexpatns.h to isolate our embedded copy ofthe expat C library so that its symbols do not conflict at link or dynamicloading time with an embedding application or other extension modules withtheir own version of libexpat.

  • bpo-28015: Have --with-lto works correctly with clang.

  • bpo-34765: Update the outdated install-sh file to the latest revision fromautomake v1.16.1

  • bpo-34585: Check for floating-point byte order in configure.ac usingcompilation tests instead of executing code, so that these checks work incross-compiled builds.

  • bpo-34710: Fixed SSL module build with OpenSSL & pedantic CFLAGS.

  • bpo-34582: Add JUnit XML output for regression tests and update AzureDevOps builds.

  • bpo-34081: Make Sphinx warnings as errors in the Docs Makefile.

  • bpo-34555: Fix for case where it was not possible to have bothHAVE_LINUX_VM_SOCKETS_H andHAVE_SOCKADDR_ALG be undefined.

  • bpo-33015: Fix an undefined behaviour in the pthread implementation ofPyThread_start_new_thread(): add a function wrapper to alwaysreturnNULL.

  • bpo-34245: The Python shared library is now installed with writepermission (mode 0755), which is the standard way of installing suchlibraries.

  • bpo-34121: Fix detection of C11 atomic support on clang.

  • bpo-32430: Rename Modules/Setup.dist to Modules/Setup, and remove thenecessity to copy the former manually to the latter when updating thelocal source tree.

  • bpo-30345: Add -g to LDFLAGS when compiling with LTO to get debug symbols.

  • bpo-5755: Move-Wstrict-prototypes option toCFLAGS_NODIST fromOPT. This option emitted annoying warnings when building extensionmodules written in C++.

  • bpo-33614: Ensures module definition files for the stable ABI on Windowsare correctly regenerated.

  • bpo-33648: The --with-c-locale-warning configuration flag has beenremoved. It has had no effect for about a year.

  • bpo-33522: Enable CI builds on Visual Studio Team Services athttps://python.visualstudio.com/cpython

  • bpo-33512: configure's check for "long double" has been simplified

  • bpo-33483: C compiler is now correctly detected from the standardenvironment variables. --without-gcc and --with-icc options have beenremoved.

  • bpo-33394: Enable the verbose build for extension modules, when GNU makeis passed macros on the command line.

  • bpo-33393: Update config.guess and config.sub files.

  • bpo-33377: Add new triplets for mips r6 and riscv variants (used inextension suffixes).

  • bpo-32232: By default, modules configured inModules/Setup are nolonger built with-DPy_BUILD_CORE. Instead, modules that specificallyneed that preprocessor definition include it in their individual entries.

  • bpo-33182: The embedding tests can once again be built with clang 6.0

  • bpo-33163: Upgrade pip to 9.0.3 and setuptools to v39.0.1.

  • bpo-33012: gcc 8 has added a new warning heuristic to detect invalidfunction casts and a stock python build seems to hit that warning quiteoften. The most common is the cast of a METH_NOARGS function (that usesjust one argument) to a PyCFunction. Fix this by adding a dummy argumentto all functions that implement METH_NOARGS.

  • bpo-32898: Fix the python debug build when using COUNT_ALLOCS.

  • bpo-29442: Replace optparse with argparse in setup.py

Windows

  • bpo-35890: Fix API calling consistency of GetVersionEx and wcstok.

  • bpo-32560: Thepy launcher now forwards itsSTARTUPINFO structureto child processes.

  • bpo-35854: Fix EnvBuilder and --symlinks in venv on Windows

  • bpo-35811: Avoid propagating venv settings when launching via py.exe

  • bpo-35797: Fix default executable used by the multiprocessing module

  • bpo-35758: Allow building on ARM with MSVC.

  • bpo-29734: Fix handle leaks in os.stat on Windows.

  • bpo-35596: Use unchecked PYCs for the embeddable distro to avoid zipimportrestrictions.

  • bpo-35596: Fix vcruntime140.dll being added to embeddable distro multipletimes.

  • bpo-35402: Update Windows build to use Tcl and Tk 8.6.9

  • bpo-35401: Updates Windows build to OpenSSL 1.1.0j

  • bpo-34977: venv on Windows will now use a python.exe redirector ratherthan copying the actual binaries from the base environment.

  • bpo-34977: Adds support for building a Windows App Store package

  • bpo-35067: Remove _distutils_findvs module and use vswhere.exe instead.

  • bpo-32557: Allow shutil.disk_usage to take a file path on Windows

  • bpo-34770: Fix a possible null pointer dereference in pyshellext.cpp.

  • bpo-34603: Fix returning structs from functions produced by MSVC

  • bpo-34581: Guard MSVC-specific code in socketmodule.c with#ifdef_MSC_VER.

  • bpo-34532: Fixes exit code of list version arguments for py.exe.

  • bpo-34062: Fixed the '--list' and '--list-paths' arguments for the py.exelauncher

  • bpo-34225: Ensure INCLUDE and LIB directories do not end with a backslash.

  • bpo-34011: A suite of code has been changed which copied across DLLs andinit.tcl from the running Python location into a venv being created. Thesecopies are needed only when running from a Python source build, and thecopying code is now only run when that is the case, rather than whenever avenv is created.

  • bpo-34006: Revert line length limit for Windows help docs. The line-lengthlimit is not needed because the pages appear in a separate app rather thanon a browser tab. It can also interact badly with the DPI setting.

  • bpo-31546: Restore running PyOS_InputHook while waiting for user input atthe prompt. The restores integration of interactive GUI windows (such asMatplotlib figures) with the prompt on Windows.

  • bpo-30237: Output error when ReadConsole is canceled byCancelSynchronousIo instead of crashing.

  • bpo-33895: GIL is released while calling functions that acquire Windowsloader lock.

  • bpo-33720: Reduces maximum marshal recursion depth on release builds.

  • bpo-29097: Fix bug wheredatetime.fromtimestamp() erroneously throwsanOSError on Windows for values between 0 and 86400. Patch byAmmar Askar.

  • bpo-33316: PyThread_release_lock always fails

  • bpo-33184: Update Windows installer to use OpenSSL 1.1.0h.

  • bpo-32890: Fix usage of GetLastError() instead of errno in os.execve() andos.truncate().

  • bpo-33016: Fix potential use of uninitialized memory innt._getfinalpathname

  • bpo-32903: Fix a memory leak in os.chdir() on Windows if the currentdirectory is set to a UNC path.

  • bpo-32901: Update Tcl and Tk versions to 8.6.8

  • bpo-31966: Fixed WindowsConsoleIO.write() for writing empty data.

  • bpo-32409: Ensures activate.bat can handle Unicode contents.

  • bpo-32457: Improves handling of denormalized executable path whenlaunching Python.

  • bpo-32370: Use the correct encoding for ipconfig output in the uuidmodule. Patch by Segev Finer.

  • bpo-29248: Fixos.readlink() on Windows, which was mistakenlytreating thePrintNameOffset field of the reparse data buffer as anumber of characters instead of bytes. Patch by Craig Holmquist and SSE4.

  • bpo-1104: Correctly handle string length inmsilib.SummaryInfo.GetProperty() to prevent it from truncating thelast character.

macOS

  • bpo-35401: Update macOS installer to use OpenSSL 1.1.0j.

  • bpo-35025: Properly guard the use of theCLOCK_GETTIME et al. macrosintimemodule on macOS.

  • bpo-24658: On macOS, fix reading from and writing into a file with a sizelarger than 2 GiB.

  • bpo-34405: Update to OpenSSL 1.1.0i for macOS installer builds.

  • bpo-33635: In macOS stat on some file descriptors (/dev/fd/3 f.e) willresult in bad file descriptor OSError. Guard against this exception wasadded in is_dir, is_file and similar methods. DirEntry.is_dir can alsothrow this exception so _RecursiveWildcardSelector._iterate_directorieswas also extended with the same error ignoring pattern.

  • bpo-13631: The .editrc file in user's home directory is now processedcorrectly during the readline initialization through editline emulation onmacOS.

  • bpo-33184: Update macOS installer build to use OpenSSL 1.1.0h.

  • bpo-32726: Build and link with private copy of Tcl/Tk 8.6 for the macOS10.6+ installer. The 10.9+ installer variant already does this. Thismeans that the Python 3.7 provided by the python.org macOS installers nolonger need or use any external versions of Tcl/Tk, either system-providedor user-installed, such as ActiveTcl.

  • bpo-32901: Update macOS 10.9+ installer to Tcl/Tk 8.6.8.

  • bpo-31903: In_scproxy, drop the GIL when calling intoSystemConfiguration to avoid deadlocks.

IDLE

  • bpo-35770: IDLE macosx deletes Options => Configure IDLE. It previouslydeleted Window => Zoom Height by mistake. (Zoom Height is now on theOptions menu). On Mac, the settings dialog is accessed via Preferences onthe IDLE menu.

  • bpo-35769: Change IDLE's new file name from 'Untitled' to 'untitled'

  • bpo-35660: Fix imports in idlelib.window.

  • bpo-35641: Proper formatcalltip when the function has no docstring.

  • bpo-33987: Use ttk Frame for ttk widgets.

  • bpo-34055: Fix erroneous 'smart' indents and newlines in IDLE Shell.

  • bpo-35591: Find Selection now works when selection not found.

  • bpo-35196: Speed up squeezer line counting.

  • bpo-35598: Update config_key: use PEP 8 names and ttk widgets, make someobjects global, and add tests.

  • bpo-28097: Add Previous/Next History entries to Shell menu.

  • bpo-35208: Squeezer now properly counts wrapped lines before newlines.

  • bpo-35555: Gray out Code Context menu entry when it's not applicable.

  • bpo-35521: Document the IDLE editor code context feature. Add someinternal references within the IDLE doc.

  • bpo-22703: The Code Context menu label now toggles between Show/Hide CodeContext. The Zoom Height menu now toggles between Zoom/Restore Height.Zoom Height has moved from the Window menu to the Options menu.

  • bpo-35213: Where appropriate, use 'macOS' in idlelib.

  • bpo-34864: On macOS, warn if the system preference "Prefer tabs whenopening documents" is set to "Always".

  • bpo-34864: Document two IDLE on MacOS issues. The System Preferences Dock"prefer tabs always" setting disables some IDLE features. Menus are a bitdifferent than as described for Windows and Linux.

  • bpo-35202: Remove unused imports from lib/idlelib

  • bpo-33000: Document that IDLE's shell has no line limit. A program thatruns indefinitely can overfill memory.

  • bpo-23220: Explain how IDLE's Shell displays output.

  • bpo-35099: Improve the doc about IDLE running user code. The section isrenamed from "IDLE -- console differences" is renamed "Running user code".It mostly covers the implications of using customsys.stdxxxobjects.

  • bpo-35097: Add IDLE doc subsection explaining editor windows. Topicsinclude opening, title and status bar, .py* extension, and running.

  • bpo-35093: Document the IDLE document viewer in the IDLE doc. Add aparagraph in "Help and preferences", "Help sources" subsection.

  • bpo-35088: Update idlelib.help.copy_string docstring. We now use git andbackporting instead of hg and forward merging.

  • bpo-35087: Update idlelib help files for the current doc build. The mainchange is the elimination of chapter-section numbers.

  • bpo-34548: Use configured color theme for read-only text views.

  • bpo-1529353: Enable "squeezing" of long outputs in the shell, to avoidperformance degradation and to clean up the history without losing it.Squeezed outputs may be copied, viewed in a separate window, and"unsqueezed".

  • bpo-34047: Fixed mousewheel scrolling direction on macOS.

  • bpo-34275: Make IDLE calltips always visible on Mac. Some MacOS-tkcombinations need .update_idletasks(). Patch by Kevin Walzer.

  • bpo-34120: Fix unresponsiveness after closing certain windows and dialogs.

  • bpo-33975: Avoid small type when running htests. Since part of the purposeof human-viewed tests is to determine that widgets look right, it isimportant that they look the same for testing as when running IDLE.

  • bpo-33905: Add test for idlelib.stackview.StackBrowser.

  • bpo-33924: Change mainmenu.menudefs key 'windows' to 'window'. Every othermenudef key is lowercase version of main menu entry.

  • bpo-33906: Rename idlelib.windows as window Match Window on the main menuand remove last plural module name.

  • bpo-33917: Fix and document idlelib/idle_test/template.py. The revisedfile compiles, runs, and tests OK. idle_test/README.txt explains how touse it to create new IDLE test files.

  • bpo-33904: IDLE: In rstrip, rename class RstripExtension as Rstrip

  • bpo-33907: For consistency and clarity, rename an IDLE module and classes.Module calltips and its class CallTips are now calltip and Calltip. Inmodule calltip_w, class CallTip is now CalltipWindow.

  • bpo-33856: Add "help" in the welcome message of IDLE

  • bpo-33839: IDLE: refactor ToolTip and CallTip and add documentation andtests

  • bpo-33855: Minimally test all IDLE modules. Add missing files, importmodule, instantiate classes, and check coverage. Check existing files.

  • bpo-33656: On Windows, add API call saying that tk scales for DPI. OnWindows 8.1+ or 10, with DPI compatibility properties of the Python binaryunchanged, and a monitor resolution greater than 96 DPI, this should maketext and lines sharper. It should otherwise have no effect.

  • bpo-33768: Clicking on a context line moves that line to the top of theeditor window.

  • bpo-33763: IDLE: Use read-only text widget for code context instead oflabel widget.

  • bpo-33664: Scroll IDLE editor text by lines. Previously, the mouse wheeland scrollbar slider moved text by a fixed number of pixels, resulting inpartial lines at the top of the editor box. The change also applies tothe shell and grep output windows, but not to read-only text views.

  • bpo-33679: Enable theme-specific color configuration for Code Context. Usethe Highlights tab to see the setting for built-in themes or add settingsto custom themes.

  • bpo-33642: Display up to maxlines non-blank lines for Code Context. Ifthere is no current context, show a single blank line.

  • bpo-33628: IDLE: Cleanup codecontext.py and its test.

  • bpo-33564: IDLE's code context now recognizes async as a block opener.

  • bpo-21474: Update word/identifier definition from ascii to unicode. Intext and entry boxes, this affects selection by double-click, movementleft/right by control-left/right, and deletion left/right bycontrol-BACKSPACE/DEL.

  • bpo-33204: IDLE: consistently color invalid string prefixes. A 'u' stringprefix cannot be paired with either 'r' or 'f'. Consistently color as muchof the prefix, starting at the right, as is valid. Revise and extendcolorizer test.

  • bpo-32984: Set__file__ while running a startup file. Like Python,IDLE optionally runs one startup file in the Shell window beforepresenting the first interactive input prompt. For IDLE,-s runs afile named in environmental variableIDLESTARTUP orPYTHONSTARTUP;-rfile runsfile. Python sets__file__ to the startup file name before running the file and unsetsit before the first prompt. IDLE now does the same when run normally,without the-n option.

  • bpo-32940: Simplify and rename StringTranslatePseudoMapping in pyparse.

  • bpo-32916: Changestr tocode in pyparse.

  • bpo-32905: Remove unused code in pyparse module.

  • bpo-32874: Add tests for pyparse.

  • bpo-32837: Using the system and place-dependent default encoding foropen() is a bad idea for IDLE's system and location-independent files.

  • bpo-32826: Add "encoding=utf-8" to open() in IDLE's test_help_about. GUItest test_file_buttons() only looks at initial ascii-only lines, butfailed on systems where open() defaults to 'ascii' because readline()internally reads and decodes far enough ahead to encounter a non-asciicharacter in CREDITS.txt.

  • bpo-32831: Add docstrings and tests for codecontext.

  • bpo-32765: Update configdialog General tab docstring to add new widgets tothe widget list.

Tools/Demos

  • bpo-35884: Add a benchmark script for timing various ways to accessvariables:Tools/scripts/var_access_benchmark.py.

  • bpo-34989: python-gdb.py now handles errors on computing the line numberof a Python frame.

  • bpo-20260: Argument Clinic now has non-bitwise unsigned int converters.

  • bpo-32962: python-gdb now catchesUnicodeDecodeError exceptions whencallingstring().

  • bpo-32962: python-gdb now catches ValueError on read_var(): when Pythonhas no debug symbols for example.

  • bpo-33189:pygettext.py now recognizes only literal strings asdocstrings and translatable strings, and rejects bytes literals andf-string expressions.

  • bpo-31920: Fixed handling directories as arguments in thepygettextscript. Based on patch by Oleg Krasnikov.

  • bpo-29673: Fix pystackv and pystack gdbinit macros.

  • bpo-25427: Remove the pyvenv script in favor ofpython3-mvenv inorder to lower confusion as to what Python interpreter a virtualenvironment will be created for.

  • bpo-32885: Add an-n flag forTools/scripts/pathfix.py to disableautomatic backup creation (files with~ suffix).

  • bpo-32222: Fix pygettext not extracting docstrings for functions with typeannotated arguments. Patch by Toby Harradine.

  • bpo-31583: Fix 2to3 for using with --add-suffix option but without--output-dir option for relative path to files in current directory.

C API

Python 3.7.0 final

Release date: 2018-06-27

Library

C API

  • bpo-33932: Calling Py_Initialize() twice does nothing, instead of failingwith a fatal error: restore the Python 3.6 behaviour.

Python 3.7.0 release candidate 1

Release date: 2018-06-12

Core and Builtins

  • bpo-33803: Fix a crash in hamt.c caused by enabling GC tracking for anobject that hadn't all of its fields set to NULL.

  • bpo-33706: Fix a crash in Python initialization when parsing the commandline options. Thanks Christoph Gohlke for the bug report and the fix!

  • bpo-30654: Fixed reset of the SIGINT handler to SIG_DFL on interpretershutdown even when there was a custom handler set previously. Patch byPhilipp Kerling.

  • bpo-31849: Fix signed/unsigned comparison warning in pyhash.c.

Library

  • bpo-30167: Prevent site.main() exception if PYTHONSTARTUP is set. Patch bySteve Weber.

  • bpo-33812: Datetime instance d with non-None tzinfo, but withd.tzinfo.utcoffset(d) returning None is now treated as naive by theastimezone() method.

  • bpo-30805: Avoid race condition with debug logging

  • bpo-33694: asyncio: Fix a race condition causing data loss onpause_reading()/resume_reading() when using the ProactorEventLoop.

  • bpo-32493: Correct test foruuid_enc_be availability inconfigure.ac. Patch by Michael Felt.

  • bpo-33792: Add asyncio.WindowsSelectorEventLoopPolicy andasyncio.WindowsProactorEventLoopPolicy.

  • bpo-33778: Updateunicodedata's database to Unicode version 11.0.0.

  • bpo-33770: improve base64 exception message for encoded inputs of invalidlength

  • bpo-33769: asyncio/start_tls: Fix error message; cancel callbacks in caseof an unhandled error; mark SSLTransport as closed if it is aborted.

  • bpo-33767: The concatenation (+) and repetition (*) sequenceoperations now raiseTypeError instead ofSystemError whenperformed onmmap.mmap objects. Patch by Zackery Spytz.

  • bpo-33734: asyncio/ssl: Fix AttributeError, increase default handshaketimeout

  • bpo-11874: Use a better regex when breaking usage into wrappable parts.Avoids bogus assertion errors from custom metavar strings.

  • bpo-33582: Emit a deprecation warning for inspect.formatargspec

Documentation

Build

  • bpo-5755: Move-Wstrict-prototypes option toCFLAGS_NODIST fromOPT. This option emitted annoying warnings when building extensionmodules written in C++.

Windows

  • bpo-33720: Reduces maximum marshal recursion depth on release builds.

IDLE

  • bpo-33656: On Windows, add API call saying that tk scales for DPI. OnWindows 8.1+ or 10, with DPI compatibility properties of the Python binaryunchanged, and a monitor resolution greater than 96 DPI, this should maketext and lines sharper. It should otherwise have no effect.

  • bpo-33768: Clicking on a context line moves that line to the top of theeditor window.

  • bpo-33763: IDLE: Use read-only text widget for code context instead oflabel widget.

  • bpo-33664: Scroll IDLE editor text by lines. Previously, the mouse wheeland scrollbar slider moved text by a fixed number of pixels, resulting inpartial lines at the top of the editor box. The change also applies tothe shell and grep output windows, but not to read-only text views.

  • bpo-33679: Enable theme-specific color configuration for Code Context. Usethe Highlights tab to see the setting for built-in themes or add settingsto custom themes.

  • bpo-33642: Display up to maxlines non-blank lines for Code Context. Ifthere is no current context, show a single blank line.

Python 3.7.0 beta 5

Release date: 2018-05-30

Core and Builtins

  • bpo-33622: Fixed a leak when the garbage collector fails to add an objectwith the__del__ method or referenced by it into thegc.garbage list.PyGC_Collect() can now be called when anexception is set and preserves it.

  • bpo-33509: Fix module_globals parameter of warnings.warn_explicit(): don'tcrash if module_globals is not a dict.

  • bpo-20104: The newos.posix_spawn added in 3.7.0b1 was removed as weare still working on what the API should look like. Expect this in 3.8instead.

  • bpo-33475: Fixed miscellaneous bugs in converting annotations to stringsand optimized parentheses in the string representation.

  • bpo-33391: Fix a leak in set_symmetric_difference().

  • bpo-28055: Fix unaligned accesses in siphash24(). Patch by Rolf Eike Beer.

  • bpo-32911: Due to unexpected compatibility issues discovered duringdownstream beta testing, revertedbpo-29463.docstring field isremoved from Module, ClassDef, FunctionDef, and AsyncFunctionDef ast nodeswhich was added in 3.7a1. Docstring expression is restored as a firststatement in their body. Based on patch by Inada Naoki.

  • bpo-21983: Fix a crash inctypes.cast() in case the type argument is actypes structured data type. Patch by Eryk Sun and Oren Milman.

Library

  • bpo-32751: When cancelling the task due to a timeout,asyncio.wait_for() will now wait until the cancellation is complete.

  • bpo-32684: Fix gather to propagate cancellation of itself even withreturn_exceptions.

  • bpo-33654: Support protocol type switching in SSLTransport.set_protocol().

  • bpo-33674: Pause the transport as early as possible to further reduce therisk of data_received() being called before connection_made().

  • bpo-33674: Fix a race condition in SSLProtocol.connection_made() ofasyncio.sslproto: start immediately the handshake instead of usingcall_soon(). Previously, data_received() could be called before thehandshake started, causing the handshake to hang or fail.

  • bpo-31647: Fixed bug where calling write_eof() on a_SelectorSocketTransport after it's already closed raises AttributeError.

  • bpo-32610: Make asyncio.all_tasks() return only pending tasks.

  • bpo-32410: Avoid blocking on file IO in sendfile fallback code

  • bpo-33469: Fix RuntimeError after closing loop that used run_in_executor

  • bpo-33672: Fix Task.__repr__ crash with Cython's bogus coroutines

  • bpo-33654: Fix transport.set_protocol() to support switching betweenasyncio.Protocol and asyncio.BufferedProtocol. Fix loop.start_tls() towork with asyncio.BufferedProtocols.

  • bpo-33652: Pickles of type variables and subscripted generics are nowfuture-proof and compatible with older Python versions.

  • bpo-32493: Fixeduuid.uuid1() on FreeBSD.

  • bpo-33618: Finalize and document preliminary and experimental TLS 1.3support with OpenSSL 1.1.1

  • bpo-33623: Fix possible SIGSGV when asyncio.Future is created in __del__

  • bpo-30877: Fixed a bug in the Python implementation of the JSON decoderthat prevented the cache of parsed strings from clearing after finishingthe decoding. Based on patch by c-fos.

  • bpo-33570: Change TLS 1.3 cipher suite settings for compatibility withOpenSSL 1.1.1-pre6 and newer. OpenSSL 1.1.1 will have TLS 1.3 ciphersenabled by default.

  • bpo-28556: Do not simplify arguments totyping.Union. NowUnion[Manager,Employee] is not simplified toEmployee at runtime.Such simplification previously caused several bugs and limitedpossibilities for introspection.

  • bpo-33540: Add a newblock_on_close class attribute toForkingMixIn andThreadingMixIn classes ofsocketserver.

  • bpo-33548: tempfile._candidate_tempdir_list should consider common TEMPlocations

  • bpo-33109: argparse subparsers are once again not required by default,reverting the change in behavior introduced bybpo-26510 in 3.7.0a2.

  • bpo-33536: dataclasses.make_dataclass now checks for invalid field namesand duplicate fields. Also, added a check for invalid fieldspecifications.

  • bpo-33542: Preventuuid.get_node from using a DUID instead of a MAC onWindows. Patch by Zvi Effron

  • bpo-26819: Fix race condition withReadTransport.resume_reading inWindows proactor event loop.

  • Fix failure intyping.get_type_hints() when ClassVar was provided as astring forward reference.

  • bpo-33505: Optimize asyncio.ensure_future() by reordering if checks: 1.17xfaster.

  • bpo-33497: Add errors param to cgi.parse_multipart and make an encoding inFieldStorage use the given errors (needed for Twisted). Patch by AmberBrown.

  • bpo-33495: Change dataclasses.Fields repr to use the repr of each of itsmembers, instead of str. This makes it more clear what each fieldactually represents. This is especially true for the 'type' member.

  • bpo-33453: Fix dataclasses to work if using literal string typeannotations or if using PEP 563 "Postponed Evaluation of Annotations".Only specific string prefixes are detected for both ClassVar ("ClassVar"and "typing.ClassVar") and InitVar ("InitVar" and "dataclasses.InitVar").

  • bpo-28556: Minor fixes in typing module: add annotations toNamedTuple.__new__, pass*args and**kwds inGeneric.__new__. Original PRs by Paulius Šarka and Chad Dombrova.

  • bpo-20087: Updated alias mapping with glibc 2.27 supported locales.

  • bpo-33422: Fix trailing quotation marks getting deleted when looking upbyte/string literals on pydoc. Patch by Andrés Delfino.

  • bpo-28167: The functionplatform.linux_distribution andplatform.dist now trigger aDeprecationWarning and have beenmarked for removal in Python 3.8

  • bpo-33197: Update error message when constructing invalidinspect.Parameters Patch by Donghee Na.

  • bpo-33263: Fix FD leak in_SelectorSocketTransport Patch by VladStarostin.

  • bpo-32861: The urllib.robotparser's__str__ representation nowincludes wildcard entries and the "Crawl-delay" and "Request-rate" fields.Patch by Michael Lazar.

  • bpo-32257: The ssl module now contains OP_NO_RENEGOTIATION constant,available with OpenSSL 1.1.0h or 1.1.1.

  • bpo-16865: Support arrays >=2GiB inctypes. Patch by Segev Finer.

Documentation

  • bpo-23859: Document thatasyncio.wait() does not cancel its futures ontimeout.

  • bpo-32436: DocumentPEP 567 changes to asyncio.

  • bpo-33604: Update HMAC md5 default to a DeprecationWarning, bump removalto 3.8.

  • bpo-33503: Fix broken pypi link

  • bpo-33421: Add missing documentation fortyping.AsyncContextManager.

Tests

  • bpo-33655: Ignore test_posix_fallocate failures on BSD platforms thatmight be due to running on ZFS.

  • bpo-32604: Remove the _xxsubinterpreters module (meant for testing) andassociated helpers. This module was originally added recently in 3.7b1.

Build

  • bpo-33614: Ensures module definition files for the stable ABI on Windowsare correctly regenerated.

  • bpo-33522: Enable CI builds on Visual Studio Team Services athttps://python.visualstudio.com/cpython

  • bpo-33012: Add-Wno-cast-function-type for gcc 8 for silencingwarnings about function casts like casting to PyCFunction in methoddefinition lists.

macOS

  • bpo-13631: The .editrc file in user's home directory is now processedcorrectly during the readline initialization through editline emulation onmacOS.

IDLE

  • bpo-33628: IDLE: Cleanup codecontext.py and its test.

  • bpo-33564: IDLE's code context now recognizes async as a block opener.

  • bpo-32831: Add docstrings and tests for codecontext.

Python 3.7.0 beta 4

Release date: 2018-05-02

Core and Builtins

  • bpo-33363: Raise a SyntaxError forasyncwith andasyncforstatements outside of async functions.

  • bpo-33128: Fix a bug that causes PathFinder to appear twice onsys.meta_path. Patch by Pablo Galindo Salgado.

  • bpo-33312: Fixed clang ubsan (undefined behavior sanitizer) warnings indictobject.c by adjusting how the internal struct _dictkeysobject sharedkeys structure is declared.

  • bpo-33231: Fix potential memory leak innormalizestring().

  • bpo-33205: Change dict growth function fromround_up_to_power_2(used*2+hashtable_size/2) toround_up_to_power_2(used*3). Previously, dict is shrinked only whenused==0. Now dict has more chance to be shrinked.

  • bpo-29922: Improved error messages in 'async with' when__aenter__()or__aexit__() return non-awaitable object.

  • bpo-33199: Fixma_version_tag in dict implementation is uninitializedwhen copying from key-sharing dict.

Library

  • bpo-33281: Fix ctypes.util.find_library regression on macOS.

  • bpo-33383: Fixed crash in the get() method of thedbm.ndbm databaseobject when it is called with a single argument.

  • bpo-33329: Fix multiprocessing regression on newer glibcs

  • bpo-991266: Fix quoting of theComment attribute ofhttp.cookies.SimpleCookie.

  • bpo-33131: Upgrade bundled version of pip to 10.0.1.

  • bpo-33308: Fixed a crash in theparser module when converting an STobject to a tree of tuples or lists withline_info=False andcol_info=True.

  • bpo-33266: lib2to3 now recognizesrf'...' strings.

  • bpo-11594: Ensure line-endings are respected when using lib2to3.

  • bpo-33254: Haveimportlib.resources.contents() andimportlib.abc.ResourceReader.contents() return aniterableinstead of aniterator.

  • bpo-33256: Fix display of<module> call in the html produced bycgitb.html(). Patch by Stéphane Blondon.

  • bpo-33185: Fixed regression when running pydoc with the-mswitch. (The regression was introduced in 3.7.0b3 by the resolution ofbpo-33053) This fix also changed pydoc to addos.getcwd() tosys.path when necessary, rather than adding".".

  • bpo-33169: Delete entries ofNone insys.path_importer_cachewhenimportlib.machinery.invalidate_caches() is called.

  • bpo-33217: Deprecate looking up non-Enum objects in Enum classes and Enummembers (will raiseTypeError in 3.8+).

  • bpo-33203:random.Random.choice() now raisesIndexError for emptysequences consistently even when called from subclasses without agetrandbits() implementation.

  • bpo-33224: Update difflib.mdiff() forPEP 479. Convert an uncaughtStopIteration in a generator into a return-statement.

  • bpo-33209: End framing at the end of C implementation ofpickle.Pickler.dump().

  • bpo-20104: Improved error handling and fixed a reference leak inos.posix_spawn().

  • bpo-33175: In dataclasses, Field.__set_name__ now looks up the__set_name__ special method on the class, not the instance, of the defaultvalue.

  • bpo-33097: Raise RuntimeError whenexecutor.submit is called duringinterpreter shutdown.

  • bpo-31908: Fix output of cover files fortrace module command-linetool. Previously emitted cover files only when--missing option wasused. Patch by Michael Selik.

Documentation

  • bpo-33378: Add Korean language switcher forhttps://docs.python.org/3/

  • bpo-33276: Clarify that the__path__ attribute on modules cannot bejust any value.

  • bpo-33201: Modernize documentation for writing C extension types.

  • bpo-33195: DeprecatePy_UNICODE usage inc-api/arg document.Py_UNICODE related APIs are deprecated since Python 3.3, but it ismissed in the document.

  • bpo-8243: Add a note about curses.addch and curses.addstr exceptionbehavior when writing outside a window, or pad.

  • bpo-32337: Update documentation related withdict order.

Tests

  • bpo-33358: Fixtest_embed.test_pre_initialization_sys_options() whenthe interpreter is built with--enable-shared.

Build

  • bpo-33394: Enable the verbose build for extension modules, when GNU makeis passed macros on the command line.

  • bpo-33393: Update config.guess and config.sub files.

  • bpo-33377: Add new triplets for mips r6 and riscv variants (used inextension suffixes).

  • bpo-32232: By default, modules configured inModules/Setup are nolonger built with-DPy_BUILD_CORE. Instead, modules that specificallyneed that preprocessor definition include it in their individual entries.

  • bpo-33182: The embedding tests can once again be built with clang 6.0

Windows

  • bpo-33184: Update Windows installer to use OpenSSL 1.1.0h.

macOS

  • bpo-33184: Update macOS installer build to use OpenSSL 1.1.0h.

IDLE

  • bpo-21474: Update word/identifier definition from ascii to unicode. Intext and entry boxes, this affects selection by double-click, movementleft/right by control-left/right, and deletion left/right bycontrol-BACKSPACE/DEL.

  • bpo-33204: IDLE: consistently color invalid string prefixes. A 'u' stringprefix cannot be paired with either 'r' or 'f'. Consistently color as muchof the prefix, starting at the right, as is valid. Revise and extendcolorizer test.

Tools/Demos

  • bpo-33189:pygettext.py now recognizes only literal strings asdocstrings and translatable strings, and rejects bytes literals andf-string expressions.

  • bpo-31920: Fixed handling directories as arguments in thepygettextscript. Based on patch by Oleg Krasnikov.

  • bpo-29673: Fix pystackv and pystack gdbinit macros.

  • bpo-31583: Fix 2to3 for using with --add-suffix option but without--output-dir option for relative path to files in current directory.

Python 3.7.0 beta 3

Release date: 2018-03-29

Security

  • bpo-33136: Harden ssl module against LibreSSLCVE 2018-8970.X509_VERIFY_PARAM_set1_host() is called with an explicit namelen. A newtest ensures that NULL bytes are not allowed.

  • bpo-33001: Minimal fix to prevent buffer overrun in os.symlink on Windows

  • bpo-32981: Regexes in difflib and poplib were vulnerable to catastrophicbacktracking. These regexes formed potential DOS vectors (REDOS). Theyhave been refactored. This resolvesCVE 2018-1060 andCVE 2018-1061.Patch by Jamie Davis.

Core and Builtins

  • bpo-33053: When using the -m switch, sys.path[0] is now explicitlyexpanded as thestarting working directory, rather than being left asthe empty path (which allows imports from the current working directory atthe time of the import)

  • bpo-33018: Improve consistency of errors raised byissubclass() whencalled with a non-class and an abstract base class as the first and secondarguments, respectively. Patch by Josh Bronson.

  • bpo-33041: Fixed jumping when the function contains anasyncfor loop.

  • bpo-33026: Fixed jumping out of "with" block by setting f_lineno.

  • bpo-33005: Fix a crash on fork when using a custom memory allocator (ex:using PYTHONMALLOC env var). _PyGILState_Reinit() and_PyInterpreterState_Enable() now use the default RAW memory allocator toallocate a new interpreters mutex on fork.

  • bpo-17288: Prevent jumps from 'return' and 'exception' trace events.

  • bpo-32836: Don't use temporary variables in cases of list/dict/setcomprehensions

Library

  • bpo-33141: Have Field objects pass through __set_name__ to their defaultvalues, if they have their own __set_name__.

  • bpo-33096: Allow ttk.Treeview.insert to insert iid that has a falseboolean value. Note iid=0 and iid=False would be same. Patch by GarvitKhatri.

  • bpo-32873: Treat type variables and special typing forms as immutable bycopy and pickle. This fixes several minor issues and inconsistencies, andimproves backwards compatibility with Python 3.6.

  • bpo-33134: When computing dataclass's __hash__, use the lookup table tocontain the function which returns the __hash__ value. This is animprovement over looking up a string, and then testing that string to seewhat to do.

  • bpo-33127: The ssl module now compiles with LibreSSL 2.7.1.

  • bpo-32505: Raise TypeError if a member variable of a dataclass is of typeField, but doesn't have a type annotation.

  • bpo-33078: Fix the failure on OSX caused by the tests relying onsem_getvalue

  • bpo-33116: Add 'Field' to dataclasses.__all__.

  • bpo-32896: Fix an error where subclassing a dataclass with a field thatuses a default_factory would generate an incorrect class.

  • bpo-33100: Dataclasses: If a field has a default value that's aMemberDescriptorType, then it's from that field being in __slots__, not anactual default value.

  • bpo-32953: If a non-dataclass inherits from a frozen dataclass, allowattributes to be added to the derived class. Only attributes from thefrozen dataclass cannot be assigned to. Require all dataclasses in ahierarchy to be either all frozen or all non-frozen.

  • bpo-33061: Add missingNoReturn to__all__ in typing.py

  • bpo-33078: Fix the size handling in multiprocessing.Queue when a picklingerror occurs.

  • bpo-33064: lib2to3 now properly supports trailing commas after*argsand**kwargs in function signatures.

  • bpo-33056: FIX properly close leaking fds inconcurrent.futures.ProcessPoolExecutor.

  • bpo-33021: Release the GIL during fstat() calls, avoiding hang of allthreads when calling mmap.mmap(), os.urandom(), and random.seed(). Patchby Nir Soffer.

  • bpo-31804: Avoid failing in multiprocessing.Process if the standardstreams are closed or None at exit.

  • bpo-33037: Skip sending/receiving data after SSL transport closing.

  • bpo-27683: Fix a regression inipaddress that result ofhosts() is empty when the network is constructed by a tuplecontaining an integer mask and only 1 bit left for addresses.

  • bpo-32999: Fix C implementation ofABC.__subclasscheck__(cls,subclass) crashed whensubclass is not a type object.

  • bpo-33009: Fix inspect.signature() for single-parameter partialmethods.

  • bpo-32969: Expose several missing constants in zlib and fix correspondingdocumentation.

  • bpo-32056: Improved exceptions raised for invalid number of channels andsample width when read an audio file in modulesaifc,waveandsunau.

  • bpo-32844: Fix wrong redirection of a low descriptor (0 or 1) to stderr insubprocess if another low descriptor is closed.

  • bpo-32857: Intkinter,after_cancel(None) now raises aValueError instead of canceling the first scheduled function.Patch by Cheryl Sabella.

  • bpo-31639: http.server now exposes a ThreadedHTTPServer class and uses itwhen the module is run with-m to cope with web browsers pre-openingsockets.

  • bpo-27645:sqlite3.Connection now exposes abackup method, if the underlying SQLitelibrary is at version 3.6.11 or higher. Patch by Lele Gaifax.

Documentation

  • bpo-33126: Document PyBuffer_ToContiguous().

  • bpo-27212: Modify documentation for theislice() recipe to consumeinitial values up to the start index.

  • bpo-28247: Updatezipapp documentation to describe how to makestandalone applications.

  • bpo-18802: Documentation changes for ipaddress. Patch by Jon Foster andBerker Peksag.

  • bpo-27428: Update documentation to clarify thatWindowsRegistryFinderimplementsMetaPathFinder. (Patch by Himanshu Lakhara)

Tests

  • bpo-32872: Avoid regrtest compatibility issue with namespace packages.

  • bpo-32517: Fix failingtest_asyncio on macOS 10.12.2+ due to transportofKqueueSelector loop was not being closed.

  • bpo-19417: Add test_bdb.py.

Build

  • bpo-33163: Upgrade pip to 9.0.3 and setuptools to v39.0.1.

Windows

  • bpo-33016: Fix potential use of uninitialized memory innt._getfinalpathname

  • bpo-32903: Fix a memory leak in os.chdir() on Windows if the currentdirectory is set to a UNC path.

macOS

  • bpo-32726: Build and link with private copy of Tcl/Tk 8.6 for the macOS10.6+ installer. The 10.9+ installer variant already does this. Thismeans that the Python 3.7 provided by the python.org macOS installers nolonger need or use any external versions of Tcl/Tk, either system-providedor user-installed, such as ActiveTcl.

IDLE

  • bpo-32984: Set__file__ while running a startup file. Like Python,IDLE optionally runs one startup file in the Shell window beforepresenting the first interactive input prompt. For IDLE,-s runs afile named in environmental variableIDLESTARTUP orPYTHONSTARTUP;-rfile runsfile. Python sets__file__ to the startup file name before running the file and unsetsit before the first prompt. IDLE now does the same when run normally,without the-n option.

  • bpo-32940: Simplify and rename StringTranslatePseudoMapping in pyparse.

Tools/Demos

  • bpo-32885: Add an-n flag forTools/scripts/pathfix.py to disableautomatic backup creation (files with~ suffix).

C API

  • bpo-33042: Embedding applications may once again callPySys_ResetWarnOptions, PySys_AddWarnOption, and PySys_AddXOption prior tocalling Py_Initialize.

  • bpo-32374: Document that m_traverse for multi-phase initialized modulescan be called with m_state=NULL, and add a sanity check

Python 3.7.0 beta 2

Release date: 2018-02-27

Security

  • bpo-28414: The ssl module now allows users to perform their own IDNen/decoding when using SNI.

Core and Builtins

  • bpo-32889: Update Valgrind suppression list to account for the rename ofPy_ADDRESS_IN_RANG toaddress_in_range.

  • bpo-31356: Remove the new API added inbpo-31356 (gc.ensure_disabled()context manager).

  • bpo-32305: For namespace packages, ensure that both__file__ and__spec__.origin are set to None.

  • bpo-32303: Make sure__spec__.loader matches__loader__ fornamespace packages.

  • bpo-32711: Fix the warning messages for Python/ast_unparse.c. Patch byStéphane Wirtel

  • bpo-32583: Fix possible crashing in builtin Unicode decoders caused bywrite out-of-bound errors when using customized decode error handlers.

Library

  • bpo-32960: For dataclasses, disallow inheriting frozen from non-frozenclasses, and also disallow inheriting non-frozen from frozen classes. Thisrestriction will be relaxed at a future date.

  • bpo-32713: Fixed tarfile.itn handling of out-of-bounds float values. Patchby Joffrey Fuhrer.

  • bpo-32951: Direct instantiation of SSLSocket and SSLObject objects is nowprohibited. The constructors were never documented, tested, or designed aspublic constructors. Users were suppose to use ssl.wrap_socket() orSSLContext.

  • bpo-32929: Remove the tri-state parameter "hash", and add the boolean"unsafe_hash". If unsafe_hash is True, add a __hash__ function, but if a__hash__ exists, raise TypeError. If unsafe_hash is False, add a __hash__based on the values of eq= and frozen=. The unsafe_hash=False behavior isthe same as the old hash=None behavior. unsafe_hash=False is the default,just as hash=None used to be.

  • bpo-32947: Add OP_ENABLE_MIDDLEBOX_COMPAT and test workaround for TLSv1.3for future compatibility with OpenSSL 1.1.1.

  • bpo-30622: The ssl module now detects missing NPN support in LibreSSL.

  • bpo-32922: dbm.open() now encodes filename with the filesystem encodingrather than default encoding.

  • bpo-32859: Inos.dup2, don't check every call whether thedup3syscall exists or not.

  • bpo-32556: nt._getfinalpathname, nt._getvolumepathname andnt._getdiskusage now correctly convert from bytes.

  • bpo-25988: Emit aDeprecationWarning when using or importing an ABCdirectly fromcollections rather than fromcollections.abc.

  • bpo-21060: Rewrite confusing message from setup.py upload from "No distfile created in earlier command" to the more helpful "Must create andupload files in one command".

  • bpo-32852: Make sure sys.argv remains as a list when running trace.

  • bpo-31333:_abc module is added. It is a speedup module with Cimplementations for various functions and methods inabc. Creating anABC subclass and callingisinstance orissubclass with an ABCsubclass are up to 1.5x faster. In addition, this makes Python start-up upto 10% faster. Note that the new implementation hides internal registryand caches, previously accessible via private attributes_abc_registry,_abc_cache, and_abc_negative_cache. There arethree debugging helper methods that can be used instead_dump_registry,_abc_registry_clear, and_abc_caches_clear.

  • bpo-32841: Fixedasyncio.Condition issue which silently ignoredcancellation after notifying and cancelling a conditional lock. Patch byBar Harel.

  • bpo-32819: ssl.match_hostname() has been simplified and no longer dependson re and ipaddress module for wildcard and IP addresses. Error reportingfor invalid wildcards has been improved.

  • bpo-32394: socket: RemoveTCP_FASTOPEN,TCP_KEEPCNT,TCP_KEEPIDLE,TCP_KEEPINTVL flags on older versionWindows during run-time.

  • bpo-31787: Fixed refleaks of__init__() methods in various modules.(Contributed by Oren Milman)

  • bpo-30157: Fixed guessing quote and delimiter in csv.Sniffer.sniff() whenonly the last field is quoted. Patch by Jake Davis.

  • bpo-32792: collections.ChainMap() preserves the order of the underlyingmappings.

  • bpo-32775:fnmatch.translate() no longer produces patterns whichcontain set operations. Sets starting with '[' or containing '--', '&&','~~' or '||' will be interpreted differently in regular expressions infuture versions. Currently they emit warnings. fnmatch.translate() nowavoids producing patterns containing such sets by accident.

  • bpo-32622: Implement native fast sendfile for Windows proactor event loop.

  • bpo-32777: Fix a rare but potential pre-exec child process deadlock insubprocess on POSIX systems when marking file descriptors inheritable onexec in the child process. This bug appears to have been introduced in3.4.

  • bpo-32647: The ctypes module used to depend on indirect linking fordlopen. The shared extension is now explicitly linked against libdl onplatforms with dl.

  • bpo-32741: Implementasyncio.TimerHandle.when() method.

  • bpo-32691: Use mod_spec.parent when running modules with pdb

  • bpo-32734: Fixedasyncio.Lock() safety issue which allowed acquiringand locking the same lock multiple times, without it being free. Patch byBar Harel.

  • bpo-32727: Do not include name field in SMTP envelope from address. Patchby Stéphane Wirtel

  • bpo-31453: Add TLSVersion constants and SSLContext.maximum_version /minimum_version attributes. The new API wraps OpenSSL 1.1https://web.archive.org/web/20180309043602/https://www.openssl.org/docs/man1.1.0/ssl/SSL_CTX_set_min_proto_version.htmlfeature.

  • bpo-24334: Internal implementation details of ssl module were cleaned up.The SSLSocket has one less layer of indirection. Owner and sessioninformation are now handled by the SSLSocket and SSLObject constructor.Channel binding implementation has been simplified.

  • bpo-31848: Fix the error handling in Aifc_read.initfp() when the SSNDchunk is not found. Patch by Zackery Spytz.

  • bpo-32585: Add Ttk spinbox widget totkinter.ttk. Patch by Alan DMoore.

  • bpo-32221: Various functions returning tuple containing IPv6 addresses nowomit%scope part since the same information is already encoded inscopeid tuple item. Especially this speeds upsocket.recvfrom()when it receives multicast packet since useless resolving of networkinterface name is omitted.

  • bpo-30693: The TarFile class now recurses directories in a reproducibleway.

  • bpo-30693: The ZipFile class now recurses directories in a reproducibleway.

Documentation

  • bpo-28124: The ssl module function ssl.wrap_socket() has beende-emphasized and deprecated in favor of the more secure and efficientSSLContext.wrap_socket() method.

  • bpo-17232: Clarify docs for -O and -OO. Patch by Terry Reedy.

  • bpo-32436: Add documentation for the contextvars module (PEP 567).

  • bpo-32800: Update link to w3c doc for xml default namespaces.

  • bpo-11015: Updatetest.support documentation.

  • bpo-8722: Document__getattr__() behavior when propertyget()method raisesAttributeError.

  • bpo-32614: Modify RE examples in documentation to use raw strings topreventDeprecationWarning and add text to REGEX HOWTO to highlightthe deprecation.

  • bpo-31972: Improve docstrings forpathlib.PurePath subclasses.

Tests

  • bpo-31809: Add tests to verify connection with secp ECDH curves.

Build

  • bpo-32898: Fix the python debug build when using COUNT_ALLOCS.

Windows

  • bpo-32901: Update Tcl and Tk versions to 8.6.8

  • bpo-31966: Fixed WindowsConsoleIO.write() for writing empty data.

  • bpo-32409: Ensures activate.bat can handle Unicode contents.

  • bpo-32457: Improves handling of denormalized executable path whenlaunching Python.

  • bpo-32370: Use the correct encoding for ipconfig output in the uuidmodule. Patch by Segev Finer.

  • bpo-29248: Fixos.readlink() on Windows, which was mistakenlytreating thePrintNameOffset field of the reparse data buffer as anumber of characters instead of bytes. Patch by Craig Holmquist and SSE4.

macOS

  • bpo-32901: Update macOS 10.9+ installer to Tcl/Tk 8.6.8.

IDLE

  • bpo-32916: Changestr tocode in pyparse.

  • bpo-32905: Remove unused code in pyparse module.

  • bpo-32874: Add tests for pyparse.

  • bpo-32837: Using the system and place-dependent default encoding foropen() is a bad idea for IDLE's system and location-independent files.

  • bpo-32826: Add "encoding=utf-8" to open() in IDLE's test_help_about. GUItest test_file_buttons() only looks at initial ascii-only lines, butfailed on systems where open() defaults to 'ascii' because readline()internally reads and decodes far enough ahead to encounter a non-asciicharacter in CREDITS.txt.

  • bpo-32765: Update configdialog General tab docstring to add new widgets tothe widget list.

Tools/Demos

  • bpo-32222: Fix pygettext not extracting docstrings for functions with typeannotated arguments. Patch by Toby Harradine.

Python 3.7.0 beta 1

Release date: 2018-01-30

Core and Builtins

  • bpo-32703: Fix coroutine's ResourceWarning when there's an active errorset when it's being finalized.

  • bpo-32650: Pdb and other debuggers dependent on bdb.py will correctly stepover (next command) native coroutines. Patch by Pablo Galindo.

  • bpo-28685: Optimize list.sort() and sorted() by using type specializedcomparisons when possible.

  • bpo-32685: Improve suggestion when the Python 2 form of print statement iseither present on the same line as the header of a compound statement orelse terminated by a semi-colon instead of a newline. Patch by NitishChandra.

  • bpo-32697: Python now explicitly preserves the definition order ofkeyword-only parameters. It's always preserved their order, but thisbehavior was never guaranteed before; this behavior is now guaranteed andtested.

  • bpo-32690: The locals() dictionary now displays in the lexical order thatvariables were defined. Previously, the order was reversed.

  • bpo-32677: Add.isascii() method tostr,bytes andbytearray. It can be used to test that string contains only ASCIIcharacters.

  • bpo-32670: EnforcePEP 479 for all code. This means that manuallyraising a StopIteration exception from a generator is prohibited for allcode, regardless of whether 'from __future__ import generator_stop' wasused or not.

  • bpo-32591: Added built-in support for tracking the origin of coroutineobjects; see sys.set_coroutine_origin_tracking_depth andCoroutineType.cr_origin. This replaces the asyncio debug mode's use ofcoroutine wrapping for native coroutine objects.

  • bpo-31368: Expose preadv and pwritev system calls in the os module. Patchby Pablo Galindo

  • bpo-32544:hasattr(obj,name) andgetattr(obj,name,default) areabout 4 times faster than before whenname is not found andobjdoesn't override__getattr__ or__getattribute__.

  • bpo-26163: Improved frozenset() hash to create more distinct hash valueswhen faced with datasets containing many similar values.

  • bpo-32550: Remove the STORE_ANNOTATION bytecode.

  • bpo-20104: Expose posix_spawn as a low level API in the os module.(removed before 3.7.0rc1)

  • bpo-24340: Fixed estimation of the code stack size.

  • bpo-32436: ImplementPEP 567 Context Variables.

  • bpo-18533:repr() on a dict containing its ownvalues() oritems() no longer raisesRecursionError; OrderedDict similarly.Instead, use..., as for other recursive structures. Patch by BenNorth.

  • bpo-20891: Py_Initialize() now creates the GIL. The GIL is no longercreated "on demand" to fix a race condition when PyGILState_Ensure() iscalled in a non-Python thread.

  • bpo-32028: Leading whitespace is now correctly ignored when generatingsuggestions for converting Py2 print statements to Py3 builtin printfunction calls. Patch by Sanyam Khurana.

  • bpo-31179: Make dict.copy() up to 5.5 times faster.

  • bpo-31113: Get rid of recursion in the compiler for normal control flow.

Library

  • bpo-25988: Deprecate exposing the contents of collections.abc in theregular collections module.

  • bpo-31429: The default cipher suite selection of the ssl module now uses ablacklist approach rather than a hard-coded whitelist. Python no longerre-enables ciphers that have been blocked by OpenSSL security update.Default cipher suite selection can be configured on compile time.

  • bpo-30306: contextlib.contextmanager now releases the arguments passed tothe underlying generator as soon as the context manager is entered.Previously it would keep them alive for as long as the context manager wasalive, even when not being used as a function decorator. Patch by MartinTeichmann.

  • bpo-21417: Added support for setting the compression level forzipfile.ZipFile.

  • bpo-32251: Implement asyncio.BufferedProtocol (provisional API).

  • bpo-32513: In dataclasses, allow easier overriding of dunder methodswithout specifying decorator parameters.

  • bpo-32660:termios makes availableFIONREAD,FIONCLEX,FIOCLEX,FIOASYNC andFIONBIO also under Solaris/derivatives.

  • bpo-27931: Fix email address header parsing error when the username is anempty quoted string. Patch by Xiang Zhang.

  • bpo-32659: Under Solaris and derivatives,os.stat_result providesa st_fstype attribute.

  • bpo-32662: Implement Server.start_serving(), Server.serve_forever(), andServer.is_serving() methods. Add 'start_serving' keyword parameter toloop.create_server() and loop.create_unix_server().

  • bpo-32391: Implementasyncio.StreamWriter.wait_closed() andasyncio.StreamWriter.is_closing() methods

  • bpo-32643: Make Task._step, Task._wakeup and Future._schedule_callbacksmethods private.

  • bpo-32630: Refactor decimal module to use contextvars to store decimalcontext.

  • bpo-32622: Addasyncio.AbstractEventLoop.sendfile() method.

  • bpo-32304: distutils' upload command no longer corrupts tar files endingwith a CR byte, and no longer tries to convert CR to CRLF in any of theupload text fields.

  • bpo-32502: uuid.uuid1 no longer raises an exception if a 64-bit hardwareaddress is encountered.

  • bpo-32596:concurrent.futures importsThreadPoolExecutor andProcessPoolExecutor lazily (usingPEP 562). It makesimportasyncio about 15% faster because asyncio uses onlyThreadPoolExecutor by default.

  • bpo-31801: Add_ignore_ toEnum so temporary variables can be usedduring class construction without being turned into members.

  • bpo-32576: Use queue.SimpleQueue() in places where it can be invoked froma weakref callback.

  • bpo-32574: Fix memory leak in asyncio.Queue, when the queue has limitedsize and it is full, the cancelation of queue.put() can cause a memoryleak. Patch by: José Melero.

  • bpo-32521: The nis module is now compatible with new libnsl and headerslocation.

  • bpo-32467: collections.abc.ValuesView now inherits fromcollections.abc.Collection.

  • bpo-32473: Improve ABCMeta._dump_registry() output readability

  • bpo-32102: New argumentcapture_output for subprocess.run

  • bpo-32521: glibc has removed Sun RPC. Use replacement libtirpc headers andlibrary in nis module.

  • bpo-32493: UUID module fixes build for FreeBSD/OpenBSD

  • bpo-32503: Pickling with protocol 4 no longer creates too small frames.

  • bpo-29237: Create enum for pstats sorting options

  • bpo-32454: Add close(fd) function to the socket module.

  • bpo-25942: The subprocess module is now more graceful when handling aCtrl-C KeyboardInterrupt during subprocess.call, subprocess.run, or aPopen context manager. It now waits a short amount of time for the child(presumed to have also gotten the SIGINT) to exit, before continuing theKeyboardInterrupt exception handling. This still includes a SIGKILL inthe call() and run() APIs, but at least the child had a chance first.

  • bpo-32433: The hmac module now has hmac.digest(), which provides anoptimized HMAC digest.

  • bpo-28134: Sockets now auto-detect family, type and protocol from filedescriptor by default.

  • bpo-32404: Fix bug wheredatetime.datetime.fromtimestamp() did notcall __new__ indatetime.datetime subclasses.

  • bpo-32403: Improved speed ofdatetime.date anddatetime.datetime alternate constructors.

  • bpo-32228: Ensure thattruncate() preserves the file position (asreported bytell()) after writes longer than the buffer size.

  • bpo-32410: Implementloop.sock_sendfile for asyncio event loop.

  • bpo-22908: Added seek and tell to the ZipExtFile class. This only works ifthe file object used to open the zipfile is seekable.

  • bpo-32373: Add socket.getblocking() method.

  • bpo-32248: Addimportlib.resources andimportlib.abc.ResourceReader as the unified API for readingresources contained within packages. Loaders wishing to support resourcereading must implement theget_resource_reader() method. File-basedand zipimport-based loaders both implement these APIs.importlib.abc.ResourceLoader is deprecated in favor of these newAPIs.

  • bpo-32320: collections.namedtuple() now supports default values.

  • bpo-29302: Add contextlib.AsyncExitStack. Patch by Alexander Mohr and IlyaKulakov.

  • bpo-31961:Removed in Python 3.7.0b2. Theargs argument ofsubprocess.Popen can now be apath-like object. Ifargs is givenas a sequence, it's first element can now be apath-like object aswell.

  • bpo-31900: Thelocale.localeconv() function now sets temporarily theLC_CTYPE locale to theLC_NUMERIC locale to decodedecimal_point andthousands_sep byte strings if they are non-ASCIIor longer than 1 byte, and theLC_NUMERIC locale is different than theLC_CTYPE locale. This temporary change affects other threads. Samechange for thestr.format() method when formatting a number(int,float,float and subclasses) with then type (ex:'{:n}'.format(1234)).

  • bpo-31853: Use super().method instead of socket.method in SSLSocket. Theywere there most likely for legacy reasons.

  • bpo-31399: The ssl module now uses OpenSSL's X509_VERIFY_PARAM_set1_host()and X509_VERIFY_PARAM_set1_ip() API to verify hostname and IP addresses.Subject common name fallback can be disabled withSSLContext.hostname_checks_common_name.

  • bpo-14976: Add a queue.SimpleQueue class, an unbounded FIFO queue with areentrant C implementation of put().

Documentation

  • bpo-32724: Add references to some commands in the documentation of Pdb.Patch by Stéphane Wirtel

  • bpo-32649: Complete the C API documentation, profiling and tracing partwith the newly added per-opcode events.

  • bpo-17799: Explain real behaviour of sys.settrace and sys.setprofile andtheir C-API counterparts regarding which type of events are received ineach function. Patch by Pablo Galindo Salgado.

Tests

  • bpo-32721: Fix test_hashlib to not fail if the _md5 module is not built.

  • bpo-28414: Add test cases for IDNA 2003 and 2008 host names. IDNA 2003internationalized host names are working sincebpo-31399 has landed. IDNA2008 are still broken.

  • bpo-32604: Add a new "_xxsubinterpreters" extension module that exposesthe existing subinterpreter C-API and a new cross-interpreter data sharingmechanism. The module is primarily intended for more thorough testing ofthe existing subinterpreter support. Note that the _xxsubinterpretersmodule has been removed in 3.7.0rc1.

  • bpo-32602: Add test certs and test for ECDSA cert and EC/RSA dual mode.

  • bpo-32549: On Travis CI, Python now Compiles and uses a local copy ofOpenSSL 1.1.0g for testing.

Build

  • bpo-32635: Fix segfault of the crypt module when libxcrypt is providedinstead of libcrypt at the system.

  • bpo-32598: Use autoconf to detect OpenSSL libs, headers and supportedfeatures. The ax_check_openssl M4 macro uses pkg-config to locate OpenSSLand falls back to manual search.

  • bpo-32593: Drop support of FreeBSD 9 and older.

  • bpo-29708: If theSOURCE_DATE_EPOCH environment variable is set,py_compile will always create hash-based.pyc files.

Windows

  • bpo-32588: Create standalone _distutils_findvs module and add missing_queue module to installer.

  • bpo-29911: Ensure separate Modify and Uninstall buttons are displayed.

  • bpo-32507: Use app-local UCRT install rather than the proper update forold versions of Windows.

macOS

  • bpo-32726: Provide an additional, more modern macOS installer variant thatsupports macOS 10.9+ systems in 64-bit mode only. Upgrade the suppliedthird-party libraries to OpenSSL 1.1.0g and to SQLite 3.22.0. The 10.9+installer now links with and supplies its own copy of Tcl/Tk 8.6.

  • bpo-28440: No longer add /Library/Python/3.x/site-packages to sys.path formacOS framework builds to avoid future conflicts.

C API

  • bpo-32681: Fix uninitialized variable 'res' in the C implementation ofos.dup2. Patch by Stéphane Wirtel

  • bpo-10381: Add C API access to thedatetime.timezone constructor anddatetime.timzone.UTC singleton.

Python 3.7.0 alpha 4

Release date: 2018-01-08

Core and Builtins

  • bpo-31975: The default warning filter list now starts with a"default::DeprecationWarning:__main__" entry, so deprecation warnings areonce again shown by default in single-file scripts and at the interactiveprompt.

  • bpo-32226:__class_getitem__ is now an automatic class method.

  • bpo-32399: Add AIX uuid library support for RFC4122 using uuid_create() inlibc.a

  • bpo-32390: Fix the compilation failure on AIX after the f_fsid field hasbeen added to the object returned by os.statvfs() (bpo-32143). Originalpatch by Michael Felt.

  • bpo-32379: Make MRO computation faster when a class inherits from a singlebase.

  • bpo-32259: The error message of a TypeError raised when unpacknon-iterable is now more specific.

  • bpo-27169: The__debug__ constant is now optimized out at compiletime. This fixes alsobpo-22091.

  • bpo-32329: The-R option now turns on hash randomization whenthePYTHONHASHSEED environment variable is set to0.Previously, the option was ignored. Moreover,sys.flags.hash_randomization is now properly set to 0 when hashrandomization is turned off byPYTHONHASHSEED=0.

  • bpo-30416: The optimizer is now protected from spending much time doingcomplex calculations and consuming much memory for creating largeconstants in constant folding. Increased limits for constants that can beproduced in constant folding.

  • bpo-32282: Fix an unnecessary ifdef in the include of VersionHelpers.h insocketmodule on Windows.

  • bpo-30579: Implement TracebackType.__new__ to allow Python-level creationof traceback objects, and make TracebackType.tb_next mutable.

  • bpo-32260: Don't byte swap the input keys to the SipHash algorithm onbig-endian platforms. This should ensure siphash gives consistent resultsacross platforms.

  • bpo-31506: Improve the error message logic for object.__new__ andobject.__init__. Patch by Sanyam Khurana.

  • bpo-20361:-b and-bb now inject'default::BytesWarning' anderror::BytesWarning entries intosys.warnoptions, ensuring thatthey take precedence over any other warning filters configured via the-W option or thePYTHONWARNINGS environment variable.

  • bpo-32230:-Xdev now injects a'default' entry intosys.warnoptions, ensuring that it behaves identically to actually passing-Wdefault at the command line.

  • bpo-29240: Add a new UTF-8 mode: implementation of thePEP 540.

  • bpo-32226:PEP 560: Add support for__mro_entries__ and__class_getitem__. Implemented by Ivan Levkivskyi.

  • bpo-32225:PEP 562: Add support for module__getattr__ and__dir__. Implemented by Ivan Levkivskyi.

  • bpo-31901: Theatexit module now has its callback stored perinterpreter.

  • bpo-31650: ImplementPEP 552 (Deterministic pycs). Python now supportsinvalidating bytecode cache files bashed on a source content hash ratherthan source last-modified time.

  • bpo-29469: Move constant folding from bytecode layer to AST layer.Original patch by Eugene Toder.

Library

  • bpo-32506: Now that dict is defined as keeping insertion order, dropOrderedDict and just use plain dict.

  • bpo-32279: Add params to dataclasses.make_dataclasses(): init, repr, eq,order, hash, and frozen. Pass them through to dataclass().

  • bpo-32278: Make type information optional on dataclasses.make_dataclass().If omitted, the string 'typing.Any' is used.

  • bpo-32499: Add dataclasses.is_dataclass(obj), which returns True if obj isa dataclass or an instance of one.

  • bpo-32468: Improve frame repr() to mention filename, code name and currentline number.

  • bpo-23749: asyncio: Implement loop.start_tls()

  • bpo-32441: Return the new file descriptor (i.e., the second argument) fromos.dup2. Previously,None was always returned.

  • bpo-32422:functools.lru_cache uses less memory (3 words for eachcached key) and takes about 1/3 time for cyclic GC.

  • bpo-31721: Prevent Python crash from happening when Future._log_tracebackis set to True manually. Now it can only be set to False, or a ValueErroris raised.

  • bpo-32415: asyncio: Add Task.get_loop() and Future.get_loop()

  • bpo-26133: Don't unsubscribe signals in asyncio UNIX event loop oninterpreter shutdown.

  • bpo-32363: Make asyncio.Task.set_exception() and set_result() raiseNotImplementedError. Task._step() and Future.__await__() raise properexceptions when they are in an invalid state, instead of raising anAssertionError.

  • bpo-32357: Optimize asyncio.iscoroutine() and loop.create_task() fornon-native coroutines (e.g. async/await compiled with Cython).'loop.create_task(python_coroutine)' used to be 20% faster than'loop.create_task(cython_coroutine)'. Now, the latter is as fast.

  • bpo-32356: asyncio.transport.resume_reading() and pause_reading() are nowidempotent. New transport.is_reading() method is added.

  • bpo-32355: Optimize asyncio.gather(); now up to 15% faster.

  • bpo-32351: Use fastpath in asyncio.sleep if delay<0 (2x boost)

  • bpo-32348: Optimize asyncio.Future schedule/add/remove callback. Theoptimization shows 3-6% performance improvements of async/await code.

  • bpo-32331: Fix socket.settimeout() and socket.setblocking() to keepsocket.type as is. Fix socket.socket() constructor to reset any bit flagsapplied to socket's type. This change only affects OSes that haveSOCK_NONBLOCK and/or SOCK_CLOEXEC.

  • bpo-32248: Addimportlib.abc.ResourceReader as an ABC for loadersto provide a unified API for reading resources contained within packages.Also addimportlib.resources as the port ofimportlib_resources.

  • bpo-32311: Implement asyncio.create_task(coro) shortcut

  • bpo-32327: Convert asyncio functions that were documented as coroutines tocoroutines. Affected functions: loop.sock_sendall, loop.sock_recv,loop.sock_accept, loop.getaddrinfo, loop.getnameinfo.

  • bpo-32323:urllib.parse.urlsplit() does not convert zone-id (scope)to lower case for scoped IPv6 addresses in hostnames now.

  • bpo-32302: Fix bdist_wininst of distutils for CRT v142: it binarycompatible with CRT v140.

  • bpo-29711: Fixstop_serving in asyncio proactor loop kill alllistening servers

  • bpo-32308:re.sub() now replaces empty matches adjacent to aprevious non-empty match.

  • bpo-29970: Abort asyncio SSLProtocol connection if handshake not completewithin 10 seconds.

  • bpo-32314: Implement asyncio.run().

  • bpo-17852: Revert incorrect fix based on misunderstanding of_Py_PyAtExit() semantics.

  • bpo-32296: Implement asyncio._get_running_loop() and get_event_loop() inC. This makes them 4x faster.

  • bpo-32250: Implementasyncio.current_task() andasyncio.all_tasks(). Add helpers intended to be used by alternativetask implementations:asyncio._register_task,asyncio._enter_task,asyncio._leave_task andasyncio._unregister_task. Deprecateasyncio.Task.current_task() andasyncio.Task.all_tasks().

  • bpo-32255: A single empty field is now always quoted when written into aCSV file. This allows to distinguish an empty row from a row consisting ofa single empty field. Patch by Licht Takeuchi.

  • bpo-32277: RaiseNotImplementedError instead ofSystemError onplatforms wherechmod(...,follow_symlinks=False) is not supported.Patch by Anthony Sottile.

  • bpo-30050: New argument warn_on_full_buffer to signal.set_wakeup_fd letsyou control whether Python prints a warning on stderr when the wakeup fdbuffer overflows.

  • bpo-29137: Thefpectl library has been removed. It was never enabledby default, never worked correctly on x86-64, and it changed the PythonABI in ways that caused unexpected breakage of C extensions.

  • bpo-32273: Move asyncio.test_utils to test.test_asyncio.

  • bpo-32272: Remove asyncio.async() function.

  • bpo-32269: Add asyncio.get_running_loop() function.

  • bpo-32265: All class and static methods of builtin types now are correctlyclassified by inspect.classify_class_attrs() and grouped in pydoc ouput.Added types.ClassMethodDescriptorType for unbound class methods of builtintypes.

  • bpo-32253: Deprecateyieldfromlock,awaitlock,with(yieldfromlock) andwithawaitlock for asyncio synchronizationprimitives.

  • bpo-22589: Changed MIME type of .bmp from 'image/x-ms-bmp' to 'image/bmp'

  • bpo-32193: Convert asyncio to useasync/await syntax. Old styledyieldfrom is still supported too.

  • bpo-32206: Add support to run modules with pdb

  • bpo-32227:functools.singledispatch now supports registeringimplementations using type annotations.

  • bpo-15873: Added new alternate constructorsdatetime.datetime.fromisoformat(),datetime.time.fromisoformat() anddatetime.date.fromisoformat() as the inverse operation of eachclasses's respectiveisoformat methods.

  • bpo-32199: The getnode() ip getter now uses 'ip link' instead of 'ip linklist'.

  • bpo-32143: os.statvfs() includes the f_fsid field from statvfs(2)

  • bpo-26439: Fix ctypes.util.find_library() for AIX by implementingctypes._aix.find_library() Patch by: Michael Felt

  • bpo-31993: The pickler now uses less memory when serializing large bytesand str objects into a file. Pickles created with protocol 4 will requireless memory for unpickling large bytes and str objects.

  • bpo-27456: Ensure TCP_NODELAY is set on Linux. Tests by Victor Stinner.

  • bpo-31778: ast.literal_eval() is now more strict. Addition and subtractionof arbitrary numbers no longer allowed.

  • bpo-31802: Importing native path module (posixpath,ntpath) nowworks even if theos module still is not imported.

  • bpo-30241: Add contextlib.AbstractAsyncContextManager. Patch by JelleZijlstra.

  • bpo-31699: Fix deadlocks inconcurrent.futures.ProcessPoolExecutor when task arguments orresults cause pickling or unpickling errors. This should make sure thatcalls to theProcessPoolExecutor API always eventually return.

  • bpo-15216:TextIOWrapper.reconfigure() supports changingencoding,errors, andnewline.

Documentation

  • bpo-32418: Add get_loop() method to Server and AbstractServer classes.

Tests

  • bpo-32252: Fix faulthandler_suppress_crash_report() used to prevent coredump files when testing crashes. getrlimit() returns zero on success.

  • bpo-32002: Adjust C locale coercion testing for the empty locale and POSIXlocale cases to more readily adjust to platform dependent behaviour.

Windows

  • bpo-19764: Implement support forsubprocess.Popen(close_fds=True) onWindows. Patch by Segev Finer.

Tools/Demos

  • bpo-24960: 2to3 and lib2to3 can now read pickled grammar files usingpkgutil.get_data() rather than probing the filesystem. This lets 2to3 andlib2to3 work when run from a zipfile.

C API

  • bpo-32030: Py_Initialize() doesn't reset the memory allocators to defaultif thePYTHONMALLOC environment variable is not set.

  • bpo-29084: Undocumented C API for OrderedDict has been excluded from thelimited C API. It was added by mistake and actually never worked in thelimited C API.

  • bpo-32264: Moved the pygetopt.h header into internal/, since it has nopublic APIs.

  • bpo-32241:Py_SetProgramName() andPy_SetPythonHome()now take theconstwchar* arguments instead ofwchar*.

Python 3.7.0 alpha 3

Release date: 2017-12-05

Core and Builtins

  • bpo-32176: co_flags.CO_NOFREE is now always set correctly by the codeobject constructor based on freevars and cellvars, rather than needing tobe set correctly by the caller. This ensures it will be clearedautomatically when additional cell references are injected into a modifiedcode object and function.

  • bpo-10544: Yield expressions are now deprecated in comprehensions andgenerator expressions. They are still permitted in the definition of theoutermost iterable, as that is evaluated directly in the enclosing scope.

  • bpo-32137: The repr of deeply nested dict now raises a RecursionErrorinstead of crashing due to a stack overflow.

  • bpo-32096: Revert memory allocator changes in the C API: move structuresback from _PyRuntime to Objects/obmalloc.c. The memory allocators are onceagain initialized statically, and so PyMem_RawMalloc() andPy_DecodeLocale() can be called before _PyRuntime_Initialize().

  • bpo-32043: Add a new "developer mode": new "-X dev" command line option toenable debug checks at runtime.

  • bpo-32023: SyntaxError is now correctly raised when a generator expressionwithout parenthesis is used instead of an inheritance list in a classdefinition. The duplication of the parentheses can be omitted only oncalls.

  • bpo-32012: SyntaxError is now correctly raised when a generator expressionwithout parenthesis is passed as an argument, but followed by a trailingcomma. A generator expression always needs to be directly inside a set ofparentheses and cannot have a comma on either side.

  • bpo-28180: A new internal_Py_SetLocaleFromEnv(category) helperfunction has been added in order to improve the consistency of behaviouracross differentlibc implementations (e.g. Android doesn't supportsetting the locale from the environment by default).

  • bpo-31949: Fixed several issues in printing tracebacks(PyTraceBack_Print()). Setting sys.tracebacklimit to 0 or less nowsuppresses printing tracebacks. Setting sys.tracebacklimit to None nowcauses using the default limit. Setting sys.tracebacklimit to an integerlarger than LONG_MAX now means using the limit LONG_MAX rather than thedefault limit. Fixed integer overflows in the case of more than2**31traceback items on Windows. Fixed output errors handling.

  • bpo-30696: Fix the interactive interpreter looping endlessly when nomemory.

  • bpo-20047: Bytearray methods partition() and rpartition() now accept onlybytes-like objects as separator, as documented. In particular they nowraise TypeError rather of returning a bogus result when an integer ispassed as a separator.

  • bpo-21720: BytesWarning no longer emitted when thefromlist argument of__import__() or the__all__ attribute of the module contain bytesinstances.

  • bpo-31845: Environment variables are once more read correctly atinterpreter startup.

  • bpo-28936: Ensure that lexically first syntax error involving a parameterandglobal ornonlocal is detected first at a given scope. Patchby Ivan Levkivskyi.

  • bpo-31825: Fixed OverflowError in the 'unicode-escape' codec and incodecs.escape_decode() when decode an escaped non-ascii byte.

  • bpo-31618: The per-frame tracing logic added in 3.7a1 has been altered sothatframe->f_lineno is updated before either"line" or"opcode" events are emitted. Previously, opcode events were emittedfirst, and therefore would occasionally see stale line numbers on theframe. The behavior of this feature has changed slightly as a result: whenbothf_trace_lines andf_trace_opcodes are enabled, line eventsnow occur first.

  • bpo-28603: Print the full context/cause chain of exceptions on interpreterexit, even if an exception in the chain is unhashable or compares equal tolater ones. Patch by Zane Bitter.

  • bpo-31786: Fix timeout rounding in the select module to round correctlynegative timeouts between -1.0 and 0.0. The functions now block waitingfor events as expected. Previously, the call was incorrectly non-blocking.Patch by Pablo Galindo.

  • bpo-31781: Prevent crashes when calling methods of an uninitializedzipimport.zipimporter object. Patch by Oren Milman.

  • bpo-30399: Standard repr() of BaseException with a single argument nolonger contains redundant trailing comma.

  • bpo-31626: Fixed a bug in debug memory allocator. There was a write tofreed memory after shrinking a memory block.

  • bpo-30817:PyErr_PrintEx() clears now the ignored exception that maybe raised by_PySys_SetObjectId(), for example when no memory.

Library

  • bpo-28556: Two minor fixes fortyping module: allow shallow copyinginstances of generic classes, improve interaction of__init_subclass__with generics. Original PRs by Ivan Levkivskyi.

  • bpo-32214: PEP 557, Data Classes. Provides a decorator which addsboilerplate methods to classes which use type annotations so specifyfields.

  • bpo-27240: The header folding algorithm for the new email policies hasbeen rewritten, which also fixesbpo-30788,bpo-31831, andbpo-32182. Inparticular, RFC2231 folding is now done correctly.

  • bpo-32186: io.FileIO.readall() and io.FileIO.read() now release the GILwhen getting the file size. Fixed hang of all threads with inaccessibleNFS server. Patch by Nir Soffer.

  • bpo-32101: Addsys.flags.dev_mode flag

  • bpo-32154: Theasyncio.windows_utils.socketpair() function has beenremoved: use directlysocket.socketpair() which is available on allplatforms since Python 3.5 (before, it wasn't available on Windows).asyncio.windows_utils.socketpair() was just an alias tosocket.socketpair on Python 3.5 and newer.

  • bpo-32089: warnings: In development (-X dev) and debug mode (pydebugbuild), use the "default" action for ResourceWarning, rather than the"always" action, in the default warnings filters.

  • bpo-32107:uuid.getnode() now preferentially returns universallyadministered MAC addresses if available, over locally administered MACaddresses. This makes a better guarantee for global uniqueness of UUIDsreturned fromuuid.uuid1(). If only locally administered MACaddresses are available, the first such one found is returned.

  • bpo-23033: Wildcard is now supported in hostname when it is one and onlycharacter in the left most segment of hostname in second argument ofssl.match_hostname(). Patch by Mandeep Singh.

  • bpo-12239: Makemsilib.SummaryInformation.GetProperty() returnNone when the value of property isVT_EMPTY. Initial patch byMark Mc Mahon.

  • bpo-28334: Useos.path.expanduser() to find the~/.netrc file innetrc.netrc. If it does not exist,FileNotFoundError israised. Patch by Dimitri Merejkowsky.

  • bpo-32121: Madetracemalloc.Traceback behave more like the tracebackmodule, sorting the frames from oldest to most recent.Traceback.format() now accepts negativelimit, truncating the resultto theabs(limit) oldest frames. To get the old behaviour, one can usethe newmost_recent_first argument toTraceback.format(). (Patch byJesse Bakker.)

  • bpo-31325: Fix wrong usage ofcollections.namedtuple() in theRobotFileParser.parse()method. Initial patch by Robin Wellner.

  • bpo-12382:msilib.OpenDatabase() now raises a better exceptionmessage when it couldn't open or create an MSI file. Initial patch byWilliam Tisäter.

  • bpo-19610:setup() now warns about invalid types for some fields. Thedistutils.dist.Distribution class now warns whenclassifiers,keywords andplatforms fields are not specified as a list or astring.

  • bpo-32071: Added the-k command-line option topython-munittestto run only tests that match the given pattern(s).

  • bpo-10049: Addednullcontext no-op context manager to contextlib. Thisprovides a simpler and faster alternative to ExitStack() when handlingoptional context managers.

  • bpo-28684: The new test.support.skip_unless_bind_unix_socket() decoratoris used here to skip asyncio tests that fail because the platform lacks afunctional bind() function for unix domain sockets (as it is the case fornon root users on the recent Android versions that run now SELinux inenforcing mode).

  • bpo-32110:codecs.StreamReader.read(n) now returns not more thanncharacters/bytes for non-negativen. This makes it compatible withread() methods of other file-like objects.

  • bpo-27535: The warnings module doesn't leak memory anymore in the hiddenwarnings registry for the "ignore" action of warnings filters.warn_explicit() function doesn't add the warning key to the registryanymore for the "ignore" action.

  • bpo-32088: warnings: When Python is build is debug mode (Py_DEBUG),DeprecationWarning,PendingDeprecationWarning andImportWarning warnings are now displayed by default.

  • bpo-1647489: Fixed searching regular expression patterns that could matchan empty string. Non-empty string can now be correctly found aftermatching an empty string.

  • bpo-25054: Added support of splitting on a pattern that could match anempty string.

  • bpo-32072: Fixed issues with binary plists: Fixed saving bytearrays.Identical objects will be saved only once. Equal references will be loadas identical objects. Added support for saving and loading recursive datastructures.

  • bpo-32069: Drop legacy SSL transport from asyncio, ssl.MemoryBIO is alwaysused anyway.

  • bpo-32066: asyncio: Support pathlib.Path in create_unix_connection; sockarg should be optional

  • bpo-32046: Updates 2to3 to convert from operator.isCallable(obj) tocallable(obj). Patch by Donghee Na.

  • bpo-32018: inspect.signature should followPEP 8, if the parameter hasan annotation and a default value. Patch by Donghee Na.

  • bpo-32025: Add time.thread_time() and time.thread_time_ns()

  • bpo-32037: Integers that fit in a signed 32-bit integer will be nowpickled with protocol 0 using the INT opcode. This will decrease the sizeof a pickle, speed up pickling and unpickling, and make these integers beunpickled as int instances in Python 2.

  • bpo-32034: Make asyncio.IncompleteReadError and LimitOverrunErrorpickleable.

  • bpo-32015: Fixed the looping of asyncio in the case of reconnection thesocket during waiting async read/write from/to the socket.

  • bpo-32011: Restored support of loading marshal files with the TYPE_INT64code. These files can be produced in Python 2.7.

  • bpo-28369: Enhance add_reader/writer check that socket is not used by sometransport. Before, only cases when add_reader/writer were called with anint FD were supported. Now the check is implemented correctly for allfile-like objects.

  • bpo-31976: Fix race condition when flushing a file is slow, which cancause a segfault if closing the file from another thread.

  • bpo-31985: Formally deprecated aifc.openfp, sunau.openfp, and wave.openfp.Since change 7bc817d5ba917528e8bd07ec461c635291e7b06a in 1993, openfp ineach of the three modules had been pointing to that module's open functionas a matter of backwards compatibility, though it had been both untestedand undocumented.

  • bpo-21862: cProfile command line now accepts-mmodule_name as analternative to script path. Patch by Sanyam Khurana.

  • bpo-31970: Reduce performance overhead of asyncio debug mode.

  • bpo-31843:database argument of sqlite3.connect() now accepts apath-like object, instead of just a string.

  • bpo-31945: Add Configurableblocksize toHTTPConnection andHTTPSConnection for improved upload throughput. Patch by Nir Soffer.

  • bpo-31943: Add acancelled() method toasyncio.Handle. Patchby Marat Sharafutdinov.

  • bpo-9678: Fixed determining the MAC address in the uuid module: Usingifconfig on NetBSD and OpenBSD. Using arp on Linux, FreeBSD, NetBSD andOpenBSD. Based on patch by Takayuki Shimizukawa.

  • bpo-30057: Fix potential missed signal in signal.signal().

  • bpo-31933: Fix Blake2 params leaf_size and node_offset on big endianplatforms. Patch by Jack O'Connor.

  • bpo-21423: Add an initializer argument to {Process,Thread}PoolExecutor

  • bpo-31927: Fixed compilation of the socket module on NetBSD 8. Fixedassertion failure or reading arbitrary data when parse a AF_BLUETOOTHaddress on NetBSD and DragonFly BSD.

  • bpo-27666: Fixed stack corruption in curses.box() and curses.ungetmouse()when the size of types chtype or mmask_t is less than the size of C long.curses.box() now accepts characters as arguments. Based on patch by SteveFink.

  • bpo-31917: Add 3 new clock identifiers:time.CLOCK_BOOTTIME,time.CLOCK_PROF andtime.CLOCK_UPTIME.

  • bpo-31897: plistlib now catches more errors when read binary plists andraises InvalidFileException instead of unexpected exceptions.

  • bpo-25720: Fix the method for checking pad state of curses WINDOW. Patchby Masayuki Yamamoto.

  • bpo-31893: Fixed the layout of the kqueue_event structure on OpenBSD andNetBSD. Fixed the comparison of the kqueue_event objects.

  • bpo-31891: Fixed building the curses module on NetBSD.

  • bpo-31884: added required constants to subprocess module for settingpriority on windows

  • bpo-28281: Remove year (1-9999) limits on the Calendar.weekday() function.Patch by Mark Gollahon.

  • bpo-31702: crypt.mksalt() now allows to specify the number of rounds forSHA-256 and SHA-512 hashing.

  • bpo-30639:inspect.getfile() no longer computes the repr of unknownobjects to display in an error message, to protect against badly behavedcustom reprs.

  • bpo-30768: Fix the pthread+semaphore implementation ofPyThread_acquire_lock_timed() when called with timeout > 0 andintr_flag=0: recompute the timeout if sem_timedwait() is interrupted by asignal (EINTR). See also thePEP 475.

  • bpo-31854: Addmmap.ACCESS_DEFAULT constant.

  • bpo-31834: Use optimized code for BLAKE2 only with SSSE3+. The pure SSE2implementation is slower than the pure C reference implementation.

  • bpo-28292: Calendar.itermonthdates() will now consistently raise anexception when a date falls outside of the 0001-01-01 through 9999-12-31range. To support applications that cannot tolerate such exceptions, thenew methods itermonthdays3() and itermonthdays4() are added. The newmethods return tuples and are not restricted by the range supported bydatetime.date.

  • bpo-28564: The shutil.rmtree() function has been sped up to 20--40%. Thiswas done using the os.scandir() function.

  • bpo-28416: Instances of pickle.Pickler subclass with the persistent_id()method and pickle.Unpickler subclass with the persistent_load() method nolonger create reference cycles.

  • bpo-31653: Don't release the GIL if we can acquire a multiprocessingsemaphore immediately.

  • bpo-28326: Fix multiprocessing.Process when stdout and/or stderr is closedor None.

  • bpo-20825: Addsubnet_of andsuperset_of containment tests toipaddress.IPv6Network andipaddress.IPv4Network. Patchby Michel Albert and Cheryl Sabella.

  • bpo-31827: Remove the os.stat_float_times() function. It was introduced inPython 2.3 for backward compatibility with Python 2.2, and was deprecatedsince Python 3.1.

  • bpo-31756: Add asubprocess.Popen(text=False) keyword argument tosubprocess functions to be more explicit about when the library shouldattempt to decode outputs into text. Patch by Andrew Clegg.

  • bpo-31819: Add AbstractEventLoop.sock_recv_into().

  • bpo-31457: If nested log adapters are used, the innerprocess()methods are no longer omitted.

  • bpo-31457: Themanager property on LoggerAdapter objects is nowproperly settable.

  • bpo-31806: Fix timeout rounding in time.sleep(), threading.Lock.acquire()and socket.socket.settimeout() to round correctly negative timeoutsbetween -1.0 and 0.0. The functions now block waiting for events asexpected. Previously, the call was incorrectly non-blocking. Patch byPablo Galindo.

  • bpo-31803: time.clock() and time.get_clock_info('clock') now emit aDeprecationWarning warning.

  • bpo-31800: Extended support for parsing UTC offsets. strptime '%z' can nowparse the output generated by datetime.isoformat, including seconds andmicroseconds.

  • bpo-28603: traceback: Fix a TypeError that occurred during printing ofexception tracebacks when either the current exception or an exception inits context/cause chain is unhashable. Patch by Zane Bitter.

  • bpo-30541: Add new function to seal a mock and prevent the automaticallycreation of child mocks. Patch by Mario Corchero.

  • bpo-31784: Implement thePEP 564, add new 6 new functions withnanosecond resolution to thetime module:clock_gettime_ns(),clock_settime_ns(),monotonic_ns(),perf_counter_ns(),process_time_ns(),time_ns().

  • bpo-30143: 2to3 now generates a code that uses abstract collection classesfrom collections.abc rather than collections.

  • bpo-31770: Prevent a crash when calling the__init__() method of asqlite3.Cursor object more than once. Patch by Oren Milman.

  • bpo-31764: Prevent a crash insqlite3.Cursor.close() in case theCursor object is uninitialized. Patch by Oren Milman.

  • bpo-31752: Fix possible crash in timedelta constructor called with customintegers.

  • bpo-31620: an empty asyncio.Queue now doesn't leak memory when queue.getpollers timeout

  • bpo-31690: Allow the flags re.ASCII, re.LOCALE, and re.UNICODE to be usedas group flags for regular expressions.

  • bpo-30349: FutureWarning is now emitted if a regular expression containscharacter set constructs that will change semantically in the future(nested sets and set operations).

  • bpo-31664: Added support for the Blowfish hashing in the crypt module.

  • bpo-31632: Fix method set_protocol() of class _SSLProtocolTransport inasyncio module. This method was previously modifying a wrong reference tothe protocol.

  • bpo-15037: Added a workaround for getkey() in curses for ncurses 5.7 andearlier.

  • bpo-31307: Allow use of bytes objects for arguments toconfigparser.ConfigParser.read(). Patch by Vincent Michel.

  • bpo-31334: Fixpoll.poll([timeout]) in theselect module forarbitrary negative timeouts on all OSes where it can only be anon-negative integer or -1. Patch by Riccardo Coccioli.

  • bpo-31310: multiprocessing's semaphore tracker should be launched again ifcrashed.

  • bpo-31308: Make multiprocessing's forkserver process immune to Ctrl-C andother user interruptions. If it crashes, restart it when necessary.

  • bpo-31245: Added support for AF_UNIX socket in asynciocreate_datagram_endpoint.

  • bpo-30553: Add HTTP/2 status code 421 (Misdirected Request) tohttp.HTTPStatus. Patch by Vitor Pereira.

Documentation

  • bpo-32105: Added asyncio.BaseEventLoop.connect_accepted_socketversionadded marker.

Tests

  • bpo-31380: Skip test_httpservers test_undecodable_file on macOS: fails onAPFS.

  • bpo-31705: Skip test_socket.test_sha256() on Linux kernel older than 4.5.The test fails with ENOKEY on kernel 3.10 (on ppc64le). A fix was mergedinto the kernel 4.5.

  • bpo-32138: Skip on Android test_faulthandler tests that raise SIGSEGV andremove the test.support.requires_android_level decorator.

  • bpo-32136: The runtime embedding tests have been split out fromLib/test/test_capi.py into a newLib/test/test_embed.py file.

  • bpo-28668: test.support.requires_multiprocessing_queue is removed. Skiptests with test.support.import_module('multiprocessing.synchronize')instead when the semaphore implementation is broken or missing.

  • bpo-32126: Skip test_get_event_loop_new_process intest.test_asyncio.test_events when sem_open() is not functional.

  • bpo-31174: Fix test_tools.test_unparse: DirectoryTestCase now stores thenames sample to always test the same files. It prevents false alarms whenhunting reference leaks.

Build

  • bpo-28538: Revert the previous changes, the if_nameindex structure isdefined by Unified Headers.

  • bpo-28762: Revert the last commit, the F_LOCK macro is defined by AndroidUnified Headers.

  • bpo-29040: Support building Android with Unified Headers. The first NDKrelease to support Unified Headers is android-ndk-r14.

  • bpo-32059:detect_modules() insetup.py now also searches thesysroot paths when cross-compiling.

  • bpo-31957: Fixes Windows SDK version detection when building for Windows.

  • bpo-31609: Fixes quotes in PCbuild/clean.bat

  • bpo-31934: Abort the build when building out of a not clean source tree.

  • bpo-31926: Fixed Argument Clinic sometimes causing compilation errors whenthere was more than one function and/or method in a .c file with the samename.

  • bpo-28791: Update Windows builds to use SQLite 3.21.0.

  • bpo-28791: Update OS X installer to use SQLite 3.21.0.

  • bpo-28643: Record profile-opt build progress with stamp files.

  • bpo-31866: Finish removing support for AtheOS.

Windows

  • bpo-1102: ReturnNone whenView.Fetch() returnsERROR_NO_MORE_ITEMS instead of raisingMSIError. Initial patch byAnthony Tuininga.

  • bpo-31944: Fixes Modify button in Apps and Features dialog.

  • bpo-20486: Implement theDatabase.Close() method to help closing MSIdatabase objects.

  • bpo-31857: Make the behavior of USE_STACKCHECK deterministic in amulti-threaded environment.

macOS

  • bpo-31392: Update macOS installer to use OpenSSL 1.0.2m

IDLE

  • bpo-32207: Improve tk event exception tracebacks in IDLE. When tk eventhandling is driven by IDLE's run loop, a confusing and distractingqueue.EMPTY traceback context is no longer added to tk event exceptiontracebacks. The traceback is now the same as when event handling isdriven by user code. Patch based on a suggestion by Serhiy Storchaka.

  • bpo-32164: Delete unused file idlelib/tabbedpages.py. Use of TabbedPageSetin configdialog was replaced by ttk.Notebook.

  • bpo-32100: IDLE: Fix old and new bugs in pathbrowser; improve tests. Patchmostly by Cheryl Sabella.

  • bpo-31858: IDLE -- Restrict shell prompt manipulation to the shell. Editorand output windows only see an empty last prompt line. This simplifiesthe code and fixes a minor bug when newline is inserted. Sys.ps1, ifpresent, is read on Shell start-up, but is not set or changed.

  • bpo-31860: The font sample in the IDLE configuration dialog is noweditable. Changes persist while IDLE remains open

  • bpo-31836: Test_code_module now passes if run after test_idle, which setsps1. The code module uses sys.ps1 if present or sets it to '>>> ' if not.Test_code_module now properly tests both behaviors. Ditto for ps2.

  • bpo-28603: Fix a TypeError that caused a shell restart when printing atraceback that includes an exception that is unhashable. Patch by ZaneBitter.

  • bpo-13802: Use non-Latin characters in the IDLE's Font settings sample.Even if one selects a font that defines a limited subset of the unicodeBasic Multilingual Plane, tcl/tk will use other fonts that define acharacter. The expanded example give users of non-Latin characters abetter idea of what they might see in IDLE's shell and editors. To makeroom for the expanded sample, frames on the Font tab are re-arranged. TheFont/Tabs help explains a bit about the additions.

Tools/Demos

  • bpo-32159: Remove CVS and Subversion tools: remove svneol.py andtreesync.py scripts. CPython migrated from CVS to Subversion, toMercurial, and then to Git. CVS and Subversion are no longer used todevelop CPython.

  • bpo-30722: Make redemo work with Python 3.6 and newer versions. Also,remove theLOCALE option since it doesn't work with string patterns inPython 3. Patch by Christoph Sarnowski.

C API

  • bpo-20891: Fix PyGILState_Ensure(). When PyGILState_Ensure() is called ina non-Python thread before PyEval_InitThreads(), only callPyEval_InitThreads() after calling PyThreadState_New() to fix a crash.

  • bpo-32125: ThePy_UseClassExceptionsFlag flag has been removed. It wasdeprecated and wasn't used anymore since Python 2.0.

  • bpo-25612: Move the current exception state from the frame object to theco-routine. This simplifies the interpreter and fixes a couple of obscurebugs caused by having swap exception state when entering or exiting agenerator.

  • bpo-23699: Add Py_RETURN_RICHCOMPARE macro to reduce boilerplate code inrich comparison functions.

  • bpo-30697: ThePyExc_RecursionErrorInst singleton is removed andPyErr_NormalizeException() does not use it anymore. This singleton ispersistent and its members being never cleared may cause a segfault duringfinalization of the interpreter. See alsobpo-22898.

Python 3.7.0 alpha 2

Release date: 2017-10-16

Core and Builtins

  • bpo-31558:gc.freeze() is a new API that allows for moving all objectscurrently tracked by the garbage collector to a permanent generation,effectively removing them from future collection events. This can be usedto protect those objects from having their PyGC_Head mutated. In effect,this enables great copy-on-write stability at fork().

  • bpo-31642: Restored blocking "from package import module" by settingsys.modules["package.module"] to None.

  • bpo-31708: Allow use of asynchronous generator expressions in synchronousfunctions.

  • bpo-31709: Drop support of asynchronous __aiter__.

  • bpo-30404: The -u option now makes the stdout and stderr streamsunbuffered rather than line-buffered.

  • bpo-31619: Fixed a ValueError when convert a string with large number ofunderscores to integer with binary base.

  • bpo-31602: Fix an assertion failure inzipimporter.get_source() incase of a badzlib.decompress(). Patch by Oren Milman.

  • bpo-31592: Fixed an assertion failure in Python parser in case of a badunicodedata.normalize(). Patch by Oren Milman.

  • bpo-31588: Raise aTypeError with a helpful error message when classcreation fails due to a metaclass with a bad__prepare__() method.Patch by Oren Milman.

  • bpo-31574: Importlib was instrumented with two dtrace probes to profileimport timing.

  • bpo-31566: Fix an assertion failure in_warnings.warn() in case of abad__name__ global. Patch by Oren Milman.

  • bpo-31506: Improved the error message logic forobject.__new__ andobject.__init__.

  • bpo-31505: Fix an assertion failure injson, in case_json.make_encoder() received a badencoder() argument. Patch byOren Milman.

  • bpo-31492: Fix assertion failures in case of failing to import from amodule with a bad__name__ attribute, and in case of failing to accessan attribute of such a module. Patch by Oren Milman.

  • bpo-31478: Fix an assertion failure in_random.Random.seed() in casethe argument has a bad__abs__() method. Patch by Oren Milman.

  • bpo-31336: Speed up class creation by 10-20% by reducing the overhead inthe necessary special method lookups. Patch by Stefan Behnel.

  • bpo-31415: Add-Ximporttime option to show how long each importtakes. It can be used to optimize application's startup time. Support thePYTHONPROFILEIMPORTTIME as an equivalent way to enable this.

  • bpo-31410: Optimized calling wrapper and classmethod descriptors.

  • bpo-31353:PEP 553 - Add a new built-in calledbreakpoint() whichcallssys.breakpointhook(). By default this importspdb and callspdb.set_trace(), but users may overridesys.breakpointhook() tocall whatever debugger they want. The original value of the hook is savedinsys.__breakpointhook__.

  • bpo-17852: Maintain a list of open buffered files, flush them beforeexiting the interpreter. Based on a patch from Armin Rigo.

  • bpo-31315: Fix an assertion failure in imp.create_dynamic(), whenspec.name is not a string. Patch by Oren Milman.

  • bpo-31311: Fix a crash in the__setstate__() method ofctypes._CData, in case of a bad__dict__. Patch by Oren Milman.

  • bpo-31293: Fix crashes in true division and multiplication of a timedeltaobject by a float with a bad as_integer_ratio() method. Patch by OrenMilman.

  • bpo-31285: Fix an assertion failure inwarnings.warn_explicit, whenthe return value of the received loader'sget_source() has a badsplitlines() method. Patch by Oren Milman.

  • bpo-30406: Makeasync andawait proper keywords, as specified inPEP 492.

Library

  • bpo-30058: Fixed buffer overflow in select.kqueue.control().

  • bpo-31672:idpattern instring.Template matched some non-ASCIIcharacters. Now it uses-i regular expression local flag to avoidnon-ASCII characters.

  • bpo-31701: On Windows, faulthandler.enable() now ignores MSC and COMexceptions.

  • bpo-31728: Prevent crashes in_elementtree due to unsafe cleanup ofElement.text andElement.tail. Patch by Oren Milman.

  • bpo-31671: Nowre.compile() converts passed RegexFlag to normal intobject before compiling. bm_regex_compile benchmark shows 14% performanceimprovements.

  • bpo-30397: The types of compiled regular objects and match objects are nowexposed asre.Pattern andre.Match. This adds information inpydoc output for there module.

  • bpo-31675: Fixed memory leaks in Tkinter's methods splitlist() and split()when pass a string larger than 2 GiB.

  • bpo-31673: Fixed typo in the name of Tkinter's method adderrorinfo().

  • bpo-31648: Improvements to path predicates in ElementTree: Allowwhitespace around predicate parts, i.e. "[a = 'text']" instead ofrequiring the less readable "[a='text']". Add support for text comparisonof the current node, like "[.='text']". Patch by Stefan Behnel.

  • bpo-30806: Fix the string representation of a netrc object.

  • bpo-31638: Add optional argumentcompressed tozipapp.create_archive, and add option--compress to the commandline interface ofzipapp.

  • bpo-25351: Avoid venv activate failures with undefined variables

  • bpo-20519: Avoid ctypes use (if possible) and improve import time foruuid.

  • bpo-28293: The regular expression cache is no longer completely dumpedwhen it is full.

  • bpo-31596: Added pthread_getcpuclockid() to the time module

  • bpo-27494: Make 2to3 accept a trailing comma in generator expressions. Forexample,set(xforxin[],) is now allowed.

  • bpo-30347: Stop crashes when concurrently iterate over itertools.groupby()iterators.

  • bpo-30346: An iterator produced by itertools.groupby() iterator nowbecomes exhausted after advancing the groupby iterator.

  • bpo-31556: Cancel asyncio.wait_for future faster if timeout <= 0

  • bpo-31540: Allow passing a context object inconcurrent.futures.ProcessPoolExecutor constructor. Also, freejob resources inconcurrent.futures.ProcessPoolExecutor earlierto improve memory usage when a worker waits for new jobs.

  • bpo-31516:threading.current_thread() should not return a dummy threadat shutdown.

  • bpo-31525: In the sqlite module, require the sqlite3_prepare_v2 API. Thus,the sqlite module now requires sqlite version at least 3.3.9.

  • bpo-26510: argparse subparsers are now required by default. This matchesbehaviour in Python 2. For optional subparsers, use the new parameteradd_subparsers(required=False). Patch by Anthony Sottile. (As of3.7.0rc1, the default was changed to not required as had been the casesince Python 3.3.)

  • bpo-27541: Reprs of subclasses of some collection and iterator classes(bytearray,array.array,collections.deque,collections.defaultdict,itertools.count,itertools.repeat)now contain actual type name instead of hardcoded names of the base class.

  • bpo-31351: python -m ensurepip now exits with non-zero exit code if pipbootstrapping has failed.

  • bpo-31389:pdb.set_trace() now takes an optional keyword-only argumentheader. If given, this is printed to the console just before debuggingbegins.

Documentation

  • bpo-31537: Fix incorrect usage ofget_history_length in readlinedocumentation example code. Patch by Brad Smith.

  • bpo-30085: The operator functions without double underscores are preferredfor clarity. The one with underscores are only kept forback-compatibility.

Build

  • bpo-31696: Improve compiler version information insys.versionwhen Python is built with Clang.

  • bpo-31625: Stop using ranlib on static libraries. Instead, we assume arsupports the 's' flag.

  • bpo-31624: Remove support for BSD/OS.

  • bpo-22140: Prevent double substitution of prefix in python-config.sh.

  • bpo-31569: Correct PCBuild/ case to PCbuild/ in build scripts anddocumentation.

  • bpo-31536: Avoid wholesale rebuild aftermakeregen-all if nothingchanged.

IDLE

  • bpo-31460: Simplify the API of IDLE's Module Browser. Passing a widgetinstead of an flist with a root widget opens the option of creating abrowser frame that is only part of a window. Passing a full file nameinstead of pieces assumed to come from a .py file opens the possibility ofbrowsing python files that do not end in .py.

  • bpo-31649: IDLE - Make _htest, _utest parameters keyword only.

  • bpo-31559: Remove test order dependence in idle_test.test_browser.

  • bpo-31459: Rename IDLE's module browser from Class Browser to ModuleBrowser. The original module-level class and method browser became amodule browser, with the addition of module-level functions, years ago.Nested classes and functions were added yesterday. Forback-compatibility, the virtual event <<open-class-browser>>, whichappears on the Keys tab of the Settings dialog, is not changed. Patch byCheryl Sabella.

  • bpo-31500: Default fonts now are scaled on HiDPI displays.

  • bpo-1612262: IDLE module browser now shows nested classes and functions.Original patches for code and tests by Guilherme Polo and Cheryl Sabella,respectively.

C API

  • bpo-28280: MakePyMapping_Keys(),PyMapping_Values() andPyMapping_Items() always return alist (rather than alist oratuple). Patch by Oren Milman.

  • bpo-31532: Fix memory corruption due to allocator mix in getpath.c betweenPy_GetPath() and Py_SetPath()

  • bpo-25658: ImplementPEP 539 for Thread Specific Storage (TSS) API: itis a new Thread Local Storage (TLS) API to CPython which would supersedeuse of the existing TLS API within the CPython interpreter, whiledeprecating the existing API. PEP written by Erik M. Bray, patch byMasayuki Yamamoto.

Python 3.7.0 alpha 1

Release date: 2017-09-19

Security

  • bpo-29781: SSLObject.version() now correctly returns None when handshakeover BIO has not been performed yet.

  • bpo-29505: Add fuzz tests for float(str), int(str), unicode(str); foross-fuzz.

  • bpo-30947: Upgrade libexpat embedded copy from version 2.2.1 to 2.2.3 toget security fixes.

  • bpo-30730: Prevent environment variables injection in subprocess onWindows. Prevent passing other environment variables and commandarguments.

  • bpo-30694: Upgrade expat copy from 2.2.0 to 2.2.1 to get fixes of multiplesecurity vulnerabilities including:CVE 2017-9233 (External entityinfinite loop DoS),CVE 2016-9063 (Integer overflow, re-fix),CVE 2016-0718 (Fix regression bugs from 2.2.0's fix toCVE 2016-0718) andCVE 2012-0876 (Counter hash flooding withSipHash). Note: theCVE 2016-5300 (Use os-specific entropy sources likegetrandom) doesn't impact Python, since Python already gets entropy fromthe OS to set the expat secret usingXML_SetHashSalt().

  • bpo-30500: Fix urllib.parse.splithost() to correctly parse fragments. Forexample,splithost('//127.0.0.1#@evil.com/') now correctly returns the127.0.0.1 host, instead of treating@evil.com as the host in anauthentication (login@host).

  • bpo-29591: Update expat copy from 2.1.1 to 2.2.0 to get fixes ofCVE 2016-0718 andCVE 2016-4472. Seehttps://sourceforge.net/p/expat/bugs/537/ for more information.

Core and Builtins

  • bpo-31490: Fix an assertion failure inctypes class definition, incase the class has an attribute whose name is specified in_anonymous_but not in_fields_. Patch by Oren Milman.

  • bpo-31471: Fix an assertion failure insubprocess.Popen() on Windows,in case the env argument has a badkeys() method. Patch by OrenMilman.

  • bpo-31418: Fix an assertion failure inPyErr_WriteUnraisable() in caseof an exception with a bad__module__ attribute. Patch by Oren Milman.

  • bpo-31416: Fix assertion failures in case of a bad warnings.filters orwarnings.defaultaction. Patch by Oren Milman.

  • bpo-28411: Change direct usage of PyInterpreterState.modules toPyImport_GetModuleDict(). Also introduce more uniformity in other codethat deals with sys.modules. This helps reduce complications when workingon sys.modules.

  • bpo-28411: Switch to the abstract API when dealing withPyInterpreterState.modules. This allows later support for all dictsubclasses and other Mapping implementations. Also add aPyImport_GetModule() function to reduce a bunch of duplicated code.

  • bpo-31411: Raise a TypeError instead of SystemError in casewarnings.onceregistry is not a dictionary. Patch by Oren Milman.

  • bpo-31344: For finer control of tracing behaviour when testing theinterpreter, two new frame attributes have been added to control theemission of particular trace events:f_trace_lines (True bydefault) to turn off per-line trace events; andf_trace_opcodes(False by default) to turn on per-opcode trace events.

  • bpo-31373: Fix several possible instances of undefined behavior due tofloating-point demotions.

  • bpo-30465: Location information (lineno andcol_offset) inf-strings is now (mostly) correct. This fixes tools like flake8 fromshowing warnings on the wrong line (typically the first line of the file).

  • bpo-30860: Consolidate CPython's global runtime state under a singlestruct. This improves discoverability of the runtime state.

  • bpo-31347: Fix possible undefined behavior in _PyObject_FastCall_Prepend.

  • bpo-31343: Include sys/sysmacros.h for major(), minor(), and makedev().GNU C libray plans to remove the functions from sys/types.h.

  • bpo-31291: Fix an assertion failure inzipimport.zipimporter.get_dataon Windows, when the return value ofpathname.replace('/','\\') isn'ta string. Patch by Oren Milman.

  • bpo-31271: Fix an assertion failure in thewrite() method ofio.TextIOWrapper, when the encoder doesn't return a bytes object.Patch by Oren Milman.

  • bpo-31243: Fix a crash in some methods ofio.TextIOWrapper, when thedecoder's state is invalid. Patch by Oren Milman.

  • bpo-30721:print now shows correct usage hint for using Python 2redirection syntax. Patch by Sanyam Khurana.

  • bpo-31070: Fix a race condition in importlib _get_module_lock().

  • bpo-30747: Add a non-dummy implementation of _Py_atomic_store and_Py_atomic_load on MSVC.

  • bpo-31095: Fix potential crash during GC caused bytp_dealloc whichdoesn't callPyObject_GC_UnTrack().

  • bpo-31071: Avoid masking original TypeError in call with * unpacking whenother arguments are passed.

  • bpo-30978: str.format_map() now passes key lookup exceptions through.Previously any exception was replaced with a KeyError exception.

  • bpo-30808: Use _Py_atomic API for concurrency-sensitive signal state.

  • bpo-30876: Relative import from unloaded package now reimports the packageinstead of failing with SystemError. Relative import from non-package nowfails with ImportError rather than SystemError.

  • bpo-30703: Improve signal delivery. Avoid using Py_AddPendingCall fromsignal handler, to avoid calling signal-unsafe functions. The tests I'madding here fail without the rest of the patch, on Linux and OS X. Thismeans our signal delivery logic had defects (some signals could be lost).

  • bpo-30765: Avoid blocking in pthread_mutex_lock() whenPyThread_acquire_lock() is asked not to block.

  • bpo-31161: Make sure the 'Missing parentheses' syntax error message isonly applied to SyntaxError, not to subclasses. Patch by Martijn Pieters.

  • bpo-30814: Fixed a race condition when import a submodule from a package.

  • bpo-30736: The internal unicodedata database has been upgraded to Unicode10.0.

  • bpo-30604: Move co_extra_freefuncs from per-thread to per-interpreter toavoid crashes.

  • bpo-30597:print now shows expected input in custom error message whenused as a Python 2 statement. Patch by Sanyam Khurana.

  • bpo-30682: Removed a too-strict assertion that failed for certainf-strings, such as eval("f'\n'") and eval("f'\r'").

  • bpo-30501: The compiler now produces more optimal code for complexcondition expressions in the "if", "while" and "assert" statement, the"if" expression, and generator expressions and comprehensions.

  • bpo-28180: ImplementPEP 538 (legacy C locale coercion). This meansthat when a suitable coercion target locale is available, both the coreinterpreter and locale-aware C extensions will assume the use of UTF-8 asthe default text encoding, rather than ASCII.

  • bpo-30486: Allows setting cell values for __closure__. Patch by LisaRoach.

  • bpo-30537: itertools.islice now accepts integer-like objects (having an__index__ method) as start, stop, and slice arguments

  • bpo-25324: Tokens needed for parsing in Python moved to C.COMMENT,NL andENCODING. This way the tokens and tok_names in the tokenmodule don't get changed when you import the tokenize module.

  • bpo-29104: Fixed parsing backslashes in f-strings.

  • bpo-27945: Fixed various segfaults with dict when input collections aremutated during searching, inserting or comparing. Based on patches byDuane Griffin and Tim Mitchell.

  • bpo-25794: Fixed type.__setattr__() and type.__delattr__() fornon-interned attribute names. Based on patch by Eryk Sun.

  • bpo-30039: If a KeyboardInterrupt happens when the interpreter is in themiddle of resuming a chain of nested 'yield from' or 'await' calls, it'snow correctly delivered to the innermost frame.

  • bpo-28974:object.__format__(x,'') is now equivalent tostr(x)rather thanformat(str(self),'').

  • bpo-30024: Circular imports involving absolute imports with binding asubmodule to a name are now supported.

  • bpo-12414: sys.getsizeof() on a code object now returns the sizes whichincludes the code struct and sizes of objects which it references. Patchby Donghee Na.

  • bpo-29839: len() now raises ValueError rather than OverflowError if__len__() returned a large negative integer.

  • bpo-11913: README.rst is now included in the list of distutils standardREADMEs and therefore included in source distributions.

  • bpo-29914: Fixed default implementations of __reduce__ and__reduce_ex__(). object.__reduce__() no longer takes arguments,object.__reduce_ex__() now requires one argument.

  • bpo-29949: Fix memory usage regression of set and frozenset object.

  • bpo-29935: Fixed error messages in the index() method of tuple, list anddeque when pass indices of wrong type.

  • bpo-29816: Shift operation now has less opportunity to raiseOverflowError. ValueError always is raised rather than OverflowError fornegative counts. Shifting zero with non-negative count always returnszero.

  • bpo-24821: Fixed the slowing down to 25 times in the searching of someunlucky Unicode characters.

  • bpo-29102: Add a unique ID to PyInterpreterState. This makes it easier toidentify each subinterpreter.

  • bpo-29894: The deprecation warning is emitted if __complex__ returns aninstance of a strict subclass of complex. In a future versions of Pythonthis can be an error.

  • bpo-29859: Show correct error messages when any of the pthread_* calls inthread_pthread.h fails.

  • bpo-29849: Fix a memory leak when an ImportError is raised during fromimport.

  • bpo-28856: Fix an oversight that %b format for bytes should supportobjects follow the buffer protocol.

  • bpo-29723: Thesys.path[0] initialization change forbpo-29139 causeda regression by revealing an inconsistency in how sys.path is initializedwhen executing__main__ from a zipfile, directory, or other importlocation. The interpreter now consistently avoids ever adding the importlocation's parent directory tosys.path, and ensures no othersys.path entries are inadvertently modified when inserting the importlocation named on the command line.

  • bpo-29568: Escaped percent "%%" in the format string for classic stringformatting no longer allows any characters between two percents.

  • bpo-29714: Fix a regression that bytes format may fail when containingzero bytes inside.

  • bpo-29695: bool(), float(), list() and tuple() no longer take keywordarguments. The first argument of int() can now be passes only aspositional argument.

  • bpo-28893: Set correct __cause__ for errors about invalid awaitablesreturned from __aiter__ and __anext__.

  • bpo-28876:bool(range) works even iflen(range) raisesOverflowError.

  • bpo-29683: Fixes to memory allocation in _PyCode_SetExtra. Patch by BrianColeman.

  • bpo-29684: Fix minor regression of PyEval_CallObjectWithKeywords. Itshould raise TypeError when kwargs is not a dict. But it might cause segvwhen args=NULL and kwargs is not a dict.

  • bpo-28598: Support __rmod__ for subclasses of str being called beforestr.__mod__. Patch by Martijn Pieters.

  • bpo-29607: Fix stack_effect computation for CALL_FUNCTION_EX. Patch byMatthieu Dartiailh.

  • bpo-29602: Fix incorrect handling of signed zeros in complex constructorfor complex subclasses and for inputs having a __complex__ method. Patchby Serhiy Storchaka.

  • bpo-29347: Fixed possibly dereferencing undefined pointers when creatingweakref objects.

  • bpo-29463: Adddocstring field to Module, ClassDef, FunctionDef, andAsyncFunctionDef ast nodes. docstring is not first stmt in their bodyanymore. It affectsco_firstlineno andco_lnotab of code objectfor module and class. (Reverted inbpo-32911.)

  • bpo-29438: Fixed use-after-free problem in key sharing dict.

  • bpo-29546: Set the 'path' and 'name' attribute on ImportError forfrom...import....

  • bpo-29546: Improve from-import error message with location

  • bpo-29478: If max_line_length=None is specified while using the Compat32policy, it is no longer ignored. Patch by Mircea Cosbuc.

  • bpo-29319: Prevent RunMainFromImporter overwriting sys.path[0].

  • bpo-29337: Fixed possible BytesWarning when compare the code objects.Warnings could be emitted at compile time.

  • bpo-29327: Fixed a crash when pass the iterable keyword argument tosorted().

  • bpo-29034: Fix memory leak and use-after-free in os module(path_converter).

  • bpo-29159: Fix regression in bytes(x) when x.__index__() raises Exception.

  • bpo-29049: Call _PyObject_GC_TRACK() lazily when calling Python function.Calling function is up to 5% faster.

  • bpo-28927: bytes.fromhex() and bytearray.fromhex() now ignore all ASCIIwhitespace, not only spaces. Patch by Robert Xiao.

  • bpo-28932: Do not include <sys/random.h> if it does not exist.

  • bpo-25677: Correct the positioning of the syntax error caret for indentedblocks. Based on patch by Michael Layzell.

  • bpo-29000: Fixed bytes formatting of octals with zero padding in alternateform.

  • bpo-18896: Python function can now have more than 255 parameters.collections.namedtuple() now supports tuples with more than 255 elements.

  • bpo-28596: The preferred encoding is UTF-8 on Android. Patch written byChi Hsuan Yen.

  • bpo-22257: Clean up interpreter startup (seePEP 432).

  • bpo-26919: On Android, operating system data is now always encoded/decodedto/from UTF-8, instead of the locale encoding to avoid inconsistencieswith os.fsencode() and os.fsdecode() which are already using UTF-8.

  • bpo-28991: functools.lru_cache() was susceptible to an obscure reentrancybug triggerable by a monkey-patched len() function.

  • bpo-28147: Fix a memory leak in split-table dictionaries: setattr() mustnot convert combined table into split table. Patch written by INADA Naoki.

  • bpo-28739: f-string expressions are no longer accepted as docstrings andby ast.literal_eval() even if they do not include expressions.

  • bpo-28512: Fixed setting the offset attribute of SyntaxError byPyErr_SyntaxLocationEx() and PyErr_SyntaxLocationObject().

  • bpo-28918: Fix the cross compilation of xxlimited when Python has beenbuilt with Py_DEBUG defined.

  • bpo-23722: Rather than silently producing a class that doesn't supportzero-argumentsuper() in methods, failing to pass the new__classcell__ namespace entry up totype.__new__ now results in aDeprecationWarning and a class that supports zero-argumentsuper().

  • bpo-28797: Modifying the class __dict__ inside the __set_name__ method ofa descriptor that is used inside that class no longer prevents calling the__set_name__ method of other descriptors.

  • bpo-28799: Remove thePyEval_GetCallStats() function and deprecate theuntested and undocumentedsys.callstats() function. Remove theCALL_PROFILE special build: use thesys.setprofile() function,cProfile orprofile to profile function calls.

  • bpo-12844: More than 255 arguments can now be passed to a function.

  • bpo-28782: Fix a bug in the implementationyieldfrom when checking ifthe next instruction is YIELD_FROM. Regression introduced by WORDCODE(bpo-26647).

  • bpo-28774: Fix error position of the unicode error in ASCII and Latin1encoders when a string returned by the error handler contains multiplenon-encodable characters (non-ASCII for the ASCII codec, characters out ofthe U+0000-U+00FF range for Latin1).

  • bpo-28731: Optimize _PyDict_NewPresized() to create correct size dict.Improve speed of dict literal with constant keys up to 30%.

  • bpo-28532: Show sys.version when -V option is supplied twice.

  • bpo-27100: The with-statement now checks for __enter__ before it checksfor __exit__. This gives less confusing error messages when both methodsare missing. Patch by Jonathan Ellington.

  • bpo-28746: Fix the set_inheritable() file descriptor method on platformsthat do not have the ioctl FIOCLEX and FIONCLEX commands.

  • bpo-26920: Fix not getting the locale's charset upon initializing theinterpreter, on platforms that do not have langinfo.

  • bpo-28648: Fixed crash in Py_DecodeLocale() in debug build on Mac OS Xwhen decode astral characters. Patch by Xiang Zhang.

  • bpo-28665: Improve speed of the STORE_DEREF opcode by 40%.

  • bpo-19398: Extra slash no longer added to sys.path components in case ofempty compile-time PYTHONPATH components.

  • bpo-28621: Sped up converting int to float by reusing faster bits countingimplementation. Patch by Adrian Wielgosik.

  • bpo-28580: Optimize iterating split table values. Patch by Xiang Zhang.

  • bpo-28583: PyDict_SetDefault didn't combine split table when needed. Patchby Xiang Zhang.

  • bpo-28128: Deprecation warning for invalid str and byte escape sequencesnow prints better information about where the error occurs. Patch bySerhiy Storchaka and Eric Smith.

  • bpo-28509: dict.update() no longer allocate unnecessary large memory.

  • bpo-28426: Fixed potential crash in PyUnicode_AsDecodedObject() in debugbuild.

  • bpo-28517: Fixed of-by-one error in the peephole optimizer that causedkeeping unreachable code.

  • bpo-28214: Improved exception reporting for problematic __set_name__attributes.

  • bpo-23782: Fixed possible memory leak in _PyTraceback_Add() and exceptionloss in PyTraceBack_Here().

  • bpo-28183: Optimize and cleanup dict iteration.

  • bpo-26081: Added C implementation of asyncio.Future. Original patch byYury Selivanov.

  • bpo-28379: Added sanity checks and tests for PyUnicode_CopyCharacters().Patch by Xiang Zhang.

  • bpo-28376: The type of long range iterator is now registered as Iterator.Patch by Oren Milman.

  • bpo-28376: Creating instances of range_iterator by calling range_iteratortype now is disallowed. Calling iter() on range instance is the only way.Patch by Oren Milman.

  • bpo-26906: Resolving special methods of uninitialized type now causesimplicit initialization of the type instead of a fail.

  • bpo-18287: PyType_Ready() now checks that tp_name is not NULL. Originalpatch by Niklas Koep.

  • bpo-24098: Fixed possible crash when AST is changed in process ofcompiling it.

  • bpo-28201: Dict reduces possibility of 2nd conflict in hash table whenhashes have same lower bits.

  • bpo-28350: String constants with null character no longer interned.

  • bpo-26617: Fix crash when GC runs during weakref callbacks.

  • bpo-27942: String constants now interned recursively in tuples andfrozensets.

  • bpo-28289: ImportError.__init__ now resets not specified attributes.

  • bpo-21578: Fixed misleading error message when ImportError called withinvalid keyword args.

  • bpo-28203: Fix incorrect type in complex(1.0, {2:3}) error message. Patchby Soumya Sharma.

  • bpo-28086: Single var-positional argument of tuple subtype was passedunscathed to the C-defined function. Now it is converted to exact tuple.

  • bpo-28214: Now __set_name__ is looked up on the class instead of theinstance.

  • bpo-27955: Fallback on reading /dev/urandom device when the getrandom()syscall fails with EPERM, for example when blocked by SECCOMP.

  • bpo-28192: Don't import readline in isolated mode.

  • bpo-27441: Remove some redundant assignments to ob_size in longobject.c.Thanks Oren Milman.

  • bpo-27222: Clean up redundant code in long_rshift function. Thanks OrenMilman.

  • Upgrade internal unicode databases to Unicode version 9.0.0.

  • bpo-28131: Fix a regression in zipimport's compile_source(). zipimportshould use the same optimization level as the interpreter.

  • bpo-28126: Replace Py_MEMCPY with memcpy(). Visual Studio can properlyoptimize memcpy().

  • bpo-28120: Fix dict.pop() for splitted dictionary when trying to remove a"pending key" (Not yet inserted in split-table). Patch by Xiang Zhang.

  • bpo-26182: Raise DeprecationWarning when async and await keywords are usedas variable/attribute/class/function name.

  • bpo-26182: Fix a refleak in code that raises DeprecationWarning.

  • bpo-28721: Fix asynchronous generators aclose() and athrow() to handleStopAsyncIteration propagation properly.

  • bpo-26110: Speed-up method calls: add LOAD_METHOD and CALL_METHOD opcodes.

Library

  • bpo-31499: xml.etree: Fix a crash when a parser is part of a referencecycle.

  • bpo-31482:random.seed() now works with bytes in version=1

  • bpo-28556: typing.get_type_hints now finds the right globalns for classesand modules by default (when noglobalns was specified by the caller).

  • bpo-28556: Speed improvements to thetyping module. Original PRs byIvan Levkivskyi and Mitar.

  • bpo-31544: The C accelerator module of ElementTree ignored exceptionsraised when looking up TreeBuilder target methods in XMLParser().

  • bpo-31234: socket.create_connection() now fixes manually a referencecycle: clear the variable storing the last exception on success.

  • bpo-31457: LoggerAdapter objects can now be nested.

  • bpo-31431: SSLContext.check_hostname now automatically setsSSLContext.verify_mode to ssl.CERT_REQUIRED instead of failing with aValueError.

  • bpo-31233: socketserver.ThreadingMixIn now keeps a list of non-daemonicthreads to wait until all these threads complete in server_close().

  • bpo-28638: Changed the implementation strategy forcollections.namedtuple() to substantially reduce the use of exec() infavor of precomputed methods. As a result, theverbose parameter and_source attribute are no longer supported. The benefits include 1)having a smaller memory footprint for applications using multiple namedtuples, 2) faster creation of the named tuple class (approx 4x to 6xdepending on how it is measured), and 3) minor speed-ups for instancecreation using __new__, _make, and _replace. (The primary patchcontributor is Jelle Zijlstra with further improvements by INADA Naoki,Serhiy Storchaka, and Raymond Hettinger.)

  • bpo-31400: Improves SSL error handling to avoid losing error numbers.

  • bpo-27629: Make return types of SSLContext.wrap_bio() andSSLContext.wrap_socket() customizable.

  • bpo-28958: ssl.SSLContext() now uses OpenSSL error information when acontext cannot be instantiated.

  • bpo-28182: The SSL module now raises SSLCertVerificationError when OpenSSLfails to verify the peer's certificate. The exception contains moreinformation about the error.

  • bpo-27340: SSLSocket.sendall() now uses memoryview to create slices ofdata. This fixes support for all bytes-like object. It is also moreefficient and avoids costly copies.

  • bpo-14191: A new functionargparse.ArgumentParser.parse_intermixed_args provides the ability toparse command lines where there user intermixes options and positionalarguments.

  • bpo-31178: Fix string concatenation bug in rare error path in thesubprocess module

  • bpo-31350: Micro-optimizeasyncio._get_running_loop() to become upto 10% faster.

  • bpo-31170: expat: Update libexpat from 2.2.3 to 2.2.4. Fix copying ofpartial characters for UTF-8 input (libexpat bug 115):https://github.com/libexpat/libexpat/issues/115

  • bpo-29136: Add TLS 1.3 cipher suites and OP_NO_TLSv1_3.

  • bpo-1198569:string.Template subclasses can optionally definebraceidpattern if they want to specify different placeholder patternsinside and outside the braces. If None (the default) it falls back toidpattern.

  • bpo-31326: concurrent.futures.ProcessPoolExecutor.shutdown() nowexplicitly closes the call queue. Moreover, shutdown(wait=True) now alsojoin the call queue thread, to prevent leaking a dangling thread.

  • bpo-27144: Themap() andas_completed() iterators inconcurrent.futures now avoid keeping a reference to yielded objects.

  • bpo-31281: Fixfileinput.FileInput(files,inplace=True) whenfilescontainpathlib.Path objects.

  • bpo-10746: Fix ctypes producing wrongPEP 3118 type codes for integertypes.

  • bpo-27584:AF_VSOCK has been added to the socket interface whichallows communication between virtual machines and their host.

  • bpo-22536: The subprocess module now sets the filename whenFileNotFoundError is raised on POSIX systems due to the executable or cwdnot being found.

  • bpo-29741: Update some methods in the _pyio module to also accept integertypes. Patch by Oren Milman.

  • bpo-31249: concurrent.futures: WorkItem.run() used by ThreadPoolExecutornow breaks a reference cycle between an exception object and the WorkItemobject.

  • bpo-31247: xmlrpc.server now explicitly breaks reference cycles when usingsys.exc_info() in code handling exceptions.

  • bpo-23835: configparser: reading defaults in theConfigParser()constructor is now usingread_dict(), making its behavior consistentwith the rest of the parser. Non-string keys and values in the defaultsdictionary are now being implicitly converted to strings. Patch by JamesTocknell.

  • bpo-31238: pydoc: the stop() method of the private ServerThread class nowwaits until DocServer.serve_until_quit() completes and then explicitlysets its docserver attribute to None to break a reference cycle.

  • bpo-5001: Many asserts inmultiprocessing are now more informative,and some error types have been changed to more specific ones.

  • bpo-31109: Convert zipimport to use Argument Clinic.

  • bpo-30102: The ssl and hashlib modules now callOPENSSL_add_all_algorithms_noconf() on OpenSSL < 1.1.0. The functiondetects CPU features and enables optimizations on some CPU architecturessuch as POWER8. Patch is based on research from Gustavo Serra Scalet.

  • bpo-18966: Non-daemonic threads created by a multiprocessing.Process arenow joined on child exit.

  • bpo-31183:dis now works with asynchronous generator and coroutineobjects. Patch by George Collins based on diagnosis by Luciano Ramalho.

  • bpo-5001: There are a number of uninformative asserts in themultiprocessing module, as noted in issue 5001. This change fixes twoof the most potentially problematic ones, since they are inerror-reporting code, in themultiprocessing.managers.convert_to_errorfunction. (It also makes more informative a ValueError message.) The onlypotentially problematic change is that the AssertionError is now aTypeError; however, this should also help distinguish it from anAssertionError beingreported by the function/its caller (such as inissue 31169). - Patch by Allen W. Smith (drallensmith on github).

  • bpo-31185: Fixed miscellaneous errors in asyncio speedup module.

  • bpo-31151: socketserver.ForkingMixIn.server_close() now waits until allchild processes completed to prevent leaking zombie processes.

  • bpo-31072: Add aninclude_file parameter tozipapp.create_archive()

  • bpo-24700: Optimize array.array comparison. It is now from 10x up to 70xfaster when comparing arrays holding values of the same integer type.

  • bpo-31135: ttk: fix the destroy() method of LabeledScale and OptionMenuclasses. Call the parent destroy() method even if the used attributedoesn't exist. The LabeledScale.destroy() method now also explicitlyclears label and scale attributes to help the garbage collector to destroyall widgets.

  • bpo-31107: Fixcopyreg._slotnames() mangled attribute calculation forclasses whose name begins with an underscore. Patch by Shane Harvey.

  • bpo-31080: Allowlogging.config.fileConfig to accept kwargs and/orargs.

  • bpo-30897:pathlib.Path objects now include anis_mount() method(only implemented on POSIX). This is similar toos.path.ismount(p).Patch by Cooper Ry Lees.

  • bpo-31061: Fixed a crash when using asyncio and threads.

  • bpo-30987: Added support for CAN ISO-TP protocol in the socket module.

  • bpo-30522: Added asetStream method tologging.StreamHandler toallow the stream to be set after creation.

  • bpo-30502: Fix handling of long oids in ssl. Based on patch by ChristianHeimes.

  • bpo-5288: Support tzinfo objects with sub-minute offsets.

  • bpo-30919: Fix shared memory performance regression in multiprocessing in3.x. Shared memory used anonymous memory mappings in 2.x, while 3.x mmapsactual files. Try to be careful to do as little disk I/O as possible.

  • bpo-26732: Fix too many fds in processes started with the "forkserver"method. A child process would inherit as many fds as the number ofstill-running children.

  • bpo-29403: Fixunittest.mock's autospec to not fail on method-boundbuiltin functions. Patch by Aaron Gallagher.

  • bpo-30961: Fix decrementing a borrowed reference in tracemalloc.

  • bpo-19896: Fix multiprocessing.sharedctypes to recognize typecodes'q'and'Q'.

  • bpo-30946: Remove obsolete code in readline module for platforms where GNUreadline is older than 2.1 or where select() is not available.

  • bpo-25684: Changettk.OptionMenu radiobuttons to be unique acrossinstances ofOptionMenu.

  • bpo-30886: Fix multiprocessing.Queue.join_thread(): it now waits until thethread completes, even if the thread was started by the same process whichcreated the queue.

  • bpo-29854: Fix segfault in readline when using readline's history-sizeoption. Patch by Nir Soffer.

  • bpo-30794: Added multiprocessing.Process.kill method to terminate usingthe SIGKILL signal on Unix.

  • bpo-30319: socket.close() now ignores ECONNRESET error.

  • bpo-30828: Fix out of bounds write inasyncio.CFuture.remove_done_callback().

  • bpo-30302: Use keywords in therepr ofdatetime.timedelta.

  • bpo-30807: signal.setitimer() may disable the timer when passed a tinyvalue. Tiny values (such as 1e-6) are valid non-zero values forsetitimer(), which is specified as taking microsecond-resolutionintervals. However, on some platform, our conversion routine could convert1e-6 into a zero interval, therefore disabling the timer instead of(re-)scheduling it.

  • bpo-30441: Fix bug when modifying os.environ while iterating over it

  • bpo-29585: Avoid importingsysconfig fromsite to improve startupspeed. Python startup is about 5% faster on Linux and 30% faster on macOS.

  • bpo-29293: Add missing parameter "n" onmultiprocessing.Condition.notify(). The doc claimsmultiprocessing.Condition behaves like threading.Condition, but itsnotify() method lacked the optional "n" argument (to specify the number ofsleepers to wake up) that threading.Condition.notify() accepts.

  • bpo-30532: Fix email header value parser dropping folding white space incertain cases.

  • bpo-30596: Add aclose() method tomultiprocessing.Process.

  • bpo-9146: Fix a segmentation fault in _hashopenssl when standard hashfunctions such as md5 are not available in the linked OpenSSL library. Asin some special FIPS-140 build environments.

  • bpo-29169: Update zlib to 1.2.11.

  • bpo-30119: ftplib.FTP.putline() now throws ValueError on commands thatcontains CR or LF. Patch by Donghee Na.

  • bpo-30879: os.listdir() and os.scandir() now emit bytes names when calledwith bytes-like argument.

  • bpo-30746: Prohibited the '=' character in environment variable names inos.putenv() andos.spawn*().

  • bpo-30664: The description of a unittest subtest now preserves the orderof keyword arguments of TestCase.subTest().

  • bpo-21071: struct.Struct.format type is nowstr instead ofbytes.

  • bpo-29212: Fix concurrent.futures.thread.ThreadPoolExecutor threads tohave a non repr() based thread name by default when no thread_name_prefixis supplied. They will now identify themselves as"ThreadPoolExecutor-y_n".

  • bpo-29755: Fixed the lgettext() family of functions in the gettext module.They now always return bytes.

  • bpo-30616: Functional API of enum allows to create empty enums. Patched byDonghee Na

  • bpo-30038: Fix race condition between signal delivery and wakeup filedescriptor. Patch by Nathaniel Smith.

  • bpo-23894: lib2to3 now recognizesrb'...' andf'...' strings.

  • bpo-24744: pkgutil.walk_packages function now raises ValueError ifpathis a string. Patch by Sanyam Khurana.

  • bpo-24484: Avoid race condition in multiprocessing cleanup.

  • bpo-30589: Fix multiprocessing.Process.exitcode to return the opposite ofthe signal number when the process is killed by a signal (instead of 255)when using the "forkserver" method.

  • bpo-28994: The traceback no longer displayed for SystemExit raised in acallback registered by atexit.

  • bpo-30508: Don't log exceptions if Task/Future "cancel()" method wascalled.

  • bpo-30645: Fix path calculation inimp.load_package(), fixing it forcases when a package is only shipped with bytecodes. Patch by AlexandruArdelean.

  • bpo-11822: The dis.dis() function now is able to disassemble nested codeobjects.

  • bpo-30624: selectors does not take KeyboardInterrupt and SystemExit intoaccount, leaving a fd in a bad state in case of error. Patch by GiampaoloRodola'.

  • bpo-30595: multiprocessing.Queue.get() with a timeout now polls its readerin non-blocking mode if it succeeded to acquire the lock but the acquiretook longer than the timeout.

  • bpo-28556: Updates to typing module: Add generic AsyncContextManager, addsupport for ContextManager on all versions. Original PRs by Jelle Zijlstraand Ivan Levkivskyi

  • bpo-30605: re.compile() no longer raises a BytesWarning when compiling abytes instance with misplaced inline modifier. Patch by Roy Williams.

  • bpo-29870: Fix ssl sockets leaks when connection is aborted in asyncio/sslimplementation. Patch by Michaël Sghaïer.

  • bpo-29743: Closing transport during handshake process leaks open socket.Patch by Nikolay Kim

  • bpo-27585: Fix waiter cancellation in asyncio.Lock. Patch by MathieuSornay.

  • bpo-30014: modify() method of poll(), epoll() and devpoll() based classesof selectors module is around 10% faster. Patch by Giampaolo Rodola'.

  • bpo-30418: On Windows, subprocess.Popen.communicate() now also ignoreEINVAL on stdin.write() if the child process is still running but closedthe pipe.

  • bpo-30463: Addded empty __slots__ to abc.ABC. This allows subclassers todeny __dict__ and __weakref__ creation. Patch by Aaron Hall.

  • bpo-30520: Loggers are now pickleable.

  • bpo-30557: faulthandler now correctly filters and displays exception codeson Windows

  • bpo-30526: Add TextIOWrapper.reconfigure() and aTextIOWrapper.write_through attribute.

  • bpo-30245: Fix possible overflow when organize struct.pack_into errormessage. Patch by Yuan Liu.

  • bpo-30378: Fix the problem that logging.handlers.SysLogHandler cannothandle IPv6 addresses.

  • bpo-16500: Allow registering at-fork handlers.

  • bpo-30470: Deprecate invalid ctypes call protection on Windows. Patch byMariatta Wijaya.

  • bpo-30414: multiprocessing.Queue._feed background running thread do notbreak from main loop on exception.

  • bpo-30003: Fix handling escape characters in HZ codec. Based on patch byMa Lin.

  • bpo-30149: inspect.signature() now supports callables withvariable-argument parameters wrapped with partialmethod. Patch by DongheeNa.

  • bpo-30436: importlib.find_spec() raises ModuleNotFoundError instead ofAttributeError if the specified parent module is not a package (i.e. lacksa __path__ attribute).

  • bpo-30301: Fix AttributeError when using SimpleQueue.empty() underspawnandforkserver start methods.

  • bpo-30375: Warnings emitted when compile a regular expression now alwayspoint to the line in the user code. Previously they could point intoinners of the re module if emitted from inside of groups or conditionals.

  • bpo-30329: imaplib and poplib now catch the Windows socket WSAEINVAL error(code 10022) on shutdown(SHUT_RDWR): An invalid operation was attempted.This error occurs sometimes on SSL connections.

  • bpo-29196: Removed previously deprecated in Python 2.4 classes Plist, Dictand _InternalDict in the plistlib module. Dict values in the result offunctions readPlist() and readPlistFromBytes() are now normal dicts. Youno longer can use attribute access to access items of these dictionaries.

  • bpo-9850: Themacpath is now deprecated and will be removed inPython 3.8.

  • bpo-30299: Compiling regular expression in debug mode on CPython nowdisplays the compiled bytecode in human readable form.

  • bpo-30048: FixedTask.cancel() can be ignored when the task is runningcoroutine and the coroutine returned without any moreawait.

  • bpo-30266: contextlib.AbstractContextManager now supportsanti-registration by setting __enter__ = None or __exit__ = None,following the pattern introduced inbpo-25958. Patch by Jelle Zijlstra.

  • bpo-30340: Enhanced regular expressions optimization. This increased theperformance of matching some patterns up to 25 times.

  • bpo-30298: Weaken the condition of deprecation warnings for inlinemodifiers. Now allowed several subsequential inline modifiers at the startof the pattern (e.g.'(?i)(?s)...'). In verbose mode whitespaces andcomments now are allowed before and between inline modifiers (e.g.'(?x)(?i)(?s)...').

  • bpo-30285: Optimized case-insensitive matching and searching of regularexpressions.

  • bpo-29990: Fix range checking in GB18030 decoder. Original patch by MaLin.

  • bpo-29979: rewrite cgi.parse_multipart, reusing the FieldStorage class andmaking its results consistent with those of FieldStorage formultipart/form-data requests. Patch by Pierre Quentel.

  • bpo-30243: Removed the __init__ methods of _json's scanner and encoder.Misusing them could cause memory leaks or crashes. Now scanner andencoder objects are completely initialized in the __new__ methods.

  • bpo-30215: Compiled regular expression objects with the re.LOCALE flag nolonger depend on the locale at compile time. Only the locale at matchingtime affects the result of matching.

  • bpo-30185: Avoid KeyboardInterrupt tracebacks in forkserver helper processwhen Ctrl-C is received.

  • bpo-30103: binascii.b2a_uu() and uu.encode() now support using'`' aszero instead of space.

  • bpo-28556: Various updates to typing module: add typing.NoReturn type, useWrapperDescriptorType, minor bug-fixes. Original PRs by JimFasarakis-Hilliard and Ivan Levkivskyi.

  • bpo-30205: Fix getsockname() for unbound AF_UNIX sockets on Linux.

  • bpo-30228: The seek() and tell() methods of io.FileIO now set the internalseekable attribute to avoid one syscall on open() (in buffered or textmode).

  • bpo-30190: unittest's assertAlmostEqual and assertNotAlmostEqual provide abetter message in case of failure which includes the difference betweenleft and right arguments. (patch by Giampaolo Rodola')

  • bpo-30101: Add support for curses.A_ITALIC.

  • bpo-29822: inspect.isabstract() now works during __init_subclass__. Patchby Nate Soares.

  • bpo-29960: Preserve generator state when _random.Random.setstate() raisesan exception. Patch by Bryan Olson.

  • bpo-30070: Fixed leaks and crashes in errors handling in the parsermodule.

  • bpo-22352: Column widths in the output of dis.dis() are now adjusted forlarge line numbers and instruction offsets.

  • bpo-30061: Fixed crashes in IOBase methods __next__() and readlines() whenreadline() or __next__() respectively return non-sizeable object. Fixedpossible other errors caused by not checking results of PyObject_Size(),PySequence_Size(), or PyMapping_Size().

  • bpo-30218: Fix PathLike support for shutil.unpack_archive. Patch by JelleZijlstra.

  • bpo-10076: Compiled regular expression and match objects in the re modulenow support copy.copy() and copy.deepcopy() (they are considered atomic).

  • bpo-30068: _io._IOBase.readlines will check if it's closed first when hintis present.

  • bpo-29694: Fixed race condition in pathlib mkdir with flags parents=True.Patch by Armin Rigo.

  • bpo-29692: Fixed arbitrary unchaining of RuntimeError exceptions incontextlib.contextmanager. Patch by Siddharth Velankar.

  • bpo-26187: Test that sqlite3 trace callback is not called multiple timeswhen schema is changing. Indirectly fixed by switching to usesqlite3_prepare_v2() inbpo-9303. Patch by Aviv Palivoda.

  • bpo-30017: Allowed calling the close() method of the zip entry writerobject multiple times. Writing to a closed writer now always produces aValueError.

  • bpo-29998: Pickling and copying ImportError now preserves name and pathattributes.

  • bpo-29995: re.escape() now escapes only regex special characters.

  • bpo-29962: Add math.remainder operation, implementing remainder asspecified in IEEE 754.

  • bpo-29649: Improve struct.pack_into() exception messages for problems withthe buffer size and offset. Patch by Andrew Nester.

  • bpo-29654: Support If-Modified-Since HTTP header (browser cache). Patchby Pierre Quentel.

  • bpo-29931: Fixed comparison check for ipaddress.ip_interface objects.Patch by Sanjay Sundaresan.

  • bpo-29953: Fixed memory leaks in the replace() method of datetime and timeobjects when pass out of bound fold argument.

  • bpo-29942: Fix a crash in itertools.chain.from_iterable when encounteringlong runs of empty iterables.

  • bpo-10030: Sped up reading encrypted ZIP files by 2 times.

  • bpo-29204: Element.getiterator() and the html parameter of XMLParser()were deprecated only in the documentation (since Python 3.2 and 3.4correspondingly). Now using them emits a deprecation warning.

  • bpo-27863: Fixed multiple crashes in ElementTree caused by race conditionsand wrong types.

  • bpo-25996: Added support of file descriptors in os.scandir() on Unix.os.fwalk() is sped up by 2 times by using os.scandir().

  • bpo-28699: Fixed a bug in pools in multiprocessing.pool that raising anexception at the very first of an iterable may swallow the exception ormake the program hang. Patch by Davin Potts and Xiang Zhang.

  • bpo-23890: unittest.TestCase.assertRaises() now manually breaks areference cycle to not keep objects alive longer than expected.

  • bpo-29901: The zipapp module now supports general path-like objects, notjust pathlib.Path.

  • bpo-25803: Avoid incorrect errors raised by Path.mkdir(exist_ok=True) whenthe OS gives priority to errors such as EACCES over EEXIST.

  • bpo-29861: Release references to tasks, their arguments and their resultsas soon as they are finished in multiprocessing.Pool.

  • bpo-19930: The mode argument of os.makedirs() no longer affects the filepermission bits of newly created intermediate-level directories.

  • bpo-29884: faulthandler: Restore the old sigaltstack during teardown.Patch by Christophe Zeitouny.

  • bpo-25455: Fixed crashes in repr of recursive buffered file-like objects.

  • bpo-29800: Fix crashes in partial.__repr__ if the keys of partial.keywordsare not strings. Patch by Michael Seifert.

  • bpo-8256: Fixed possible failing or crashing input() if attributes"encoding" or "errors" of sys.stdin or sys.stdout are not set or are notstrings.

  • bpo-28692: Using non-integer value for selecting a plural form in gettextis now deprecated.

  • bpo-26121: Use C library implementation for math functions erf() anderfc().

  • bpo-29619: os.stat() and os.DirEntry.inode() now convert inode (st_ino)using unsigned integers.

  • bpo-28298: Fix a bug that prevented array 'Q', 'L' and 'I' from acceptingbig intables (objects that have __int__) as elements.

  • bpo-29645: Speed up importing the webbrowser module.webbrowser.register() is now thread-safe.

  • bpo-28231: The zipfile module now accepts path-like objects for externalpaths.

  • bpo-26915: index() and count() methods of collections.abc.Sequence nowcheck identity before checking equality when do comparisons.

  • bpo-28682: Added support for bytes paths in os.fwalk().

  • bpo-29728: Add newsocket.TCP_NOTSENT_LOWAT (Linux 3.12)constant. Patch by Nathaniel J. Smith.

  • bpo-29623: Allow use of path-like object as a single argument inConfigParser.read(). Patch by David Ellis.

  • bpo-9303: Migrate sqlite3 module to _v2 API. Patch by Aviv Palivoda.

  • bpo-28963: Fix out of bound iteration inasyncio.Future.remove_done_callback implemented in C.

  • bpo-29704: asyncio.subprocess.SubprocessStreamProtocol no longer closesbefore all pipes are closed.

  • bpo-29271: Fix Task.current_task and Task.all_tasks implemented in C toaccept None argument as their pure Python implementation.

  • bpo-29703: Fix asyncio to support instantiation of new event loops inchild processes.

  • bpo-29615: SimpleXMLRPCDispatcher no longer chains KeyError (or any otherexception) to exception(s) raised in the dispatched methods. Patch by PetrMotejlek.

  • bpo-7769: Method register_function() ofxmlrpc.server.SimpleXMLRPCDispatcher and its subclasses can now be used asa decorator.

  • bpo-29376: Fix assertion error in threading._DummyThread.is_alive().

  • bpo-28624: Add a test that checks that cwd parameter of Popen() acceptsPathLike objects. Patch by Sayan Chowdhury.

  • bpo-28518: Start a transaction implicitly before a DML statement. Patch byAviv Palivoda.

  • bpo-29742: get_extra_info() raises exception if get called on closed ssltransport. Patch by Nikolay Kim.

  • bpo-16285: urllib.parse.quote is now based on RFC 3986 and hence includes'~' in the set of characters that is not quoted by default. Patch byChristian Theune and Ratnadeep Debnath.

  • bpo-29532: Altering a kwarg dictionary passed to functools.partial() nolonger affects a partial object after creation.

  • bpo-29110: Fix file object leak in aifc.open() when file is given as afilesystem path and is not in valid AIFF format. Patch by Anthony Zhang.

  • bpo-22807: Add uuid.SafeUUID and uuid.UUID.is_safe to relay informationfrom the platform about whether generated UUIDs are generated with amultiprocessing safe method.

  • bpo-29576: Improve some deprecations in importlib. Some deprecated methodsnow emit DeprecationWarnings and have better descriptive messages.

  • bpo-29534: Fixed different behaviour of Decimal.from_float() for _decimaland _pydecimal. Thanks Andrew Nester.

  • bpo-10379: locale.format_string now supports the 'monetary' keywordargument, and locale.format is deprecated.

  • bpo-29851: importlib.reload() now raises ModuleNotFoundError if the modulelacks a spec.

  • bpo-28556: Various updates to typing module: typing.Counter,typing.ChainMap, improved ABC caching, etc. Original PRs by JelleZijlstra, Ivan Levkivskyi, Manuel Krebber, and Łukasz Langa.

  • bpo-29100: Fix datetime.fromtimestamp() regression introduced in Python3.6.0: check minimum and maximum years.

  • bpo-29416: Prevent infinite loop in pathlib.Path.mkdir

  • bpo-29444: Fixed out-of-bounds buffer access in the group() method of thematch object. Based on patch by WGH.

  • bpo-29377: Add WrapperDescriptorType, MethodWrapperType, andMethodDescriptorType built-in types to types module. Original patch byManuel Krebber.

  • bpo-29218: Unused install_misc command is now removed. It has beendocumented as unused since 2000. Patch by Eric N. Vander Weele.

  • bpo-29368: The extend() method is now called instead of the append()method when unpickle collections.deque and other list-like objects. Thiscan speed up unpickling to 2 times.

  • bpo-29338: The help of a builtin or extension class now includes theconstructor signature if __text_signature__ is provided for the class.

  • bpo-29335: Fix subprocess.Popen.wait() when the child process has exitedto a stopped instead of terminated state (ex: when under ptrace).

  • bpo-29290: Fix a regression in argparse that help messages would wrap atnon-breaking spaces.

  • bpo-28735: Fixed the comparison of mock.MagickMock with mock.ANY.

  • bpo-29197: Removed deprecated function ntpath.splitunc().

  • bpo-29210: Removed support of deprecated argument "exclude" intarfile.TarFile.add().

  • bpo-29219: Fixed infinite recursion in the repr of uninitializedctypes.CDLL instances.

  • bpo-29192: Removed deprecated features in the http.cookies module.

  • bpo-29193: A format string argument for string.Formatter.format() is nowpositional-only.

  • bpo-29195: Removed support of deprecated undocumented keyword arguments inmethods of regular expression objects.

  • bpo-28969: Fixed race condition in C implementation offunctools.lru_cache. KeyError could be raised when cached function withfull cache was simultaneously called from different threads with the sameuncached arguments.

  • bpo-20804: The unittest.mock.sentinel attributes now preserve theiridentity when they are copied or pickled.

  • bpo-29142: In urllib.request, suffixes in no_proxy environment variablewith leading dots could match related hostnames again (e.g. .b.c matchesa.b.c). Patch by Milan Oberkirch.

  • bpo-28961: Fix unittest.mock._Call helper: don't ignore the name parameteranymore. Patch written by Jiajun Huang.

  • bpo-15812: inspect.getframeinfo() now correctly shows the first line of acontext. Patch by Sam Breese.

  • bpo-28985: Update authorizer constants in sqlite3 module. Patch byDingyuan Wang.

  • bpo-29079: Prevent infinite loop in pathlib.resolve() on Windows

  • bpo-13051: Fixed recursion errors in large or resizedcurses.textpad.Textbox. Based on patch by Tycho Andersen.

  • bpo-9770: curses.ascii predicates now work correctly with negativeintegers.

  • bpo-28427: old keys should not remove new values from WeakValueDictionarywhen collecting from another thread.

  • bpo-28923: Remove editor artifacts from Tix.py.

  • bpo-28871: Fixed a crash when deallocate deep ElementTree.

  • bpo-19542: Fix bugs in WeakValueDictionary.setdefault() andWeakValueDictionary.pop() when a GC collection happens in another thread.

  • bpo-20191: Fixed a crash in resource.prlimit() when passing a sequencethat doesn't own its elements as limits.

  • bpo-16255: subprocess.Popen uses /system/bin/sh on Android as the shell,instead of /bin/sh.

  • bpo-28779: multiprocessing.set_forkserver_preload() would crash theforkserver process if a preloaded module instantiated some multiprocessingobjects such as locks.

  • bpo-26937: The chown() method of the tarfile.TarFile class does not failnow when the grp module cannot be imported, as for example on Androidplatforms.

  • bpo-28847: dbm.dumb now supports reading read-only files and no longerwrites the index file when it is not changed. A deprecation warning isnow emitted if the index file is missed and recreated in the 'r' and 'w'modes (will be an error in future Python releases).

  • bpo-27030: Unknown escapes consisting of'\' and an ASCII letter inre.sub() replacement templates regular expressions now are errors.

  • bpo-28835: Fix a regression introduced in warnings.catch_warnings(): callwarnings.showwarning() if it was overridden inside the context manager.

  • bpo-27172: To assist with upgrades from 2.7, the previously documenteddeprecation ofinspect.getfullargspec() has been reversed. Thisdecision may be revisited again after the Python 2.7 branch is no longerofficially supported.

  • bpo-28740: Add sys.getandroidapilevel(): return the build time API versionof Android as an integer. Function only available on Android.

  • bpo-26273: Add newsocket.TCP_CONGESTION (Linux 2.6.13) andsocket.TCP_USER_TIMEOUT (Linux 2.6.37) constants. Patch writtenby Omar Sandoval.

  • bpo-28752: Restored the __reduce__() methods of datetime objects.

  • bpo-28727: Regular expression patterns, _sre.SRE_Pattern objects createdby re.compile(), become comparable (only x==y and x!=y operators). Thischange should fix thebpo-18383: don't duplicate warning filters whenthe warnings module is reloaded (thing usually only done in unit tests).

  • bpo-20572: Remove the subprocess.Popen.wait endtime parameter. It wasdeprecated in 3.4 and undocumented prior to that.

  • bpo-25659: In ctypes, prevent a crash calling the from_buffer() andfrom_buffer_copy() methods on abstract classes like Array.

  • bpo-28548: In the "http.server" module, parse the protocol version ifpossible, to avoid using HTTP 0.9 in some error responses.

  • bpo-19717: Makes Path.resolve() succeed on paths that do not exist. Patchby Vajrasky Kok

  • bpo-28563: Fixed possible DoS and arbitrary code execution when handleplural form selections in the gettext module. The expression parser nowsupports exact syntax supported by GNU gettext.

  • bpo-28387: Fixed possible crash in _io.TextIOWrapper deallocator when thegarbage collector is invoked in other thread. Based on patch by SebastianCufre.

  • bpo-27517: LZMA compressor and decompressor no longer raise exceptions ifgiven empty data twice. Patch by Benjamin Fogle.

  • bpo-28549: Fixed segfault in curses's addch() with ncurses6.

  • bpo-28449: tarfile.open() with mode "r" or "r:" now tries to open a tarfile with compression before trying to open it without compression.Otherwise it had 50% chance failed with ignore_zeros=True.

  • bpo-23262: The webbrowser module now supports Firefox 36+ and derivedbrowsers. Based on patch by Oleg Broytman.

  • bpo-24241: The webbrowser in an X environment now prefers using thedefault browser directly. Also, the webbrowser register() function now hasa documented 'preferred' argument, to specify browsers to be returned byget() with no arguments. Patch by David Steele

  • bpo-27939: Fixed bugs in tkinter.ttk.LabeledScale and tkinter.Scale causedby representing the scale as float value internally in Tk. tkinter.IntVarnow works if float value is set to underlying Tk variable.

  • bpo-28255: calendar.TextCalendar.prweek() no longer prints a space after aweeks's calendar. calendar.TextCalendar.pryear() no longer printsredundant newline after a year's calendar. Based on patch by Xiang Zhang.

  • bpo-28255: calendar.TextCalendar.prmonth() no longer prints a space at thestart of new line after printing a month's calendar. Patch by XiangZhang.

  • bpo-20491: The textwrap.TextWrapper class now honors non-breaking spaces.Based on patch by Kaarle Ritvanen.

  • bpo-28353: os.fwalk() no longer fails on broken links.

  • bpo-28430: Fix iterator of C implemented asyncio.Future doesn't acceptnon-None value is passed to it.send(val).

  • bpo-27025: Generated names for Tkinter widgets now start by the "!" prefixfor readability.

  • bpo-25464: Fixed HList.header_exists() in tkinter.tix module by addin aworkaround to Tix library bug.

  • bpo-28488: shutil.make_archive() no longer adds entry "./" to ZIP archive.

  • bpo-25953: re.sub() now raises an error for invalid numerical groupreference in replacement template even if the pattern is not found in thestring. Error message for invalid group reference now includes the groupindex and the position of the reference. Based on patch by SilentGhost.

  • bpo-28469: timeit now uses the sequence 1, 2, 5, 10, 20, 50,... instead of1, 10, 100,... for autoranging.

  • bpo-28115: Command-line interface of the zipfile module now uses argparse.Added support of long options.

  • bpo-18219: Optimize csv.DictWriter for large number of columns. Patch byMariatta Wijaya.

  • bpo-28448: Fix C implemented asyncio.Future didn't work on Windows.

  • bpo-23214: In the "io" module, the argument to BufferedReader andBytesIO's read1() methods is now optional and can be -1, matching theBufferedIOBase specification.

  • bpo-28480: Fix error building socket module when multithreading isdisabled.

  • bpo-28240: timeit: remove-c/--clock and-t/--time command lineoptions which were deprecated since Python 3.3.

  • bpo-28240: timeit now repeats the benchmarks 5 times instead of only 3 tomake benchmarks more reliable.

  • bpo-28240: timeit autorange now uses a single loop iteration if thebenchmark takes less than 10 seconds, instead of 10 iterations. "python3-m timeit -s 'import time' 'time.sleep(1)'" now takes 4 seconds instead of40 seconds.

  • Distutils.sdist now looks for README and setup.py files with casesensitivity. This behavior matches that found in Setuptools 6.0 and later.Seesetuptools 100 forrationale.

  • bpo-24452: Make webbrowser support Chrome on Mac OS X. Patch by NedBatchelder.

  • bpo-20766: Fix references leaked by pdb in the handling of SIGINThandlers.

  • bpo-27998: Fixed bytes path support in os.scandir() on Windows. Patch byEryk Sun.

  • bpo-28317: The disassembler now decodes FORMAT_VALUE argument.

  • bpo-28380: unittest.mock Mock autospec functions now properly supportassert_called, assert_not_called, and assert_called_once.

  • bpo-28229: lzma module now supports pathlib.

  • bpo-28321: Fixed writing non-BMP characters with binary format inplistlib.

  • bpo-28225: bz2 module now supports pathlib. Initial patch by EthanFurman.

  • bpo-28227: gzip now supports pathlib. Patch by Ethan Furman.

  • bpo-28332: Deprecated silent truncations in socket.htons and socket.ntohs.Original patch by Oren Milman.

  • bpo-27358: Optimized merging var-keyword arguments and improved errormessage when passing a non-mapping as a var-keyword argument.

  • bpo-28257: Improved error message when passing a non-iterable as avar-positional argument. Added opcode BUILD_TUPLE_UNPACK_WITH_CALL.

  • bpo-28322: Fixed possible crashes when unpickle itertools objects fromincorrect pickle data. Based on patch by John Leitch.

  • bpo-28228: imghdr now supports pathlib.

  • bpo-28226: compileall now supports pathlib.

  • bpo-28314: Fix function declaration (C flags) for the getiterator() methodof xml.etree.ElementTree.Element.

  • bpo-28148: Stop using localtime() and gmtime() in the time module.Introduced platform independent _PyTime_localtime API that is similar toPOSIX localtime_r, but available on all platforms. Patch by Ed Schouten.

  • bpo-28253: Fixed calendar functions for extreme months: 0001-01 and9999-12. Methods itermonthdays() and itermonthdays2() are reimplemented sothat they don't call itermonthdates() which can cause datetime.dateunder/overflow.

  • bpo-28275: Fixed possible use after free in the decompress() methods ofthe LZMADecompressor and BZ2Decompressor classes. Original patch by JohnLeitch.

  • bpo-27897: Fixed possible crash in sqlite3.Connection.create_collation()if pass invalid string-like object as a name. Patch by Xiang Zhang.

  • bpo-18844: random.choices() now has k as a keyword-only argument toimprove the readability of common cases and come into line with thesignature used in other languages.

  • bpo-18893: Fix invalid exception handling in Lib/ctypes/macholib/dyld.py.Patch by Madison May.

  • bpo-27611: Fixed support of default root window in the tkinter.tix module.Added the master parameter in the DisplayStyle constructor.

  • bpo-27348: In the traceback module, restore the formatting of exceptionmessages like "Exception: None". This fixes a regression introduced in3.5a2.

  • bpo-25651: Allow false values to be used for msg parameter of subTest().

  • bpo-27778: Fix a memory leak in os.getrandom() when the getrandom() isinterrupted by a signal and a signal handler raises a Python exception.

  • bpo-28200: Fix memory leak on Windows in the os module (fixpath_converter() function).

  • bpo-25400: RobotFileParser now correctly returns default values forcrawl_delay and request_rate. Initial patch by Peter Wirtz.

  • bpo-27932: Prevent memory leak in win32_ver().

  • Fix UnboundLocalError in socket._sendfile_use_sendfile.

  • bpo-28075: Check for ERROR_ACCESS_DENIED in Windows implementation ofos.stat(). Patch by Eryk Sun.

  • bpo-22493: Warning message emitted by using inline flags in the middle ofregular expression now contains a (truncated) regex pattern. Patch by TimGraham.

  • bpo-25270: Prevent codecs.escape_encode() from raising SystemError when anempty bytestring is passed.

  • bpo-28181: Get antigravity over HTTPS. Patch by Kaartic Sivaraam.

  • bpo-25895: Enable WebSocket URL schemes in urllib.parse.urljoin. Patch byGergely Imreh and Markus Holtermann.

  • bpo-28114: Fix a crash in parse_envlist() when env contains byte strings.Patch by Eryk Sun.

  • bpo-27599: Fixed buffer overrun in binascii.b2a_qp() andbinascii.a2b_qp().

  • bpo-27906: Fix socket accept exhaustion during high TCP traffic. Patch byKevin Conway.

  • bpo-28174: Handle when SO_REUSEPORT isn't properly supported. Patch bySeth Michael Larson.

  • bpo-26654: Inspect functools.partial in asyncio.Handle.__repr__. Patch byiceboy.

  • bpo-26909: Fix slow pipes IO in asyncio. Patch by INADA Naoki.

  • bpo-28176: Fix callbacks race in asyncio.SelectorLoop.sock_connect.

  • bpo-27759: Fix selectors incorrectly retain invalid file descriptors.Patch by Mark Williams.

  • bpo-28325: Remove vestigial MacOS 9 macurl2path module and its tests.

  • bpo-28368: Refuse monitoring processes if the child watcher has no loopattached. Patch by Vincent Michel.

  • bpo-28369: Raise RuntimeError when transport's FD is used with add_reader,add_writer, etc.

  • bpo-28370: Speedup asyncio.StreamReader.readexactly. Patch by КоренбергМарк.

  • bpo-28371: Deprecate passing asyncio.Handles to run_in_executor.

  • bpo-28372: Fix asyncio to support formatting of non-python coroutines.

  • bpo-28399: Remove UNIX socket from FS before binding. Patch by КоренбергМарк.

  • bpo-27972: Prohibit Tasks to await on themselves.

  • bpo-24142: Reading a corrupt config file left configparser in an invalidstate. Original patch by Florian Höch.

  • bpo-29581: ABCMeta.__new__ now accepts**kwargs, allowing abstractbase classes to use keyword parameters in __init_subclass__. Patch by NateSoares.

  • bpo-25532: inspect.unwrap() will now only try to unwrap an objectsys.getrecursionlimit() times, to protect against objects which create anew object on every attribute access.

  • bpo-30177: path.resolve(strict=False) no longer cuts the path after thefirst element not present in the filesystem. Patch by Antoine Pietri.

Documentation

  • bpo-31294: Fix incomplete code snippet in the ZeroMQSocketListener andZeroMQSocketHandler examples and adapt them to Python 3.

  • bpo-21649: Add RFC 7525 and Mozilla server side TLS links to SSLdocumentation.

  • bpo-31128: Allow the pydoc server to bind to arbitrary hostnames.

  • bpo-30803: Clarify doc on truth value testing. Original patch by PeterThomassen.

  • bpo-30176: Add missing attribute related constants in cursesdocumentation.

  • bpo-30052: the link targets forbytes() andbytearray() arenow their respective type definitions, rather than the correspondingbuiltin function entries. Usebytes andbytearray to reference the latter. In order toensure this and future cross-reference updates are applied automatically,the daily documentation builds now disable the default output cachingfeatures in Sphinx.

  • bpo-26985: Add missing info of code object in inspect documentation.

  • bpo-19824: Improve the documentation for, and links to, template stringsby emphasizing their utility for internationalization, and by clarifyingsome usage constraints. (See also:bpo-20314,bpo-12518)

  • bpo-28929: Link the documentation to its source file on GitHub.

  • bpo-25008: Document smtpd.py as effectively deprecated and add a pointerto aiosmtpd, a third-party asyncio-based replacement.

  • bpo-26355: Add canonical header link on each page to corresponding majorversion of the documentation. Patch by Matthias Bussonnier.

  • bpo-29349: Fix Python 2 syntax in code for building the documentation.

  • bpo-23722: The data model reference and the porting section in the 3.6What's New guide now cover the additional__classcell__ handlingneeded for custom metaclasses to fully supportPEP 487 andzero-argumentsuper().

  • bpo-28513: Documented command-line interface of zipfile.

Tests

  • bpo-29639: test.support.HOST is now "localhost", a new HOSTv4 constant hasbeen added for your127.0.0.1 needs, similar to the existing HOSTv6constant.

  • bpo-31320: Silence traceback in test_ssl

  • bpo-31346: Prefer PROTOCOL_TLS_CLIENT and PROTOCOL_TLS_SERVER protocolsfor SSLContext.

  • bpo-25674: Remove sha256.tbs-internet.com ssl test

  • bpo-30715: Address ALPN callback changes for OpenSSL 1.1.0f. The latestversion behaves like OpenSSL 1.0.2 and no longer aborts handshake.

  • bpo-30822: regrtest: Exclude tzdata from regrtest --all. When running thetest suite using --use=all / -u all, exclude tzdata since it makestest_datetime too slow (15-20 min on some buildbots) which then times outon some buildbots. Fix also regrtest command line parser to allow passing-u extralargefile to run test_zipfile64.

  • bpo-30695: Add theset_nomemory(start,stop) andremove_mem_hooks() functions to the_testcapi module.

  • bpo-30357: test_thread: setUp() now uses support.threading_setup() andsupport.threading_cleanup() to wait until threads complete to avoid randomside effects on following tests. Initial patch written by GrzegorzGrzywacz.

  • bpo-30197: Enhanced functions swap_attr() and swap_item() in thetest.support module. They now work when delete replaced attribute or iteminside the with statement. The old value of the attribute or item (orNone if it doesn't exist) now will be assigned to the target of the "as"clause, if there is one.

  • bpo-24932: Use proper command line parsing in _testembed

  • bpo-28950: Disallow -j0 to be combined with -T/-l in regrtest command linearguments.

  • bpo-28683: Fix the tests that bind() a unix socket and raisePermissionError on Android for a non-root user.

  • bpo-26936: Fix the test_socket failures on Android - getservbyname(),getservbyport() and getaddrinfo() are broken on some Android API levels.

  • bpo-28666: Now test.support.rmtree is able to remove unwritable orunreadable directories.

  • bpo-23839: Various caches now are cleared before running every test file.

  • bpo-26944: Fix test_posix for Android where 'id -G' is entirely wrong ormissing the effective gid.

  • bpo-28409: regrtest: fix the parser of command line arguments.

  • bpo-28217: Adds _testconsole module to test console input.

  • bpo-26939: Add the support.setswitchinterval() function to fixtest_functools hanging on the Android armv7 qemu emulator.

Build

  • bpo-31354: Allow--with-lto to be used on all builds, not justmakeprofile-opt.

  • bpo-31370: Remove support for building --without-threads. This option isnot really useful anymore in the 21st century. Removing lots ofconditional paths allows us to simplify the code base, including indifficult to maintain low-level internal code.

  • bpo-31341: PerPEP 11, support for the IRIX operating system wasremoved.

  • bpo-30854: Fix compile error when compiling --without-threads. Patch byMasayuki Yamamoto.

  • bpo-30687: Locate msbuild.exe on Windows when building rather thanvcvarsall.bat

  • bpo-20210: Support thedisabled marker in Setup files. Extension moduleslisted after this marker are not built at all, neither by the Makefile norby setup.py.

  • bpo-29941: Add--with-assertions configure flag to explicitly enable Cassert() checks. Defaults to off.--with-pydebug implies--with-assertions.

  • bpo-28787: Fix out-of-tree builds of Python when configured with--with--dtrace.

  • bpo-29243: Prevent unnecessary rebuilding of Python duringmaketest,makeinstall and some other make targets when configured with--enable-optimizations.

  • bpo-23404: Don't regenerate generated files based on file modificationtime anymore: the action is now explicit. Replacemaketouch withmakeregen-all.

  • bpo-29643: Fix--enable-optimization didn't work.

  • bpo-27593: sys.version and the platform module python_build(),python_branch(), and python_revision() functions now use git informationrather than hg when building from a repo.

  • bpo-29572: Update Windows build and OS X installers to use OpenSSL 1.0.2k.

  • bpo-27659: Prohibit implicit C function declarations: use-Werror=implicit-function-declaration when possible (GCC and Clang,but it depends on the compiler version). Patch written by Chi Hsuan Yen.

  • bpo-29384: Remove old Be OS helper scripts.

  • bpo-26851: Set Android compilation and link flags.

  • bpo-28768: Fix implicit declaration of function _setmode. Patch byMasayuki Yamamoto

  • bpo-29080: Removes hard dependency on hg.exe from PCBuild/build.bat

  • bpo-23903: Added missed names to PC/python3.def.

  • bpo-28762: lockf() is available on Android API level 24, but the F_LOCKmacro is not defined in android-ndk-r13.

  • bpo-28538: Fix the compilation error that occurs because if_nameindex() isavailable on Android API level 24, but the if_nameindex structure is notdefined.

  • bpo-20211: Do not add the directory for installing C header files and thedirectory for installing object code libraries to the cross compilationsearch paths. Original patch by Thomas Petazzoni.

  • bpo-28849: Do not define sys.implementation._multiarch on Android.

  • bpo-10656: Fix out-of-tree building on AIX. Patch by Tristan Carel andMichael Haubenwallner.

  • bpo-26359: Rename --with-optimiations to --enable-optimizations.

  • bpo-28444: Fix missing extensions modules when cross compiling.

  • bpo-28208: Update Windows build and OS X installers to use SQLite 3.14.2.

  • bpo-28248: Update Windows build and OS X installers to use OpenSSL 1.0.2j.

  • bpo-21124: Fix building the _struct module on Cygwin by passingNULLinstead of&PyType_Type to PyVarObject_HEAD_INIT. Patch by MasayukiYamamoto.

  • bpo-13756: Fix building extensions modules on Cygwin. Patch by RoumenPetrov, based on original patch by Jason Tishler.

  • bpo-21085: Add configure check for siginfo_t.si_band, which Cygwin doesnot provide. Patch by Masayuki Yamamoto with review and rebase by ErikBray.

  • bpo-28258: Fixed build with Estonian locale (python-config and distcleantargets in Makefile). Patch by Arfrever Frehtes Taifersar Arahesis.

  • bpo-26661: setup.py now detects system libffi with multiarch wrapper.

  • bpo-27979: A full copy of libffi is no longer bundled for use whenbuilding _ctypes on non-OSX UNIX platforms. An installed copy of libffiis now required when building _ctypes on such platforms.

  • bpo-15819: Remove redundant include search directory option for buildingoutside the source tree.

  • bpo-28676: Prevent missing 'getentropy' declaration warning on macOS.Patch by Gareth Rees.

Windows

  • bpo-31392: Update Windows build to use OpenSSL 1.1.0f

  • bpo-30389: Adds detection of Visual Studio 2017 to distutils on Windows.

  • bpo-31358: zlib is no longer bundled in the CPython source, instead it isdownloaded on demand just like bz2, lzma, OpenSSL, Tcl/Tk, and SQLite.

  • bpo-31340: Change to building with MSVC v141 (included with Visual Studio2017)

  • bpo-30581: os.cpu_count() now returns the correct number of processors onWindows when the number of logical processors is greater than 64.

  • bpo-30916: Pre-build OpenSSL, Tcl and Tk and include the binaries in thebuild.

  • bpo-30731: Add a missing xmlns to python.manifest so that it matches theschema.

  • bpo-30291: Allow requiring 64-bit interpreters from py.exe using -64suffix. Contributed by Steve (Gadget) Barnes.

  • bpo-30362: Adds list options (-0, -0p) to py.exe launcher. Contributed bySteve Barnes.

  • bpo-23451: Fix socket deprecation warnings in socketmodule.c. Patch bySegev Finer.

  • bpo-30450: The build process on Windows no longer depends on Subversion,instead pulling external code from GitHub via a Python script. If Python3.6 is not found on the system (viapy-3.6), NuGet is used todownload a copy of 32-bit Python.

  • bpo-29579: Removes readme.txt from the installer.

  • bpo-25778: winreg does not truncate string correctly (Patch by Eryk Sun)

  • bpo-28896: Deprecate WindowsRegistryFinder and disable it by default

  • bpo-28522: Fixes mishandled buffer reallocation in getpathp.c

  • bpo-28402: Adds signed catalog files for stdlib on Windows.

  • bpo-28333: Enables Unicode for ps1/ps2 and input() prompts. (Patch by ErykSun)

  • bpo-28251: Improvements to help manuals on Windows.

  • bpo-28110: launcher.msi has different product codes between 32-bit and64-bit

  • bpo-28161: Opening CON for write access fails

  • bpo-28162: WindowsConsoleIO readall() fails if first line starts withCtrl+Z

  • bpo-28163: WindowsConsoleIO fileno() passes wrong flags to _open_osfhandle

  • bpo-28164: _PyIO_get_console_type fails for various paths

  • bpo-28137: Renames Windows path file to ._pth

  • bpo-28138: Windows ._pth file should allow import site

IDLE

  • bpo-31493: IDLE code context -- fix code update and font update timers.Canceling timers prevents a warning message when test_idle completes.

  • bpo-31488: IDLE - Update non-key options in former extension classes. Whenapplying configdialog changes, call .reload for each feature class. ChangeParenMatch so updated options affect existing instances attached toexisting editor windows.

  • bpo-31477: IDLE - Improve rstrip entry in doc. Strip trailing whitespacestrips more than blank spaces. Multiline string literals are not skipped.

  • bpo-31480: IDLE - make tests pass with zzdummy extension disabled bydefault.

  • bpo-31421: Document how IDLE runs tkinter programs. IDLE calls tcl/tkupdate in the background in order to make live interaction andexperimentation with tkinter applications much easier.

  • bpo-31414: IDLE -- fix tk entry box tests by deleting first. Adding to anint entry is not the same as deleting and inserting because int('') willfail.

  • bpo-31051: Rearrange IDLE configdialog GenPage into Window, Editor, andHelp sections.

  • bpo-30617: IDLE - Add docstrings and tests for outwin subclass of editor.Move some data and functions from the class to module level. Patch byCheryl Sabella.

  • bpo-31287: IDLE - Do not modify tkinter.message in test_configdialog.

  • bpo-27099: Convert IDLE's built-in 'extensions' to regular features. About10 IDLE features were implemented as supposedly optional extensions. Theirdifferent behavior could be confusing or worse for users and not good formaintenance. Hence the conversion. The main difference for users is thatuser configurable key bindings for builtin features are now handleduniformly. Now, editing a binding in a keyset only affects its value inthe keyset. All bindings are defined together in the system-specificdefault keysets in config-extensions.def. All custom keysets are saved asa whole in config-extension.cfg. All take effect as soon as one clicksApply or Ok. The affected events are '<<force-open-completions>>','<<expand-word>>', '<<force-open-calltip>>', '<<flash-paren>>','<<format-paragraph>>', '<<run-module>>', '<<check-module>>', and'<<zoom-height>>'. Any (global) customizations made before 3.6.3 will notaffect their keyset-specific customization after 3.6.3. and vice versa.Initial patch by Charles Wohlganger.

  • bpo-31206: IDLE: Factor HighPage(Frame) class from ConfigDialog. Patch byCheryl Sabella.

  • bpo-31001: Add tests for configdialog highlight tab. Patch by CherylSabella.

  • bpo-31205: IDLE: Factor KeysPage(Frame) class from ConfigDialog. Theslightly modified tests continue to pass. Patch by Cheryl Sabella.

  • bpo-31130: IDLE -- stop leaks in test_configdialog. Initial patch byVictor Stinner.

  • bpo-31002: Add tests for configdialog keys tab. Patch by Cheryl Sabella.

  • bpo-19903: IDLE: Calltips useinspect.signature instead ofinspect.getfullargspec. This improves calltips for builtins convertedto use Argument Clinic. Patch by Louie Lu.

  • bpo-31083: IDLE - Add an outline of a TabPage class in configdialog.Update existing classes to match outline. Initial patch by Cheryl Sabella.

  • bpo-31050: Factor GenPage(Frame) class from ConfigDialog. The slightlymodified tests continue to pass. Patch by Cheryl Sabella.

  • bpo-31004: IDLE - Factor FontPage(Frame) class from ConfigDialog. Slightlymodified tests continue to pass. Fix General tests. Patch mostly by CherylSabella.

  • bpo-30781: IDLE - Use ttk widgets in ConfigDialog. Patches by Terry JanReedy and Cheryl Sabella.

  • bpo-31060: IDLE - Finish rearranging methods of ConfigDialog Groupingmethods pertaining to each tab and the buttons will aid writing tests andimproving the tabs and will enable splitting the groups into classes.

  • bpo-30853: IDLE -- Factor a VarTrace class out of ConfigDialog. Instancetracers manages pairs consisting of a tk variable and a callback function.When tracing is turned on, setting the variable calls the function. Testcoverage for the new class is 100%.

  • bpo-31003: IDLE: Add more tests for General tab.

  • bpo-30993: IDLE - Improve configdialog font page and tests. Inconfigdialog: Document causal pathways in create_font_tab docstring.Simplify some attribute names. Move set_samples calls to var_changed_font(idea from Cheryl Sabella). Move related functions to positions after thecreate widgets function. In test_configdialog: Fix test_font_set so notorder dependent. Fix renamed test_indent_scale so it tests the widget.Adjust tests for movement of set_samples call. Add tests for loadfunctions. Put all font tests in one class and tab indent tests inanother. Except for two lines, these tests completely cover the relatedfunctions.

  • bpo-30981: IDLE -- Add more configdialog font page tests.

  • bpo-28523: IDLE: replace 'colour' with 'color' in configdialog.

  • bpo-30917: Add tests for idlelib.config.IdleConf. Increase coverage from46% to 96%. Patch by Louie Lu.

  • bpo-30934: Document coverage details for idlelib tests. Add section toidlelib/idle-test/README.txt. Include check that branches are taken bothways. Exclude IDLE-specific code that does not run during unit tests.

  • bpo-30913: IDLE: Document ConfigDialog tk Vars, methods, and widgets indocstrings This will facilitate improving the dialog and splitting up theclass. Original patch by Cheryl Sabella.

  • bpo-30899: IDLE: Add tests for ConfigParser subclasses in config. Patch byLouie Lu.

  • bpo-30881: IDLE: Add docstrings to browser.py. Patch by Cheryl Sabella.

  • bpo-30851: IDLE: Remove unused variables in configdialog. One is aduplicate, one is set but cannot be altered by users. Patch by CherylSabella.

  • bpo-30870: IDLE: In Settings dialog, select font with Up, Down keys aswell as mouse. Initial patch by Louie Lu.

  • bpo-8231: IDLE: call config.IdleConf.GetUserCfgDir only once.

  • bpo-30779: IDLE: Factor ConfigChanges class from configdialog, put inconfig; test. * In config, put dump test code in a function; run it andunittest in 'if __name__ == '__main__'. * Add class config.ConfigChangesbased on changes_class_v4.py on bpo issue. * Add classtest_config.ChangesTest, partly using configdialog_tests_v1.py. * Reviseconfigdialog to use ConfigChanges; see tracker msg297804. * Revisetest_configdialog to match configdialog changes. * Remove configdialogfunctions unused or moved to ConfigChanges. Cheryl Sabella contributedparts of the patch.

  • bpo-30777: IDLE: configdialog - Add docstrings and fix comments. Patch byCheryl Sabella.

  • bpo-30495: IDLE: Improve textview with docstrings, PEP8 names, and moretests. Patch by Cheryl Sabella.

  • bpo-30723: IDLE: Make several improvements to parenmatch. Add 'parens'style to highlight both opener and closer. Make 'default' style, which isnot default, a synonym for 'opener'. Make time-delay work the same withall styles. Add help for config dialog extensions tab, including help forparenmatch. Add new tests. Original patch by Charles Wohlganger.

  • bpo-30674: IDLE: add docstrings to grep module. Patch by Cheryl Sabella

  • bpo-21519: IDLE's basic custom key entry dialog now detects duplicatesproperly. Original patch by Saimadhav Heblikar.

  • bpo-29910: IDLE no longer deletes a character after commenting out aregion by a key shortcut. Addreturn'break' for this and otherpotential conflicts between IDLE and default key bindings.

  • bpo-30728: Review and change idlelib.configdialog names. Lowercase methodand attribute names. Replace 'colour' with 'color', expand overly crypticnames, delete unneeded underscores. Replaceimport* with specificimports. Patches by Cheryl Sabella.

  • bpo-6739: IDLE: Verify user-entered key sequences by trying to bind themwith tk. Add tests for all 3 validation functions. Original patch by GPolo. Tests added by Cheryl Sabella.

  • bpo-15786: Fix several problems with IDLE's autocompletion box. Thefollowing should now work: clicking on selection box items; using thescrollbar; selecting an item by hitting Return. Hangs on MacOSX should nolonger happen. Patch by Louie Lu.

  • bpo-25514: Add doc subsubsection about IDLE failure to start. Popupno-connection message directs users to this section.

  • bpo-30642: Fix reference leaks in IDLE tests. Patches by Louie Lu andTerry Jan Reedy.

  • bpo-30495: Add docstrings for textview.py and use PEP8 names. Patches byCheryl Sabella and Terry Jan Reedy.

  • bpo-30290: Help-about: use pep8 names and add tests. Increase coverage to100%. Patches by Louie Lu, Cheryl Sabella, and Terry Jan Reedy.

  • bpo-30303: Add _utest option to textview; add new tests. Increase coverageto 100%. Patches by Louie Lu and Terry Jan Reedy.

  • bpo-29071: IDLE colors f-string prefixes (but not invalid ur prefixes).

  • bpo-28572: Add 10% to coverage of IDLE's test_configdialog. Update andaugment description of the configuration system.

Tools/Demos

  • bpo-30983: gdb integration commands (py-bt, etc.) work on optimized sharedbuilds now, too.PEP 523 introduced _PyEval_EvalFrameDefault whichinlines PyEval_EvalFrameEx on non-debug shared builds. This broke theability to use py-bt, py-up, and a few other Python-specific gdbintegrations. The problem is fixed by only looking for_PyEval_EvalFrameDefault frames in python-gdb.py. Original patch by Bruno"Polaco" Penteado.

  • bpo-29748: Added the slice index converter in Argument Clinic.

  • bpo-24037: Argument Clinic now uses the converterbool(accept={int})rather thanint for semantical booleans. This avoids repeating thedefault value for Python and C and will help in converting tobool infuture.

  • bpo-29367: python-gdb.py now supports alsomethod-wrapper(wrapperobject) objects.

  • bpo-28023: Fix python-gdb.py didn't support new dict implementation.

  • bpo-15369: The pybench and pystone microbenchmark have been removed fromTools. Please use the new Python benchmark suitehttps://github.com/python/pyperformance which is more reliable andincludes a portable version of pybench working on Python 2 and Python 3.

  • bpo-28102: The zipfile module CLI now prints usage to stderr. Patch byStephen J. Turnbull.

C API

  • bpo-31338: Added thePy_UNREACHABLE() macro for code paths which arenever expected to be reached. This and a few other useful macros are nowdocumented in the C API manual.

  • bpo-30832: Remove own implementation for thread-local storage. CPython hasprovided the own implementation for thread-local storage (TLS) onPython/thread.c, it's used in the case which a platform has not suppliednative TLS. However, currently all supported platforms (Windows andpthreads) have provided native TLS and defined the Py_HAVE_NATIVE_TLSmacro with unconditional in any case.

  • bpo-30708: PyUnicode_AsWideCharString() now raises a ValueError if thesecond argument is NULL and the wchar_t* string contains null characters.

  • bpo-16500: Deprecate PyOS_AfterFork() and add PyOS_BeforeFork(),PyOS_AfterFork_Parent() and PyOS_AfterFork_Child().

  • bpo-6532: The type of results of PyThread_start_new_thread() andPyThread_get_thread_ident(), and the id parameter ofPyThreadState_SetAsyncExc() changed from "long" to "unsigned long".

  • bpo-27867: Function PySlice_GetIndicesEx() is deprecated and replaced witha macro if Py_LIMITED_API is not set or set to the value between0x03050400 and 0x03060000 (not including) or 0x03060100 or higher. Addedfunctions PySlice_Unpack() and PySlice_AdjustIndices().

  • bpo-29083: Fixed the declaration of some public API functions.PyArg_VaParse() and PyArg_VaParseTupleAndKeywords() were not available inlimited API. PyArg_ValidateKeywordArguments(), PyArg_UnpackTuple() andPy_BuildValue() were not available in limited API of version < 3.3 whenPY_SSIZE_T_CLEAN is defined.

  • bpo-28769: The result of PyUnicode_AsUTF8AndSize() and PyUnicode_AsUTF8()is now of typeconstchar* rather ofchar*.

  • bpo-29058: All stable API extensions added after Python 3.2 are nowavailable only when Py_LIMITED_API is set to the PY_VERSION_HEX value ofthe minimum Python version supporting this API.

  • bpo-28822: The index parametersstart andend of PyUnicode_FindChar()are now adjusted to behave likestr[start:end].

  • bpo-28808: PyUnicode_CompareWithASCIIString() now never raises exceptions.

  • bpo-28761: The fields name and doc of structures PyMemberDef, PyGetSetDef,PyStructSequence_Field, PyStructSequence_Desc, and wrapperbase are now oftypeconstchar* rather ofchar*.

  • bpo-28748: Private variable _Py_PackageContext is now of typeconstchar* rather ofchar*.

  • bpo-19569: Compiler warnings are now emitted if use most of deprecatedfunctions.

  • bpo-28426: Deprecated undocumented functions PyUnicode_AsEncodedObject(),PyUnicode_AsDecodedObject(), PyUnicode_AsDecodedUnicode() andPyUnicode_AsEncodedUnicode().

Python 3.6.6 final

Release date: 2018-06-27

There were no new changes in version 3.6.6.

Python 3.6.6 release candidate 1

Release date: 2018-06-11

Core and Builtins

  • bpo-33786: Fix asynchronous generators to handle GeneratorExit in athrow()correctly

  • bpo-30654: Fixed reset of the SIGINT handler to SIG_DFL on interpretershutdown even when there was a custom handler set previously. Patch byPhilipp Kerling.

  • bpo-33622: Fixed a leak when the garbage collector fails to add an objectwith the__del__ method or referenced by it into thegc.garbage list.PyGC_Collect() can now be called when anexception is set and preserves it.

  • bpo-31849: Fix signed/unsigned comparison warning in pyhash.c.

  • bpo-33391: Fix a leak in set_symmetric_difference().

  • bpo-28055: Fix unaligned accesses in siphash24(). Patch by Rolf Eike Beer.

  • bpo-33231: Fix potential memory leak innormalizestring().

  • bpo-29922: Improved error messages in 'async with' when__aenter__()or__aexit__() return non-awaitable object.

  • bpo-33199: Fixma_version_tag in dict implementation is uninitializedwhen copying from key-sharing dict.

  • bpo-33041: Fixed jumping when the function contains anasyncfor loop.

  • bpo-32282: Fix an unnecessary ifdef in the include of VersionHelpers.h insocketmodule on Windows.

  • bpo-21983: Fix a crash inctypes.cast() in case the type argument is actypes structured data type. Patch by Eryk Sun and Oren Milman.

Library

  • bpo-30167: Prevent site.main() exception if PYTHONSTARTUP is set. Patch bySteve Weber.

  • bpo-33812: Datetime instance d with non-None tzinfo, but withd.tzinfo.utcoffset(d) returning None is now treated as naive by theastimezone() method.

  • bpo-30805: Avoid race condition with debug logging

  • bpo-33767: The concatenation (+) and repetition (*) sequenceoperations now raiseTypeError instead ofSystemError whenperformed onmmap.mmap objects. Patch by Zackery Spytz.

  • bpo-32684: Fix gather to propagate cancellation of itself even withreturn_exceptions.

  • bpo-33674: Fix a race condition in SSLProtocol.connection_made() ofasyncio.sslproto: start immediately the handshake instead of usingcall_soon(). Previously, data_received() could be called before thehandshake started, causing the handshake to hang or fail.

  • bpo-31647: Fixed bug where calling write_eof() on a_SelectorSocketTransport after it's already closed raises AttributeError.

  • bpo-33672: Fix Task.__repr__ crash with Cython's bogus coroutines

  • bpo-33469: Fix RuntimeError after closing loop that used run_in_executor

  • bpo-11874: Use a better regex when breaking usage into wrappable parts.Avoids bogus assertion errors from custom metavar strings.

  • bpo-30877: Fixed a bug in the Python implementation of the JSON decoderthat prevented the cache of parsed strings from clearing after finishingthe decoding. Based on patch by c-fos.

  • bpo-33548: tempfile._candidate_tempdir_list should consider common TEMPlocations

  • bpo-33542: Preventuuid.get_node from using a DUID instead of a MAC onWindows. Patch by Zvi Effron

  • bpo-26819: Fix race condition withReadTransport.resume_reading inWindows proactor event loop.

  • bpo-28556: Minor fixes in typing module: add annotations toNamedTuple.__new__, pass*args and**kwds inGeneric.__new__. Original PRs by Paulius Šarka and Chad Dombrova.

  • bpo-20087: Updated alias mapping with glibc 2.27 supported locales.

  • bpo-33422: Fix trailing quotation marks getting deleted when looking upbyte/string literals on pydoc. Patch by Andrés Delfino.

  • bpo-33197: Update error message when constructing invalidinspect.Parameters Patch by Donghee Na.

  • bpo-33383: Fixed crash in the get() method of thedbm.ndbm databaseobject when it is called with a single argument.

  • bpo-33329: Fix multiprocessing regression on newer glibcs

  • bpo-991266: Fix quoting of theComment attribute ofhttp.cookies.SimpleCookie.

  • bpo-33131: Upgrade bundled version of pip to 10.0.1.

  • bpo-33308: Fixed a crash in theparser module when converting an STobject to a tree of tuples or lists withline_info=False andcol_info=True.

  • bpo-33263: Fix FD leak in_SelectorSocketTransport Patch by VladStarostin.

  • bpo-33256: Fix display of<module> call in the html produced bycgitb.html(). Patch by Stéphane Blondon.

  • bpo-33203:random.Random.choice() now raisesIndexError for emptysequences consistently even when called from subclasses without agetrandbits() implementation.

  • bpo-33224: Update difflib.mdiff() forPEP 479. Convert an uncaughtStopIteration in a generator into a return-statement.

  • bpo-33209: End framing at the end of C implementation ofpickle.Pickler.dump().

  • bpo-32861: The urllib.robotparser's__str__ representation nowincludes wildcard entries and the "Crawl-delay" and "Request-rate" fields.Patch by Michael Lazar.

  • bpo-33096: Allow ttk.Treeview.insert to insert iid that has a falseboolean value. Note iid=0 and iid=False would be same. Patch by GarvitKhatri.

  • bpo-33127: The ssl module now compiles with LibreSSL 2.7.1.

  • bpo-33021: Release the GIL during fstat() calls, avoiding hang of allthreads when calling mmap.mmap(), os.urandom(), and random.seed(). Patchby Nir Soffer.

  • bpo-27683: Fix a regression inipaddress that result ofhosts() is empty when the network is constructed by a tuplecontaining an integer mask and only 1 bit left for addresses.

  • bpo-32844: Fix wrong redirection of a low descriptor (0 or 1) to stderr insubprocess if another low descriptor is closed.

  • bpo-31908: Fix output of cover files fortrace module command-linetool. Previously emitted cover files only when--missing option wasused. Patch by Michael Selik.

  • bpo-31457: If nested log adapters are used, the innerprocess()methods are no longer omitted.

  • bpo-16865: Support arrays >=2GiB inctypes. Patch by Segev Finer.

  • bpo-31238: pydoc: the stop() method of the private ServerThread class nowwaits until DocServer.serve_until_quit() completes and then explicitlysets its docserver attribute to None to break a reference cycle.

Documentation

  • bpo-33503: Fix broken pypi link

  • bpo-33421: Add missing documentation fortyping.AsyncContextManager.

  • bpo-33378: Add Korean language switcher forhttps://docs.python.org/3/

  • bpo-33276: Clarify that the__path__ attribute on modules cannot bejust any value.

  • bpo-33201: Modernize documentation for writing C extension types.

  • bpo-33195: DeprecatePy_UNICODE usage inc-api/arg document.Py_UNICODE related APIs are deprecated since Python 3.3, but it ismissed in the document.

  • bpo-33126: Document PyBuffer_ToContiguous().

  • bpo-27212: Modify documentation for theislice() recipe to consumeinitial values up to the start index.

  • bpo-28247: Updatezipapp documentation to describe how to makestandalone applications.

  • bpo-18802: Documentation changes for ipaddress. Patch by Jon Foster andBerker Peksag.

  • bpo-27428: Update documentation to clarify thatWindowsRegistryFinderimplementsMetaPathFinder. (Patch by Himanshu Lakhara)

  • bpo-8243: Add a note about curses.addch and curses.addstr exceptionbehavior when writing outside a window, or pad.

  • bpo-31432: Clarify meaning of CERT_NONE, CERT_OPTIONAL, and CERT_REQUIREDflags for ssl.SSLContext.verify_mode.

Tests

  • bpo-33655: Ignore test_posix_fallocate failures on BSD platforms thatmight be due to running on ZFS.

  • bpo-19417: Add test_bdb.py.

Build

  • bpo-5755: Move-Wstrict-prototypes option toCFLAGS_NODIST fromOPT. This option emitted annoying warnings when building extensionmodules written in C++.

  • bpo-33614: Ensures module definition files for the stable ABI on Windowsare correctly regenerated.

  • bpo-33522: Enable CI builds on Visual Studio Team Services athttps://python.visualstudio.com/cpython

  • bpo-33012: Add-Wno-cast-function-type for gcc 8 for silencingwarnings about function casts like casting to PyCFunction in methoddefinition lists.

  • bpo-33394: Enable the verbose build for extension modules, when GNU makeis passed macros on the command line.

Windows

  • bpo-33184: Update Windows installer to OpenSSL 1.0.2o.

macOS

  • bpo-33184: Update macOS installer build to use OpenSSL 1.0.2o.

IDLE

  • bpo-33656: On Windows, add API call saying that tk scales for DPI. OnWindows 8.1+ or 10, with DPI compatibility properties of the Python binaryunchanged, and a monitor resolution greater than 96 DPI, this should maketext and lines sharper. It should otherwise have no effect.

  • bpo-33768: Clicking on a context line moves that line to the top of theeditor window.

  • bpo-33763: IDLE: Use read-only text widget for code context instead oflabel widget.

  • bpo-33664: Scroll IDLE editor text by lines. Previously, the mouse wheeland scrollbar slider moved text by a fixed number of pixels, resulting inpartial lines at the top of the editor box. The change also applies tothe shell and grep output windows, but not to read-only text views.

  • bpo-33679: Enable theme-specific color configuration for Code Context. Usethe Highlights tab to see the setting for built-in themes or add settingsto custom themes.

  • bpo-33642: Display up to maxlines non-blank lines for Code Context. Ifthere is no current context, show a single blank line.

  • bpo-33628: IDLE: Cleanup codecontext.py and its test.

  • bpo-33564: IDLE's code context now recognizes async as a block opener.

  • bpo-29706: IDLE now colors async and await as keywords in 3.6. They becomefull keywords in 3.7.

  • bpo-21474: Update word/identifier definition from ascii to unicode. Intext and entry boxes, this affects selection by double-click, movementleft/right by control-left/right, and deletion left/right bycontrol-BACKSPACE/DEL.

  • bpo-33204: IDLE: consistently color invalid string prefixes. A 'u' stringprefix cannot be paired with either 'r' or 'f'. Consistently color as muchof the prefix, starting at the right, as is valid. Revise and extendcolorizer test.

  • bpo-32831: Add docstrings and tests for codecontext.

Tools/Demos

  • bpo-33189:pygettext.py now recognizes only literal strings asdocstrings and translatable strings, and rejects bytes literals andf-string expressions.

  • bpo-31920: Fixed handling directories as arguments in thepygettextscript. Based on patch by Oleg Krasnikov.

  • bpo-29673: Fix pystackv and pystack gdbinit macros.

  • bpo-32885: Add an-n flag forTools/scripts/pathfix.py to disableautomatic backup creation (files with~ suffix).

  • bpo-31583: Fix 2to3 for using with --add-suffix option but without--output-dir option for relative path to files in current directory.

C API

  • bpo-32374: Document that m_traverse for multi-phase initialized modulescan be called with m_state=NULL, and add a sanity check

Python 3.6.5 final

Release date: 2018-03-28

Tests

  • bpo-32872: Avoid regrtest compatibility issue with namespace packages.

Build

  • bpo-33163: Upgrade pip to 9.0.3 and setuptools to v39.0.1.

Python 3.6.5 release candidate 1

Release date: 2018-03-13

Security

  • bpo-33001: Minimal fix to prevent buffer overrun in os.symlink on Windows

  • bpo-32981: Regexes in difflib and poplib were vulnerable to catastrophicbacktracking. These regexes formed potential DOS vectors (REDOS). Theyhave been refactored. This resolvesCVE 2018-1060 andCVE 2018-1061.Patch by Jamie Davis.

Core and Builtins

  • bpo-33026: Fixed jumping out of "with" block by setting f_lineno.

  • bpo-17288: Prevent jumps from 'return' and 'exception' trace events.

  • bpo-32889: Update Valgrind suppression list to account for the rename ofPy_ADDRESS_IN_RANG toaddress_in_range.

  • bpo-32650: Pdb and other debuggers dependent on bdb.py will correctly stepover (next command) native coroutines. Patch by Pablo Galindo.

  • bpo-32685: Improve suggestion when the Python 2 form of print statement iseither present on the same line as the header of a compound statement orelse terminated by a semi-colon instead of a newline. Patch by NitishChandra.

  • bpo-32583: Fix possible crashing in builtin Unicode decoders caused bywrite out-of-bound errors when using customized decode error handlers.

  • bpo-26163: Improved frozenset() hash to create more distinct hash valueswhen faced with datasets containing many similar values.

  • bpo-27169: The__debug__ constant is now optimized out at compiletime. This fixes alsobpo-22091.

  • bpo-32329:sys.flags.hash_randomization is now properly set to 0 whenhash randomization is turned off byPYTHONHASHSEED=0.

  • bpo-30416: The optimizer is now protected from spending much time doingcomplex calculations and consuming much memory for creating largeconstants in constant folding.

  • bpo-18533:repr() on a dict containing its ownvalues() oritems() no longer raisesRecursionError; OrderedDict similarly.Instead, use..., as for other recursive structures. Patch by BenNorth.

  • bpo-32028: Leading whitespace is now correctly ignored when generatingsuggestions for converting Py2 print statements to Py3 builtin printfunction calls. Patch by Sanyam Khurana.

  • bpo-32137: The repr of deeply nested dict now raises a RecursionErrorinstead of crashing due to a stack overflow.

Library

  • bpo-33064: lib2to3 now properly supports trailing commas after*argsand**kwargs in function signatures.

  • bpo-31804: Avoid failing in multiprocessing.Process if the standardstreams are closed or None at exit.

  • bpo-33037: Skip sending/receiving data after SSL transport closing.

  • bpo-30353: Fix ctypes pass-by-value for structs on 64-bit Cygwin/MinGW.

  • bpo-33009: Fix inspect.signature() for single-parameter partialmethods.

  • bpo-32969: Expose several missing constants in zlib and fix correspondingdocumentation.

  • bpo-32713: Fixed tarfile.itn handling of out-of-bounds float values. Patchby Joffrey Fuhrer.

  • bpo-30622: The ssl module now detects missing NPN support in LibreSSL.

  • bpo-32922: dbm.open() now encodes filename with the filesystem encodingrather than default encoding.

  • bpo-32859: Inos.dup2, don't check every call whether thedup3syscall exists or not.

  • bpo-21060: Rewrite confusing message from setup.py upload from "No distfile created in earlier command" to the more helpful "Must create andupload files in one command".

  • bpo-32857: Intkinter,after_cancel(None) now raises aValueError instead of canceling the first scheduled function.Patch by Cheryl Sabella.

  • bpo-32852: Make sure sys.argv remains as a list when running trace.

  • bpo-32841: Fixedasyncio.Condition issue which silently ignoredcancellation after notifying and cancelling a conditional lock. Patch byBar Harel.

  • bpo-31787: Fixed refleaks of__init__() methods in various modules.(Contributed by Oren Milman)

  • bpo-30157: Fixed guessing quote and delimiter in csv.Sniffer.sniff() whenonly the last field is quoted. Patch by Jake Davis.

  • bpo-32394: socket: Remove TCP_FASTOPEN, TCP_KEEPCNT flags on older versionWindows during run-time.

  • bpo-32777: Fix a rare but potential pre-exec child process deadlock insubprocess on POSIX systems when marking file descriptors inheritable onexec in the child process. This bug appears to have been introduced in3.4.

  • bpo-32647: The ctypes module used to depend on indirect linking fordlopen. The shared extension is now explicitly linked against libdl onplatforms with dl.

  • bpo-32734: Fixedasyncio.Lock() safety issue which allowed acquiringand locking the same lock multiple times, without it being free. Patch byBar Harel.

  • bpo-32727: Do not include name field in SMTP envelope from address. Patchby Stéphane Wirtel

  • bpo-27931: Fix email address header parsing error when the username is anempty quoted string. Patch by Xiang Zhang.

  • bpo-32304: distutils' upload command no longer corrupts tar files endingwith a CR byte, and no longer tries to convert CR to CRLF in any of theupload text fields.

  • bpo-32502: uuid.uuid1 no longer raises an exception if a 64-bit hardwareaddress is encountered.

  • bpo-31848: Fix the error handling in Aifc_read.initfp() when the SSNDchunk is not found. Patch by Zackery Spytz.

  • bpo-32555: On FreeBSD and Solaris, os.strerror() now always decode thebyte string from the current locale encoding, rather than usingASCII/surrogateescape in some cases.

  • bpo-32521: The nis module is now compatible with new libnsl and headerslocation.

  • bpo-32473: Improve ABCMeta._dump_registry() output readability

  • bpo-32521: glibc has removed Sun RPC. Use replacement libtirpc headers andlibrary in nis module.

  • bpo-32228: Ensure thattruncate() preserves the file position (asreported bytell()) after writes longer than the buffer size.

  • bpo-26133: Don't unsubscribe signals in asyncio UNIX event loop oninterpreter shutdown.

  • bpo-32185: The SSL module no longer sends IP addresses in SNI TLSextension on platforms with OpenSSL 1.0.2+ or inet_pton.

  • bpo-32323:urllib.parse.urlsplit() does not convert zone-id (scope)to lower case for scoped IPv6 addresses in hostnames now.

  • bpo-32302: Fix bdist_wininst of distutils for CRT v142: it binarycompatible with CRT v140.

  • bpo-32255: A single empty field is now always quoted when written into aCSV file. This allows to distinguish an empty row from a row consisting ofa single empty field. Patch by Licht Takeuchi.

  • bpo-32277: RaiseNotImplementedError instead ofSystemError onplatforms wherechmod(...,follow_symlinks=False) is not supported.Patch by Anthony Sottile.

  • bpo-32199: The getnode() ip getter now uses 'ip link' instead of 'ip linklist'.

  • bpo-27456: Ensure TCP_NODELAY is set on Linux. Tests by Victor Stinner.

  • bpo-31900: Thelocale.localeconv() function now sets temporarily theLC_CTYPE locale to theLC_NUMERIC locale to decodedecimal_point andthousands_sep byte strings if they are non-ASCIIor longer than 1 byte, and theLC_NUMERIC locale is different than theLC_CTYPE locale. This temporary change affects other threads. Samechange for thestr.format() method when formatting a number(int,float,float and subclasses) with then type (ex:'{:n}'.format(1234)).

  • bpo-31802: Importing native path module (posixpath,ntpath) nowworks even if theos module still is not imported.

Documentation

  • bpo-17232: Clarify docs for -O and -OO. Patch by Terry Reedy.

  • bpo-32800: Update link to w3c doc for xml default namespaces.

  • bpo-8722: Document__getattr__() behavior when propertyget()method raisesAttributeError.

  • bpo-32614: Modify RE examples in documentation to use raw strings topreventDeprecationWarning and add text to REGEX HOWTO to highlightthe deprecation.

  • bpo-31972: Improve docstrings forpathlib.PurePath subclasses.

  • bpo-17799: Explain real behaviour of sys.settrace and sys.setprofile andtheir C-API counterparts regarding which type of events are received ineach function. Patch by Pablo Galindo Salgado.

Tests

  • bpo-32517: Fix failingtest_asyncio on macOS 10.12.2+ due to transportofKqueueSelector loop was not being closed.

  • bpo-32721: Fix test_hashlib to not fail if the _md5 module is not built.

  • bpo-32252: Fix faulthandler_suppress_crash_report() used to prevent coredump files when testing crashes. getrlimit() returns zero on success.

  • bpo-31518: Debian Unstable has disabled TLS 1.0 and 1.1 forSSLv23_METHOD(). Change TLS/SSL protocol of some tests to PROTOCOL_TLS orPROTOCOL_TLSv1_2 to make them pass on Debian.

Build

  • bpo-32635: Fix segfault of the crypt module when libxcrypt is providedinstead of libcrypt at the system.

Windows

  • bpo-33016: Fix potential use of uninitialized memory innt._getfinalpathname

  • bpo-32903: Fix a memory leak in os.chdir() on Windows if the currentdirectory is set to a UNC path.

  • bpo-31966: Fixed WindowsConsoleIO.write() for writing empty data.

  • bpo-32409: Ensures activate.bat can handle Unicode contents.

  • bpo-32457: Improves handling of denormalized executable path whenlaunching Python.

  • bpo-32370: Use the correct encoding for ipconfig output in the uuidmodule. Patch by Segev Finer.

  • bpo-29248: Fixos.readlink() on Windows, which was mistakenlytreating thePrintNameOffset field of the reparse data buffer as anumber of characters instead of bytes. Patch by Craig Holmquist and SSE4.

  • bpo-32588: Create standalone _distutils_findvs module.

macOS

  • bpo-32726: Provide an additional, more modern macOS installer variant thatsupports macOS 10.9+ systems in 64-bit mode only. Upgrade the suppliedthird-party libraries to OpenSSL 1.0.2n, XZ 5.2.3, and SQLite 3.22.0. The10.9+ installer now links with and supplies its own copy of Tcl/Tk 8.6.8.

IDLE

  • bpo-32984: Set__file__ while running a startup file. Like Python,IDLE optionally runs one startup file in the Shell window beforepresenting the first interactive input prompt. For IDLE,-s runs afile named in environmental variableIDLESTARTUP orPYTHONSTARTUP;-rfile runsfile. Python sets__file__ to the startup file name before running the file and unsetsit before the first prompt. IDLE now does the same when run normally,without the-n option.

  • bpo-32940: Simplify and rename StringTranslatePseudoMapping in pyparse.

  • bpo-32916: Changestr tocode in pyparse.

  • bpo-32905: Remove unused code in pyparse module.

  • bpo-32874: Add tests for pyparse.

  • bpo-32837: Using the system and place-dependent default encoding foropen() is a bad idea for IDLE's system and location-independent files.

  • bpo-32826: Add "encoding=utf-8" to open() in IDLE's test_help_about. GUItest test_file_buttons() only looks at initial ascii-only lines, butfailed on systems where open() defaults to 'ascii' because readline()internally reads and decodes far enough ahead to encounter a non-asciicharacter in CREDITS.txt.

  • bpo-32765: Update configdialog General tab docstring to add new widgets tothe widget list.

Tools/Demos

  • bpo-24960: 2to3 and lib2to3 can now read pickled grammar files usingpkgutil.get_data() rather than probing the filesystem. This lets 2to3 andlib2to3 work when run from a zipfile.

  • bpo-32222: Fix pygettext not extracting docstrings for functions with typeannotated arguments. Patch by Toby Harradine.

C API

  • bpo-29084: Undocumented C API for OrderedDict has been excluded from thelimited C API. It was added by mistake and actually never worked in thelimited C API.

Python 3.6.4 final

Release date: 2017-12-18

There were no new code changes in version 3.6.4 since v3.6.4rc1.

Python 3.6.4 release candidate 1

Release date: 2017-12-05

Core and Builtins

  • bpo-32176: co_flags.CO_NOFREE is now always set correctly by the codeobject constructor based on freevars and cellvars, rather than needing tobe set correctly by the caller. This ensures it will be clearedautomatically when additional cell references are injected into a modifiedcode object and function.

  • bpo-31949: Fixed several issues in printing tracebacks(PyTraceBack_Print()). Setting sys.tracebacklimit to 0 or less nowsuppresses printing tracebacks. Setting sys.tracebacklimit to None nowcauses using the default limit. Setting sys.tracebacklimit to an integerlarger than LONG_MAX now means using the limit LONG_MAX rather than thedefault limit. Fixed integer overflows in the case of more than2**31traceback items on Windows. Fixed output errors handling.

  • bpo-30696: Fix the interactive interpreter looping endlessly when nomemory.

  • bpo-20047: Bytearray methods partition() and rpartition() now accept onlybytes-like objects as separator, as documented. In particular they nowraise TypeError rather of returning a bogus result when an integer ispassed as a separator.

  • bpo-31852: Fix a segmentation fault caused by a combination of the asyncsoft keyword and continuation lines.

  • bpo-21720: BytesWarning no longer emitted when thefromlist argument of__import__() or the__all__ attribute of the module contain bytesinstances.

  • bpo-31825: Fixed OverflowError in the 'unicode-escape' codec and incodecs.escape_decode() when decode an escaped non-ascii byte.

  • bpo-28603: Print the full context/cause chain of exceptions on interpreterexit, even if an exception in the chain is unhashable or compares equal tolater ones. Patch by Zane Bitter.

  • bpo-31786: Fix timeout rounding in the select module to round correctlynegative timeouts between -1.0 and 0.0. The functions now block waitingfor events as expected. Previously, the call was incorrectly non-blocking.Patch by Pablo Galindo.

  • bpo-31642: Restored blocking "from package import module" by settingsys.modules["package.module"] to None.

  • bpo-31626: Fixed a bug in debug memory allocator. There was a write tofreed memory after shrinking a memory block.

  • bpo-31619: Fixed a ValueError when convert a string with large number ofunderscores to integer with binary base.

  • bpo-31592: Fixed an assertion failure in Python parser in case of a badunicodedata.normalize(). Patch by Oren Milman.

  • bpo-31588: Raise aTypeError with a helpful error message when classcreation fails due to a metaclass with a bad__prepare__() method.Patch by Oren Milman.

  • bpo-31566: Fix an assertion failure in_warnings.warn() in case of abad__name__ global. Patch by Oren Milman.

  • bpo-31505: Fix an assertion failure injson, in case_json.make_encoder() received a badencoder() argument. Patch byOren Milman.

  • bpo-31492: Fix assertion failures in case of failing to import from amodule with a bad__name__ attribute, and in case of failing to accessan attribute of such a module. Patch by Oren Milman.

  • bpo-31490: Fix an assertion failure inctypes class definition, incase the class has an attribute whose name is specified in_anonymous_but not in_fields_. Patch by Oren Milman.

  • bpo-31478: Fix an assertion failure in_random.Random.seed() in casethe argument has a bad__abs__() method. Patch by Oren Milman.

  • bpo-31315: Fix an assertion failure in imp.create_dynamic(), whenspec.name is not a string. Patch by Oren Milman.

  • bpo-31311: Fix a crash in the__setstate__() method ofctypes._CData, in case of a bad__dict__. Patch by Oren Milman.

  • bpo-31293: Fix crashes in true division and multiplication of a timedeltaobject by a float with a bad as_integer_ratio() method. Patch by OrenMilman.

  • bpo-31285: Fix an assertion failure inwarnings.warn_explicit, whenthe return value of the received loader'sget_source() has a badsplitlines() method. Patch by Oren Milman.

  • bpo-30817:PyErr_PrintEx() clears now the ignored exception that maybe raised by_PySys_SetObjectId(), for example when no memory.

Library

  • bpo-28556: Two minor fixes fortyping module: allow shallow copyinginstances of generic classes, improve interaction of__init_subclass__with generics. Original PRs by Ivan Levkivskyi.

  • bpo-27240: The header folding algorithm for the new email policies hasbeen rewritten, which also fixesbpo-30788,bpo-31831, andbpo-32182. Inparticular, RFC2231 folding is now done correctly.

  • bpo-32186: io.FileIO.readall() and io.FileIO.read() now release the GILwhen getting the file size. Fixed hang of all threads with inaccessibleNFS server. Patch by Nir Soffer.

  • bpo-12239: Makemsilib.SummaryInformation.GetProperty() returnNone when the value of property isVT_EMPTY. Initial patch byMark Mc Mahon.

  • bpo-31325: Fix wrong usage ofcollections.namedtuple() in theRobotFileParser.parse()method. Initial patch by Robin Wellner.

  • bpo-12382:msilib.OpenDatabase() now raises a better exceptionmessage when it couldn't open or create an MSI file. Initial patch byWilliam Tisäter.

  • bpo-32110:codecs.StreamReader.read(n) now returns not more thanncharacters/bytes for non-negativen. This makes it compatible withread() methods of other file-like objects.

  • bpo-32072: Fixed issues with binary plists: Fixed saving bytearrays.Identical objects will be saved only once. Equal references will be loadas identical objects. Added support for saving and loading recursive datastructures.

  • bpo-32034: Make asyncio.IncompleteReadError and LimitOverrunErrorpickleable.

  • bpo-32015: Fixed the looping of asyncio in the case of reconnection thesocket during waiting async read/write from/to the socket.

  • bpo-32011: Restored support of loading marshal files with the TYPE_INT64code. These files can be produced in Python 2.7.

  • bpo-31970: Reduce performance overhead of asyncio debug mode.

  • bpo-9678: Fixed determining the MAC address in the uuid module: Usingifconfig on NetBSD and OpenBSD. Using arp on Linux, FreeBSD, NetBSD andOpenBSD. Based on patch by Takayuki Shimizukawa.

  • bpo-30057: Fix potential missed signal in signal.signal().

  • bpo-31933: Fix Blake2 params leaf_size and node_offset on big endianplatforms. Patch by Jack O'Connor.

  • bpo-31927: Fixed compilation of the socket module on NetBSD 8. Fixedassertion failure or reading arbitrary data when parse a AF_BLUETOOTHaddress on NetBSD and DragonFly BSD.

  • bpo-27666: Fixed stack corruption in curses.box() and curses.ungetmouse()when the size of types chtype or mmask_t is less than the size of C long.curses.box() now accepts characters as arguments. Based on patch by SteveFink.

  • bpo-31897: plistlib now catches more errors when read binary plists andraises InvalidFileException instead of unexpected exceptions.

  • bpo-25720: Fix the method for checking pad state of curses WINDOW. Patchby Masayuki Yamamoto.

  • bpo-31893: Fixed the layout of the kqueue_event structure on OpenBSD andNetBSD. Fixed the comparison of the kqueue_event objects.

  • bpo-31891: Fixed building the curses module on NetBSD.

  • bpo-28416: Instances of pickle.Pickler subclass with the persistent_id()method and pickle.Unpickler subclass with the persistent_load() method nolonger create reference cycles.

  • bpo-28326: Fix multiprocessing.Process when stdout and/or stderr is closedor None.

  • bpo-31457: If nested log adapters are used, the innerprocess()methods are no longer omitted.

  • bpo-31457: Themanager property on LoggerAdapter objects is nowproperly settable.

  • bpo-31806: Fix timeout rounding in time.sleep(), threading.Lock.acquire()and socket.socket.settimeout() to round correctly negative timeoutsbetween -1.0 and 0.0. The functions now block waiting for events asexpected. Previously, the call was incorrectly non-blocking. Patch byPablo Galindo.

  • bpo-28603: traceback: Fix a TypeError that occurred during printing ofexception tracebacks when either the current exception or an exception inits context/cause chain is unhashable. Patch by Zane Bitter.

  • bpo-30058: Fixed buffer overflow in select.kqueue.control().

  • bpo-31770: Prevent a crash when calling the__init__() method of asqlite3.Cursor object more than once. Patch by Oren Milman.

  • bpo-31672:idpattern instring.Template matched some non-ASCIIcharacters. Now it uses-i regular expression local flag to avoidnon-ASCII characters.

  • bpo-31764: Prevent a crash insqlite3.Cursor.close() in case theCursor object is uninitialized. Patch by Oren Milman.

  • bpo-31752: Fix possible crash in timedelta constructor called with customintegers.

  • bpo-31701: On Windows, faulthandler.enable() now ignores MSC and COMexceptions.

  • bpo-31728: Prevent crashes in_elementtree due to unsafe cleanup ofElement.text andElement.tail. Patch by Oren Milman.

  • bpo-31620: an empty asyncio.Queue now doesn't leak memory when queue.getpollers timeout

  • bpo-31632: Fix method set_protocol() of class _SSLProtocolTransport inasyncio module. This method was previously modifying a wrong reference tothe protocol.

  • bpo-31675: Fixed memory leaks in Tkinter's methods splitlist() and split()when pass a string larger than 2 GiB.

  • bpo-31673: Fixed typo in the name of Tkinter's method adderrorinfo().

  • bpo-30806: Fix the string representation of a netrc object.

  • bpo-15037: Added a workaround for getkey() in curses for ncurses 5.7 andearlier.

  • bpo-25351: Avoid venv activate failures with undefined variables

  • bpo-25532: inspect.unwrap() will now only try to unwrap an objectsys.getrecursionlimit() times, to protect against objects which create anew object on every attribute access.

  • bpo-30347: Stop crashes when concurrently iterate over itertools.groupby()iterators.

  • bpo-31516:threading.current_thread() should not return a dummy threadat shutdown.

  • bpo-31351: python -m ensurepip now exits with non-zero exit code if pipbootstrapping has failed.

  • bpo-31482:random.seed() now works with bytes in version=1

  • bpo-31334: Fixpoll.poll([timeout]) in theselect module forarbitrary negative timeouts on all OSes where it can only be anon-negative integer or -1. Patch by Riccardo Coccioli.

  • bpo-31310: multiprocessing's semaphore tracker should be launched again ifcrashed.

  • bpo-31308: Make multiprocessing's forkserver process immune to Ctrl-C andother user interruptions. If it crashes, restart it when necessary.

Documentation

  • bpo-32105: Added asyncio.BaseEventLoop.connect_accepted_socketversionadded marker.

  • bpo-31537: Fix incorrect usage ofget_history_length in readlinedocumentation example code. Patch by Brad Smith.

  • bpo-30085: The operator functions without double underscores are preferredfor clarity. The one with underscores are only kept forback-compatibility.

Tests

  • bpo-31380: Skip test_httpservers test_undecodable_file on macOS: fails onAPFS.

  • bpo-31705: Skip test_socket.test_sha256() on Linux kernel older than 4.5.The test fails with ENOKEY on kernel 3.10 (on ppc64le). A fix was mergedinto the kernel 4.5.

  • bpo-31174: Fix test_tools.test_unparse: DirectoryTestCase now stores thenames sample to always test the same files. It prevents false alarms whenhunting reference leaks.

  • bpo-30695: Add theset_nomemory(start,stop) andremove_mem_hooks() functions to the_testcapi module.

Build

  • bpo-32059:detect_modules() insetup.py now also searches thesysroot paths when cross-compiling.

  • bpo-31957: Fixes Windows SDK version detection when building for Windows.

  • bpo-31609: Fixes quotes in PCbuild/clean.bat

  • bpo-31934: Abort the build when building out of a not clean source tree.

  • bpo-31926: Fixed Argument Clinic sometimes causing compilation errors whenthere was more than one function and/or method in a .c file with the samename.

  • bpo-28791: Update Windows builds to use SQLite 3.21.0.

  • bpo-28791: Update OS X installer to use SQLite 3.21.0.

  • bpo-22140: Prevent double substitution of prefix in python-config.sh.

  • bpo-31536: Avoid wholesale rebuild aftermakeregen-all if nothingchanged.

Windows

  • bpo-1102: ReturnNone whenView.Fetch() returnsERROR_NO_MORE_ITEMS instead of raisingMSIError. Initial patch byAnthony Tuininga.

  • bpo-31944: Fixes Modify button in Apps and Features dialog.

macOS

  • bpo-31392: Update macOS installer to use OpenSSL 1.0.2m

IDLE

  • bpo-32207: Improve tk event exception tracebacks in IDLE. When tk eventhandling is driven by IDLE's run loop, a confusing and distractingqueue.EMPTY traceback context is no longer added to tk event exceptiontracebacks. The traceback is now the same as when event handling isdriven by user code. Patch based on a suggestion by Serhiy Storchaka.

  • bpo-32164: Delete unused file idlelib/tabbedpages.py. Use of TabbedPageSetin configdialog was replaced by ttk.Notebook.

  • bpo-32100: IDLE: Fix old and new bugs in pathbrowser; improve tests. Patchmostly by Cheryl Sabella.

  • bpo-31858: IDLE -- Restrict shell prompt manipulation to the shell. Editorand output windows only see an empty last prompt line. This simplifiesthe code and fixes a minor bug when newline is inserted. Sys.ps1, ifpresent, is read on Shell start-up, but is not set or changed.

  • bpo-31860: The font sample in the IDLE configuration dialog is noweditable. Changes persist while IDLE remains open

  • bpo-31836: Test_code_module now passes if run after test_idle, which setsps1. The code module uses sys.ps1 if present or sets it to '>>> ' if not.Test_code_module now properly tests both behaviors. Ditto for ps2.

  • bpo-28603: Fix a TypeError that caused a shell restart when printing atraceback that includes an exception that is unhashable. Patch by ZaneBitter.

  • bpo-13802: Use non-Latin characters in the IDLE's Font settings sample.Even if one selects a font that defines a limited subset of the unicodeBasic Multilingual Plane, tcl/tk will use other fonts that define acharacter. The expanded example give users of non-Latin characters abetter idea of what they might see in IDLE's shell and editors. To makeroom for the expanded sample, frames on the Font tab are re-arranged. TheFont/Tabs help explains a bit about the additions.

  • bpo-31460: Simplify the API of IDLE's Module Browser. Passing a widgetinstead of an flist with a root widget opens the option of creating abrowser frame that is only part of a window. Passing a full file nameinstead of pieces assumed to come from a .py file opens the possibility ofbrowsing python files that do not end in .py.

  • bpo-31649: IDLE - Make _htest, _utest parameters keyword only.

  • bpo-31559: Remove test order dependence in idle_test.test_browser.

  • bpo-31459: Rename IDLE's module browser from Class Browser to ModuleBrowser. The original module-level class and method browser became amodule browser, with the addition of module-level functions, years ago.Nested classes and functions were added yesterday. Forback-compatibility, the virtual event <<open-class-browser>>, whichappears on the Keys tab of the Settings dialog, is not changed. Patch byCheryl Sabella.

  • bpo-31500: Default fonts now are scaled on HiDPI displays.

  • bpo-1612262: IDLE module browser now shows nested classes and functions.Original patches for code and tests by Guilherme Polo and Cheryl Sabella,respectively.

Tools/Demos

  • bpo-30722: Make redemo work with Python 3.6 and newer versions. Also,remove theLOCALE option since it doesn't work with string patterns inPython 3. Patch by Christoph Sarnowski.

C API

  • bpo-20891: Fix PyGILState_Ensure(). When PyGILState_Ensure() is called ina non-Python thread before PyEval_InitThreads(), only callPyEval_InitThreads() after calling PyThreadState_New() to fix a crash.

  • bpo-31532: Fix memory corruption due to allocator mix in getpath.c betweenPy_GetPath() and Py_SetPath()

  • bpo-30697: ThePyExc_RecursionErrorInst singleton is removed andPyErr_NormalizeException() does not use it anymore. This singleton ispersistent and its members being never cleared may cause a segfault duringfinalization of the interpreter. See alsobpo-22898.

Python 3.6.3 final

Release date: 2017-10-03

Library

  • bpo-31641: Re-allow arbitrary iterables inconcurrent.futures.as_completed(). Fixes regression in 3.6.3rc1.

Build

  • bpo-31662: Fix typos in Windowsuploadrelease.bat script. Fix WindowsDoc build issues inDoc/make.bat.

  • bpo-31423: Fix building the PDF documentation with newer versions ofSphinx.

Python 3.6.3 release candidate 1

Release date: 2017-09-18

Security

  • bpo-29781: SSLObject.version() now correctly returns None when handshakeover BIO has not been performed yet.

  • bpo-30947: Upgrade libexpat embedded copy from version 2.2.1 to 2.2.3 toget security fixes.

Core and Builtins

  • bpo-31471: Fix an assertion failure insubprocess.Popen() on Windows,in case the env argument has a badkeys() method. Patch by OrenMilman.

  • bpo-31418: Fix an assertion failure inPyErr_WriteUnraisable() in caseof an exception with a bad__module__ attribute. Patch by Oren Milman.

  • bpo-31416: Fix assertion failures in case of a bad warnings.filters orwarnings.defaultaction. Patch by Oren Milman.

  • bpo-31411: Raise a TypeError instead of SystemError in casewarnings.onceregistry is not a dictionary. Patch by Oren Milman.

  • bpo-31373: Fix several possible instances of undefined behavior due tofloating-point demotions.

  • bpo-30465: Location information (lineno andcol_offset) inf-strings is now (mostly) correct. This fixes tools like flake8 fromshowing warnings on the wrong line (typically the first line of the file).

  • bpo-31343: Include sys/sysmacros.h for major(), minor(), and makedev().GNU C libray plans to remove the functions from sys/types.h.

  • bpo-31291: Fix an assertion failure inzipimport.zipimporter.get_dataon Windows, when the return value ofpathname.replace('/','\\') isn'ta string. Patch by Oren Milman.

  • bpo-31271: Fix an assertion failure in thewrite() method ofio.TextIOWrapper, when the encoder doesn't return a bytes object.Patch by Oren Milman.

  • bpo-31243: Fix a crash in some methods ofio.TextIOWrapper, when thedecoder's state is invalid. Patch by Oren Milman.

  • bpo-30721:print now shows correct usage hint for using Python 2redirection syntax. Patch by Sanyam Khurana.

  • bpo-31070: Fix a race condition in importlib _get_module_lock().

  • bpo-31095: Fix potential crash during GC caused bytp_dealloc whichdoesn't callPyObject_GC_UnTrack().

  • bpo-31071: Avoid masking original TypeError in call with * unpacking whenother arguments are passed.

  • bpo-30978: str.format_map() now passes key lookup exceptions through.Previously any exception was replaced with a KeyError exception.

  • bpo-30808: Use _Py_atomic API for concurrency-sensitive signal state.

  • bpo-30876: Relative import from unloaded package now reimports the packageinstead of failing with SystemError. Relative import from non-package nowfails with ImportError rather than SystemError.

  • bpo-30703: Improve signal delivery. Avoid using Py_AddPendingCall fromsignal handler, to avoid calling signal-unsafe functions. The tests I'madding here fail without the rest of the patch, on Linux and OS X. Thismeans our signal delivery logic had defects (some signals could be lost).

  • bpo-30765: Avoid blocking in pthread_mutex_lock() whenPyThread_acquire_lock() is asked not to block.

  • bpo-31161: Make sure the 'Missing parentheses' syntax error message isonly applied to SyntaxError, not to subclasses. Patch by Martijn Pieters.

  • bpo-30814: Fixed a race condition when import a submodule from a package.

  • bpo-30597:print now shows expected input in custom error message whenused as a Python 2 statement. Patch by Sanyam Khurana.

Library

  • bpo-31499: xml.etree: Fix a crash when a parser is part of a referencecycle.

  • bpo-28556: typing.get_type_hints now finds the right globalns for classesand modules by default (when noglobalns was specified by the caller).

  • bpo-28556: Speed improvements to thetyping module. Original PRs byIvan Levkivskyi and Mitar.

  • bpo-31544: The C accelerator module of ElementTree ignored exceptionsraised when looking up TreeBuilder target methods in XMLParser().

  • bpo-31234: socket.create_connection() now fixes manually a referencecycle: clear the variable storing the last exception on success.

  • bpo-31457: LoggerAdapter objects can now be nested.

  • bpo-31400: Improves SSL error handling to avoid losing error numbers.

  • bpo-28958: ssl.SSLContext() now uses OpenSSL error information when acontext cannot be instantiated.

  • bpo-27340: SSLSocket.sendall() now uses memoryview to create slices ofdata. This fixes support for all bytes-like object. It is also moreefficient and avoids costly copies.

  • bpo-31178: Fix string concatenation bug in rare error path in thesubprocess module

  • bpo-31350: Micro-optimizeasyncio._get_running_loop() to become upto 10% faster.

  • bpo-31170: expat: Update libexpat from 2.2.3 to 2.2.4. Fix copying ofpartial characters for UTF-8 input (libexpat bug 115):https://github.com/libexpat/libexpat/issues/115

  • bpo-29136: Add TLS 1.3 cipher suites and OP_NO_TLSv1_3.

  • bpo-29212: Fix concurrent.futures.thread.ThreadPoolExecutor threads tohave a non repr() based thread name by default when no thread_name_prefixis supplied. They will now identify themselves as"ThreadPoolExecutor-y_n".

  • bpo-9146: Fix a segmentation fault in _hashopenssl when standard hashfunctions such as md5 are not available in the linked OpenSSL library. Asin some special FIPS-140 build environments.

  • bpo-27144: Themap() andas_completed() iterators inconcurrent.futures now avoid keeping a reference to yielded objects.

  • bpo-10746: Fix ctypes producing wrongPEP 3118 type codes for integertypes.

  • bpo-22536: The subprocess module now sets the filename whenFileNotFoundError is raised on POSIX systems due to the executable or cwdnot being found.

  • bpo-31249: concurrent.futures: WorkItem.run() used by ThreadPoolExecutornow breaks a reference cycle between an exception object and the WorkItemobject.

  • bpo-31247: xmlrpc.server now explicitly breaks reference cycles when usingsys.exc_info() in code handling exceptions.

  • bpo-30102: The ssl and hashlib modules now callOPENSSL_add_all_algorithms_noconf() on OpenSSL < 1.1.0. The functiondetects CPU features and enables optimizations on some CPU architecturessuch as POWER8. Patch is based on research from Gustavo Serra Scalet.

  • bpo-31185: Fixed miscellaneous errors in asyncio speedup module.

  • bpo-31135: ttk: fix the destroy() method of LabeledScale and OptionMenuclasses. Call the parent destroy() method even if the used attributedoesn't exist. The LabeledScale.destroy() method now also explicitlyclears label and scale attributes to help the garbage collector to destroyall widgets.

  • bpo-31107: Fixcopyreg._slotnames() mangled attribute calculation forclasses whose name begins with an underscore. Patch by Shane Harvey.

  • bpo-31061: Fixed a crash when using asyncio and threads.

  • bpo-30502: Fix handling of long oids in ssl. Based on patch by ChristianHeimes.

  • bpo-30119: ftplib.FTP.putline() now throws ValueError on commands thatcontains CR or LF. Patch by Donghee Na.

  • bpo-30595: multiprocessing.Queue.get() with a timeout now polls its readerin non-blocking mode if it succeeded to acquire the lock but the acquiretook longer than the timeout.

  • bpo-29403: Fixunittest.mock's autospec to not fail on method-boundbuiltin functions. Patch by Aaron Gallagher.

  • bpo-30961: Fix decrementing a borrowed reference in tracemalloc.

  • bpo-25684: Changettk.OptionMenu radiobuttons to be unique acrossinstances ofOptionMenu.

  • bpo-30886: Fix multiprocessing.Queue.join_thread(): it now waits until thethread completes, even if the thread was started by the same process whichcreated the queue.

  • bpo-29854: Fix segfault in readline when using readline's history-sizeoption. Patch by Nir Soffer.

  • bpo-30319: socket.close() now ignores ECONNRESET error.

  • bpo-30828: Fix out of bounds write inasyncio.CFuture.remove_done_callback().

  • bpo-30807: signal.setitimer() may disable the timer when passed a tinyvalue. Tiny values (such as 1e-6) are valid non-zero values forsetitimer(), which is specified as taking microsecond-resolutionintervals. However, on some platform, our conversion routine could convert1e-6 into a zero interval, therefore disabling the timer instead of(re-)scheduling it.

  • bpo-30441: Fix bug when modifying os.environ while iterating over it

  • bpo-30532: Fix email header value parser dropping folding white space incertain cases.

  • bpo-30879: os.listdir() and os.scandir() now emit bytes names when calledwith bytes-like argument.

  • bpo-30746: Prohibited the '=' character in environment variable names inos.putenv() andos.spawn*().

  • bpo-29755: Fixed the lgettext() family of functions in the gettext module.They now always return bytes.

Documentation

  • bpo-31294: Fix incomplete code snippet in the ZeroMQSocketListener andZeroMQSocketHandler examples and adapt them to Python 3.

  • bpo-21649: Add RFC 7525 and Mozilla server side TLS links to SSLdocumentation.

  • bpo-30803: Clarify doc on truth value testing. Original patch by PeterThomassen.

Tests

  • bpo-31320: Silence traceback in test_ssl

  • bpo-25674: Remove sha256.tbs-internet.com ssl test

  • bpo-30715: Address ALPN callback changes for OpenSSL 1.1.0f. The latestversion behaves like OpenSSL 1.0.2 and no longer aborts handshake.

  • bpo-30822: regrtest: Exclude tzdata from regrtest --all. When running thetest suite using --use=all / -u all, exclude tzdata since it makestest_datetime too slow (15-20 min on some buildbots) which then times outon some buildbots. Fix also regrtest command line parser to allow passing-u extralargefile to run test_zipfile64.

Build

  • bpo-30854: Fix compile error when compiling --without-threads. Patch byMasayuki Yamamoto.

Windows

  • bpo-30389: Adds detection of Visual Studio 2017 to distutils on Windows.

  • bpo-31340: Change to building with MSVC v141 (included with Visual Studio2017)

  • bpo-30581: os.cpu_count() now returns the correct number of processors onWindows when the number of logical processors is greater than 64.

  • bpo-30731: Add a missing xmlns to python.manifest so that it matches theschema.

IDLE

  • bpo-31493: IDLE code context -- fix code update and font update timers.Canceling timers prevents a warning message when test_idle completes.

  • bpo-31488: IDLE - Update non-key options in former extension classes. Whenapplying configdialog changes, call .reload for each feature class. ChangeParenMatch so updated options affect existing instances attached toexisting editor windows.

  • bpo-31477: IDLE - Improve rstrip entry in doc. Strip trailing whitespacestrips more than blank spaces. Multiline string literals are not skipped.

  • bpo-31480: IDLE - make tests pass with zzdummy extension disabled bydefault.

  • bpo-31421: Document how IDLE runs tkinter programs. IDLE calls tcl/tkupdate in the background in order to make live interaction andexperimentation with tkinter applications much easier.

  • bpo-31414: IDLE -- fix tk entry box tests by deleting first. Adding to anint entry is not the same as deleting and inserting because int('') willfail.

  • bpo-31051: Rearrange IDLE configdialog GenPage into Window, Editor, andHelp sections.

  • bpo-30617: IDLE - Add docstrings and tests for outwin subclass of editor.Move some data and functions from the class to module level. Patch byCheryl Sabella.

  • bpo-31287: IDLE - Do not modify tkinter.message in test_configdialog.

  • bpo-27099: Convert IDLE's built-in 'extensions' to regular features. About10 IDLE features were implemented as supposedly optional extensions. Theirdifferent behavior could be confusing or worse for users and not good formaintenance. Hence the conversion. The main difference for users is thatuser configurable key bindings for builtin features are now handleduniformly. Now, editing a binding in a keyset only affects its value inthe keyset. All bindings are defined together in the system-specificdefault keysets in config-extensions.def. All custom keysets are saved asa whole in config-extension.cfg. All take effect as soon as one clicksApply or Ok. The affected events are '<<force-open-completions>>','<<expand-word>>', '<<force-open-calltip>>', '<<flash-paren>>','<<format-paragraph>>', '<<run-module>>', '<<check-module>>', and'<<zoom-height>>'. Any (global) customizations made before 3.6.3 will notaffect their keyset-specific customization after 3.6.3. and vice versa.Initial patch by Charles Wohlganger.

  • bpo-31206: IDLE: Factor HighPage(Frame) class from ConfigDialog. Patch byCheryl Sabella.

  • bpo-31001: Add tests for configdialog highlight tab. Patch by CherylSabella.

  • bpo-31205: IDLE: Factor KeysPage(Frame) class from ConfigDialog. Theslightly modified tests continue to pass. Patch by Cheryl Sabella.

  • bpo-31130: IDLE -- stop leaks in test_configdialog. Initial patch byVictor Stinner.

  • bpo-31002: Add tests for configdialog keys tab. Patch by Cheryl Sabella.

  • bpo-19903: IDLE: Calltips useinspect.signature instead ofinspect.getfullargspec. This improves calltips for builtins convertedto use Argument Clinic. Patch by Louie Lu.

  • bpo-31083: IDLE - Add an outline of a TabPage class in configdialog.Update existing classes to match outline. Initial patch by Cheryl Sabella.

  • bpo-31050: Factor GenPage(Frame) class from ConfigDialog. The slightlymodified tests continue to pass. Patch by Cheryl Sabella.

  • bpo-31004: IDLE - Factor FontPage(Frame) class from ConfigDialog. Slightlymodified tests continue to pass. Fix General tests. Patch mostly by CherylSabella.

  • bpo-30781: IDLE - Use ttk widgets in ConfigDialog. Patches by Terry JanReedy and Cheryl Sabella.

  • bpo-31060: IDLE - Finish rearranging methods of ConfigDialog Groupingmethods pertaining to each tab and the buttons will aid writing tests andimproving the tabs and will enable splitting the groups into classes.

  • bpo-30853: IDLE -- Factor a VarTrace class out of ConfigDialog. Instancetracers manages pairs consisting of a tk variable and a callback function.When tracing is turned on, setting the variable calls the function. Testcoverage for the new class is 100%.

  • bpo-31003: IDLE: Add more tests for General tab.

  • bpo-30993: IDLE - Improve configdialog font page and tests. Inconfigdialog: Document causal pathways in create_font_tab docstring.Simplify some attribute names. Move set_samples calls to var_changed_font(idea from Cheryl Sabella). Move related functions to positions after thecreate widgets function. In test_configdialog: Fix test_font_set so notorder dependent. Fix renamed test_indent_scale so it tests the widget.Adjust tests for movement of set_samples call. Add tests for loadfunctions. Put all font tests in one class and tab indent tests inanother. Except for two lines, these tests completely cover the relatedfunctions.

  • bpo-30981: IDLE -- Add more configdialog font page tests.

  • bpo-28523: IDLE: replace 'colour' with 'color' in configdialog.

  • bpo-30917: Add tests for idlelib.config.IdleConf. Increase coverage from46% to 96%. Patch by Louie Lu.

  • bpo-30934: Document coverage details for idlelib tests. Add section toidlelib/idle-test/README.txt. Include check that branches are taken bothways. Exclude IDLE-specific code that does not run during unit tests.

  • bpo-30913: IDLE: Document ConfigDialog tk Vars, methods, and widgets indocstrings This will facilitate improving the dialog and splitting up theclass. Original patch by Cheryl Sabella.

  • bpo-30899: IDLE: Add tests for ConfigParser subclasses in config. Patch byLouie Lu.

  • bpo-30881: IDLE: Add docstrings to browser.py. Patch by Cheryl Sabella.

  • bpo-30851: IDLE: Remove unused variables in configdialog. One is aduplicate, one is set but cannot be altered by users. Patch by CherylSabella.

  • bpo-30870: IDLE: In Settings dialog, select font with Up, Down keys aswell as mouse. Initial patch by Louie Lu.

  • bpo-8231: IDLE: call config.IdleConf.GetUserCfgDir only once.

  • bpo-30779: IDLE: Factor ConfigChanges class from configdialog, put inconfig; test. * In config, put dump test code in a function; run it andunittest in 'if __name__ == '__main__'. * Add class config.ConfigChangesbased on changes_class_v4.py on bpo issue. * Add classtest_config.ChangesTest, partly using configdialog_tests_v1.py. * Reviseconfigdialog to use ConfigChanges; see tracker msg297804. * Revisetest_configdialog to match configdialog changes. * Remove configdialogfunctions unused or moved to ConfigChanges. Cheryl Sabella contributedparts of the patch.

  • bpo-30777: IDLE: configdialog - Add docstrings and fix comments. Patch byCheryl Sabella.

  • bpo-30495: IDLE: Improve textview with docstrings, PEP8 names, and moretests. Patch by Cheryl Sabella.

  • bpo-30723: IDLE: Make several improvements to parenmatch. Add 'parens'style to highlight both opener and closer. Make 'default' style, which isnot default, a synonym for 'opener'. Make time-delay work the same withall styles. Add help for config dialog extensions tab, including help forparenmatch. Add new tests. Original patch by Charles Wohlganger.

  • bpo-30674: IDLE: add docstrings to grep module. Patch by Cheryl Sabella

  • bpo-21519: IDLE's basic custom key entry dialog now detects duplicatesproperly. Original patch by Saimadhav Heblikar.

  • bpo-29910: IDLE no longer deletes a character after commenting out aregion by a key shortcut. Addreturn'break' for this and otherpotential conflicts between IDLE and default key bindings.

  • bpo-30728: Review and change idlelib.configdialog names. Lowercase methodand attribute names. Replace 'colour' with 'color', expand overly crypticnames, delete unneeded underscores. Replaceimport* with specificimports. Patches by Cheryl Sabella.

  • bpo-6739: IDLE: Verify user-entered key sequences by trying to bind themwith tk. Add tests for all 3 validation functions. Original patch by GPolo. Tests added by Cheryl Sabella.

Tools/Demos

  • bpo-30983: gdb integration commands (py-bt, etc.) work on optimized sharedbuilds now, too.PEP 523 introduced _PyEval_EvalFrameDefault whichinlines PyEval_EvalFrameEx on non-debug shared builds. This broke theability to use py-bt, py-up, and a few other Python-specific gdbintegrations. The problem is fixed by only looking for_PyEval_EvalFrameDefault frames in python-gdb.py. Original patch by Bruno"Polaco" Penteado.

Python 3.6.2 final

Release date: 2017-07-17

No changes since release candidate 2

Python 3.6.2 release candidate 2

Release date: 2017-07-07

Security

  • bpo-30730: Prevent environment variables injection in subprocess onWindows. Prevent passing other environment variables and commandarguments.

  • bpo-30694: Upgrade expat copy from 2.2.0 to 2.2.1 to get fixes of multiplesecurity vulnerabilities including:CVE 2017-9233 (External entityinfinite loop DoS),CVE 2016-9063 (Integer overflow, re-fix),CVE 2016-0718 (Fix regression bugs from 2.2.0's fix toCVE 2016-0718) andCVE 2012-0876 (Counter hash flooding withSipHash). Note: theCVE 2016-5300 (Use os-specific entropy sources likegetrandom) doesn't impact Python, since Python already gets entropy fromthe OS to set the expat secret usingXML_SetHashSalt().

  • bpo-30500: Fix urllib.parse.splithost() to correctly parse fragments. Forexample,splithost('//127.0.0.1#@evil.com/') now correctly returns the127.0.0.1 host, instead of treating@evil.com as the host in anauthentication (login@host).

Python 3.6.2 release candidate 1

Release date: 2017-06-17

Security

Core and Builtins

  • bpo-30682: Removed a too-strict assertion that failed for certainf-strings, such as eval("f'\n'") and eval("f'\r'").

  • bpo-30604: Move co_extra_freefuncs to not be per-thread to avoid crashes

  • bpo-29104: Fixed parsing backslashes in f-strings.

  • bpo-27945: Fixed various segfaults with dict when input collections aremutated during searching, inserting or comparing. Based on patches byDuane Griffin and Tim Mitchell.

  • bpo-25794: Fixed type.__setattr__() and type.__delattr__() fornon-interned attribute names. Based on patch by Eryk Sun.

  • bpo-30039: If a KeyboardInterrupt happens when the interpreter is in themiddle of resuming a chain of nested 'yield from' or 'await' calls, it'snow correctly delivered to the innermost frame.

  • bpo-12414: sys.getsizeof() on a code object now returns the sizes whichincludes the code struct and sizes of objects which it references. Patchby Donghee Na.

  • bpo-29949: Fix memory usage regression of set and frozenset object.

  • bpo-29935: Fixed error messages in the index() method of tuple, list anddeque when pass indices of wrong type.

  • bpo-29859: Show correct error messages when any of the pthread_* calls inthread_pthread.h fails.

  • bpo-28876:bool(range) works even iflen(range) raisesOverflowError.

  • bpo-29600: Fix wrapping coroutine return values in StopIteration.

  • bpo-28856: Fix an oversight that %b format for bytes should supportobjects follow the buffer protocol.

  • bpo-29714: Fix a regression that bytes format may fail when containingzero bytes inside.

  • bpo-29478: If max_line_length=None is specified while using the Compat32policy, it is no longer ignored. Patch by Mircea Cosbuc.

Library

  • bpo-30616: Functional API of enum allows to create empty enums. Patched byDonghee Na

  • bpo-30038: Fix race condition between signal delivery and wakeup filedescriptor. Patch by Nathaniel Smith.

  • bpo-23894: lib2to3 now recognizesrb'...' andf'...' strings.

  • bpo-23890: unittest.TestCase.assertRaises() now manually breaks areference cycle to not keep objects alive longer than expected.

  • bpo-30149: inspect.signature() now supports callables withvariable-argument parameters wrapped with partialmethod. Patch by DongheeNa.

  • bpo-30645: Fix path calculation in imp.load_package(), fixing it for caseswhen a package is only shipped with bytecodes. Patch by AlexandruArdelean.

  • bpo-29931: Fixed comparison check for ipaddress.ip_interface objects.Patch by Sanjay Sundaresan.

  • bpo-30605: re.compile() no longer raises a BytesWarning when compiling abytes instance with misplaced inline modifier. Patch by Roy Williams.

  • bpo-24484: Avoid race condition in multiprocessing cleanup (#2159)

  • bpo-28994: The traceback no longer displayed for SystemExit raised in acallback registered by atexit.

  • bpo-30508: Don't log exceptions if Task/Future "cancel()" method wascalled.

  • bpo-28556: Updates to typing module: Add generic AsyncContextManager, addsupport for ContextManager on all versions. Original PRs by Jelle Zijlstraand Ivan Levkivskyi

  • bpo-29870: Fix ssl sockets leaks when connection is aborted in asyncio/sslimplementation. Patch by Michaël Sghaïer.

  • bpo-29743: Closing transport during handshake process leaks open socket.Patch by Nikolay Kim

  • bpo-27585: Fix waiter cancellation in asyncio.Lock. Patch by MathieuSornay.

  • bpo-30418: On Windows, subprocess.Popen.communicate() now also ignoreEINVAL on stdin.write() if the child process is still running but closedthe pipe.

  • bpo-29822: inspect.isabstract() now works during __init_subclass__. Patchby Nate Soares.

  • bpo-29581: ABCMeta.__new__ now accepts**kwargs, allowing abstractbase classes to use keyword parameters in __init_subclass__. Patch by NateSoares.

  • bpo-30557: faulthandler now correctly filters and displays exception codeson Windows

  • bpo-30378: Fix the problem that logging.handlers.SysLogHandler cannothandle IPv6 addresses.

  • bpo-29960: Preserve generator state when _random.Random.setstate() raisesan exception. Patch by Bryan Olson.

  • bpo-30414: multiprocessing.Queue._feed background running thread do notbreak from main loop on exception.

  • bpo-30003: Fix handling escape characters in HZ codec. Based on patch byMa Lin.

  • bpo-30301: Fix AttributeError when using SimpleQueue.empty() underspawnandforkserver start methods.

  • bpo-30329: imaplib and poplib now catch the Windows socket WSAEINVAL error(code 10022) on shutdown(SHUT_RDWR): An invalid operation was attempted.This error occurs sometimes on SSL connections.

  • bpo-30375: Warnings emitted when compile a regular expression now alwayspoint to the line in the user code. Previously they could point intoinners of the re module if emitted from inside of groups or conditionals.

  • bpo-30048: FixedTask.cancel() can be ignored when the task is runningcoroutine and the coroutine returned without any moreawait.

  • bpo-30266: contextlib.AbstractContextManager now supportsanti-registration by setting __enter__ = None or __exit__ = None,following the pattern introduced inbpo-25958. Patch by Jelle Zijlstra.

  • bpo-30298: Weaken the condition of deprecation warnings for inlinemodifiers. Now allowed several subsequential inline modifiers at the startof the pattern (e.g.'(?i)(?s)...'). In verbose mode whitespaces andcomments now are allowed before and between inline modifiers (e.g.'(?x)(?i)(?s)...').

  • bpo-29990: Fix range checking in GB18030 decoder. Original patch by MaLin.

  • bpo-26293: Change resulted because of zipfile breakage. (See also:bpo-29094)

  • bpo-30243: Removed the __init__ methods of _json's scanner and encoder.Misusing them could cause memory leaks or crashes. Now scanner andencoder objects are completely initialized in the __new__ methods.

  • bpo-30185: Avoid KeyboardInterrupt tracebacks in forkserver helper processwhen Ctrl-C is received.

  • bpo-28556: Various updates to typing module: add typing.NoReturn type, useWrapperDescriptorType, minor bug-fixes. Original PRs by JimFasarakis-Hilliard and Ivan Levkivskyi.

  • bpo-30205: Fix getsockname() for unbound AF_UNIX sockets on Linux.

  • bpo-30070: Fixed leaks and crashes in errors handling in the parsermodule.

  • bpo-30061: Fixed crashes in IOBase methods __next__() and readlines() whenreadline() or __next__() respectively return non-sizeable object. Fixedpossible other errors caused by not checking results of PyObject_Size(),PySequence_Size(), or PyMapping_Size().

  • bpo-30017: Allowed calling the close() method of the zip entry writerobject multiple times. Writing to a closed writer now always produces aValueError.

  • bpo-30068: _io._IOBase.readlines will check if it's closed first when hintis present.

  • bpo-29694: Fixed race condition in pathlib mkdir with flags parents=True.Patch by Armin Rigo.

  • bpo-29692: Fixed arbitrary unchaining of RuntimeError exceptions incontextlib.contextmanager. Patch by Siddharth Velankar.

  • bpo-29998: Pickling and copying ImportError now preserves name and pathattributes.

  • bpo-29953: Fixed memory leaks in the replace() method of datetime and timeobjects when pass out of bound fold argument.

  • bpo-29942: Fix a crash in itertools.chain.from_iterable when encounteringlong runs of empty iterables.

  • bpo-27863: Fixed multiple crashes in ElementTree caused by race conditionsand wrong types.

  • bpo-28699: Fixed a bug in pools in multiprocessing.pool that raising anexception at the very first of an iterable may swallow the exception ormake the program hang. Patch by Davin Potts and Xiang Zhang.

  • bpo-25803: Avoid incorrect errors raised by Path.mkdir(exist_ok=True) whenthe OS gives priority to errors such as EACCES over EEXIST.

  • bpo-29861: Release references to tasks, their arguments and their resultsas soon as they are finished in multiprocessing.Pool.

  • bpo-29884: faulthandler: Restore the old sigaltstack during teardown.Patch by Christophe Zeitouny.

  • bpo-25455: Fixed crashes in repr of recursive buffered file-like objects.

  • bpo-29800: Fix crashes in partial.__repr__ if the keys of partial.keywordsare not strings. Patch by Michael Seifert.

  • bpo-29742: get_extra_info() raises exception if get called on closed ssltransport. Patch by Nikolay Kim.

  • bpo-8256: Fixed possible failing or crashing input() if attributes"encoding" or "errors" of sys.stdin or sys.stdout are not set or are notstrings.

  • bpo-28298: Fix a bug that prevented array 'Q', 'L' and 'I' from acceptingbig intables (objects that have __int__) as elements. Patch by OrenMilman.

  • bpo-28231: The zipfile module now accepts path-like objects for externalpaths.

  • bpo-26915: index() and count() methods of collections.abc.Sequence nowcheck identity before checking equality when do comparisons.

  • bpo-29615: SimpleXMLRPCDispatcher no longer chains KeyError (or any otherexception) to exception(s) raised in the dispatched methods. Patch by PetrMotejlek.

  • bpo-30177: path.resolve(strict=False) no longer cuts the path after thefirst element not present in the filesystem. Patch by Antoine Pietri.

IDLE

  • bpo-15786: Fix several problems with IDLE's autocompletion box. Thefollowing should now work: clicking on selection box items; using thescrollbar; selecting an item by hitting Return. Hangs on MacOSX should nolonger happen. Patch by Louie Lu.

  • bpo-25514: Add doc subsubsection about IDLE failure to start. Popupno-connection message directs users to this section.

  • bpo-30642: Fix reference leaks in IDLE tests. Patches by Louie Lu andTerry Jan Reedy.

  • bpo-30495: Add docstrings for textview.py and use PEP8 names. Patches byCheryl Sabella and Terry Jan Reedy.

  • bpo-30290: Help-about: use pep8 names and add tests. Increase coverage to100%. Patches by Louie Lu, Cheryl Sabella, and Terry Jan Reedy.

  • bpo-30303: Add _utest option to textview; add new tests. Increase coverageto 100%. Patches by Louie Lu and Terry Jan Reedy.

C API

  • bpo-27867: Function PySlice_GetIndicesEx() no longer replaced with a macroif Py_LIMITED_API is not set.

Build

  • bpo-29941: Add--with-assertions configure flag to explicitly enable Cassert() checks. Defaults to off.--with-pydebug implies--with-assertions.

  • bpo-28787: Fix out-of-tree builds of Python when configured with--with--dtrace.

  • bpo-29243: Prevent unnecessary rebuilding of Python duringmaketest,makeinstall and some other make targets when configured with--enable-optimizations.

  • bpo-23404: Don't regenerate generated files based on file modificationtime anymore: the action is now explicit. Replacemaketouch withmakeregen-all.

  • bpo-29643: Fix--enable-optimization didn't work.

Documentation

  • bpo-30176: Add missing attribute related constants in cursesdocumentation.

  • bpo-30052: the link targets forbytes() andbytearray() arenow their respective type definitions, rather than the correspondingbuiltin function entries. Usebytes andbytearray to reference the latter. In order toensure this and future cross-reference updates are applied automatically,the daily documentation builds now disable the default output cachingfeatures in Sphinx.

  • bpo-26985: Add missing info of code object in inspect documentation.

Tools/Demos

  • bpo-29367: python-gdb.py now supports alsomethod-wrapper(wrapperobject) objects.

Tests

  • bpo-30357: test_thread: setUp() now uses support.threading_setup() andsupport.threading_cleanup() to wait until threads complete to avoid randomside effects on following tests. Initial patch written by GrzegorzGrzywacz.

  • bpo-30197: Enhanced functions swap_attr() and swap_item() in thetest.support module. They now work when delete replaced attribute or iteminside the with statement. The old value of the attribute or item (orNone if it doesn't exist) now will be assigned to the target of the "as"clause, if there is one.

Windows

  • bpo-30687: Locate msbuild.exe on Windows when building rather thanvcvarsall.bat

  • bpo-30450: The build process on Windows no longer depends on Subversion,instead pulling external code from GitHub via a Python script. If Python3.6 is not found on the system (viapy-3.6), NuGet is used todownload a copy of 32-bit Python.

Python 3.6.1 final

Release date: 2017-03-21

Core and Builtins

  • bpo-29723: Thesys.path[0] initialization change forbpo-29139 causeda regression by revealing an inconsistency in how sys.path is initializedwhen executing__main__ from a zipfile, directory, or other importlocation. The interpreter now consistently avoids ever adding the importlocation's parent directory tosys.path, and ensures no othersys.path entries are inadvertently modified when inserting the importlocation named on the command line.

Build

  • bpo-27593: fix format of git information used in sys.version

  • Fix incompatible comment in python.h

Python 3.6.1 release candidate 1

Release date: 2017-03-04

Core and Builtins

  • bpo-28893: Set correct __cause__ for errors about invalid awaitablesreturned from __aiter__ and __anext__.

  • bpo-29683: Fixes to memory allocation in _PyCode_SetExtra. Patch by BrianColeman.

  • bpo-29684: Fix minor regression of PyEval_CallObjectWithKeywords. Itshould raise TypeError when kwargs is not a dict. But it might cause segvwhen args=NULL and kwargs is not a dict.

  • bpo-28598: Support __rmod__ for subclasses of str being called beforestr.__mod__. Patch by Martijn Pieters.

  • bpo-29607: Fix stack_effect computation for CALL_FUNCTION_EX. Patch byMatthieu Dartiailh.

  • bpo-29602: Fix incorrect handling of signed zeros in complex constructorfor complex subclasses and for inputs having a __complex__ method. Patchby Serhiy Storchaka.

  • bpo-29347: Fixed possibly dereferencing undefined pointers when creatingweakref objects.

  • bpo-29438: Fixed use-after-free problem in key sharing dict.

  • bpo-29319: Prevent RunMainFromImporter overwriting sys.path[0].

  • bpo-29337: Fixed possible BytesWarning when compare the code objects.Warnings could be emitted at compile time.

  • bpo-29327: Fixed a crash when pass the iterable keyword argument tosorted().

  • bpo-29034: Fix memory leak and use-after-free in os module(path_converter).

  • bpo-29159: Fix regression in bytes(x) when x.__index__() raises Exception.

  • bpo-28932: Do not include <sys/random.h> if it does not exist.

  • bpo-25677: Correct the positioning of the syntax error caret for indentedblocks. Based on patch by Michael Layzell.

  • bpo-29000: Fixed bytes formatting of octals with zero padding in alternateform.

  • bpo-26919: On Android, operating system data is now always encoded/decodedto/from UTF-8, instead of the locale encoding to avoid inconsistencieswith os.fsencode() and os.fsdecode() which are already using UTF-8.

  • bpo-28991: functools.lru_cache() was susceptible to an obscure reentrancybug triggerable by a monkey-patched len() function.

  • bpo-28739: f-string expressions are no longer accepted as docstrings andby ast.literal_eval() even if they do not include expressions.

  • bpo-28512: Fixed setting the offset attribute of SyntaxError byPyErr_SyntaxLocationEx() and PyErr_SyntaxLocationObject().

  • bpo-28918: Fix the cross compilation of xxlimited when Python has beenbuilt with Py_DEBUG defined.

  • bpo-28731: Optimize _PyDict_NewPresized() to create correct size dict.Improve speed of dict literal with constant keys up to 30%.

Library

  • bpo-29169: Update zlib to 1.2.11.

  • bpo-29623: Allow use of path-like object as a single argument inConfigParser.read(). Patch by David Ellis.

  • bpo-28963: Fix out of bound iteration inasyncio.Future.remove_done_callback implemented in C.

  • bpo-29704: asyncio.subprocess.SubprocessStreamProtocol no longer closesbefore all pipes are closed.

  • bpo-29271: Fix Task.current_task and Task.all_tasks implemented in C toaccept None argument as their pure Python implementation.

  • bpo-29703: Fix asyncio to support instantiation of new event loops inchild processes.

  • bpo-29376: Fix assertion error in threading._DummyThread.is_alive().

  • bpo-28624: Add a test that checks that cwd parameter of Popen() acceptsPathLike objects. Patch by Sayan Chowdhury.

  • bpo-28518: Start a transaction implicitly before a DML statement. Patch byAviv Palivoda.

  • bpo-29532: Altering a kwarg dictionary passed to functools.partial() nolonger affects a partial object after creation.

  • bpo-29110: Fix file object leak in aifc.open() when file is given as afilesystem path and is not in valid AIFF format. Patch by Anthony Zhang.

  • bpo-28556: Various updates to typing module: typing.Counter,typing.ChainMap, improved ABC caching, etc. Original PRs by JelleZijlstra, Ivan Levkivskyi, Manuel Krebber, and Łukasz Langa.

  • bpo-29100: Fix datetime.fromtimestamp() regression introduced in Python3.6.0: check minimum and maximum years.

  • bpo-29519: Fix weakref spewing exceptions during interpreter shutdown whenused with a rare combination of multiprocessing and custom codecs.

  • bpo-29416: Prevent infinite loop in pathlib.Path.mkdir

  • bpo-29444: Fixed out-of-bounds buffer access in the group() method of thematch object. Based on patch by WGH.

  • bpo-29335: Fix subprocess.Popen.wait() when the child process has exitedto a stopped instead of terminated state (ex: when under ptrace).

  • bpo-29290: Fix a regression in argparse that help messages would wrap atnon-breaking spaces.

  • bpo-28735: Fixed the comparison of mock.MagickMock with mock.ANY.

  • bpo-29316: Restore the provisional status of typing module, addcorresponding note to documentation. Patch by Ivan L.

  • bpo-29219: Fixed infinite recursion in the repr of uninitializedctypes.CDLL instances.

  • bpo-29011: Fix an important omission by adding Deque to the typing module.

  • bpo-28969: Fixed race condition in C implementation offunctools.lru_cache. KeyError could be raised when cached function withfull cache was simultaneously called from different threads with the sameuncached arguments.

  • bpo-29142: In urllib.request, suffixes in no_proxy environment variablewith leading dots could match related hostnames again (e.g. .b.c matchesa.b.c). Patch by Milan Oberkirch.

  • bpo-28961: Fix unittest.mock._Call helper: don't ignore the name parameteranymore. Patch written by Jiajun Huang.

  • bpo-29203: functools.lru_cache() now respectsPEP 468 and preserves theorder of keyword arguments. f(a=1, b=2) is now cached separately fromf(b=2, a=1) since both calls could potentially give different results.

  • bpo-15812: inspect.getframeinfo() now correctly shows the first line of acontext. Patch by Sam Breese.

  • bpo-29094: Offsets in a ZIP file created with extern file object and modes"w" and "x" now are relative to the start of the file.

  • bpo-29085: Allow random.Random.seed() to use high quality OS randomnessrather than the pid and time.

  • bpo-29061: Fixed bug in secrets.randbelow() which would hang when given anegative input. Patch by Brendan Donegan.

  • bpo-29079: Prevent infinite loop in pathlib.resolve() on Windows

  • bpo-13051: Fixed recursion errors in large or resizedcurses.textpad.Textbox. Based on patch by Tycho Andersen.

  • bpo-29119: Fix weakrefs in the pure python version ofcollections.OrderedDict move_to_end() method. Contributed by AndraBogildea.

  • bpo-9770: curses.ascii predicates now work correctly with negativeintegers.

  • bpo-28427: old keys should not remove new values from WeakValueDictionarywhen collecting from another thread.

  • bpo-28923: Remove editor artifacts from Tix.py.

  • bpo-29055: Neaten-up empty population error on random.choice() bysuppressing the upstream exception.

  • bpo-28871: Fixed a crash when deallocate deep ElementTree.

  • bpo-19542: Fix bugs in WeakValueDictionary.setdefault() andWeakValueDictionary.pop() when a GC collection happens in another thread.

  • bpo-20191: Fixed a crash in resource.prlimit() when passing a sequencethat doesn't own its elements as limits.

  • bpo-28779: multiprocessing.set_forkserver_preload() would crash theforkserver process if a preloaded module instantiated some multiprocessingobjects such as locks.

  • bpo-28847: dbm.dumb now supports reading read-only files and no longerwrites the index file when it is not changed.

  • bpo-26937: The chown() method of the tarfile.TarFile class does not failnow when the grp module cannot be imported, as for example on Androidplatforms.

IDLE

  • bpo-29071: IDLE colors f-string prefixes (but not invalid ur prefixes).

  • bpo-28572: Add 10% to coverage of IDLE's test_configdialog. Update andaugment description of the configuration system.

Windows

  • bpo-29579: Removes readme.txt from the installer

  • bpo-29326: Ignores blank lines in ._pth files (Patch by Alexey Izbyshev)

  • bpo-28164: Correctly handle special console filenames (patch by Eryk Sun)

  • bpo-29409: ImplementPEP 529 for io.FileIO (Patch by Eryk Sun)

  • bpo-29392: Prevent crash when passing invalid arguments into msvcrtmodule.

  • bpo-25778: winreg does not truncate string correctly (Patch by Eryk Sun)

  • bpo-28896: Deprecate WindowsRegistryFinder and disable it by default.

C API

  • bpo-27867: Function PySlice_GetIndicesEx() is replaced with a macro ifPy_LIMITED_API is not set or set to the value between 0x03050400 and0x03060000 (not including) or 0x03060100 or higher.

  • bpo-29083: Fixed the declaration of some public API functions.PyArg_VaParse() and PyArg_VaParseTupleAndKeywords() were not available inlimited API. PyArg_ValidateKeywordArguments(), PyArg_UnpackTuple() andPy_BuildValue() were not available in limited API of version < 3.3 whenPY_SSIZE_T_CLEAN is defined.

  • bpo-29058: All stable API extensions added after Python 3.2 are nowavailable only when Py_LIMITED_API is set to the PY_VERSION_HEX value ofthe minimum Python version supporting this API.

Documentation

  • bpo-28929: Link the documentation to its source file on GitHub.

  • bpo-25008: Document smtpd.py as effectively deprecated and add a pointerto aiosmtpd, a third-party asyncio-based replacement.

  • bpo-26355: Add canonical header link on each page to corresponding majorversion of the documentation. Patch by Matthias Bussonnier.

  • bpo-29349: Fix Python 2 syntax in code for building the documentation.

Tests

  • bpo-28087: Skip test_asyncore and test_eintr poll failures on macOS. Skipsome tests of select.poll when running on macOS due to unresolved issueswith the underlying system poll function on some macOS versions.

  • bpo-29571: to match the behaviour of there.LOCALE flag,test_re.test_locale_flag now useslocale.getpreferredencoding(False)to determine the candidate encoding for the test regex (allowing it tocorrectly skip the test when the default locale encoding is a multi-byteencoding)

  • bpo-28950: Disallow -j0 to be combined with -T/-l in regrtest command linearguments.

  • bpo-28683: Fix the tests that bind() a unix socket and raisePermissionError on Android for a non-root user.

  • bpo-26939: Add the support.setswitchinterval() function to fixtest_functools hanging on the Android armv7 qemu emulator.

Build

  • bpo-27593: sys.version and the platform module python_build(),python_branch(), and python_revision() functions now use git informationrather than hg when building from a repo.

  • bpo-29572: Update Windows build and OS X installers to use OpenSSL 1.0.2k.

  • bpo-26851: Set Android compilation and link flags.

  • bpo-28768: Fix implicit declaration of function _setmode. Patch byMasayuki Yamamoto

  • bpo-29080: Removes hard dependency on hg.exe from PCBuild/build.bat

  • bpo-23903: Added missed names to PC/python3.def.

  • bpo-28762: lockf() is available on Android API level 24, but the F_LOCKmacro is not defined in android-ndk-r13.

  • bpo-28538: Fix the compilation error that occurs because if_nameindex() isavailable on Android API level 24, but the if_nameindex structure is notdefined.

  • bpo-20211: Do not add the directory for installing C header files and thedirectory for installing object code libraries to the cross compilationsearch paths. Original patch by Thomas Petazzoni.

  • bpo-28849: Do not define sys.implementation._multiarch on Android.

Python 3.6.0 final

Release date: 2016-12-23

No changes since release candidate 2

Python 3.6.0 release candidate 2

Release date: 2016-12-16

Core and Builtins

  • bpo-28147: Fix a memory leak in split-table dictionaries: setattr() mustnot convert combined table into split table. Patch written by INADA Naoki.

  • bpo-28990: Fix asyncio SSL hanging if connection is closed beforehandshake is completed. (Patch by HoHo-Ho)

Tools/Demos

Windows

Build

  • bpo-28898: Prevent gdb build errors due to HAVE_LONG_LONG redefinition.

Python 3.6.0 release candidate 1

Release date: 2016-12-06

Core and Builtins

  • bpo-23722: Rather than silently producing a class that doesn't supportzero-argumentsuper() in methods, failing to pass the new__classcell__ namespace entry up totype.__new__ now results in aDeprecationWarning and a class that supports zero-argumentsuper().

  • bpo-28797: Modifying the class __dict__ inside the __set_name__ method ofa descriptor that is used inside that class no longer prevents calling the__set_name__ method of other descriptors.

  • bpo-28782: Fix a bug in the implementationyieldfrom when checking ifthe next instruction is YIELD_FROM. Regression introduced by WORDCODE(bpo-26647).

Library

  • bpo-27030: Unknown escapes in re.sub() replacement template are allowedagain. But they still are deprecated and will be disabled in 3.7.

  • bpo-28835: Fix a regression introduced in warnings.catch_warnings(): callwarnings.showwarning() if it was overridden inside the context manager.

  • bpo-27172: To assist with upgrades from 2.7, the previously documenteddeprecation ofinspect.getfullargspec() has been reversed. Thisdecision may be revisited again after the Python 2.7 branch is no longerofficially supported.

  • bpo-26273: Add newsocket.TCP_CONGESTION (Linux 2.6.13) andsocket.TCP_USER_TIMEOUT (Linux 2.6.37) constants. Patch writtenby Omar Sandoval.

  • bpo-24142: Reading a corrupt config file left configparser in an invalidstate. Original patch by Florian Höch.

  • bpo-28843: Fix asyncio C Task to handle exceptions __traceback__.

C API

  • bpo-28808: PyUnicode_CompareWithASCIIString() now never raises exceptions.

Documentation

  • bpo-23722: The data model reference and the porting section in the What'sNew guide now cover the additional__classcell__ handling needed forcustom metaclasses to fully supportPEP 487 and zero-argumentsuper().

Tools/Demos

  • bpo-28023: Fix python-gdb.py didn't support new dict implementation.

Python 3.6.0 beta 4

Release date: 2016-11-21

Core and Builtins

  • bpo-28532: Show sys.version when -V option is supplied twice.

  • bpo-27100: The with-statement now checks for __enter__ before it checksfor __exit__. This gives less confusing error messages when both methodsare missing. Patch by Jonathan Ellington.

  • bpo-28746: Fix the set_inheritable() file descriptor method on platformsthat do not have the ioctl FIOCLEX and FIONCLEX commands.

  • bpo-26920: Fix not getting the locale's charset upon initializing theinterpreter, on platforms that do not have langinfo.

  • bpo-28648: Fixed crash in Py_DecodeLocale() in debug build on Mac OS Xwhen decode astral characters. Patch by Xiang Zhang.

  • bpo-19398: Extra slash no longer added to sys.path components in case ofempty compile-time PYTHONPATH components.

  • bpo-28665: Improve speed of the STORE_DEREF opcode by 40%.

  • bpo-28583: PyDict_SetDefault didn't combine split table when needed. Patchby Xiang Zhang.

  • bpo-27243: Change PendingDeprecationWarning -> DeprecationWarning. As itwas agreed in the issue, __aiter__ returning an awaitable should result inPendingDeprecationWarning in 3.5 and in DeprecationWarning in 3.6.

  • bpo-26182: Fix a refleak in code that raises DeprecationWarning.

  • bpo-28721: Fix asynchronous generators aclose() and athrow() to handleStopAsyncIteration propagation properly.

Library

  • bpo-28752: Restored the __reduce__() methods of datetime objects.

  • bpo-28727: Regular expression patterns, _sre.SRE_Pattern objects createdby re.compile(), become comparable (only x==y and x!=y operators). Thischange should fix thebpo-18383: don't duplicate warning filters whenthe warnings module is reloaded (thing usually only done in unit tests).

  • bpo-20572: The subprocess.Popen.wait method's undocumented endtimeparameter now raises a DeprecationWarning.

  • bpo-25659: In ctypes, prevent a crash calling the from_buffer() andfrom_buffer_copy() methods on abstract classes like Array.

  • bpo-19717: Makes Path.resolve() succeed on paths that do not exist. Patchby Vajrasky Kok

  • bpo-28563: Fixed possible DoS and arbitrary code execution when handleplural form selections in the gettext module. The expression parser nowsupports exact syntax supported by GNU gettext.

  • bpo-28387: Fixed possible crash in _io.TextIOWrapper deallocator when thegarbage collector is invoked in other thread. Based on patch by SebastianCufre.

  • bpo-28600: Optimize loop.call_soon.

  • bpo-28613: Fix get_event_loop() return the current loop if called fromcoroutines/callbacks.

  • bpo-28634: Fix asyncio.isfuture() to support unittest.Mock.

  • bpo-26081: Fix refleak in _asyncio.Future.__iter__().throw.

  • bpo-28639: Fix inspect.isawaitable to always return bool Patch by JustinMayfield.

  • bpo-28652: Make loop methods reject socket kinds they do not support.

  • bpo-28653: Fix a refleak in functools.lru_cache.

  • bpo-28703: Fix asyncio.iscoroutinefunction to handle Mock objects.

  • bpo-28704: Fix create_unix_server to support Path-like objects (PEP 519).

  • bpo-28720: Add collections.abc.AsyncGenerator.

Documentation

  • bpo-28513: Documented command-line interface of zipfile.

Tests

  • bpo-28666: Now test.support.rmtree is able to remove unwritable orunreadable directories.

  • bpo-23839: Various caches now are cleared before running every test file.

Build

  • bpo-10656: Fix out-of-tree building on AIX. Patch by Tristan Carel andMichael Haubenwallner.

  • bpo-26359: Rename --with-optimiations to --enable-optimizations.

  • bpo-28676: Prevent missing 'getentropy' declaration warning on macOS.Patch by Gareth Rees.

Python 3.6.0 beta 3

Release date: 2016-10-31

Core and Builtins

  • bpo-28128: Deprecation warning for invalid str and byte escape sequencesnow prints better information about where the error occurs. Patch bySerhiy Storchaka and Eric Smith.

  • bpo-28509: dict.update() no longer allocate unnecessary large memory.

  • bpo-28426: Fixed potential crash in PyUnicode_AsDecodedObject() in debugbuild.

  • bpo-28517: Fixed of-by-one error in the peephole optimizer that causedkeeping unreachable code.

  • bpo-28214: Improved exception reporting for problematic __set_name__attributes.

  • bpo-23782: Fixed possible memory leak in _PyTraceback_Add() and exceptionloss in PyTraceBack_Here().

  • bpo-28471: Fix "Python memory allocator called without holding the GIL"crash in socket.setblocking.

Library

  • bpo-27517: LZMA compressor and decompressor no longer raise exceptions ifgiven empty data twice. Patch by Benjamin Fogle.

  • bpo-28549: Fixed segfault in curses's addch() with ncurses6.

  • bpo-28449: tarfile.open() with mode "r" or "r:" now tries to open a tarfile with compression before trying to open it without compression.Otherwise it had 50% chance failed with ignore_zeros=True.

  • bpo-23262: The webbrowser module now supports Firefox 36+ and derivedbrowsers. Based on patch by Oleg Broytman.

  • bpo-27939: Fixed bugs in tkinter.ttk.LabeledScale and tkinter.Scale causedby representing the scale as float value internally in Tk. tkinter.IntVarnow works if float value is set to underlying Tk variable.

  • bpo-18844: The various ways of specifying weights for random.choices() nowproduce the same result sequences.

  • bpo-28255: calendar.TextCalendar().prmonth() no longer prints a space atthe start of new line after printing a month's calendar. Patch by XiangZhang.

  • bpo-20491: The textwrap.TextWrapper class now honors non-breaking spaces.Based on patch by Kaarle Ritvanen.

  • bpo-28353: os.fwalk() no longer fails on broken links.

  • bpo-28430: Fix iterator of C implemented asyncio.Future doesn't acceptnon-None value is passed to it.send(val).

  • bpo-27025: Generated names for Tkinter widgets now start by the "!" prefixfor readability.

  • bpo-25464: Fixed HList.header_exists() in tkinter.tix module by addin aworkaround to Tix library bug.

  • bpo-28488: shutil.make_archive() no longer adds entry "./" to ZIP archive.

  • bpo-25953: re.sub() now raises an error for invalid numerical groupreference in replacement template even if the pattern is not found in thestring. Error message for invalid group reference now includes the groupindex and the position of the reference. Based on patch by SilentGhost.

  • bpo-18219: Optimize csv.DictWriter for large number of columns. Patch byMariatta Wijaya.

  • bpo-28448: Fix C implemented asyncio.Future didn't work on Windows.

  • bpo-28480: Fix error building socket module when multithreading isdisabled.

  • bpo-24452: Make webbrowser support Chrome on Mac OS X.

  • bpo-20766: Fix references leaked by pdb in the handling of SIGINThandlers.

  • bpo-28492: Fix how StopIteration exception is raised in _asyncio.Future.

  • bpo-28500: Fix asyncio to handle async gens GC from another thread.

  • bpo-26923: Fix asyncio.Gather to refuse being cancelled once all childrenare done. Patch by Johannes Ebke.

  • bpo-26796: Don't configure the number of workers for default threadpoolexecutor. Initial patch by Hans Lawrenz.

  • bpo-28544: Implement asyncio.Task in C.

Windows

  • bpo-28522: Fixes mishandled buffer reallocation in getpathp.c

Build

  • bpo-28444: Fix missing extensions modules when cross compiling.

  • bpo-28208: Update Windows build and OS X installers to use SQLite 3.14.2.

  • bpo-28248: Update Windows build and OS X installers to use OpenSSL 1.0.2j.

Tests

  • bpo-26944: Fix test_posix for Android where 'id -G' is entirely wrong ormissing the effective gid.

  • bpo-28409: regrtest: fix the parser of command line arguments.

Python 3.6.0 beta 2

Release date: 2016-10-10

Core and Builtins

  • bpo-28183: Optimize and cleanup dict iteration.

  • bpo-26081: Added C implementation of asyncio.Future. Original patch byYury Selivanov.

  • bpo-28379: Added sanity checks and tests for PyUnicode_CopyCharacters().Patch by Xiang Zhang.

  • bpo-28376: The type of long range iterator is now registered as Iterator.Patch by Oren Milman.

  • bpo-28376: Creating instances of range_iterator by calling range_iteratortype now is deprecated. Patch by Oren Milman.

  • bpo-28376: The constructor of range_iterator now checks that step is not0. Patch by Oren Milman.

  • bpo-26906: Resolving special methods of uninitialized type now causesimplicit initialization of the type instead of a fail.

  • bpo-18287: PyType_Ready() now checks that tp_name is not NULL. Originalpatch by Niklas Koep.

  • bpo-24098: Fixed possible crash when AST is changed in process ofcompiling it.

  • bpo-28201: Dict reduces possibility of 2nd conflict in hash table whenhashes have same lower bits.

  • bpo-28350: String constants with null character no longer interned.

  • bpo-26617: Fix crash when GC runs during weakref callbacks.

  • bpo-27942: String constants now interned recursively in tuples andfrozensets.

  • bpo-21578: Fixed misleading error message when ImportError called withinvalid keyword args.

  • bpo-28203: Fix incorrect type in complex(1.0, {2:3}) error message. Patchby Soumya Sharma.

  • bpo-28086: Single var-positional argument of tuple subtype was passedunscathed to the C-defined function. Now it is converted to exact tuple.

  • bpo-28214: Now __set_name__ is looked up on the class instead of theinstance.

  • bpo-27955: Fallback on reading /dev/urandom device when the getrandom()syscall fails with EPERM, for example when blocked by SECCOMP.

  • bpo-28192: Don't import readline in isolated mode.

  • Upgrade internal unicode databases to Unicode version 9.0.0.

  • bpo-28131: Fix a regression in zipimport's compile_source(). zipimportshould use the same optimization level as the interpreter.

  • bpo-28126: Replace Py_MEMCPY with memcpy(). Visual Studio can properlyoptimize memcpy().

  • bpo-28120: Fix dict.pop() for splitted dictionary when trying to remove a"pending key" (Not yet inserted in split-table). Patch by Xiang Zhang.

  • bpo-26182: Raise DeprecationWarning when async and await keywords are usedas variable/attribute/class/function name.

Library

  • bpo-27998: Fixed bytes path support in os.scandir() on Windows. Patch byEryk Sun.

  • bpo-28317: The disassembler now decodes FORMAT_VALUE argument.

  • bpo-26293: Fixed writing ZIP files that starts not from the start of thefile. Offsets in ZIP file now are relative to the start of the archive inconforming to the specification.

  • bpo-28380: unittest.mock Mock autospec functions now properly supportassert_called, assert_not_called, and assert_called_once.

  • bpo-27181: remove statistics.geometric_mean and defer until 3.7.

  • bpo-28229: lzma module now supports pathlib.

  • bpo-28321: Fixed writing non-BMP characters with binary format inplistlib.

  • bpo-28225: bz2 module now supports pathlib. Initial patch by EthanFurman.

  • bpo-28227: gzip now supports pathlib. Patch by Ethan Furman.

  • bpo-27358: Optimized merging var-keyword arguments and improved errormessage when passing a non-mapping as a var-keyword argument.

  • bpo-28257: Improved error message when passing a non-iterable as avar-positional argument. Added opcode BUILD_TUPLE_UNPACK_WITH_CALL.

  • bpo-28322: Fixed possible crashes when unpickle itertools objects fromincorrect pickle data. Based on patch by John Leitch.

  • bpo-28228: imghdr now supports pathlib.

  • bpo-28226: compileall now supports pathlib.

  • bpo-28314: Fix function declaration (C flags) for the getiterator() methodof xml.etree.ElementTree.Element.

  • bpo-28148: Stop using localtime() and gmtime() in the time module.Introduced platform independent _PyTime_localtime API that is similar toPOSIX localtime_r, but available on all platforms. Patch by Ed Schouten.

  • bpo-28253: Fixed calendar functions for extreme months: 0001-01 and9999-12. Methods itermonthdays() and itermonthdays2() are reimplemented sothat they don't call itermonthdates() which can cause datetime.dateunder/overflow.

  • bpo-28275: Fixed possible use after free in the decompress() methods ofthe LZMADecompressor and BZ2Decompressor classes. Original patch by JohnLeitch.

  • bpo-27897: Fixed possible crash in sqlite3.Connection.create_collation()if pass invalid string-like object as a name. Patch by Xiang Zhang.

  • bpo-18844: random.choices() now has k as a keyword-only argument toimprove the readability of common cases and come into line with thesignature used in other languages.

  • bpo-18893: Fix invalid exception handling in Lib/ctypes/macholib/dyld.py.Patch by Madison May.

  • bpo-27611: Fixed support of default root window in the tkinter.tix module.Added the master parameter in the DisplayStyle constructor.

  • bpo-27348: In the traceback module, restore the formatting of exceptionmessages like "Exception: None". This fixes a regression introduced in3.5a2.

  • bpo-25651: Allow false values to be used for msg parameter of subTest().

  • bpo-27778: Fix a memory leak in os.getrandom() when the getrandom() isinterrupted by a signal and a signal handler raises a Python exception.

  • bpo-28200: Fix memory leak on Windows in the os module (fixpath_converter() function).

  • bpo-25400: RobotFileParser now correctly returns default values forcrawl_delay and request_rate. Initial patch by Peter Wirtz.

  • bpo-27932: Prevent memory leak in win32_ver().

  • Fix UnboundLocalError in socket._sendfile_use_sendfile.

  • bpo-28075: Check for ERROR_ACCESS_DENIED in Windows implementation ofos.stat(). Patch by Eryk Sun.

  • bpo-22493: Warning message emitted by using inline flags in the middle ofregular expression now contains a (truncated) regex pattern. Patch by TimGraham.

  • bpo-25270: Prevent codecs.escape_encode() from raising SystemError when anempty bytestring is passed.

  • bpo-28181: Get antigravity over HTTPS. Patch by Kaartic Sivaraam.

  • bpo-25895: Enable WebSocket URL schemes in urllib.parse.urljoin. Patch byGergely Imreh and Markus Holtermann.

  • bpo-28114: Fix a crash in parse_envlist() when env contains byte strings.Patch by Eryk Sun.

  • bpo-27599: Fixed buffer overrun in binascii.b2a_qp() andbinascii.a2b_qp().

  • bpo-27906: Fix socket accept exhaustion during high TCP traffic. Patch byKevin Conway.

  • bpo-28174: Handle when SO_REUSEPORT isn't properly supported. Patch bySeth Michael Larson.

  • bpo-26654: Inspect functools.partial in asyncio.Handle.__repr__. Patch byiceboy.

  • bpo-26909: Fix slow pipes IO in asyncio. Patch by INADA Naoki.

  • bpo-28176: Fix callbacks race in asyncio.SelectorLoop.sock_connect.

  • bpo-27759: Fix selectors incorrectly retain invalid file descriptors.Patch by Mark Williams.

  • bpo-28368: Refuse monitoring processes if the child watcher has no loopattached. Patch by Vincent Michel.

  • bpo-28369: Raise RuntimeError when transport's FD is used with add_reader,add_writer, etc.

  • bpo-28370: Speedup asyncio.StreamReader.readexactly. Patch by КоренбергМарк.

  • bpo-28371: Deprecate passing asyncio.Handles to run_in_executor.

  • bpo-28372: Fix asyncio to support formatting of non-python coroutines.

  • bpo-28399: Remove UNIX socket from FS before binding. Patch by КоренбергМарк.

  • bpo-27972: Prohibit Tasks to await on themselves.

Windows

  • bpo-28402: Adds signed catalog files for stdlib on Windows.

  • bpo-28333: Enables Unicode for ps1/ps2 and input() prompts. (Patch by ErykSun)

  • bpo-28251: Improvements to help manuals on Windows.

  • bpo-28110: launcher.msi has different product codes between 32-bit and64-bit

  • bpo-28161: Opening CON for write access fails

  • bpo-28162: WindowsConsoleIO readall() fails if first line starts withCtrl+Z

  • bpo-28163: WindowsConsoleIO fileno() passes wrong flags to _open_osfhandle

  • bpo-28164: _PyIO_get_console_type fails for various paths

  • bpo-28137: Renames Windows path file to ._pth

  • bpo-28138: Windows ._pth file should allow import site

C API

  • bpo-28426: Deprecated undocumented functions PyUnicode_AsEncodedObject(),PyUnicode_AsDecodedObject(), PyUnicode_AsDecodedUnicode() andPyUnicode_AsEncodedUnicode().

Build

  • bpo-28258: Fixed build with Estonian locale (python-config and distcleantargets in Makefile). Patch by Arfrever Frehtes Taifersar Arahesis.

  • bpo-26661: setup.py now detects system libffi with multiarch wrapper.

  • bpo-15819: Remove redundant include search directory option for buildingoutside the source tree.

Tests

  • bpo-28217: Adds _testconsole module to test console input.

Python 3.6.0 beta 1

Release date: 2016-09-12

Core and Builtins

  • bpo-23722: The __class__ cell used by zero-argument super() is nowinitialized from type.__new__ rather than __build_class__, so classmethods relying on that will now work correctly when called from metaclassmethods during class creation. Patch by Martin Teichmann.

  • bpo-25221: Fix corrupted result from PyLong_FromLong(0) when Python iscompiled with NSMALLPOSINTS = 0.

  • bpo-27080: Implement formatting support forPEP 515. Initial patch byChris Angelico.

  • bpo-27199: In tarfile, expose copyfileobj bufsize to improve throughput.Patch by Jason Fried.

  • bpo-27948: In f-strings, only allow backslashes inside the braces (wherethe expressions are). This is a breaking change from the 3.6 alphareleases, where backslashes are allowed anywhere in an f-string. Also,require that expressions inside f-strings be enclosed within literalbraces, and not escapes likef'\x7b"hi"\x7d'.

  • bpo-28046: Remove platform-specific directories from sys.path.

  • bpo-28071: Add early-out for differencing from an empty set.

  • bpo-25758: Prevents zipimport from unnecessarily encoding a filename(patch by Eryk Sun)

  • bpo-25856: The __module__ attribute of extension classes and functions nowis interned. This leads to more compact pickle data with protocol 4.

  • bpo-27213: Rework CALL_FUNCTION* opcodes to produce shorter and moreefficient bytecode. Patch by Demur Rumed, design by Serhiy Storchaka,reviewed by Serhiy Storchaka and Victor Stinner.

  • bpo-26331: Implement tokenizing support forPEP 515. Patch by GeorgBrandl.

  • bpo-27999: Make "global after use" a SyntaxError, and ditto for nonlocal.Patch by Ivan Levkivskyi.

  • bpo-28003: ImplementPEP 525 -- Asynchronous Generators.

  • bpo-27985: ImplementPEP 526 -- Syntax for Variable Annotations. Patchby Ivan Levkivskyi.

  • bpo-26058: Add a new private version to the builtin dict type, incrementedat each dictionary creation and at each dictionary change. Implementationof the PEP 509.

  • bpo-27364: A backslash-character pair that is not a valid escape sequencenow generates a DeprecationWarning. Patch by Emanuel Barry.

  • bpo-27350:dict implementation is changed like PyPy. It is morecompact and preserves insertion order. (Concept developed by RaymondHettinger and patch by Inada Naoki.)

  • bpo-27911: Remove unnecessary error checks inexec_builtin_or_dynamic().

  • bpo-27078: Added BUILD_STRING opcode. Optimized f-strings evaluation.

  • bpo-17884: Python now requires systems with inttypes.h and stdint.h

  • bpo-27961: Require platforms to supportlonglong. Python hasn'tcompiled withoutlonglong for years, so this is basically aformality.

  • bpo-27355: Removed support for Windows CE. It was never finished, andWindows CE is no longer a relevant platform for Python.

  • ImplementPEP 523.

  • bpo-27870: A left shift of zero by a large integer no longer attempts toallocate large amounts of memory.

  • bpo-25402: In int-to-decimal-string conversion, improve the estimate ofthe intermediate memory required, and remove an unnecessarily strictoverflow check. Patch by Serhiy Storchaka.

  • bpo-27214: In long_invert, be more careful about modifying object returnedby long_add, and remove an unnecessary check for small longs. Thanks OrenMilman for analysis and patch.

  • bpo-27506: Support passing the bytes/bytearray.translate() "delete"argument by keyword.

  • bpo-27812: Properly clear out a generator's frame's backreference to thegenerator to prevent crashes in frame.clear().

  • bpo-27811: Fix a crash when a coroutine that has not been awaited isfinalized with warnings-as-errors enabled.

  • bpo-27587: Fix another issue found by PVS-Studio: Null pointer check afteruse of 'def' in _PyState_AddModule(). Initial patch by Christian Heimes.

  • bpo-27792: The modulo operation applied tobool and otherintsubclasses now always returns anint. Previously the return typedepended on the input values. Patch by Xiang Zhang.

  • bpo-26984: int() now always returns an instance of exact int.

  • bpo-25604: Fix a minor bug in integer true division; this bug couldpotentially have caused off-by-one-ulp results on platforms withunreliable ldexp implementations.

  • bpo-24254: Make class definition namespace ordered by default.

  • bpo-27662: Fix an overflow check inList_New: the original code waschecking againstPy_SIZE_MAX instead of the correct upper bound ofPy_SSIZE_T_MAX. Patch by Xiang Zhang.

  • bpo-27782: Multi-phase extension module import now correctly allows them_methods field to be used to add module level functions to instancesof non-module types returned fromPy_create_mod. Patch by Xiang Zhang.

  • bpo-27936: The round() function accepted a second None argument for sometypes but not for others. Fixed the inconsistency by accepting None forall numeric types.

  • bpo-27487: Warn if a submodule argument to "python -m" orrunpy.run_module() is found in sys.modules after parent packages areimported, but before the submodule is executed.

  • bpo-27157: Make only type() itself accept the one-argument form. Patch byEryk Sun and Emanuel Barry.

  • bpo-27558: Fix a SystemError in the implementation of "raise" statement.In a brand new thread, raise a RuntimeError since there is no activeexception to reraise. Patch written by Xiang Zhang.

  • bpo-28008: ImplementPEP 530 -- asynchronous comprehensions.

  • bpo-27942: Fix memory leak in codeobject.c

Library

  • bpo-28732: Fix crash in os.spawnv() with no elements in args

  • bpo-28485: Always raise ValueError for negativecompileall.compile_dir(workers=...) parameter, even when multithreading isunavailable.

  • bpo-28037: Use sqlite3_get_autocommit() instead of settingConnection->inTransaction manually.

  • bpo-25283: Attributes tm_gmtoff and tm_zone are now available on allplatforms in the return values of time.localtime() and time.gmtime().

  • bpo-24454: Regular expression match object groups are now accessible using__getitem__. "mo[x]" is equivalent to "mo.group(x)".

  • bpo-10740: sqlite3 no longer implicitly commit an open transaction beforeDDL statements.

  • bpo-17941: Add amodule parameter to collections.namedtuple().

  • bpo-22493: Inline flags now should be used only at the start of theregular expression. Deprecation warning is emitted if uses them in themiddle of the regular expression.

  • bpo-26885: xmlrpc now supports unmarshalling additional data types used byApache XML-RPC implementation for numerics and None.

  • bpo-28070: Fixed parsing inline verbose flag in regular expressions.

  • bpo-19500: Add client-side SSL session resumption to the ssl module.

  • bpo-28022: Deprecate ssl-related arguments in favor of SSLContext. Thedeprecation include manual creation of SSLSocket and certfile/keyfile (orsimilar) in ftplib, httplib, imaplib, smtplib, poplib and urllib.

  • bpo-28043: SSLContext has improved default settings: OP_NO_SSLv2,OP_NO_SSLv3, OP_NO_COMPRESSION, OP_CIPHER_SERVER_PREFERENCE,OP_SINGLE_DH_USE, OP_SINGLE_ECDH_USE and HIGH ciphers without MD5.

  • bpo-24693: Changed some RuntimeError's in the zipfile module to moreappropriate types. Improved some error messages and debugging output.

  • bpo-17909:json.load andjson.loads now support binary inputencoded as UTF-8, UTF-16 or UTF-32. Patch by Serhiy Storchaka.

  • bpo-27137: the pure Python fallback implementation offunctools.partial now matches the behaviour of its accelerated Ccounterpart for subclassing, pickling and text representation purposes.Patch by Emanuel Barry and Serhiy Storchaka.

  • Fix possible integer overflows and crashes in the mmap module with unusualusage patterns.

  • bpo-1703178: Fix the ability to pass the --link-objects option to thedistutils build_ext command.

  • bpo-28019: itertools.count() no longer rounds non-integer step in rangebetween 1.0 and 2.0 to 1.

  • bpo-18401: Pdb now supports the 'readrc' keyword argument to controlwhether .pdbrc files should be read. Patch by Martin Matusiak and SamKimbrel.

  • bpo-25969: Update the lib2to3 grammar to handle the unpackinggeneralizations added in 3.5.

  • bpo-14977: mailcap now respects the order of the lines in the mailcapfiles ("first match"), as required by RFC 1542. Patch by Michael Lazar.

  • bpo-28082: Convert re flag constants to IntFlag.

  • bpo-28025: Convert all ssl module constants to IntEnum and IntFlags.SSLContext properties now return flags and enums.

  • bpo-23591: Add Flag, IntFlag, and auto() to enum module.

  • bpo-433028: Added support of modifier spans in regular expressions.

  • bpo-24594: Validates persist parameter when opening MSI database

  • bpo-17582: xml.etree.ElementTree nows preserves whitespaces in attributes(Patch by Duane Griffin. Reviewed and approved by Stefan Behnel.)

  • bpo-28047: Fixed calculation of line length used for the base64 CTE in thenew email policies.

  • bpo-27576: Fix call order in OrderedDict.__init__().

  • email.generator.DecodedGenerator now supports the policy keyword.

  • bpo-28027: Remove undocumented modules fromLib/plat-*: IN, CDROM,DLFCN, TYPES, CDIO, and STROPTS.

  • bpo-27445: Don't pass str(_charset) to MIMEText.set_payload(). Patch byClaude Paroz.

  • bpo-24277: The new email API is no longer provisional, and the docs havebeen reorganized and rewritten to emphasize the new API.

  • bpo-22450: urllib now includes anAccept:*/* header among the defaultheaders. This makes the results of REST API requests more consistent andpredictable especially when proxy servers are involved.

  • lib2to3.pgen3.driver.load_grammar() now creates a stable cache filebetween runs given the same Grammar.txt input regardless of the hashrandomization setting.

  • bpo-28005: Allow ImportErrors in encoding implementation to propagate.

  • bpo-26667: Support path-like objects in importlib.util.

  • bpo-27570: Avoid zero-length memcpy() etc calls with null source pointersin the "ctypes" and "array" modules.

  • bpo-22233: Break email header linesonly on the RFC specified CR and LFcharacters, not on arbitrary unicode line breaks. This also fixes a bugin HTTP header parsing.

  • bpo-27331: The email.mime classes now all accept an optional policykeyword.

  • bpo-27988: Fix email iter_attachments incorrect mutation of payload list.

  • bpo-16113: Add SHA-3 and SHAKE support to hashlib module.

  • Eliminate a tautological-pointer-compare warning in _scproxy.c.

  • bpo-27776: Theos.urandom() function does now block on Linux 3.17and newer until the system urandom entropy pool is initialized to increasethe security. This change is part of thePEP 524.

  • bpo-27778: Expose the Linuxgetrandom() syscall as a newos.getrandom() function. This change is part of thePEP 524.

  • bpo-27691: Fix ssl module's parsing of GEN_RID subject alternative namefields in X.509 certs.

  • bpo-18844: Add random.choices().

  • bpo-25761: Improved error reporting about truncated pickle data in Cimplementation of unpickler. UnpicklingError is now raised instead ofAttributeError and ValueError in some cases.

  • bpo-26798: Add BLAKE2 (blake2b and blake2s) to hashlib.

  • bpo-26032: Optimized globbing in pathlib by using os.scandir(); it is nowabout 1.5--4 times faster.

  • bpo-25596: Optimized glob() and iglob() functions in the glob module; theyare now about 3--6 times faster.

  • bpo-27928: Add scrypt (password-based key derivation function) to hashlibmodule (requires OpenSSL 1.1.0).

  • bpo-27850: Remove 3DES from ssl module's default cipher list to countermeasure sweet32 attack (CVE 2016-2183).

  • bpo-27766: Add ChaCha20 Poly1305 to ssl module's default cipher list.(Required OpenSSL 1.1.0 or LibreSSL).

  • bpo-25387: Check return value of winsound.MessageBeep.

  • bpo-27866: Add SSLContext.get_ciphers() method to get a list of allenabled ciphers.

  • bpo-27744: Add AF_ALG (Linux Kernel crypto) to socket module.

  • bpo-26470: Port ssl and hashlib module to OpenSSL 1.1.0.

  • bpo-11620: Fix support for SND_MEMORY in winsound.PlaySound. Based on apatch by Tim Lesher.

  • bpo-11734: Add support for IEEE 754 half-precision floats to the structmodule. Based on a patch by Eli Stevens.

  • bpo-27919: Deprecatedextra_path distribution option in distutilspackaging.

  • bpo-23229: Add newcmath constants:cmath.inf andcmath.nan tomatchmath.inf andmath.nan, and alsocmath.infj andcmath.nanj to match the format used by complex repr.

  • bpo-27842: The csv.DictReader now returns rows of type OrderedDict.(Contributed by Steve Holden.)

  • Remove support for passing a file descriptor to os.access. It never workedbut previously didn't raise.

  • bpo-12885: Fix error when distutils encounters symlink.

  • bpo-27881: Fixed possible bugs when settingsqlite3.Connection.isolation_level. Based on patch by Xiang Zhang.

  • bpo-27861: Fixed a crash in sqlite3.Connection.cursor() when a factorycreates not a cursor. Patch by Xiang Zhang.

  • bpo-19884: Avoid spurious output on OS X with Gnu Readline.

  • bpo-27706: Restore deterministic behavior of random.Random().seed() forstring seeds using seeding version 1. Allows sequences of calls torandom() to exactly match those obtained in Python 2. Patch by NofarSchnider.

  • bpo-10513: Fix a regression in Connection.commit(). Statements should notbe reset after a commit.

  • bpo-12319: Chunked transfer encoding support added tohttp.client.HTTPConnection requests. Theurllib.request.AbstractHTTPHandler class does not enforce a Content-Lengthheader any more. If a HTTP request has a file or iterable body, but noContent-Length header, the library now falls back to use chunkedtransfer-encoding.

  • A new version of typing.py fromhttps://github.com/python/typing: -Collection (only for 3.6) (bpo-27598) - Add FrozenSet to __all__(upstream #261) - fix crash in _get_type_vars() (upstream #259) - Removethe dict constraint in ForwardRef._eval_type (upstream #252)

  • bpo-27832: Make_normalize parameter toFraction constructorkeyword-only, so thatFraction(2,3,4) now raisesTypeError.

  • bpo-27539: Fix unnormalisedFraction.__pow__ result in the case ofnegative exponent and negative base.

  • bpo-21718: cursor.description is now available for queries using CTEs.

  • bpo-27819: In distutils sdists, simply produce the "gztar" (gzipped tarformat) distributions on all platforms unless "formats" is supplied.

  • bpo-2466: posixpath.ismount now correctly recognizes mount points whichthe user does not have permission to access.

  • bpo-9998: On Linux, ctypes.util.find_library now looks in LD_LIBRARY_PATHfor shared libraries.

  • bpo-27573: exit message for code.interact is now configurable.

  • bpo-27930: Improved behaviour of logging.handlers.QueueListener. Thanks toPaulo Andrade and Petr Viktorin for the analysis and patch.

  • bpo-6766: Distributed reference counting added to multiprocessing tosupport nesting of shared values / proxy objects.

  • bpo-21201: Improves readability of multiprocessing error message. Thanksto Wojciech Walczak for patch.

  • asyncio: Add set_protocol / get_protocol to Transports.

  • bpo-27456: asyncio: Set TCP_NODELAY by default.

IDLE

  • bpo-15308: Add 'interrupt execution' (^C) to Shell menu. Patch by RogerSerwy, updated by Bayard Randel.

  • bpo-27922: Stop IDLE tests from 'flashing' gui widgets on the screen.

  • bpo-27891: Consistently group and sort imports within idlelib modules.

  • bpo-17642: add larger font sizes for classroom projection.

  • Add version to title of IDLE help window.

  • bpo-25564: In section on IDLE -- console differences, mention that usingexec means that __builtins__ is defined for each statement.

  • bpo-27821: Fix 3.6.0a3 regression that prevented custom key sets frombeing selected when no custom theme was defined.

C API

  • bpo-26900: Excluded underscored names and other private API from limitedAPI.

  • bpo-26027: Add support for path-like objects in PyUnicode_FSConverter() &PyUnicode_FSDecoder().

Tests

  • bpo-27427: Additional tests for the math module. Patch by Francisco Couzo.

  • bpo-27953: Skip math and cmath tests that fail on OS X 10.4 due to a poorlibm implementation of tan.

  • bpo-26040: Improve test_math and test_cmath coverage and rigour. Patch byJeff Allen.

  • bpo-27787: Call gc.collect() before checking each test for "danglingthreads", since the dangling threads are weak references.

Build

  • bpo-27566: Fix clean target in freeze makefile (patch by Lisa Roach)

  • bpo-27705: Update message in validate_ucrtbase.py

  • bpo-27976: Deprecate building _ctypes with the bundled copy of libffi onnon-OSX UNIX platforms.

  • bpo-27983: Cause lack of llvm-profdata tool when using clang as requiredfor PGO linking to be a configure time error rather than make time when--with-optimizations is enabled. Also improve our ability to find thellvm-profdata tool on MacOS and some Linuxes.

  • bpo-21590: Support for DTrace and SystemTap probes.

  • bpo-26307: The profile-opt build now applies PGO to the built-in modules.

  • bpo-26359: Add the --with-optimizations flag to turn on LTO and PGO buildsupport when available.

  • bpo-27917: Set platform triplets for Android builds.

  • bpo-25825: Update references to the $(LIBPL) installation path on AIX.This path was changed in 3.2a4.

  • Update OS X installer to use SQLite 3.14.1 and XZ 5.2.2.

  • bpo-21122: Fix LTO builds on OS X.

  • bpo-17128: Build OS X installer with a private copy of OpenSSL. Alsoprovide a sample Install Certificates command script to install a set ofroot certificates from the third-party certifi module.

Tools/Demos

  • bpo-27952: Get Tools/scripts/fixcid.py working with Python 3 and thecurrent "re" module, avoid invalid Python backslash escapes, and fix a bugparsing escaped C quote signs.

Windows

  • bpo-28065: Update xz dependency to 5.2.2 and build it from source.

  • bpo-25144: Ensures TargetDir is set before continuing with custom install.

  • bpo-1602: Windows console doesn't input or print Unicode (PEP 528)

  • bpo-27781: Change file system encoding on Windows to UTF-8 (PEP 529)

  • bpo-27731: Opt-out of MAX_PATH on Windows 10

  • bpo-6135: Adds encoding and errors parameters to subprocess.

  • bpo-27959: Adds oem encoding, alias ansi to mbcs, move aliasmbcs to codeclookup.

  • bpo-27982: The functions of the winsound module now accept keywordarguments.

  • bpo-20366: Build full text search support into SQLite on Windows.

  • bpo-27756: Adds new icons for Python files and processes on Windows.Designs by Cherry Wang.

  • bpo-27883: Update sqlite to 3.14.1.0 on Windows.

Python 3.6.0 alpha 4

Release date: 2016-08-15

Core and Builtins

  • bpo-27704: Optimized creating bytes and bytearray from byte-like objectsand iterables. Speed up to 3 times for short objects. Original patch byNaoki Inada.

  • bpo-26823: Large sections of repeated lines in tracebacks are nowabbreviated as "[Previous line repeated {count} more times]" by thebuiltin traceback rendering. Patch by Emanuel Barry.

  • bpo-27574: Decreased an overhead of parsing keyword arguments in functionsimplemented with using Argument Clinic.

  • bpo-22557: Now importing already imported modules is up to 2.5 timesfaster.

  • bpo-17596: Include <wincrypt.h> to help with Min GW building.

  • bpo-17599: On Windows, rename the privately defined REPARSE_DATA_BUFFERstructure to avoid conflicting with the definition from Min GW.

  • bpo-27507: Add integer overflow check in bytearray.extend(). Patch byXiang Zhang.

  • bpo-27581: Don't rely on wrapping for overflow check inPySequence_Tuple(). Patch by Xiang Zhang.

  • bpo-1621: Avoid signed integer overflow in list and tuple operations.Patch by Xiang Zhang.

  • bpo-27419: Standard __import__() no longer look up "__import__" in globalsor builtins for importing submodules or "from import". Fixed a crash ifraise a warning about unabling to resolve package from __spec__ or__package__.

  • bpo-27083: Respect the PYTHONCASEOK environment variable under Windows.

  • bpo-27514: Make having too many statically nested blocks a SyntaxErrorinstead of SystemError.

  • bpo-27366: ImplementedPEP 487 (Simpler customization of classcreation). Upon subclassing, the __init_subclass__ classmethod is calledon the base class. Descriptors are initialized with __set_name__ afterclass creation.

Library

  • bpo-26027: AddPEP 519/__fspath__() support to the os and os.pathmodules. Includes code from Jelle Zijlstra. (See also:bpo-27524)

  • bpo-27598: Add Collections to collections.abc. Patch by Ivan Levkivskyi,docs by Neil Girdhar.

  • bpo-25958: Support "anti-registration" of special methods from variousABCs, like __hash__, __iter__ or __len__. All these (and several more)can be set to None in an implementation class and the behavior will be asif the method is not defined at all. (Previously, this mechanism existedonly for __hash__, to make mutable classes unhashable.) Code contributedby Andrew Barnert and Ivan Levkivskyi.

  • bpo-16764: Support keyword arguments to zlib.decompress(). Patch by XiangZhang.

  • bpo-27736: Prevent segfault after interpreter re-initialization due to refcount problem introduced in code forbpo-27038 in 3.6.0a3. Patch byXiang Zhang.

  • bpo-25628: Theverbose andrename parameters forcollections.namedtuple are now keyword-only.

  • bpo-12345: Add mathematical constant tau to math and cmath. See alsoPEP 628.

  • bpo-26823: traceback.StackSummary.format now abbreviates large sections ofrepeated lines as "[Previous line repeated {count} more times]" (thischange then further affects other traceback display operations in themodule). Patch by Emanuel Barry.

  • bpo-27664: Add to concurrent.futures.thread.ThreadPoolExecutor() theability to specify a thread name prefix.

  • bpo-27181: Add geometric_mean and harmonic_mean to statistics module.

  • bpo-27573: code.interact now prints an message when exiting.

  • bpo-6422: Add autorange method to timeit.Timer objects.

  • bpo-27773: Correct some memory management errors server_hostname in_ssl.wrap_socket().

  • bpo-26750: unittest.mock.create_autospec() now works properly forsubclasses of property() and other data descriptors. Removes the neverpublicly used, never documented unittest.mock.DescriptorTypes tuple.

  • bpo-26754: Undocumented support of general bytes-like objects as path incompile() and similar functions is now deprecated.

  • bpo-26800: Undocumented support of general bytes-like objects as paths inos functions is now deprecated.

  • bpo-26981: Add _order_ compatibility shim to enum.Enum for Python 2/3 codebases.

  • bpo-27661: Added tzinfo keyword argument to datetime.combine.

  • In the curses module, raise an error if window.getstr() or window.instr()is passed a negative value.

  • bpo-27783: Fix possible usage of uninitialized memory inoperator.methodcaller.

  • bpo-27774: Fix possible Py_DECREF on unowned object in _sre.

  • bpo-27760: Fix possible integer overflow in binascii.b2a_qp.

  • bpo-27758: Fix possible integer overflow in the _csv module for largerecord lengths.

  • bpo-27568: Prevent HTTPoxy attack (CVE 2016-1000110). Ignore theHTTP_PROXY variable when REQUEST_METHOD environment is set, whichindicates that the script is in CGI mode.

  • bpo-7063: Remove dead code from the "array" module's slice handling. Patchby Chuck.

  • bpo-27656: Do not assume sched.h defines any SCHED_* constants.

  • bpo-27130: In the "zlib" module, fix handling of large buffers (typically4 GiB) when compressing and decompressing. Previously, inputs werelimited to 4 GiB, and compression and decompression operations did notproperly handle results of 4 GiB.

  • bpo-24773: ImplementedPEP 495 (Local Time Disambiguation).

  • Expose the EPOLLEXCLUSIVE constant (when it is defined) in the selectmodule.

  • bpo-27567: Expose the EPOLLRDHUP and POLLRDHUP constants in the selectmodule.

  • bpo-1621: Avoid signed int negation overflow in the "audioop" module.

  • bpo-27533: Release GIL in nt._isdir

  • bpo-17711: Fixed unpickling by the persistent ID with protocol 0. Originalpatch by Alexandre Vassalotti.

  • bpo-27522: Avoid an unintentional reference cycle in email.feedparser.

  • bpo-27512: Fix a segfault when os.fspath() called an __fspath__() methodthat raised an exception. Patch by Xiang Zhang.

IDLE

  • bpo-27714: text_textview and test_autocomplete now pass when re-run in thesame process. This occurs when test_idle fails when run with the -woption but without -jn. Fix warning from test_config.

  • bpo-27621: Put query response validation error messages in the query boxitself instead of in a separate messagebox. Redo tests to match. Add MacOSX refinements. Original patch by Mark Roseman.

  • bpo-27620: Escape key now closes Query box as cancelled.

  • bpo-27609: IDLE: tab after initial whitespace should tab, notautocomplete. This fixes problem with writing docstrings at least twiceindented.

  • bpo-27609: Explicitly return None when there are also non-None returns. Ina few cases, reverse a condition and eliminate a return.

  • bpo-25507: IDLE no longer runs buggy code because of its tkinter imports.Users must include the same imports required to run directly in Python.

  • bpo-27173: Add 'IDLE Modern Unix' to the built-in key sets. Make thedefault key set depend on the platform. Add tests for the changes to theconfig module.

  • bpo-27452: add line counter and crc to IDLE configHandler test dump.

Tests

  • bpo-25805: Skip a test in test_pkgutil as needed that doesn't work when__name__==__main__. Patch by SilentGhost.

  • bpo-27472: Add test.support.unix_shell as the path to the default shell.

  • bpo-27369: In test_pyexpat, avoid testing an error message detail thatchanged in Expat 2.2.0.

  • bpo-27594: Prevent assertion error when running test_ast with coverageenabled: ensure code object has a valid first line number. Patch suggestedby Ivan Levkivskyi.

Windows

  • bpo-27647: Update bundled Tcl/Tk to 8.6.6.

  • bpo-27610: AddsPEP 514 metadata to Windows installer

  • bpo-27469: Adds a shell extension to the launcher so that drag and dropworks correctly.

  • bpo-27309: Enables proper Windows styles in python[w].exe manifest.

Build

  • bpo-27713: Suppress spurious build warnings when updating importlib'sbootstrap files. Patch by Xiang Zhang

  • bpo-25825: Correct the references to Modules/python.exp, which is requiredon AIX. The references were accidentally changed in 3.5.0a1.

  • bpo-27453: CPP invocation in configure must use CPPFLAGS. Patch by ChiHsuan Yen.

  • bpo-27641: The configure script now inserts comments into the makefile toprevent the pgen and _freeze_importlib executables from beingcross-compiled.

  • bpo-26662: Set PYTHON_FOR_GEN in configure as the Python program to beused for file generation during the build.

  • bpo-10910: Avoid C++ compilation errors on FreeBSD and OS X. Also updateFreedBSD version checks for the original ctype UTF-8 workaround.

Python 3.6.0 alpha 3

Release date: 2016-07-11

Security

  • bpo-27278: Fix os.urandom() implementation using getrandom() on Linux.Truncate size to INT_MAX and loop until we collected enough random bytes,instead of casting a directly Py_ssize_t to int.

  • bpo-22636: Avoid shell injection problems with ctypes.util.find_library().

Core and Builtins

  • bpo-27473: Fixed possible integer overflow in bytes and bytearrayconcatenations. Patch by Xiang Zhang.

  • bpo-23034: The output of a special Python build with defined COUNT_ALLOCS,SHOW_ALLOC_COUNT or SHOW_TRACK_COUNT macros is now off by default. Itcan be re-enabled using the "-X showalloccount" option. It now outputs tostderr instead of stdout.

  • bpo-27443: __length_hint__() of bytearray iterators no longer return anegative integer for a resized bytearray.

  • bpo-27007: The fromhex() class methods of bytes and bytearray subclassesnow return an instance of corresponding subclass.

Library

  • bpo-26844: Fix error message for imp.find_module() to refer to 'path'instead of 'name'. Patch by Lev Maximov.

  • bpo-23804: Fix SSL zero-length recv() calls to not block and not raise anerror about unclean EOF.

  • bpo-27466: Change time format returned by http.cookie.time2netscape,confirming the netscape cookie format and making it consistent withdocumentation.

  • bpo-21708: Deprecated dbm.dumb behavior that differs from common dbmbehavior: creating a database in 'r' and 'w' modes and modifying adatabase in 'r' mode.

  • bpo-26721: Change the socketserver.StreamRequestHandler.wfile attribute toimplement BufferedIOBase. In particular, the write() method no longer doespartial writes.

  • bpo-22115: Added methods trace_add, trace_remove and trace_info in thetkinter.Variable class. They replace old methods trace_variable, trace,trace_vdelete and trace_vinfo that use obsolete Tcl commands and might notwork in future versions of Tcl. Fixed old tracing methods:trace_vdelete() with wrong mode no longer break tracing, trace_vinfo() nowalways returns a list of pairs of strings, tracing in the "u" mode nowworks.

  • bpo-26243: Only the level argument to zlib.compress() is keyword argumentnow. The first argument is positional-only.

  • bpo-27038: Expose the DirEntry type as os.DirEntry. Code patch by JelleZijlstra.

  • bpo-27186: Update os.fspath()/PyOS_FSPath() to check the return value of__fspath__() to be either str or bytes.

  • bpo-18726: All optional parameters of the dump(), dumps(), load() andloads() functions and JSONEncoder and JSONDecoder class constructors inthe json module are now keyword-only.

  • bpo-27319: Methods selection_set(), selection_add(), selection_remove()and selection_toggle() of ttk.TreeView now allow passing multiple items asmultiple arguments instead of passing them as a tuple. Deprecatedundocumented ability of calling the selection() method with arguments.

  • bpo-27079: Fixed curses.ascii functions isblank(), iscntrl() andispunct().

  • bpo-27294: Numerical state in the repr for Tkinter event objects is nowrepresented as a combination of known flags.

  • bpo-27177: Match objects in the re module now support index-like objectsas group indices. Based on patches by Jeroen Demeyer and Xiang Zhang.

  • bpo-26754: Some functions (compile() etc) accepted a filename argumentencoded as an iterable of integers. Now only strings and byte-like objectsare accepted.

  • bpo-26536: socket.ioctl now supports SIO_LOOPBACK_FAST_PATH. Patch byDaniel Stokes.

  • bpo-27048: Prevents distutils failing on Windows when environmentvariables contain non-ASCII characters

  • bpo-27330: Fixed possible leaks in the ctypes module.

  • bpo-27238: Got rid of bare excepts in the turtle module. Original patchby Jelle Zijlstra.

  • bpo-27122: When an exception is raised within the context being managed bya contextlib.ExitStack() and one of the exit stack generators catches andraises it in a chain, do not re-raise the original exception when exiting,let the new chained one through. This avoids thePEP 479 bug describedin issue25782.

  • bpo-16864: sqlite3.Cursor.lastrowid now supports REPLACE statement.Initial patch by Alex LordThorsen.

  • bpo-26386: Fixed ttk.TreeView selection operations with item id'scontaining spaces.

  • bpo-8637: Honor a pager set by the env var MANPAGER (in preference to oneset by the env var PAGER).

  • bpo-16182: Fix various functions in the "readline" module to use thelocale encoding, and fix get_begidx() and get_endidx() to return codepoint indexes.

  • bpo-27392: Add loop.connect_accepted_socket(). Patch by Jim Fulton.

IDLE

  • bpo-27477: IDLE search dialogs now use ttk widgets.

  • bpo-27173: Add 'IDLE Modern Unix' to the built-in key sets. Make thedefault key set depend on the platform. Add tests for the changes to theconfig module.

  • bpo-27452: make command line "idle-test> python test_help.py" work.__file__ is relative when python is started in the file's directory.

  • bpo-27452: add line counter and crc to IDLE configHandler test dump.

  • bpo-27380: IDLE: add query.py with base Query dialog and ttk widgets.Module had subclasses SectionName, ModuleName, and HelpSource, which areused to get information from users by configdialog and file =>Load Module.Each subclass has itw own validity checks. Using ModuleName allows usersto edit bad module names instead of starting over. Add tests and deletethe two files combined into the new one.

  • bpo-27372: Test_idle no longer changes the locale.

  • bpo-27365: Allow non-ascii chars in IDLE NEWS.txt, for contributor names.

  • bpo-27245: IDLE: Cleanly delete custom themes and key bindings.Previously, when IDLE was started from a console or by import, a cascadeof warnings was emitted. Patch by Serhiy Storchaka.

  • bpo-24137: Run IDLE, test_idle, and htest with tkinter default rootdisabled. Fix code and tests that fail with this restriction. Fix hteststo not create a second and redundant root and mainloop.

  • bpo-27310: Fix IDLE.app failure to launch on OS X due to vestigial import.

C API

  • bpo-26754: PyUnicode_FSDecoder() accepted a filename argument encoded asan iterable of integers. Now only strings and byte-like objects areaccepted.

Build

  • bpo-28066: Fix the logic that searches build directories for generatedinclude files when building outside the source tree.

  • bpo-27442: Expose the Android API level that python was built against, insysconfig.get_config_vars() as 'ANDROID_API_LEVEL'.

  • bpo-27434: The interpreter that runs the cross-build, found in PATH, mustnow be of the same feature version (e.g. 3.6) as the source being built.

  • bpo-26930: Update Windows builds to use OpenSSL 1.0.2h.

  • bpo-23968: Rename the platform directory from plat-$(MACHDEP) toplat-$(PLATFORM_TRIPLET). Rename the config directory (LIBPL) fromconfig-$(LDVERSION) to config-$(LDVERSION)-$(PLATFORM_TRIPLET). Installthe platform specific _sysconfigdata module into the platform directoryand rename it to include the ABIFLAGS.

  • Don't use largefile support for GNU/Hurd.

Tools/Demos

  • bpo-27332: Fixed the type of the first argument of module-level functionsgenerated by Argument Clinic. Patch by Petr Viktorin.

  • bpo-27418: Fixed Tools/importbench/importbench.py.

Documentation

  • bpo-19489: Moved the search box from the sidebar to the header and footerof each page. Patch by Ammar Askar.

  • bpo-27285: Update documentation to reflect the deprecation ofpyvenvand normalize on the term "virtual environment". Patch by Steve Piercy.

Tests

  • bpo-27027: Added test.support.is_android that is True when this is anAndroid build.

Python 3.6.0 alpha 2

Release date: 2016-06-13

Security

  • bpo-26556: Update expat to 2.1.1, fixesCVE 2015-1283.

  • Fix TLS stripping vulnerability in smtplib,CVE 2016-0772. Reported byTeam Oststrom.

  • bpo-26839: On Linux,os.urandom() now callsgetrandom() withGRND_NONBLOCK to fall back on reading/dev/urandom if the urandomentropy pool is not initialized yet. Patch written by Colm Buckley.

Core and Builtins

  • bpo-27095: Simplified MAKE_FUNCTION and removed MAKE_CLOSURE opcodes.Patch by Demur Rumed.

  • bpo-27190: Raise NotSupportedError if sqlite3 is older than 3.3.1. Patchby Dave Sawyer.

  • bpo-27286: Fixed compiling BUILD_MAP_UNPACK_WITH_CALL opcode. Callingfunction with generalized unpacking (PEP 448) and conflicting keywordnames could cause undefined behavior.

  • bpo-27140: Added BUILD_CONST_KEY_MAP opcode.

  • bpo-27186: Add support for os.PathLike objects to open() (part ofPEP 519).

  • bpo-27066: Fixed SystemError if a custom opener (for open()) returns anegative number without setting an exception.

  • bpo-26983: float() now always return an instance of exact float. Thedeprecation warning is emitted if __float__ returns an instance of astrict subclass of float. In a future versions of Python this can be anerror.

  • bpo-27097: Python interpreter is now about 7% faster due to optimizedinstruction decoding. Based on patch by Demur Rumed.

  • bpo-26647: Python interpreter now uses 16-bit wordcode instead ofbytecode. Patch by Demur Rumed.

  • bpo-23275: Allow assigning to an empty target list in round brackets: () =iterable.

  • bpo-27243: Update the __aiter__ protocol: instead of returning anawaitable that resolves to an asynchronous iterator, the asynchronousiterator should be returned directly. Doing the former will trigger aPendingDeprecationWarning.

Library

  • Comment out socket (SO_REUSEPORT) and posix (O_SHLOCK, O_EXLOCK) constantsexposed on the API which are not implemented on GNU/Hurd. They would notwork at runtime anyway.

  • bpo-27025: Generated names for Tkinter widgets are now more meaningful andrecognizable.

  • bpo-25455: Fixed crashes in repr of recursive ElementTree.Element andfunctools.partial objects.

  • bpo-27294: Improved repr for Tkinter event objects.

  • bpo-20508: Improve exception message of IPv{4,6}Network.__getitem__. Patchby Gareth Rees.

  • bpo-21386: Implement missing IPv4Address.is_global property. It wasdocumented since 07a5610bae9d. Initial patch by Roger Luethi.

  • bpo-27029: Removed deprecated support of universal newlines mode fromZipFile.open().

  • bpo-27030: Unknown escapes consisting of'\' and an ASCII letter inregular expressions now are errors. The re.LOCALE flag now can be usedonly with bytes patterns.

  • bpo-27186: Add os.PathLike support to DirEntry (part ofPEP 519).Initial patch by Jelle Zijlstra.

  • bpo-20900: distutils register command now decodes HTTP responsescorrectly. Initial patch by ingrid.

  • bpo-27186: Add os.PathLike support to pathlib, removing its provisionalstatus (part of PEP 519). Initial patch by Dusty Phillips.

  • bpo-27186: Add support for os.PathLike objects to os.fsencode() andos.fsdecode() (part ofPEP 519).

  • bpo-27186: Introduce os.PathLike and os.fspath() (part ofPEP 519).

  • A new version of typing.py provides several new classes and features:@overload outside stubs, Reversible, DefaultDict, Text, ContextManager,Type[], NewType(), TYPE_CHECKING, and numerous bug fixes (note that someof the new features are not yet implemented in mypy or other staticanalyzers). Also classes forPEP 492 (Awaitable, AsyncIterable,AsyncIterator) have been added (in fact they made it into 3.5.1 but werenever mentioned).

  • bpo-25738: Stop http.server.BaseHTTPRequestHandler.send_error() fromsending a message body for 205 Reset Content. Also, don't send Contentheader fields in responses that don't have a body. Patch by SusumuKoshiba.

  • bpo-21313: Fix the "platform" module to tolerate when sys.version containstruncated build information.

  • bpo-23883: Added missing APIs to __all__ to match the documented APIs forthe following modules: cgi, mailbox, mimetypes, plistlib and smtpd.Patches by Jacek Kołodziej.

  • bpo-27164: In the zlib module, allow decompressing raw Deflate streamswith a predefined zdict. Based on patch by Xiang Zhang.

  • bpo-24291: Fix wsgiref.simple_server.WSGIRequestHandler to completelywrite data to the client. Previously it could do partial writes andtruncate data. Also, wsgiref.handler.ServerHandler can now handle stdoutdoing partial writes, but this is deprecated.

  • bpo-21272: Use _sysconfigdata.py to initialize distutils.sysconfig.

  • bpo-19611:inspect now reports the implicit.0 parametersgenerated by the compiler for comprehension and generator expressionscopes as if they were positional-only parameters calledimplicit0.Patch by Jelle Zijlstra.

  • bpo-26809: Add__all__ tostring. Patch by Emanuel Barry.

  • bpo-26373: subprocess.Popen.communicate now correctly ignoresBrokenPipeError when the child process dies before .communicate() iscalled in more/all circumstances.

  • signal, socket, and ssl module IntEnum constant name lookups now return aconsistent name for values having multiple names. Ex: signal.Signals(6)now refers to itself as signal.SIGALRM rather than flipping between thatand signal.SIGIOT based on the interpreter's hash randomization seed.

  • bpo-27167: Clarify the subprocess.CalledProcessError error message textwhen the child process died due to a signal.

  • bpo-25931: Don't define socketserver.Forking* names on platforms such asWindows that do not support os.fork().

  • bpo-21776: distutils.upload now correctly handles HTTPError. Initial patchby Claudiu Popa.

  • bpo-26526: Replace custom parse tree validation in the parser module witha simple DFA validator.

  • bpo-27114: Fix SSLContext._load_windows_store_certs fails withPermissionError

  • bpo-18383: Avoid creating duplicate filters when using filterwarnings andsimplefilter. Based on patch by Alex Shkop.

  • bpo-23026: winreg.QueryValueEx() now return an integer for REG_QWORD type.

  • bpo-26741: subprocess.Popen destructor now emits a ResourceWarning warningif the child process is still running.

  • bpo-27056: Optimize pickle.load() and pickle.loads(), up to 10% faster todeserialize a lot of small objects.

  • bpo-21271: New keyword only parameters in reset_mock call.

IDLE

  • bpo-5124: Paste with text selected now replaces the selection on X11. Thismatches how paste works on Windows, Mac, most modern Linux apps, and ttkwidgets. Original patch by Serhiy Storchaka.

  • bpo-24750: Switch all scrollbars in IDLE to ttk versions. Where needed,minimal tests are added to cover changes.

  • bpo-24759: IDLE requires tk 8.5 and availability ttk widgets. Delete nowunneeded tk version tests and code for older versions. Add test for IDLEsyntax colorizer.

  • bpo-27239: idlelib.macosx.isXyzTk functions initialize as needed.

  • bpo-27262: move Aqua unbinding code, which enable context menus, tomacosx.

  • bpo-24759: Make clear in idlelib.idle_test.__init__ that the directory isa private implementation of test.test_idle and tool for maintainers.

  • bpo-27196: Stop 'ThemeChanged' warnings when running IDLE tests. Thesepersisted after other warnings were suppressed in #20567. Apply SerhiyStorchaka's update_idletasks solution to four test files. Record thisadditional advice in idle_test/README.txt

  • bpo-20567: Revise idle_test/README.txt with advice about avoiding tkwarning messages from tests. Apply advice to several IDLE tests.

  • bpo-24225: Update idlelib/README.txt with new file names and eventhandlers.

  • bpo-27156: Remove obsolete code not used by IDLE.

  • bpo-27117: Make colorizer htest and turtledemo work with dark themes. Movecode for configuring text widget colors to a new function.

  • bpo-24225: Rename manyidlelib/*.py andidle_test/test_*.py files.Edit files to replace old names with new names when the old name referredto the module rather than the class it contained. See the issue and IDLEsection in What's New in 3.6 for more.

  • bpo-26673: When tk reports font size as 0, change to size 10. Such fontson Linux prevented the configuration dialog from opening.

  • bpo-21939: Add test for IDLE's percolator. Original patch by SaimadhavHeblikar.

  • bpo-21676: Add test for IDLE's replace dialog. Original patch by SaimadhavHeblikar.

  • bpo-18410: Add test for IDLE's search dialog. Original patch by WestleyMartínez.

  • bpo-21703: Add test for undo delegator. Patch mostly by SaimadhavHeblikar .

  • bpo-27044: Add ConfigDialog.remove_var_callbacks to stop memory leaks.

  • bpo-23977: Add more asserts to test_delegator.

Documentation

  • bpo-16484: Change the default PYTHONDOCS URL to "https:", and fix theresulting links to use lowercase. Patch by Sean Rodman, test by KaushikNadikuditi.

  • bpo-24136: Document the newPEP 448 unpacking syntax of 3.5.

  • bpo-22558: Add remaining doc links to source code for Python-codedmodules. Patch by Yoni Lavi.

Tests

  • bpo-25285: regrtest now uses subprocesses when the -j1 command line optionis used: each test file runs in a fresh child process. Before, the -j1option was ignored.

  • bpo-25285: Tools/buildbot/test.bat script now uses -j1 by default to runeach test file in fresh child process.

Windows

Build

  • bpo-27229: Fix the cross-compiling pgen rule for in-tree builds. Patch byXavier de Gaye.

  • bpo-26930: Update OS X 10.5+ 32-bit-only installer to build and link withOpenSSL 1.0.2h.

C API

  • bpo-27186: Add the PyOS_FSPath() function (part ofPEP 519).

  • bpo-26282: PyArg_ParseTupleAndKeywords() now supports positional-onlyparameters.

Tools/Demos

  • bpo-26282: Argument Clinic now supports positional-only and keywordparameters in the same function.

Python 3.6.0 alpha 1

Release date: 2016-05-16

Security

  • bpo-26657: Fix directory traversal vulnerability with http.server onWindows. This fixes a regression that was introduced in 3.3.4rc1 and3.4.0rc1. Based on patch by Philipp Hagemeister.

  • bpo-26313: ssl.py _load_windows_store_certs fails if windows cert store isempty. Patch by Baji.

  • bpo-25939: On Windows open the cert store readonly inssl.enum_certificates.

Core and Builtins

  • bpo-20041: Fixed TypeError when frame.f_trace is set to None. Patch byXavier de Gaye.

  • bpo-26168: Fixed possible refleaks in failing Py_BuildValue() with the "N"format unit.

  • bpo-26991: Fix possible refleak when creating a function with annotations.

  • bpo-27039: Fixed bytearray.remove() for values greater than 127. Based onpatch by Joe Jevnik.

  • bpo-23640: int.from_bytes() no longer bypasses constructors forsubclasses.

  • bpo-27005: Optimized the float.fromhex() class method for exact float. Itis now 2 times faster.

  • bpo-18531: Single var-keyword argument of dict subtype was passedunscathed to the C-defined function. Now it is converted to exact dict.

  • bpo-26811: gc.get_objects() no longer contains a broken tuple with NULLpointer.

  • bpo-20120: Use RawConfigParser for .pypirc parsing, removing support forinterpolation unintentionally added with move to Python 3. Behavior nolonger does any interpolation in .pypirc files, matching behavior inPython 2.7 and Setuptools 19.0.

  • bpo-26249: Memory functions of thePyMem_Malloc() domain(PYMEM_DOMAIN_MEM) now use thepymalloc allocator rather than systemmalloc(). Applications callingPyMem_Malloc() without holding the GIL can now crash: usePYTHONMALLOC=debug environment variable to validate the usage ofmemory allocators in your application.

  • bpo-26802: Optimize function calls only using unpacking likefunc(*tuple) (no other positional argument, no keyword): avoid copyingthe tuple. Patch written by Joe Jevnik.

  • bpo-26659: Make the builtin slice type support cycle collection.

  • bpo-26718: super.__init__ no longer leaks memory if called multiple times.NOTE: A direct call of super.__init__ is not endorsed!

  • bpo-27138: Fix the doc comment for FileFinder.find_spec().

  • bpo-27147: MentionPEP 420 in the importlib docs.

  • bpo-25339: PYTHONIOENCODING now has priority over locale in setting theerror handler for stdin and stdout.

  • bpo-26494: Fixed crash on iterating exhausting iterators. Affected classesare generic sequence iterators, iterators of str, bytes, bytearray, list,tuple, set, frozenset, dict, OrderedDict, corresponding views andos.scandir() iterator.

  • bpo-26574: Optimizebytes.replace(b'',b'.') andbytearray.replace(b'',b'.'). Patch written by Josh Snider.

  • bpo-26581: If coding cookie is specified multiple times on a line inPython source code file, only the first one is taken to account.

  • bpo-19711: Add tests for reloading namespace packages.

  • bpo-21099: Switch applicable importlib tests to usePEP 451 API.

  • bpo-26563: Debug hooks on Python memory allocators now raise a fatal errorif functions of thePyMem_Malloc() family are called withoutholding the GIL.

  • bpo-26564: On error, the debug hooks on Python memory allocators now usethetracemalloc module to get the traceback where a memory blockwas allocated.

  • bpo-26558: The debug hooks on Python memory allocatorPyObject_Malloc() now detect when functions are called withoutholding the GIL.

  • bpo-26516: AddPYTHONMALLOC environment variable to set thePython memory allocators and/or install debug hooks.

  • bpo-26516: ThePyMem_SetupDebugHooks() function can now also beused on Python compiled in release mode.

  • bpo-26516: ThePYTHONMALLOCSTATS environment variable can nowalso be used on Python compiled in release mode. It now has no effect ifset to an empty string.

  • bpo-26516: In debug mode, debug hooks are now also installed on Pythonmemory allocators when Python is configured without pymalloc.

  • bpo-26464: Fix str.translate() when string is ASCII and first replacementsremoves character, but next replacement uses a non-ASCII character or astring longer than 1 character. Regression introduced in Python 3.5.0.

  • bpo-22836: Ensure exception reports from PyErr_Display() andPyErr_WriteUnraisable() are sensible even when formatting them producessecondary errors. This affects the reports produced bysys.__excepthook__() and when __del__() raises an exception.

  • bpo-26302: Correct behavior to reject comma as a legal character forcookie names.

  • bpo-26136: Upgrade the warning when a generator raises StopIteration fromPendingDeprecationWarning to DeprecationWarning. Patch by Anish Shah.

  • bpo-26204: The compiler now ignores all constant statements: bytes, str,int, float, complex, name constants (None, False, True), Ellipsis andast.Constant; not only str and int. For example,1.0 is now ignored indeff():1.0.

  • bpo-4806: Avoid masking the original TypeError exception when using star(*) unpacking in function calls. Based on patch by Hagen Fürstenauand Daniel Urban.

  • bpo-26146: Add a new kind of AST node:ast.Constant. It can be used byexternal AST optimizers, but the compiler does not emit directly suchnode.

  • bpo-23601: Sped-up allocation of dict key objects by using Python's smallobject allocator. (Contributed by Julian Taylor.)

  • bpo-18018: Import raises ImportError instead of SystemError if a relativeimport is attempted without a known parent package.

  • bpo-25843: When compiling code, don't merge constants if they are equalbut have a different types. For example,f1,f2=lambda:1,lambda:1.0 is now correctly compiled to two different functions:f1()returns1 (int) andf2() returns1.0 (float), even if1 and1.0 are equal.

  • bpo-26107: The format of theco_lnotab attribute of code objectschanges to support negative line number delta.

  • bpo-26154: Add a new private _PyThreadState_UncheckedGet() function to getthe current Python thread state, but don't issue a fatal error if it isNULL. This new function must be used instead of accessing directly the_PyThreadState_Current variable. The variable is no more exposed sincePython 3.5.1 to hide the exact implementation of atomic C types, to avoidcompiler issues.

  • bpo-25791: If __package__ != __spec__.parent or if neither __package__ or__spec__ are defined then ImportWarning is raised.

  • bpo-22995: [UPDATE] Comment out the one of the pickleability tests in_PyObject_GetState() due to regressions observed in Cython-based projects.

  • bpo-25961: Disallowed null characters in the type name.

  • bpo-25973: Fix segfault when an invalid nonlocal statement binds a namestarting with two underscores.

  • bpo-22995: Instances of extension types with a state that aren'tsubclasses of list or dict and haven't implemented any pickle-relatedmethods (__reduce__, __reduce_ex__, __getnewargs__, __getnewargs_ex__, or__getstate__), can no longer be pickled. Including memoryview.

  • bpo-20440: Massive replacing unsafe attribute setting code with specialmacro Py_SETREF.

  • bpo-25766: Special method __bytes__() now works in str subclasses.

  • bpo-25421: __sizeof__ methods of builtin types now use dynamic basic size.This allows sys.getsize() to work correctly with their subclasses with__slots__ defined.

  • bpo-25709: Fixed problem with in-place string concatenation and utf-8cache.

  • bpo-5319: New Py_FinalizeEx() API allowing Python to set an exit status of120 on failure to flush buffered streams.

  • bpo-25485: telnetlib.Telnet is now a context manager.

  • bpo-24097: Fixed crash in object.__reduce__() if slot name is freed inside__getattr__.

  • bpo-24731: Fixed crash on converting objects with special methods__bytes__, __trunc__, and __float__ returning instances of subclasses ofbytes, int, and float to subclasses of bytes, int, and floatcorrespondingly.

  • bpo-25630: Fix a possible segfault during argument parsing in functionsthat accept filesystem paths.

  • bpo-23564: Fixed a partially broken sanity check in the _posixsubprocessinternals regarding how fds_to_pass were passed to the child. The bug hadno actual impact as subprocess.py already avoided it.

  • bpo-25388: Fixed tokenizer crash when processing undecodable source codewith a null byte.

  • bpo-25462: The hash of the key now is calculated only once in mostoperations in C implementation of OrderedDict.

  • bpo-22995: Default implementation of __reduce__ and __reduce_ex__ nowrejects builtin types with not defined __new__.

  • bpo-24802: Avoid buffer overreads when int(), float(), compile(), exec()and eval() are passed bytes-like objects. These objects are notnecessarily terminated by a null byte, but the functions assumed theywere.

  • bpo-25555: Fix parser and AST: fill lineno and col_offset of "arg" nodewhen compiling AST from Python objects.

  • bpo-24726: Fixed a crash and leaking NULL in repr() of OrderedDict thatwas mutated by direct calls of dict methods.

  • bpo-25449: Iterating OrderedDict with keys with unstable hash now raisesKeyError in C implementations as well as in Python implementation.

  • bpo-25395: Fixed crash when highly nested OrderedDict structures weregarbage collected.

  • bpo-25401: Optimize bytes.fromhex() and bytearray.fromhex(): they are nowbetween 2x and 3.5x faster.

  • bpo-25399: Optimize bytearray % args using the new private _PyBytesWriterAPI. Formatting is now between 2.5 and 5 times faster.

  • bpo-25274: sys.setrecursionlimit() now raises a RecursionError if the newrecursion limit is too low depending at the current recursion depth.Modify also the "lower-water mark" formula to make it monotonic. This markis used to decide when the overflowed flag of the thread state is reset.

  • bpo-24402: Fix input() to prompt to the redirected stdout whensys.stdout.fileno() fails.

  • bpo-25349: Optimize bytes % args using the new private _PyBytesWriter API.Formatting is now up to 2 times faster.

  • bpo-24806: Prevent builtin types that are not allowed to be subclassedfrom being subclassed through multiple inheritance.

  • bpo-25301: The UTF-8 decoder is now up to 15 times as fast for errorhandlers:ignore,replace andsurrogateescape.

  • bpo-24848: Fixed a number of bugs in UTF-7 decoding of misformed data.

  • bpo-25267: The UTF-8 encoder is now up to 75 times as fast for errorhandlers:ignore,replace,surrogateescape,surrogatepass.Patch co-written with Serhiy Storchaka.

  • bpo-25280: Import trace messages emitted in verbose (-v) mode are nolonger formatted twice.

  • bpo-25227: Optimize ASCII and latin1 encoders with thesurrogateescapeerror handler: the encoders are now up to 3 times as fast. Initial patchwritten by Serhiy Storchaka.

  • bpo-25003: On Solaris 11.3 or newer, os.urandom() now uses the getrandom()function instead of the getentropy() function. The getentropy() functionis blocking to generate very good quality entropy, os.urandom() doesn'tneed such high-quality entropy.

  • bpo-9232: Modify Python's grammar to allow trailing commas in the argumentlist of a function declaration. For example, "def f(*, a = 3,): pass" isnow legal. Patch from Mark Dickinson.

  • bpo-24965: ImplementPEP 498 "Literal String Interpolation". Thisallows you to embed expressions inside f-strings, which are converted tonormal strings at run time. Given x=3, then f'value={x}' == 'value=3'.Patch by Eric V. Smith.

  • bpo-26478: Fix semantic bugs when using binary operators with dictionaryviews and tuples.

  • bpo-26171: Fix possible integer overflow and heap corruption inzipimporter.get_data().

  • bpo-25660: Fix TAB key behaviour in REPL with readline.

  • bpo-26288: Optimize PyLong_AsDouble.

  • bpo-26289: Optimize floor and modulo division for single-digit longs.Microbenchmarks show 2-2.5x improvement. Built-in 'divmod' function isnow also ~10% faster. (See also:bpo-26315)

  • bpo-25887: Raise a RuntimeError when a coroutine object is awaited morethan once.

Library

  • bpo-27057: Fix os.set_inheritable() on Android, ioctl() is blocked bySELinux and fails with EACCESS. The function now falls back to fcntl().Patch written by Michał Bednarski.

  • bpo-27014: Fix infinite recursion using typing.py. Thanks to Kalle Tuure!

  • bpo-27031: Removed dummy methods in Tkinter widget classes: tk_menuBar()and tk_bindForTraversal().

  • bpo-14132: Fix urllib.request redirect handling when the target only has aquery string. Original fix by Ján Janech.

  • bpo-17214: The "urllib.request" module now percent-encodes non-ASCII bytesfound in redirect target URLs. Some servers send Location header fieldswith non-ASCII bytes, but "http.client" requires the request target to beASCII-encodable, otherwise a UnicodeEncodeError is raised. Based on patchby Christian Heimes.

  • bpo-27033: The default value of the decode_data parameter forsmtpd.SMTPChannel and smtpd.SMTPServer constructors is changed to False.

  • bpo-27034: Removed deprecated class asynchat.fifo.

  • bpo-26870: Added readline.set_auto_history(), which can stop entries beingautomatically added to the history list. Based on patch by TylerCrompton.

  • bpo-26039: zipfile.ZipFile.open() can now be used to write data into a ZIPfile, as well as for extracting data. Patch by Thomas Kluyver.

  • bpo-26892: Honor debuglevel flag in urllib.request.HTTPHandler. Patchcontributed by Chi Hsuan Yen.

  • bpo-22274: In the subprocess module, allow stderr to be redirected tostdout even when stdout is not redirected. Patch by Akira Li.

  • bpo-26807: mock_open 'files' no longer error on readline at end of file.Patch from Yolanda Robla.

  • bpo-25745: Fixed leaking a userptr in curses panel destructor.

  • bpo-26977: Removed unnecessary, and ignored, call to sum of squares helperin statistics.pvariance.

  • bpo-26002: Use bisect in statistics.median instead of a linear search.Patch by Upendra Kuma.

  • bpo-25974: Make use of new Decimal.as_integer_ratio() method in statisticsmodule. Patch by Stefan Krah.

  • bpo-26996: Add secrets module as described inPEP 506.

  • bpo-26881: The modulefinder module now supports extended opcode arguments.

  • bpo-23815: Fixed crashes related to directly created instances of types in_tkinter and curses.panel modules.

  • bpo-17765: weakref.ref() no longer silently ignores keyword arguments.Patch by Georg Brandl.

  • bpo-26873: xmlrpc now raises ResponseError on unsupported type tagsinstead of silently return incorrect result.

  • bpo-26915: The __contains__ methods in the collections ABCs now check foridentity before checking equality. This better matches the behavior ofthe concrete classes, allows sensible handling of NaNs, and makes iteasier to reason about container invariants.

  • bpo-26711: Fixed the comparison of plistlib.Data with other types.

  • bpo-24114: Fix an uninitialized variable inctypes.util. The bug onlyoccurs on SunOS when the ctypes implementation searches for thecrleprogram. Patch by Xiang Zhang. Tested on SunOS by Kees Bos.

  • bpo-26864: In urllib.request, change the proxy bypass host checkingagainst no_proxy to be case-insensitive, and to not match unrelated hostnames that happen to have a bypassed hostname as a suffix. Patch by XiangZhang.

  • bpo-24902: Print server URL on http.server startup. Initial patch byFelix Kaiser.

  • bpo-25788: fileinput.hook_encoded() now supports an "errors" argument forpassing to open. Original patch by Joseph Hackman.

  • bpo-26634: recursive_repr() now sets __qualname__ of wrapper. Patch byXiang Zhang.

  • bpo-26804: urllib.request will prefer lower_case proxy environmentvariables over UPPER_CASE or Mixed_Case ones. Patch contributed byHans-Peter Jansen.

  • bpo-26837: assertSequenceEqual() now correctly outputs non-stringifieddiffering items (like bytes in the -b mode). This affectsassertListEqual() and assertTupleEqual().

  • bpo-26041: Remove "will be removed in Python 3.7" from deprecationmessages of platform.dist() and platform.linux_distribution(). Patch byKumaripaba Miyurusara Athukorala.

  • bpo-26822: itemgetter, attrgetter and methodcaller objects no longersilently ignore keyword arguments.

  • bpo-26733: Disassembling a class now disassembles class and staticmethods. Patch by Xiang Zhang.

  • bpo-26801: Fix error handling inshutil.get_terminal_size(), catchAttributeError instead ofNameError. Patch written byEmanuel Barry.

  • bpo-24838: tarfile's ustar and gnu formats now correctly calculate nameand link field limits for multibyte character encodings like utf-8.

  • bpo-26717: Stop encoding Latin-1-ized WSGI paths with UTF-8. Patch byAnthony Sottile.

  • bpo-26782: Add STARTUPINFO to subprocess.__all__ on Windows.

  • bpo-26404: Add context manager to socketserver. Patch by Aviv Palivoda.

  • bpo-26735: Fixos.urandom() on Solaris 11.3 and newer when readingmore than 1,024 bytes: callgetrandom() multiple times with a limit of1024 bytes per call.

  • bpo-26585: Eliminate http.server._quote_html() and usehtml.escape(quote=False). Patch by Xiang Zhang.

  • bpo-26685: Raise OSError if closing a socket fails.

  • bpo-16329: Add .webm to mimetypes.types_map. Patch by Giampaolo Rodola'.

  • bpo-13952: Add .csv to mimetypes.types_map. Patch by Geoff Wilson.

  • bpo-26587: the site module now allows .pth files to specify files to beadded to sys.path (e.g. zip files).

  • bpo-25609: Introduce contextlib.AbstractContextManager andtyping.ContextManager.

  • bpo-26709: Fixed Y2038 problem in loading binary PLists.

  • bpo-23735: Handle terminal resizing with Readline 6.3+ by installing ourown SIGWINCH handler. Patch by Eric Price.

  • bpo-25951: Change SSLSocket.sendall() to return None, as explicitlydocumented for plain socket objects. Patch by Aviv Palivoda.

  • bpo-26586: In http.server, respond with "413 Request header fields toolarge" if there are too many header fields to parse, rather than killingthe connection and raising an unhandled exception. Patch by Xiang Zhang.

  • bpo-26676: Added missing XMLPullParser to ElementTree.__all__.

  • bpo-22854: Change BufferedReader.writable() and BufferedWriter.readable()to always return False.

  • bpo-26492: Exhausted iterator of array.array now conforms with thebehavior of iterators of other mutable sequences: it lefts exhausted evenif iterated array is extended.

  • bpo-26641: doctest.DocFileTest and doctest.testfile() now support packages(module splitted into multiple directories) for the package parameter.

  • bpo-25195: Fix a regression in mock.MagicMock. _Call is a subclass oftuple (changeset 3603bae63c13 only works for classes) so we need toimplement __ne__ ourselves. Patch by Andrew Plummer.

  • bpo-26644: Raise ValueError rather than SystemError when a negative lengthis passed to SSLSocket.recv() or read().

  • bpo-23804: Fix SSL recv(0) and read(0) methods to return zero bytesinstead of up to 1024.

  • bpo-26616: Fixed a bug in datetime.astimezone() method.

  • bpo-26637: Theimportlib module now emits anImportErrorrather than aTypeError if__import__() is tried during thePython shutdown process butsys.path is already cleared (set toNone).

  • bpo-21925:warnings.formatwarning() now catches exceptions whencallinglinecache.getline() andtracemalloc.get_object_traceback() to be able to logResourceWarning emitted late during the Python shutdown process.

  • bpo-23848: On Windows, faulthandler.enable() now also installs anexception handler to dump the traceback of all Python threads on anyWindows exception, not only on UNIX signals (SIGSEGV, SIGFPE, SIGABRT).

  • bpo-26530: Add C functions_PyTraceMalloc_Track() and_PyTraceMalloc_Untrack() to track memory blocks using thetracemalloc module. Add_PyTraceMalloc_GetTraceback() toget the traceback of an object.

  • bpo-26588: The _tracemalloc now supports tracing memory allocations ofmultiple address spaces (domains).

  • bpo-24266: Ctrl+C during Readline history search now cancels the searchmode when compiled with Readline 7.

  • bpo-26590: Implement a safe finalizer for the _socket.socket type. It nowreleases the GIL to close the socket.

  • bpo-18787: spwd.getspnam() now raises a PermissionError if the userdoesn't have privileges.

  • bpo-26560: Avoid potential ValueError in BaseHandler.start_response.Initial patch by Peter Inglesby.

  • bpo-26567: Add a new functionPyErr_ResourceWarning() function topass the destroyed object. Add asource attribute towarnings.WarningMessage. Add warnings._showwarnmsg() which usestracemalloc to get the traceback where source object was allocated.

  • bpo-26569: Fixpyclbr.readmodule() andpyclbr.readmodule_ex()to support importing packages.

  • bpo-26499: Account for remaining Content-Length in HTTPResponse.readline()and read1(). Based on patch by Silent Ghost. Also document thatHTTPResponse now supports these methods.

  • bpo-25320: Handle sockets in directories unittest discovery is scanning.Patch from Victor van den Elzen.

  • bpo-16181: cookiejar.http2time() now returns None if year is higher thandatetime.MAXYEAR.

  • bpo-26513: Fixes platform module detection of Windows Server

  • bpo-23718: Fixed parsing time in week 0 before Jan 1. Original patch byTamás Bence Gedai.

  • bpo-26323: Add Mock.assert_called() and Mock.assert_called_once() methodsto unittest.mock. Patch written by Amit Saha.

  • bpo-20589: Invoking Path.owner() and Path.group() on Windows now raiseNotImplementedError instead of ImportError.

  • bpo-26177: Fixed the keys() method for Canvas and Scrollbar widgets.

  • bpo-15068: Got rid of excessive buffering in fileinput. The bufsizeparameter is now deprecated and ignored.

  • bpo-19475: Added an optional argument timespec to the datetime isoformat()method to choose the precision of the time component.

  • bpo-2202: Fix UnboundLocalError inAbstractDigestAuthHandler.get_algorithm_impls. Initial patch by MathieuDupuy.

  • bpo-26167: Minimized overhead in copy.copy() and copy.deepcopy().Optimized copying and deepcopying bytearrays, NotImplemented, slices,short lists, tuples, dicts, sets.

  • bpo-25718: Fixed pickling and copying the accumulate() iterator with totalis None.

  • bpo-26475: Fixed debugging output for regular expressions with the (?x)flag.

  • bpo-26482: Allowed pickling recursive dequeues.

  • bpo-26335: Make mmap.write() return the number of bytes written like otherwrite methods. Patch by Jakub Stasiak.

  • bpo-26457: Fixed the subnets() methods in IP network classes for the casewhen resulting prefix length is equal to maximal prefix length. Based onpatch by Xiang Zhang.

  • bpo-26385: Remove the file if the internal open() call inNamedTemporaryFile() fails. Patch by Silent Ghost.

  • bpo-26402: Fix XML-RPC client to retry when the server shuts down apersistent connection. This was a regression related to the newhttp.client.RemoteDisconnected exception in 3.5.0a4.

  • bpo-25913: Leading<~ is optional now in base64.a85decode() withadobe=True. Patch by Swati Jaiswal.

  • bpo-26186: Remove an invalid type check in importlib.util.LazyLoader.

  • bpo-26367: importlib.__import__() raises ImportError likebuiltins.__import__() whenlevel is specified but without anaccompanying package specified.

  • bpo-26309: In the "socketserver" module, shut down the request (closingthe connected socket) when verify_request() returns false. Patch by AvivPalivoda.

  • bpo-23430: Change the socketserver module to only catch exceptions raisedfrom a request handler that are derived from Exception (instead ofBaseException). Therefore SystemExit and KeyboardInterrupt no longertrigger the handle_error() method, and will now to stop a single-threadedserver.

  • bpo-25995: os.walk() no longer uses FDs proportional to the tree depth.

  • bpo-25994: Added the close() method and the support of the context managerprotocol for the os.scandir() iterator.

  • bpo-23992: multiprocessing: make MapResult not fail-fast upon exception.

  • bpo-26243: Support keyword arguments to zlib.compress(). Patch by AvivPalivoda.

  • bpo-26117: The os.scandir() iterator now closes file descriptor not onlywhen the iteration is finished, but when it was failed with error.

  • bpo-25949: __dict__ for an OrderedDict instance is now created only whenneeded.

  • bpo-25911: Restored support of bytes paths in os.walk() on Windows.

  • bpo-26045: Add UTF-8 suggestion to error message when posting anon-Latin-1 string with http.client.

  • bpo-26039: Added zipfile.ZipInfo.from_file() and zipinfo.ZipInfo.is_dir().Patch by Thomas Kluyver.

  • bpo-12923: Reset FancyURLopener's redirect counter even if there is anexception. Based on patches by Brian Brazil and Daniel Rocco.

  • bpo-25945: Fixed a crash when unpickle the functools.partial object withwrong state. Fixed a leak in failed functools.partial constructor. "args"and "keywords" attributes of functools.partial have now always types tupleand dict correspondingly.

  • bpo-26202: copy.deepcopy() now correctly copies range() objects withnon-atomic attributes.

  • bpo-23076: Path.glob() now raises a ValueError if it's called with aninvalid pattern. Patch by Thomas Nyberg.

  • bpo-19883: Fixed possible integer overflows in zipimport.

  • bpo-26227: On Windows, getnameinfo(), gethostbyaddr() andgethostbyname_ex() functions of the socket module now decode the hostnamefrom the ANSI code page rather than UTF-8.

  • bpo-26099: The site module now writes an error into stderr ifsitecustomize module can be imported but executing the module raise anImportError. Same change for usercustomize.

  • bpo-26147: xmlrpc now works with strings not encodable with used non-UTF-8encoding.

  • bpo-25935: Garbage collector now breaks reference loops with OrderedDict.

  • bpo-16620: Fixed AttributeError in msilib.Directory.glob().

  • bpo-26013: Added compatibility with broken protocol 2 pickles created inold Python 3 versions (3.4.3 and lower).

  • bpo-26129: Deprecated accepting non-integers in grp.getgrgid().

  • bpo-25850: Use cross-compilation by default for 64-bit Windows.

  • bpo-25822: Add docstrings to the fields of urllib.parse results. Patchcontributed by Swati Jaiswal.

  • bpo-22642: Convert trace module option parsing mechanism to argparse.Patch contributed by SilentGhost.

  • bpo-24705: Fix sysconfig._parse_makefile not expanding ${} vars appearingbefore $() vars.

  • bpo-26069: Remove the deprecated apis in the trace module.

  • bpo-22138: Fix mock.patch behavior when patching descriptors. Restoreoriginal values after patching. Patch contributed by Sean McCully.

  • bpo-25672: In the ssl module, enable the SSL_MODE_RELEASE_BUFFERS modeoption if it is safe to do so.

  • bpo-26012: Don't traverse into symlinks for** pattern inpathlib.Path.[r]glob().

  • bpo-24120: Ignore PermissionError when traversing a tree withpathlib.Path.[r]glob(). Patch by Ulrich Petri.

  • bpo-21815: Accept ] characters in the data portion of imap responses, inorder to handle the flags with square brackets accepted and produced byservers such as gmail.

  • bpo-25447: fileinput now uses sys.stdin as-is if it does not have a bufferattribute (restores backward compatibility).

  • bpo-25971: Optimized creating Fractions from floats by 2 times and fromDecimals by 3 times.

  • bpo-25802: Document as deprecated the remaining implementations ofimportlib.abc.Loader.load_module().

  • bpo-25928: Add Decimal.as_integer_ratio().

  • bpo-25447: Copying the lru_cache() wrapper object now always works,independently from the type of the wrapped object (by returning theoriginal object unchanged).

  • bpo-25768: Have the functions in compileall return booleans instead ofints and add proper documentation and tests for the return values.

  • bpo-24103: Fixed possible use after free in ElementTree.XMLPullParser.

  • bpo-25860: os.fwalk() no longer skips remaining directories when erroroccurs. Original patch by Samson Lee.

  • bpo-25914: Fixed and simplified OrderedDict.__sizeof__.

  • bpo-25869: Optimized deepcopying ElementTree; it is now 20 times faster.

  • bpo-25873: Optimized iterating ElementTree. Iterating elementsElement.iter() is now 40% faster, iterating text Element.itertext() is nowup to 2.5 times faster.

  • bpo-25902: Fixed various refcount issues in ElementTree iteration.

  • bpo-22227: The TarFile iterator is reimplemented using generator. Thisimplementation is simpler that using class.

  • bpo-25638: Optimized ElementTree.iterparse(); it is now 2x faster.Optimized ElementTree parsing; it is now 10% faster.

  • bpo-25761: Improved detecting errors in broken pickle data.

  • bpo-25717: Restore the previous behaviour of tolerating most fstat()errors when opening files. This was a regression in 3.5a1, and stoppedanonymous temporary files from working in special cases.

  • bpo-24903: Fix regression in number of arguments compileall accepts when'-d' is specified. The check on the number of arguments has been droppedcompletely as it never worked correctly anyway.

  • bpo-25764: In the subprocess module, preserve any exception caused byfork() failure when preexec_fn is used.

  • bpo-25771: Tweak the exception message for importlib.util.resolve_name()when 'package' isn't specified but necessary.

  • bpo-6478: _strptime's regexp cache now is reset after changing timezonewith time.tzset().

  • bpo-14285: When executing a package with the "python -m package" option,and package initialization fails, a proper traceback is now reported. The"runpy" module now lets exceptions from package initialization pass backto the caller, rather than raising ImportError.

  • bpo-19771: Also in runpy and the "-m" option, omit the irrelevant message". . . is a package and cannot be directly executed" if the package couldnot even be initialized (e.g. due to a bad*.pyc file).

  • bpo-25177: Fixed problem with the mean of very small and very largenumbers. As a side effect, statistics.mean and statistics.variance shouldbe significantly faster.

  • bpo-25718: Fixed copying object with state with boolean value is false.

  • bpo-10131: Fixed deep copying of minidom documents. Based on patch byMarian Ganisin.

  • bpo-7990: dir() on ElementTree.Element now lists properties: "tag","text", "tail" and "attrib". Original patch by Santoso Wijaya.

  • bpo-25725: Fixed a reference leak in pickle.loads() when unpicklinginvalid data including tuple instructions.

  • bpo-25663: In the Readline completer, avoid listing duplicate globalnames, and search the global namespace before searching builtins.

  • bpo-25688: Fixed file leak in ElementTree.iterparse() raising an error.

  • bpo-23914: Fixed SystemError raised by unpickler on broken pickle data.

  • bpo-25691: Fixed crash on deleting ElementTree.Element attributes.

  • bpo-25624: ZipFile now always writes a ZIP_STORED header for directoryentries. Patch by Dingyuan Wang.

  • bpo-25626: Change three zlib functions to accept sizes that fit inPy_ssize_t, but internally cap those sizes to UINT_MAX. This resolves aregression in 3.5 where GzipFile.read() failed to read chunks larger than2 or 4 GiB. The change affects the zlib.Decompress.decompress()max_length parameter, the zlib.decompress() bufsize parameter, and thezlib.Decompress.flush() length parameter.

  • bpo-25583: Avoid incorrect errors raised by os.makedirs(exist_ok=True)when the OS gives priority to errors such as EACCES over EEXIST.

  • bpo-25593: Change semantics of EventLoop.stop() in asyncio.

  • bpo-6973: When we know a subprocess.Popen process has died, do not allowthe send_signal(), terminate(), or kill() methods to do anything as theycould potentially signal a different process.

  • bpo-23883: Added missing APIs to __all__ to match the documented APIs forthe following modules: calendar, csv, enum, fileinput, ftplib, logging,optparse, tarfile, threading and wave. Also added atest.support.check__all__() helper. Patches by Jacek Kołodziej, Mauro S.M. Rodrigues and Joel Taddei.

  • bpo-25590: In the Readline completer, only call getattr() once perattribute. Also complete names of attributes such as properties and slotswhich are listed by dir() but not yet created on an instance.

  • bpo-25498: Fix a crash when garbage-collecting ctypes objects created bywrapping a memoryview. This was a regression made in 3.5a1. Based onpatch by Eryksun.

  • bpo-25584: Added "escape" to the __all__ list in the glob module.

  • bpo-25584: Fixed recursive glob() with patterns starting with**.

  • bpo-25446: Fix regression in smtplib's AUTH LOGIN support.

  • bpo-18010: Fix the pydoc web server's module search function to handleexceptions from importing packages.

  • bpo-25554: Got rid of circular references in regular expression parsing.

  • bpo-18973: Command-line interface of the calendar module now uses argparseinstead of optparse.

  • bpo-25510: fileinput.FileInput.readline() now returns b'' instead of '' atthe end if the FileInput was opened with binary mode. Patch by RyosukeIto.

  • bpo-25503: Fixed inspect.getdoc() for inherited docstrings of properties.Original patch by John Mark Vandenberg.

  • bpo-25515: Always use os.urandom as a source of randomness in uuid.uuid4.

  • bpo-21827: Fixed textwrap.dedent() for the case when largest commonwhitespace is a substring of smallest leading whitespace. Based on patchby Robert Li.

  • bpo-25447: The lru_cache() wrapper objects now can be copied and pickled(by returning the original object unchanged).

  • bpo-25390: typing: Don't crash on Union[str, Pattern].

  • bpo-25441: asyncio: Raise error from drain() when socket is closed.

  • bpo-25410: Cleaned up and fixed minor bugs in C implementation ofOrderedDict.

  • bpo-25411: Improved Unicode support in SMTPHandler through better use ofthe email package. Thanks to user simon04 for the patch.

  • Move the imp module from a PendingDeprecationWarning toDeprecationWarning.

  • bpo-25407: Remove mentions of the formatter module being removed in Python3.6.

  • bpo-25406: Fixed a bug in C implementation of OrderedDict.move_to_end()that caused segmentation fault or hang in iterating after moving severalitems to the start of ordered dict.

  • bpo-25382: pickletools.dis() now outputs implicit memo index for theMEMOIZE opcode.

  • bpo-25357: Add an optional newline parameter to binascii.b2a_base64().base64.b64encode() uses it to avoid a memory copy.

  • bpo-24164: Objects that need calling__new__ with keyword arguments,can now be pickled using pickle protocols older than protocol version 4.

  • bpo-25364: zipfile now works in threads disabled builds.

  • bpo-25328: smtpd's SMTPChannel now correctly raises a ValueError if bothdecode_data and enable_SMTPUTF8 are set to true.

  • bpo-16099: RobotFileParser now supports Crawl-delay and Request-rateextensions. Patch by Nikolay Bogoychev.

  • bpo-25316: distutils raises OSError instead of DistutilsPlatformError whenMSVC is not installed.

  • bpo-25380: Fixed protocol for the STACK_GLOBAL opcode inpickletools.opcodes.

  • bpo-23972: Updates asyncio datagram create method allowing reuseport andreuseaddr socket options to be set prior to binding the socket. Mirroringthe existing asyncio create_server method the reuseaddr option fordatagram sockets defaults to True if the O/S is 'posix' (except if theplatform is Cygwin). Patch by Chris Laws.

  • bpo-25304: Add asyncio.run_coroutine_threadsafe(). This lets you submit acoroutine to a loop from another thread, returning aconcurrent.futures.Future. By Vincent Michel.

  • bpo-25232: Fix CGIRequestHandler to split the query from the URL at thefirst question mark (?) rather than the last. Patch from Xiang Zhang.

  • bpo-24657: Prevent CGIRequestHandler from collapsing slashes in the querypart of the URL as if it were a path. Patch from Xiang Zhang.

  • bpo-25287: Don't add crypt.METHOD_CRYPT to crypt.methods if it's notsupported. Check if it is supported, it may not be supported on OpenBSDfor example.

  • bpo-23600: Default implementation of tzinfo.fromutc() was returning wrongresults in some cases.

  • bpo-25203: Failed readline.set_completer_delims() no longer left themodule in inconsistent state.

  • bpo-25011: rlcompleter now omits private and special attribute namesunless the prefix starts with underscores.

  • bpo-25209: rlcompleter now can add a space or a colon after completedkeyword.

  • bpo-22241: timezone.utc name is now plain 'UTC', not 'UTC-00:00'.

  • bpo-23517: fromtimestamp() and utcfromtimestamp() methods ofdatetime.datetime now round microseconds to nearest with ties going tonearest even integer (ROUND_HALF_EVEN), as round(float), instead ofrounding towards -Infinity (ROUND_FLOOR).

  • bpo-23552: Timeit now warns when there is substantial (4x) variancebetween best and worst times. Patch from Serhiy Storchaka.

  • bpo-24633: site-packages/README -> README.txt.

  • bpo-24879: help() and pydoc can now list named tuple fields in the orderthey were defined rather than alphabetically. The ordering is determinedby the _fields attribute if present.

  • bpo-24874: Improve speed of itertools.cycle() and make its pickle morecompact.

  • Fix crash in itertools.cycle.__setstate__() when the first argument wasn'ta list.

  • bpo-20059: urllib.parse raises ValueError on all invalid ports. Patch byMartin Panter.

  • bpo-24360: Improve __repr__ of argparse.Namespace() for invalididentifiers. Patch by Matthias Bussonnier.

  • bpo-23426: run_setup was broken in distutils. Patch from AlexanderBelopolsky.

  • bpo-13938: 2to3 converts StringTypes to a tuple. Patch from Mark Hammond.

  • bpo-2091: open() accepted a 'U' mode string containing '+', but 'U' canonly be used with 'r'. Patch from Jeff Balogh and John O'Connor.

  • bpo-8585: improved tests for zipimporter2. Patch from Mark Lawrence.

  • bpo-18622: unittest.mock.mock_open().reset_mock would recurse infinitely.Patch from Nicola Palumbo and Laurent De Buyst.

  • bpo-24426: Fast searching optimization in regular expressions now worksfor patterns that starts with capturing groups. Fast searchingoptimization now can't be disabled at compile time.

  • bpo-23661: unittest.mock side_effects can now be exceptions again. Thiswas a regression vs Python 3.4. Patch from Ignacio Rossi

  • bpo-13248: Remove deprecated inspect.getmoduleinfo function.

  • bpo-25578: Fix (another) memory leak in SSLSocket.getpeercer().

  • bpo-25530: Disable the vulnerable SSLv3 protocol by default when creatingssl.SSLContext.

  • bpo-25569: Fix memory leak in SSLSocket.getpeercert().

  • bpo-25471: Sockets returned from accept() shouldn't appear to benonblocking.

  • bpo-25319: When threading.Event is reinitialized, the underlying conditionshould use a regular lock rather than a recursive lock.

  • Skip getaddrinfo if host is already resolved. Patch by A. Jesse JiryuDavis.

  • bpo-26050: Add asyncio.StreamReader.readuntil() method. Patch by МаркКоренберг.

  • bpo-25924: Avoid unnecessary serialization of getaddrinfo(3) calls on OS Xversions 10.5 or higher. Original patch by A. Jesse Jiryu Davis.

  • bpo-26406: Avoid unnecessary serialization of getaddrinfo(3) calls oncurrent versions of OpenBSD and NetBSD. Patch by A. Jesse Jiryu Davis.

  • bpo-26848: Fix asyncio/subprocess.communicate() to handle empty input.Patch by Jack O'Connor.

  • bpo-27040: Add loop.get_exception_handler method

  • bpo-27041: asyncio: Add loop.create_future method

IDLE

  • bpo-20640: Add tests for idlelib.configHelpSourceEdit. Patch by SaimadhavHeblikar.

  • In the 'IDLE-console differences' section of the IDLE doc, clarify howrunning with IDLE affects sys.modules and the standard streams.

  • bpo-25507: fix incorrect change in IOBinding that prevented printing.Augment IOBinding htest to include all major IOBinding functions.

  • bpo-25905: Revert unwanted conversion of ' to ’ RIGHT SINGLE QUOTATIONMARK in README.txt and open this and NEWS.txt with 'ascii'. Re-encodeCREDITS.txt to utf-8 and open it with 'utf-8'.

  • bpo-15348: Stop the debugger engine (normally in a user process) beforeclosing the debugger window (running in the IDLE process). This preventsthe RuntimeErrors that were being caught and ignored.

  • bpo-24455: Prevent IDLE from hanging when a) closing the shell while thedebugger is active (15347); b) closing the debugger with the [X] button(15348); and c) activating the debugger when already active (24455). Thepatch by Mark Roseman does this by making two changes. 1. Suspend andresume the gui.interaction method with the tcl vwait mechanism intendedfor this purpose (instead of root.mainloop & .quit). 2. In gui.run, allowany existing interaction to terminate first.

  • Change 'The program' to 'Your program' in an IDLE 'kill program?' messageto make it clearer that the program referred to is the currently runninguser program, not IDLE itself.

  • bpo-24750: Improve the appearance of the IDLE editor window status bar.Patch by Mark Roseman.

  • bpo-25313: Change the handling of new built-in text color themes to betteraddress the compatibility problem introduced by the addition of IDLE Dark.Consistently use the revised idleConf.CurrentTheme everywhere in idlelib.

  • bpo-24782: Extension configuration is now a tab in the IDLE Preferencesdialog rather than a separate dialog. The former tabs are now a sortedlist. Patch by Mark Roseman.

  • bpo-22726: Re-activate the config dialog help button with some contentabout the other buttons and the new IDLE Dark theme.

  • bpo-24820: IDLE now has an 'IDLE Dark' built-in text color theme. It ismore or less IDLE Classic inverted, with a cobalt blue background.Strings, comments, keywords, ... are still green, red, orange, ... . Touse it with IDLEs released before November 2015, hit the 'Save as NewCustom Theme' button and enter a new name, such as 'Custom Dark'. Thecustom theme will work with any IDLE release, and can be modified.

  • bpo-25224: README.txt is now an idlelib index for IDLE developers andcurious users. The previous user content is now in the IDLE doc chapter.'IDLE' now means 'Integrated Development and Learning Environment'.

  • bpo-24820: Users can now set breakpoint colors in Settings -> CustomHighlighting. Original patch by Mark Roseman.

  • bpo-24972: Inactive selection background now matches active selectionbackground, as configured by users, on all systems. Found items are nowalways highlighted on Windows. Initial patch by Mark Roseman.

  • bpo-24570: Idle: make calltip and completion boxes appear on Macs affectedby a tk regression. Initial patch by Mark Roseman.

  • bpo-24988: Idle ScrolledList context menus (used in debugger) now work onMac Aqua. Patch by Mark Roseman.

  • bpo-24801: Make right-click for context menu work on Mac Aqua. Patch byMark Roseman.

  • bpo-25173: Associate tkinter messageboxes with a specific widget. For MacOSX, make them a 'sheet'. Patch by Mark Roseman.

  • bpo-25198: Enhance the initial html viewer now used for Idle Help.Properly indent fixed-pitch text (patch by Mark Roseman). Give codesnippet a very Sphinx-like light blueish-gray background. Re-use initialwidth and height set by users for shell and editor. When the Table ofContents (TOC) menu is used, put the section header at the top of thescreen.

  • bpo-25225: Condense and rewrite Idle doc section on text colors.

  • bpo-21995: Explain some differences between IDLE and console Python.

  • bpo-22820: Explain need forprint when running file from Idle editor.

  • bpo-25224: Doc: augment Idle feature list and no-subprocess section.

  • bpo-25219: Update doc for Idle command line options. Some were missing andnotes were not correct.

  • bpo-24861: Most of idlelib is private and subject to change. Useidleib.idle.* to start Idle. See idlelib.__init__.__doc__.

  • bpo-25199: Idle: add synchronization comments for future maintainers.

  • bpo-16893: Replace help.txt with help.html for Idle doc display. The newidlelib/help.html is rstripped Doc/build/html/library/idle.html. It looksbetter than help.txt and will better document Idle as released. Thetkinter html viewer that works for this file was written by Rose Roseman.The now unused EditorWindow.HelpDialog class and helt.txt file aredeprecated.

  • bpo-24199: Deprecate unused idlelib.idlever with possible removal in 3.6.

  • bpo-24790: Remove extraneous code (which also create 2 & 3 conflicts).

Documentation

  • bpo-26736: Used HTTPS for external links in the documentation if possible.

  • bpo-6953: Rework the Readline module documentation to group relatedfunctions together, and add more details such as what underlying Readlinefunctions and variables are accessed.

  • bpo-23606: Adds note to ctypes documentation regarding cdll.msvcrt.

  • bpo-24952: Clarify the default size argument of stack_size() in the"threading" and "_thread" modules. Patch from Mattip.

  • bpo-26014: Update 3.x packaging documentation: * "See also" links to thenew docs are now provided in the legacy pages * links to setuptoolsdocumentation have been updated

Tests

  • bpo-21916: Added tests for the turtle module. Patch by ingrid, GregoryLoyse and Jelle Zijlstra.

  • bpo-26295: When using "python3 -m test --testdir=TESTDIR", regrtestdoesn't add "test." prefix to test module names.

  • bpo-26523: The multiprocessing thread pool (multiprocessing.dummy.Pool)was untested.

  • bpo-26015: Added new tests for pickling iterators of mutable sequences.

  • bpo-26325: Added test.support.check_no_resource_warning() to check that noResourceWarning is emitted.

  • bpo-25940: Changed test_ssl to use its internal local server more. Thisavoids relying on svn.python.org, which recently changed root certificate.

  • bpo-25616: Tests for OrderedDict are extracted from test_collections intoseparate file test_ordered_dict.

  • bpo-25449: Added tests for OrderedDict subclasses.

  • bpo-25188: Add -P/--pgo to test.regrtest to suppress error output whenrunning the test suite for the purposes of a PGO build. Initial patch byAlecsandru Patrascu.

  • bpo-22806: Addpython-mtest--list-tests command to list tests.

  • bpo-18174:python-mtest--huntrleaks... now also checks for leak offile descriptors. Patch written by Richard Oudkerk.

  • bpo-25260: Fixpython-mtest--coverage on Windows. Remove the listof ignored directories.

  • PCbuild\rt.bat now accepts an unlimited number of arguments to passalong to regrtest.py. Previously there was a limit of 9.

  • bpo-26583: Skip test_timestamp_overflow in test_import if bytecode filescannot be written.

Build

  • bpo-21277: Don't try to link _ctypes with a ffi_convenience library.

  • bpo-26884: Fix linking extension modules for cross builds. Patch by Xavierde Gaye.

  • bpo-26932: Fixed support of RTLD_* constants defined as enum values, notvia macros (in particular on Android). Patch by Chi Hsuan Yen.

  • bpo-22359: Disable the rules for running _freeze_importlib and pgen whencross-compiling. The output of these programs is normally saved with thesource code anyway, and is still regenerated when doing a native build.Patch by Xavier de Gaye.

  • bpo-21668: Link audioop, _datetime, _ctypes_test modules to libm, excepton Mac OS X. Patch written by Chi Hsuan Yen.

  • bpo-25702: A --with-lto configure option has been added that will enablelink time optimizations at build time during a make profile-opt. Somecompilers and toolchains are known to not produce stable code when usingLTO, be sure to test things thoroughly before relying on it. It canprovide a few % speed up over profile-opt alone.

  • bpo-26624: Adds validation of ucrtbase[d].dll version with warning for oldversions.

  • bpo-17603: Avoid error about nonexistent fileblocks.o file by using alower-level check for st_blocks in struct stat.

  • bpo-26079: Fixing the build output folder for tix-8.4.3.6. Patch by BjoernThiel.

  • bpo-26465: Update Windows builds to use OpenSSL 1.0.2g.

  • bpo-25348: Added--pgo and--pgo-job arguments toPCbuild\build.bat for building with Profile-Guided Optimization. TheoldPCbuild\build_pgo.bat script is removed.

  • bpo-25827: Add support for building with ICC toconfigure, including anew--with-icc flag.

  • bpo-25696: Fix installation of Python on UNIX with make -j9.

  • bpo-24986: It is now possible to build Python on Windows without errorswhen external libraries are not available.

  • bpo-24421: Compile Modules/_math.c once, before building extensions.Previously it could fail to compile properly if the math and cmath buildswere concurrent.

  • bpo-26465: Update OS X 10.5+ 32-bit-only installer to build and link withOpenSSL 1.0.2g.

  • bpo-26268: Update Windows builds to use OpenSSL 1.0.2f.

  • bpo-25136: Support Apple Xcode 7's new textual SDK stub libraries.

  • bpo-24324: Do not enable unreachable code warnings when using gcc as theoption does not work correctly in older versions of gcc and has beensilently removed as of gcc-4.5.

Windows

  • bpo-27053: Updates make_zip.py to correctly generate library ZIP file.

  • bpo-26268: Update the prepare_ssl.py script to handle OpenSSL releasesthat don't include the contents of the include directory (that is, 1.0.2eand later).

  • bpo-26071: bdist_wininst created binaries fail to start and find 32bitPython

  • bpo-26073: Update the list of magic numbers in launcher

  • bpo-26065: Excludes venv from library when generating embeddable distro.

  • bpo-25022: Removed very outdated PC/example_nt/ directory.

Tools/Demos

  • bpo-26799: Fix python-gdb.py: don't get C types once when the Python codeis loaded, but get C types on demand. The C types can change ifpython-gdb.py is loaded before the Python executable. Patch written byThomas Ilsche.

  • bpo-26271: Fix the Freeze tool to properly use flags passed throughconfigure. Patch by Daniel Shaulov.

  • bpo-26489: Add dictionary unpacking support to Tools/parser/unparse.py.Patch by Guo Ci Teo.

  • bpo-26316: Fix variable name typo in Argument Clinic.

  • bpo-25440: Fix output of python-config --extension-suffix.

  • bpo-25154: The pyvenv script has been deprecated in favour ofpython3-mvenv.

C API

  • bpo-26312: SystemError is now raised in all programming bugs with usingPyArg_ParseTupleAndKeywords(). RuntimeError did raised before in someprogramming bugs.

  • bpo-26198: ValueError is now raised instead of TypeError on bufferoverflow in parsing "es#" and "et#" format units. SystemError is nowraised instead of TypeError on programmatical error in parsing formatstring.

Python 3.5.5 final

Release date: 2018-02-04

There were no new changes in version 3.5.5.

Python 3.5.5 release candidate 1

Release date: 2018-01-23

Security

  • bpo-32551: Thesys.path[0] initialization change forbpo-29139 causeda regression by revealing an inconsistency in how sys.path is initializedwhen executing__main__ from a zipfile, directory, or other importlocation. This is considered a potential security issue, as it may lead toprivileged processes unexpectedly loading code from user controlleddirectories in situations where that was not previously the case. Theinterpreter now consistently avoids ever adding the import location'sparent directory tosys.path, and ensures no othersys.pathentries are inadvertently modified when inserting the import locationnamed on the command line. (Originally reported asbpo-29723 againstPython 3.6rc1, but it was missed at the time that the then upcoming Python3.5.4 release would also be affected)

  • bpo-30657: Fixed possible integer overflow in PyBytes_DecodeEscape,CVE 2017-1000158. Original patch by Jay Bosamiya; rebased to Python 3by Miro Hrončok.

  • bpo-30947: Upgrade libexpat embedded copy from version 2.2.1 to 2.2.3 toget security fixes.

Core and Builtins

  • bpo-31095: Fix potential crash during GC caused bytp_dealloc whichdoesn't callPyObject_GC_UnTrack().

Library

  • bpo-32072: Fixed issues with binary plists: Fixed saving bytearrays.Identical objects will be saved only once. Equal references will be loadas identical objects. Added support for saving and loading recursive datastructures.

  • bpo-31170: expat: Update libexpat from 2.2.3 to 2.2.4. Fix copying ofpartial characters for UTF-8 input (libexpat bug 115):https://github.com/libexpat/libexpat/issues/115

Python 3.5.4 final

Release date: 2017-08-07

Library

  • bpo-30119: ftplib.FTP.putline() now throws ValueError on commands thatcontains CR or LF. Patch by Donghee Na.

Python 3.5.4 release candidate 1

Release date: 2017-07-23

Security

  • bpo-30730: Prevent environment variables injection in subprocess onWindows. Prevent passing other environment variables and commandarguments.

  • bpo-30694: Upgrade expat copy from 2.2.0 to 2.2.1 to get fixes of multiplesecurity vulnerabilities including:CVE 2017-9233 (External entityinfinite loop DoS),CVE 2016-9063 (Integer overflow, re-fix),CVE 2016-0718 (Fix regression bugs from 2.2.0's fix toCVE 2016-0718) andCVE 2012-0876 (Counter hash flooding withSipHash). Note: theCVE 2016-5300 (Use os-specific entropy sources likegetrandom) doesn't impact Python, since Python already gets entropy fromthe OS to set the expat secret usingXML_SetHashSalt().

  • bpo-30500: Fix urllib.parse.splithost() to correctly parse fragments. Forexample,splithost('//127.0.0.1#@evil.com/') now correctly returns the127.0.0.1 host, instead of treating@evil.com as the host in anauthentication (login@host).

  • bpo-29591: Update expat copy from 2.1.1 to 2.2.0 to get fixes ofCVE 2016-0718 andCVE 2016-4472. Seehttps://sourceforge.net/p/expat/bugs/537/ for more information.

Core and Builtins

  • bpo-30876: Relative import from unloaded package now reimports the packageinstead of failing with SystemError. Relative import from non-package nowfails with ImportError rather than SystemError.

  • bpo-30765: Avoid blocking in pthread_mutex_lock() whenPyThread_acquire_lock() is asked not to block.

  • bpo-27945: Fixed various segfaults with dict when input collections aremutated during searching, inserting or comparing. Based on patches byDuane Griffin and Tim Mitchell.

  • bpo-25794: Fixed type.__setattr__() and type.__delattr__() fornon-interned attribute names. Based on patch by Eryk Sun.

  • bpo-29935: Fixed error messages in the index() method of tuple, list anddeque when pass indices of wrong type.

  • bpo-28876:bool(range) works even iflen(range) raisesOverflowError.

  • bpo-29600: Fix wrapping coroutine return values in StopIteration.

  • bpo-29537: Restore runtime compatibility with bytecode files generated byCPython 3.5.0 to 3.5.2, and adjust the eval loop to avoid the problemsthat could be caused by the malformed variant of theBUILD_MAP_UNPACK_WITH_CALL opcode that they may contain. Patch by PetrViktorin, Serhiy Storchaka, and Nick Coghlan.

  • bpo-28598: Support __rmod__ for subclasses of str being called beforestr.__mod__. Patch by Martijn Pieters.

  • bpo-29602: Fix incorrect handling of signed zeros in complex constructorfor complex subclasses and for inputs having a __complex__ method. Patchby Serhiy Storchaka.

  • bpo-29347: Fixed possibly dereferencing undefined pointers when creatingweakref objects.

  • bpo-29438: Fixed use-after-free problem in key sharing dict.

  • bpo-29319: Prevent RunMainFromImporter overwriting sys.path[0].

  • bpo-29337: Fixed possible BytesWarning when compare the code objects.Warnings could be emitted at compile time.

  • bpo-29478: If max_line_length=None is specified while using the Compat32policy, it is no longer ignored. Patch by Mircea Cosbuc.

Library

  • bpo-29403: Fixunittest.mock's autospec to not fail on method-boundbuiltin functions. Patch by Aaron Gallagher.

  • bpo-30961: Fix decrementing a borrowed reference in tracemalloc.

  • bpo-30886: Fix multiprocessing.Queue.join_thread(): it now waits until thethread completes, even if the thread was started by the same process whichcreated the queue.

  • bpo-29854: Fix segfault in readline when using readline's history-sizeoption. Patch by Nir Soffer.

  • bpo-30807: signal.setitimer() may disable the timer when passed a tinyvalue. Tiny values (such as 1e-6) are valid non-zero values forsetitimer(), which is specified as taking microsecond-resolutionintervals. However, on some platform, our conversion routine could convert1e-6 into a zero interval, therefore disabling the timer instead of(re-)scheduling it.

  • bpo-30441: Fix bug when modifying os.environ while iterating over it

  • bpo-30532: Fix email header value parser dropping folding white space incertain cases.

  • bpo-29169: Update zlib to 1.2.11.

  • bpo-30879: os.listdir() and os.scandir() now emit bytes names when calledwith bytes-like argument.

  • bpo-30746: Prohibited the '=' character in environment variable names inos.putenv() andos.spawn*().

  • bpo-29755: Fixed the lgettext() family of functions in the gettext module.They now always return bytes.

  • bpo-30645: Fix path calculation in imp.load_package(), fixing it for caseswhen a package is only shipped with bytecodes. Patch by AlexandruArdelean.

  • bpo-23890: unittest.TestCase.assertRaises() now manually breaks areference cycle to not keep objects alive longer than expected.

  • bpo-30149: inspect.signature() now supports callables withvariable-argument parameters wrapped with partialmethod. Patch by DongheeNa.

  • bpo-29931: Fixed comparison check for ipaddress.ip_interface objects.Patch by Sanjay Sundaresan.

  • bpo-24484: Avoid race condition in multiprocessing cleanup.

  • bpo-28994: The traceback no longer displayed for SystemExit raised in acallback registered by atexit.

  • bpo-30508: Don't log exceptions if Task/Future "cancel()" method wascalled.

  • bpo-28556: Updates to typing module: Add generic AsyncContextManager, addsupport for ContextManager on all versions. Original PRs by Jelle Zijlstraand Ivan Levkivskyi

  • bpo-29870: Fix ssl sockets leaks when connection is aborted in asyncio/sslimplementation. Patch by Michaël Sghaïer.

  • bpo-29743: Closing transport during handshake process leaks open socket.Patch by Nikolay Kim

  • bpo-27585: Fix waiter cancellation in asyncio.Lock. Patch by MathieuSornay.

  • bpo-30418: On Windows, subprocess.Popen.communicate() now also ignoreEINVAL on stdin.write() if the child process is still running but closedthe pipe.

  • bpo-30378: Fix the problem that logging.handlers.SysLogHandler cannothandle IPv6 addresses.

  • bpo-29960: Preserve generator state when _random.Random.setstate() raisesan exception. Patch by Bryan Olson.

  • bpo-30414: multiprocessing.Queue._feed background running thread do notbreak from main loop on exception.

  • bpo-30003: Fix handling escape characters in HZ codec. Based on patch byMa Lin.

  • bpo-30301: Fix AttributeError when using SimpleQueue.empty() underspawnandforkserver start methods.

  • bpo-30329: imaplib and poplib now catch the Windows socket WSAEINVAL error(code 10022) on shutdown(SHUT_RDWR): An invalid operation was attempted.This error occurs sometimes on SSL connections.

  • bpo-30375: Warnings emitted when compile a regular expression now alwayspoint to the line in the user code. Previously they could point intoinners of the re module if emitted from inside of groups or conditionals.

  • bpo-30048: FixedTask.cancel() can be ignored when the task is runningcoroutine and the coroutine returned without any moreawait.

  • bpo-29990: Fix range checking in GB18030 decoder. Original patch by MaLin.

  • bpo-26293: Change resulted because of zipfile breakage. (See also:bpo-29094)

  • bpo-30243: Removed the __init__ methods of _json's scanner and encoder.Misusing them could cause memory leaks or crashes. Now scanner andencoder objects are completely initialized in the __new__ methods.

  • bpo-30185: Avoid KeyboardInterrupt tracebacks in forkserver helper processwhen Ctrl-C is received.

  • bpo-28556: Various updates to typing module: add typing.NoReturn type, useWrapperDescriptorType, minor bug-fixes. Original PRs by JimFasarakis-Hilliard and Ivan Levkivskyi.

  • bpo-30205: Fix getsockname() for unbound AF_UNIX sockets on Linux.

  • bpo-30070: Fixed leaks and crashes in errors handling in the parsermodule.

  • bpo-30061: Fixed crashes in IOBase methods __next__() and readlines() whenreadline() or __next__() respectively return non-sizeable object. Fixedpossible other errors caused by not checking results of PyObject_Size(),PySequence_Size(), or PyMapping_Size().

  • bpo-30068: _io._IOBase.readlines will check if it's closed first when hintis present.

  • bpo-29694: Fixed race condition in pathlib mkdir with flags parents=True.Patch by Armin Rigo.

  • bpo-29692: Fixed arbitrary unchaining of RuntimeError exceptions incontextlib.contextmanager. Patch by Siddharth Velankar.

  • bpo-29998: Pickling and copying ImportError now preserves name and pathattributes.

  • bpo-29942: Fix a crash in itertools.chain.from_iterable when encounteringlong runs of empty iterables.

  • bpo-27863: Fixed multiple crashes in ElementTree caused by race conditionsand wrong types.

  • bpo-28699: Fixed a bug in pools in multiprocessing.pool that raising anexception at the very first of an iterable may swallow the exception ormake the program hang. Patch by Davin Potts and Xiang Zhang.

  • bpo-25803: Avoid incorrect errors raised by Path.mkdir(exist_ok=True) whenthe OS gives priority to errors such as EACCES over EEXIST.

  • bpo-29861: Release references to tasks, their arguments and their resultsas soon as they are finished in multiprocessing.Pool.

  • bpo-29884: faulthandler: Restore the old sigaltstack during teardown.Patch by Christophe Zeitouny.

  • bpo-25455: Fixed crashes in repr of recursive buffered file-like objects.

  • bpo-29800: Fix crashes in partial.__repr__ if the keys of partial.keywordsare not strings. Patch by Michael Seifert.

  • bpo-29742: get_extra_info() raises exception if get called on closed ssltransport. Patch by Nikolay Kim.

  • bpo-8256: Fixed possible failing or crashing input() if attributes"encoding" or "errors" of sys.stdin or sys.stdout are not set or are notstrings.

  • bpo-28298: Fix a bug that prevented array 'Q', 'L' and 'I' from acceptingbig intables (objects that have __int__) as elements. Patch by OrenMilman.

  • bpo-29615: SimpleXMLRPCDispatcher no longer chains KeyError (or any otherexception) to exception(s) raised in the dispatched methods. Patch by PetrMotejlek.

  • bpo-29704: asyncio.subprocess.SubprocessStreamProtocol no longer closesbefore all pipes are closed.

  • bpo-29703: Fix asyncio to support instantiation of new event loops inchild processes.

  • bpo-29376: Fix assertion error in threading._DummyThread.is_alive().

  • bpo-29110: Fix file object leak in aifc.open() when file is given as afilesystem path and is not in valid AIFF format. Patch by Anthony Zhang.

  • bpo-28961: Fix unittest.mock._Call helper: don't ignore the name parameteranymore. Patch written by Jiajun Huang.

  • bpo-29532: Altering a kwarg dictionary passed to functools.partial() nolonger affects a partial object after creation.

  • bpo-28556: Various updates to typing module: typing.Counter,typing.ChainMap, improved ABC caching, etc. Original PRs by JelleZijlstra, Ivan Levkivskyi, Manuel Krebber, and Łukasz Langa.

  • bpo-29100: Fix datetime.fromtimestamp() regression introduced in Python3.6.0: check minimum and maximum years.

  • bpo-29519: Fix weakref spewing exceptions during interpreter shutdown whenused with a rare combination of multiprocessing and custom codecs.

  • bpo-29416: Prevent infinite loop in pathlib.Path.mkdir

  • bpo-29444: Fixed out-of-bounds buffer access in the group() method of thematch object. Based on patch by WGH.

  • bpo-29335: Fix subprocess.Popen.wait() when the child process has exitedto a stopped instead of terminated state (ex: when under ptrace).

  • bpo-29290: Fix a regression in argparse that help messages would wrap atnon-breaking spaces.

  • bpo-28735: Fixed the comparison of mock.MagickMock with mock.ANY.

  • bpo-29011: Fix an important omission by adding Deque to the typing module.

  • bpo-29219: Fixed infinite recursion in the repr of uninitializedctypes.CDLL instances.

  • bpo-28969: Fixed race condition in C implementation offunctools.lru_cache. KeyError could be raised when cached function withfull cache was simultaneously called from different threads with the sameuncached arguments.

  • bpo-29142: In urllib.request, suffixes in no_proxy environment variablewith leading dots could match related hostnames again (e.g. .b.c matchesa.b.c). Patch by Milan Oberkirch.

Documentation

  • bpo-30176: Add missing attribute related constants in cursesdocumentation.

  • bpo-26985: Add missing info of code object in inspect documentation.

  • bpo-28929: Link the documentation to its source file on GitHub.

  • bpo-25008: Document smtpd.py as effectively deprecated and add a pointerto aiosmtpd, a third-party asyncio-based replacement.

  • bpo-26355: Add canonical header link on each page to corresponding majorversion of the documentation. Patch by Matthias Bussonnier.

  • bpo-29349: Fix Python 2 syntax in code for building the documentation.

Tests

  • bpo-30822: Fix regrtest command line parser to allow passing -uextralargefile to run test_zipfile64.

  • bpo-30383: regrtest: Enhance regrtest and backport features from themaster branch. Add options: --coverage, --testdir, --list-tests (list testfiles, don't run them), --list-cases (list test identifiers, don't runthem,bpo-30523), --matchfile (load a list of test filters from atext file,bpo-30540), --slowest (alias to --slow). Enhance output:add timestamp, test result, currently running tests, "Tests result: xxx"summary with total duration, etc. Fix reference leak hunting in regrtest,--huntrleaks: regrtest now warms up caches, create explicitly all internalsingletons which are created on demand to prevent false positives whenchecking for reference leaks. (bpo-30675).

  • bpo-30357: test_thread: setUp() now uses support.threading_setup() andsupport.threading_cleanup() to wait until threads complete to avoid randomside effects on following tests. Initial patch written by GrzegorzGrzywacz.

  • bpo-28087: Skip test_asyncore and test_eintr poll failures on macOS. Skipsome tests of select.poll when running on macOS due to unresolved issueswith the underlying system poll function on some macOS versions.

  • bpo-30197: Enhanced functions swap_attr() and swap_item() in thetest.support module. They now work when delete replaced attribute or iteminside the with statement. The old value of the attribute or item (orNone if it doesn't exist) now will be assigned to the target of the "as"clause, if there is one.

  • bpo-29571: to match the behaviour of there.LOCALE flag,test_re.test_locale_flag now useslocale.getpreferredencoding(False)to determine the candidate encoding for the test regex (allowing it tocorrectly skip the test when the default locale encoding is a multi-byteencoding)

Build

  • bpo-29243: Prevent unnecessary rebuilding of Python duringmaketest,makeinstall and some other make targets when configured with--enable-optimizations.

  • bpo-23404: Don't regenerate generated files based on file modificationtime anymore: the action is now explicit. Replacemaketouch withmakeregen-all.

  • bpo-29643: Fix--enable-optimization didn't work.

Windows

  • bpo-30687: Locate msbuild.exe on Windows when building rather thanvcvarsall.bat

  • bpo-29392: Prevent crash when passing invalid arguments into msvcrtmodule.

C API

  • bpo-27867: Function PySlice_GetIndicesEx() is replaced with a macro ifPy_LIMITED_API is set to the value between 0x03050400 and 0x03060000 (notincluding) or 0x03060100 or higher.

  • bpo-29083: Fixed the declaration of some public API functions.PyArg_VaParse() and PyArg_VaParseTupleAndKeywords() were not available inlimited API. PyArg_ValidateKeywordArguments(), PyArg_UnpackTuple() andPy_BuildValue() were not available in limited API of version < 3.3 whenPY_SSIZE_T_CLEAN is defined.

Python 3.5.3 final

Release date: 2017-01-17

There were no code changes between 3.5.3rc1 and 3.5.3 final.

Python 3.5.3 release candidate 1

Release date: 2017-01-02

Security

  • bpo-27278: Fix os.urandom() implementation using getrandom() on Linux.Truncate size to INT_MAX and loop until we collected enough random bytes,instead of casting a directly Py_ssize_t to int.

  • bpo-22636: Avoid shell injection problems with ctypes.util.find_library().

Core and Builtins

  • bpo-29073: bytearray formatting no longer truncates on first null byte.

  • bpo-28932: Do not include <sys/random.h> if it does not exist.

  • bpo-28147: Fix a memory leak in split-table dictionaries: setattr() mustnot convert combined table into split table.

  • bpo-25677: Correct the positioning of the syntax error caret for indentedblocks. Based on patch by Michael Layzell.

  • bpo-29000: Fixed bytes formatting of octals with zero padding in alternateform.

  • bpo-28512: Fixed setting the offset attribute of SyntaxError byPyErr_SyntaxLocationEx() and PyErr_SyntaxLocationObject().

  • bpo-28991: functools.lru_cache() was susceptible to an obscure reentrancybug caused by a monkey-patched len() function.

  • bpo-28648: Fixed crash in Py_DecodeLocale() in debug build on Mac OS Xwhen decode astral characters. Patch by Xiang Zhang.

  • bpo-19398: Extra slash no longer added to sys.path components in case ofempty compile-time PYTHONPATH components.

  • bpo-28426: Fixed potential crash in PyUnicode_AsDecodedObject() in debugbuild.

  • bpo-23782: Fixed possible memory leak in _PyTraceback_Add() and exceptionloss in PyTraceBack_Here().

  • bpo-28379: Added sanity checks and tests for PyUnicode_CopyCharacters().Patch by Xiang Zhang.

  • bpo-28376: The type of long range iterator is now registered as Iterator.Patch by Oren Milman.

  • bpo-28376: The constructor of range_iterator now checks that step is not0. Patch by Oren Milman.

  • bpo-26906: Resolving special methods of uninitialized type now causesimplicit initialization of the type instead of a fail.

  • bpo-18287: PyType_Ready() now checks that tp_name is not NULL. Originalpatch by Niklas Koep.

  • bpo-24098: Fixed possible crash when AST is changed in process ofcompiling it.

  • bpo-28350: String constants with null character no longer interned.

  • bpo-26617: Fix crash when GC runs during weakref callbacks.

  • bpo-27942: String constants now interned recursively in tuples andfrozensets.

  • bpo-21578: Fixed misleading error message when ImportError called withinvalid keyword args.

  • bpo-28203: Fix incorrect type in error message fromcomplex(1.0,{2:3}). Patch by Soumya Sharma.

  • bpo-27955: Fallback on reading /dev/urandom device when the getrandom()syscall fails with EPERM, for example when blocked by SECCOMP.

  • bpo-28131: Fix a regression in zipimport's compile_source(). zipimportshould use the same optimization level as the interpreter.

  • bpo-25221: Fix corrupted result from PyLong_FromLong(0) when Python iscompiled with NSMALLPOSINTS = 0.

  • bpo-25758: Prevents zipimport from unnecessarily encoding a filename(patch by Eryk Sun)

  • bpo-28189: dictitems_contains no longer swallows compare errors. (Patch byXiang Zhang)

  • bpo-27812: Properly clear out a generator's frame's backreference to thegenerator to prevent crashes in frame.clear().

  • bpo-27811: Fix a crash when a coroutine that has not been awaited isfinalized with warnings-as-errors enabled.

  • bpo-27587: Fix another issue found by PVS-Studio: Null pointer check afteruse of 'def' in _PyState_AddModule(). Initial patch by Christian Heimes.

  • bpo-26020: set literal evaluation order did not match documentedbehaviour.

  • bpo-27782: Multi-phase extension module import now correctly allows them_methods field to be used to add module level functions to instancesof non-module types returned fromPy_create_mod. Patch by Xiang Zhang.

  • bpo-27936: The round() function accepted a second None argument for sometypes but not for others. Fixed the inconsistency by accepting None forall numeric types.

  • bpo-27487: Warn if a submodule argument to "python -m" orrunpy.run_module() is found in sys.modules after parent packages areimported, but before the submodule is executed.

  • bpo-27558: Fix a SystemError in the implementation of "raise" statement.In a brand new thread, raise a RuntimeError since there is no activeexception to reraise. Patch written by Xiang Zhang.

  • bpo-27419: Standard __import__() no longer look up "__import__" in globalsor builtins for importing submodules or "from import". Fixed handling anerror of non-string package name.

  • bpo-27083: Respect the PYTHONCASEOK environment variable under Windows.

  • bpo-27514: Make having too many statically nested blocks a SyntaxErrorinstead of SystemError.

  • bpo-27473: Fixed possible integer overflow in bytes and bytearrayconcatenations. Patch by Xiang Zhang.

  • bpo-27507: Add integer overflow check in bytearray.extend(). Patch byXiang Zhang.

  • bpo-27581: Don't rely on wrapping for overflow check inPySequence_Tuple(). Patch by Xiang Zhang.

  • bpo-27443: __length_hint__() of bytearray iterators no longer return anegative integer for a resized bytearray.

  • bpo-27942: Fix memory leak in codeobject.c

Library

  • bpo-15812: inspect.getframeinfo() now correctly shows the first line of acontext. Patch by Sam Breese.

  • bpo-29094: Offsets in a ZIP file created with extern file object and modes"w" and "x" now are relative to the start of the file.

  • bpo-13051: Fixed recursion errors in large or resizedcurses.textpad.Textbox. Based on patch by Tycho Andersen.

  • bpo-29119: Fix weakrefs in the pure python version ofcollections.OrderedDict move_to_end() method. Contributed by AndraBogildea.

  • bpo-9770: curses.ascii predicates now work correctly with negativeintegers.

  • bpo-28427: old keys should not remove new values from WeakValueDictionarywhen collecting from another thread.

  • bpo-28923: Remove editor artifacts from Tix.py.

  • bpo-28871: Fixed a crash when deallocate deep ElementTree.

  • bpo-19542: Fix bugs in WeakValueDictionary.setdefault() andWeakValueDictionary.pop() when a GC collection happens in another thread.

  • bpo-20191: Fixed a crash in resource.prlimit() when pass a sequence thatdoesn't own its elements as limits.

  • bpo-28779: multiprocessing.set_forkserver_preload() would crash theforkserver process if a preloaded module instantiated some multiprocessingobjects such as locks.

  • bpo-28847: dbm.dumb now supports reading read-only files and no longerwrites the index file when it is not changed.

  • bpo-25659: In ctypes, prevent a crash calling the from_buffer() andfrom_buffer_copy() methods on abstract classes like Array.

  • bpo-28732: Fix crash in os.spawnv() with no elements in args

  • bpo-28485: Always raise ValueError for negativecompileall.compile_dir(workers=...) parameter, even when multithreading isunavailable.

  • bpo-28387: Fixed possible crash in _io.TextIOWrapper deallocator when thegarbage collector is invoked in other thread. Based on patch by SebastianCufre.

  • bpo-27517: LZMA compressor and decompressor no longer raise exceptions ifgiven empty data twice. Patch by Benjamin Fogle.

  • bpo-28549: Fixed segfault in curses's addch() with ncurses6.

  • bpo-28449: tarfile.open() with mode "r" or "r:" now tries to open a tarfile with compression before trying to open it without compression.Otherwise it had 50% chance failed with ignore_zeros=True.

  • bpo-23262: The webbrowser module now supports Firefox 36+ and derivedbrowsers. Based on patch by Oleg Broytman.

  • bpo-27939: Fixed bugs in tkinter.ttk.LabeledScale and tkinter.Scale causedby representing the scale as float value internally in Tk. tkinter.IntVarnow works if float value is set to underlying Tk variable.

  • bpo-28255: calendar.TextCalendar().prmonth() no longer prints a space atthe start of new line after printing a month's calendar. Patch by XiangZhang.

  • bpo-20491: The textwrap.TextWrapper class now honors non-breaking spaces.Based on patch by Kaarle Ritvanen.

  • bpo-28353: os.fwalk() no longer fails on broken links.

  • bpo-25464: Fixed HList.header_exists() in tkinter.tix module by addin aworkaround to Tix library bug.

  • bpo-28488: shutil.make_archive() no longer add entry "./" to ZIP archive.

  • bpo-24452: Make webbrowser support Chrome on Mac OS X.

  • bpo-20766: Fix references leaked by pdb in the handling of SIGINThandlers.

  • bpo-26293: Fixed writing ZIP files that starts not from the start of thefile. Offsets in ZIP file now are relative to the start of the archive inconforming to the specification.

  • bpo-28321: Fixed writing non-BMP characters with binary format inplistlib.

  • bpo-28322: Fixed possible crashes when unpickle itertools objects fromincorrect pickle data. Based on patch by John Leitch.

  • Fix possible integer overflows and crashes in the mmap module with unusualusage patterns.

  • bpo-1703178: Fix the ability to pass the --link-objects option to thedistutils build_ext command.

  • bpo-28253: Fixed calendar functions for extreme months: 0001-01 and9999-12. Methods itermonthdays() and itermonthdays2() are reimplemented sothat they don't call itermonthdates() which can cause datetime.dateunder/overflow.

  • bpo-28275: Fixed possible use after free in the decompress() methods ofthe LZMADecompressor and BZ2Decompressor classes. Original patch by JohnLeitch.

  • bpo-27897: Fixed possible crash in sqlite3.Connection.create_collation()if pass invalid string-like object as a name. Patch by Xiang Zhang.

  • bpo-18893: Fix invalid exception handling in Lib/ctypes/macholib/dyld.py.Patch by Madison May.

  • bpo-27611: Fixed support of default root window in the tkinter.tix module.

  • bpo-27348: In the traceback module, restore the formatting of exceptionmessages like "Exception: None". This fixes a regression introduced in3.5a2.

  • bpo-25651: Allow false values to be used for msg parameter of subTest().

  • bpo-27932: Prevent memory leak in win32_ver().

  • Fix UnboundLocalError in socket._sendfile_use_sendfile.

  • bpo-28075: Check for ERROR_ACCESS_DENIED in Windows implementation ofos.stat(). Patch by Eryk Sun.

  • bpo-25270: Prevent codecs.escape_encode() from raising SystemError when anempty bytestring is passed.

  • bpo-28181: Get antigravity over HTTPS. Patch by Kaartic Sivaraam.

  • bpo-25895: Enable WebSocket URL schemes in urllib.parse.urljoin. Patch byGergely Imreh and Markus Holtermann.

  • bpo-27599: Fixed buffer overrun in binascii.b2a_qp() andbinascii.a2b_qp().

  • bpo-19003: m email.generator now replaces only\r and/or\n lineendings, per the RFC, instead of all unicode line endings.

  • bpo-28019: itertools.count() no longer rounds non-integer step in rangebetween 1.0 and 2.0 to 1.

  • bpo-25969: Update the lib2to3 grammar to handle the unpackinggeneralizations added in 3.5.

  • bpo-14977: mailcap now respects the order of the lines in the mailcapfiles ("first match"), as required by RFC 1542. Patch by Michael Lazar.

  • bpo-24594: Validates persist parameter when opening MSI database

  • bpo-17582: xml.etree.ElementTree nows preserves whitespaces in attributes(Patch by Duane Griffin. Reviewed and approved by Stefan Behnel.)

  • bpo-28047: Fixed calculation of line length used for the base64 CTE in thenew email policies.

  • bpo-27445: Don't pass str(_charset) to MIMEText.set_payload(). Patch byClaude Paroz.

  • bpo-22450: urllib now includes anAccept:*/* header among the defaultheaders. This makes the results of REST API requests more consistent andpredictable especially when proxy servers are involved.

  • lib2to3.pgen3.driver.load_grammar() now creates a stable cache filebetween runs given the same Grammar.txt input regardless of the hashrandomization setting.

  • bpo-27570: Avoid zero-length memcpy() etc calls with null source pointersin the "ctypes" and "array" modules.

  • bpo-22233: Break email header linesonly on the RFC specified CR and LFcharacters, not on arbitrary unicode line breaks. This also fixes a bugin HTTP header parsing.

  • bpo-27988: Fix email iter_attachments incorrect mutation of payload list.

  • bpo-27691: Fix ssl module's parsing of GEN_RID subject alternative namefields in X.509 certs.

  • bpo-27850: Remove 3DES from ssl module's default cipher list to countermeasure sweet32 attack (CVE 2016-2183).

  • bpo-27766: Add ChaCha20 Poly1305 to ssl module's default cipher list.(Required OpenSSL 1.1.0 or LibreSSL).

  • bpo-26470: Port ssl and hashlib module to OpenSSL 1.1.0.

  • Remove support for passing a file descriptor to os.access. It never workedbut previously didn't raise.

  • bpo-12885: Fix error when distutils encounters symlink.

  • bpo-27881: Fixed possible bugs when settingsqlite3.Connection.isolation_level. Based on patch by Xiang Zhang.

  • bpo-27861: Fixed a crash in sqlite3.Connection.cursor() when a factorycreates not a cursor. Patch by Xiang Zhang.

  • bpo-19884: Avoid spurious output on OS X with Gnu Readline.

  • bpo-27706: Restore deterministic behavior of random.Random().seed() forstring seeds using seeding version 1. Allows sequences of calls torandom() to exactly match those obtained in Python 2. Patch by NofarSchnider.

  • bpo-10513: Fix a regression in Connection.commit(). Statements should notbe reset after a commit.

  • A new version of typing.py fromhttps://github.com/python/typing:Collection (only for 3.6) (bpo-27598). Add FrozenSet to __all__(upstream #261). Fix crash in _get_type_vars() (upstream #259). Remove thedict constraint in ForwardRef._eval_type (upstream #252).

  • bpo-27539: Fix unnormalisedFraction.__pow__ result in the case ofnegative exponent and negative base.

  • bpo-21718: cursor.description is now available for queries using CTEs.

  • bpo-2466: posixpath.ismount now correctly recognizes mount points whichthe user does not have permission to access.

  • bpo-27773: Correct some memory management errors server_hostname in_ssl.wrap_socket().

  • bpo-26750: unittest.mock.create_autospec() now works properly forsubclasses of property() and other data descriptors.

  • In the curses module, raise an error if window.getstr() or window.instr()is passed a negative value.

  • bpo-27783: Fix possible usage of uninitialized memory inoperator.methodcaller.

  • bpo-27774: Fix possible Py_DECREF on unowned object in _sre.

  • bpo-27760: Fix possible integer overflow in binascii.b2a_qp.

  • bpo-27758: Fix possible integer overflow in the _csv module for largerecord lengths.

  • bpo-27568: Prevent HTTPoxy attack (CVE 2016-1000110). Ignore theHTTP_PROXY variable when REQUEST_METHOD environment is set, whichindicates that the script is in CGI mode.

  • bpo-27656: Do not assume sched.h defines any SCHED_* constants.

  • bpo-27130: In the "zlib" module, fix handling of large buffers (typically4 GiB) when compressing and decompressing. Previously, inputs werelimited to 4 GiB, and compression and decompression operations did notproperly handle results of 4 GiB.

  • bpo-27533: Release GIL in nt._isdir

  • bpo-17711: Fixed unpickling by the persistent ID with protocol 0. Originalpatch by Alexandre Vassalotti.

  • bpo-27522: Avoid an unintentional reference cycle in email.feedparser.

  • bpo-26844: Fix error message for imp.find_module() to refer to 'path'instead of 'name'. Patch by Lev Maximov.

  • bpo-23804: Fix SSL zero-length recv() calls to not block and not raise anerror about unclean EOF.

  • bpo-27466: Change time format returned by http.cookie.time2netscape,confirming the netscape cookie format and making it consistent withdocumentation.

  • bpo-26664: Fix activate.fish by removing mis-use of$.

  • bpo-22115: Fixed tracing Tkinter variables: trace_vdelete() with wrongmode no longer break tracing, trace_vinfo() now always returns a list ofpairs of strings, tracing in the "u" mode now works.

  • Fix a scoping issue in importlib.util.LazyLoader which triggered anUnboundLocalError when lazy-loading a module that was already put intosys.modules.

  • bpo-27079: Fixed curses.ascii functions isblank(), iscntrl() andispunct().

  • bpo-26754: Some functions (compile() etc) accepted a filename argumentencoded as an iterable of integers. Now only strings and byte-like objectsare accepted.

  • bpo-27048: Prevents distutils failing on Windows when environmentvariables contain non-ASCII characters

  • bpo-27330: Fixed possible leaks in the ctypes module.

  • bpo-27238: Got rid of bare excepts in the turtle module. Original patchby Jelle Zijlstra.

  • bpo-27122: When an exception is raised within the context being managed bya contextlib.ExitStack() and one of the exit stack generators catches andraises it in a chain, do not re-raise the original exception when exiting,let the new chained one through. This avoids thePEP 479 bug describedin issue25782.

  • bpo-26386: Fixed ttk.TreeView selection operations with item id'scontaining spaces.

  • bpo-16182: Fix various functions in the "readline" module to use thelocale encoding, and fix get_begidx() and get_endidx() to return codepoint indexes.

  • bpo-27392: Add loop.connect_accepted_socket(). Patch by Jim Fulton.

  • bpo-27930: Improved behaviour of logging.handlers.QueueListener. Thanks toPaulo Andrade and Petr Viktorin for the analysis and patch.

  • bpo-21201: Improves readability of multiprocessing error message. Thanksto Wojciech Walczak for patch.

  • bpo-27456: asyncio: Set TCP_NODELAY by default.

  • bpo-27906: Fix socket accept exhaustion during high TCP traffic. Patch byKevin Conway.

  • bpo-28174: Handle when SO_REUSEPORT isn't properly supported. Patch bySeth Michael Larson.

  • bpo-26654: Inspect functools.partial in asyncio.Handle.__repr__. Patch byiceboy.

  • bpo-26909: Fix slow pipes IO in asyncio. Patch by INADA Naoki.

  • bpo-28176: Fix callbacks race in asyncio.SelectorLoop.sock_connect.

  • bpo-27759: Fix selectors incorrectly retain invalid file descriptors.Patch by Mark Williams.

  • bpo-28368: Refuse monitoring processes if the child watcher has no loopattached. Patch by Vincent Michel.

  • bpo-28369: Raise RuntimeError when transport's FD is used with add_reader,add_writer, etc.

  • bpo-28370: Speedup asyncio.StreamReader.readexactly. Patch by КоренбергМарк.

  • bpo-28371: Deprecate passing asyncio.Handles to run_in_executor.

  • bpo-28372: Fix asyncio to support formatting of non-python coroutines.

  • bpo-28399: Remove UNIX socket from FS before binding. Patch by КоренбергМарк.

  • bpo-27972: Prohibit Tasks to await on themselves.

  • bpo-26923: Fix asyncio.Gather to refuse being cancelled once all childrenare done. Patch by Johannes Ebke.

  • bpo-26796: Don't configure the number of workers for default threadpoolexecutor. Initial patch by Hans Lawrenz.

  • bpo-28600: Optimize loop.call_soon().

  • bpo-28613: Fix get_event_loop() return the current loop if called fromcoroutines/callbacks.

  • bpo-28639: Fix inspect.isawaitable to always return bool Patch by JustinMayfield.

  • bpo-28652: Make loop methods reject socket kinds they do not support.

  • bpo-28653: Fix a refleak in functools.lru_cache.

  • bpo-28703: Fix asyncio.iscoroutinefunction to handle Mock objects.

  • bpo-24142: Reading a corrupt config file left the parser in an invalidstate. Original patch by Florian Höch.

  • bpo-28990: Fix SSL hanging if connection is closed before handshakecompleted. (Patch by HoHo-Ho)

IDLE

  • bpo-15308: Add 'interrupt execution' (^C) to Shell menu. Patch by RogerSerwy, updated by Bayard Randel.

  • bpo-27922: Stop IDLE tests from 'flashing' gui widgets on the screen.

  • Add version to title of IDLE help window.

  • bpo-25564: In section on IDLE -- console differences, mention that usingexec means that __builtins__ is defined for each statement.

  • bpo-27714: text_textview and test_autocomplete now pass when re-run in thesame process. This occurs when test_idle fails when run with the -woption but without -jn. Fix warning from test_config.

  • bpo-25507: IDLE no longer runs buggy code because of its tkinter imports.Users must include the same imports required to run directly in Python.

  • bpo-27452: add line counter and crc to IDLE configHandler test dump.

  • bpo-27365: Allow non-ascii chars in IDLE NEWS.txt, for contributor names.

  • bpo-27245: IDLE: Cleanly delete custom themes and key bindings.Previously, when IDLE was started from a console or by import, a cascadeof warnings was emitted. Patch by Serhiy Storchaka.

C API

  • bpo-28808: PyUnicode_CompareWithASCIIString() now never raises exceptions.

  • bpo-26754: PyUnicode_FSDecoder() accepted a filename argument encoded asan iterable of integers. Now only strings and bytes-like objects areaccepted.

Documentation

  • bpo-28513: Documented command-line interface of zipfile.

Tests

  • bpo-28950: Disallow -j0 to be combined with -T/-l/-M in regrtest commandline arguments.

  • bpo-28666: Now test.support.rmtree is able to remove unwritable orunreadable directories.

  • bpo-23839: Various caches now are cleared before running every test file.

  • bpo-28409: regrtest: fix the parser of command line arguments.

  • bpo-27787: Call gc.collect() before checking each test for "danglingthreads", since the dangling threads are weak references.

  • bpo-27369: In test_pyexpat, avoid testing an error message detail thatchanged in Expat 2.2.0.

Tools/Demos

  • bpo-27952: Get Tools/scripts/fixcid.py working with Python 3 and thecurrent "re" module, avoid invalid Python backslash escapes, and fix a bugparsing escaped C quote signs.

  • bpo-27332: Fixed the type of the first argument of module-level functionsgenerated by Argument Clinic. Patch by Petr Viktorin.

  • bpo-27418: Fixed Tools/importbench/importbench.py.

Windows

  • bpo-28251: Improvements to help manuals on Windows.

  • bpo-28110: launcher.msi has different product codes between 32-bit and64-bit

  • bpo-25144: Ensures TargetDir is set before continuing with custom install.

  • bpo-27469: Adds a shell extension to the launcher so that drag and dropworks correctly.

  • bpo-27309: Enabled proper Windows styles in python[w].exe manifest.

Build

  • bpo-29080: Removes hard dependency on hg.exe from PCBuild/build.bat

  • bpo-23903: Added missed names to PC/python3.def.

  • bpo-10656: Fix out-of-tree building on AIX. Patch by Tristan Carel andMichael Haubenwallner.

  • bpo-26359: Rename --with-optimiations to --enable-optimizations.

  • bpo-28444: Fix missing extensions modules when cross compiling.

  • bpo-28248: Update Windows build and OS X installers to use OpenSSL 1.0.2j.

  • bpo-28258: Fixed build with Estonian locale (python-config and distcleantargets in Makefile). Patch by Arfrever Frehtes Taifersar Arahesis.

  • bpo-26661: setup.py now detects system libffi with multiarch wrapper.

  • bpo-28066: Fix the logic that searches build directories for generatedinclude files when building outside the source tree.

  • bpo-15819: Remove redundant include search directory option for buildingoutside the source tree.

  • bpo-27566: Fix clean target in freeze makefile (patch by Lisa Roach)

  • bpo-27705: Update message in validate_ucrtbase.py

  • bpo-27983: Cause lack of llvm-profdata tool when using clang as requiredfor PGO linking to be a configure time error rather than make time when--with-optimizations is enabled. Also improve our ability to find thellvm-profdata tool on MacOS and some Linuxes.

  • bpo-26307: The profile-opt build now applies PGO to the built-in modules.

  • bpo-26359: Add the --with-optimizations configure flag.

  • bpo-27713: Suppress spurious build warnings when updating importlib'sbootstrap files. Patch by Xiang Zhang

  • bpo-25825: Correct the references to Modules/python.exp and ld_so_aix,which are required on AIX. This updates references to an installationpath that was changed in 3.2a4, and undoes changed references to the buildtree that were made in 3.5.0a1.

  • bpo-27453: CPP invocation in configure must use CPPFLAGS. Patch by ChiHsuan Yen.

  • bpo-27641: The configure script now inserts comments into the makefile toprevent the pgen and _freeze_importlib executables from beingcross-compiled.

  • bpo-26662: Set PYTHON_FOR_GEN in configure as the Python program to beused for file generation during the build.

  • bpo-10910: Avoid C++ compilation errors on FreeBSD and OS X. Also updateFreedBSD version checks for the original ctype UTF-8 workaround.

  • bpo-28676: Prevent missing 'getentropy' declaration warning on macOS.Patch by Gareth Rees.

Python 3.5.2 final

Release date: 2016-06-26

Core and Builtins

  • bpo-26930: Update Windows builds to use OpenSSL 1.0.2h.

Tests

  • bpo-26867: Ubuntu's openssl OP_NO_SSLv3 is forced on by default; fix test.

IDLE

  • bpo-27365: Allow non-ascii in idlelib/NEWS.txt - minimal part for 3.5.2.

Python 3.5.2 release candidate 1

Release date: 2016-06-12

Security

  • bpo-26556: Update expat to 2.1.1, fixesCVE 2015-1283.

  • Fix TLS stripping vulnerability in smtplib,CVE 2016-0772. Reported byTeam Oststrom.

  • bpo-26839: On Linux,os.urandom() now callsgetrandom() withGRND_NONBLOCK to fall back on reading/dev/urandom if the urandomentropy pool is not initialized yet. Patch written by Colm Buckley.

  • bpo-26657: Fix directory traversal vulnerability with http.server onWindows. This fixes a regression that was introduced in 3.3.4rc1 and3.4.0rc1. Based on patch by Philipp Hagemeister.

  • bpo-26313: ssl.py _load_windows_store_certs fails if windows cert store isempty. Patch by Baji.

  • bpo-25939: On Windows open the cert store readonly inssl.enum_certificates.

Core and Builtins

  • bpo-27066: Fixed SystemError if a custom opener (for open()) returns anegative number without setting an exception.

  • bpo-20041: Fixed TypeError when frame.f_trace is set to None. Patch byXavier de Gaye.

  • bpo-26168: Fixed possible refleaks in failing Py_BuildValue() with the "N"format unit.

  • bpo-26991: Fix possible refleak when creating a function with annotations.

  • bpo-27039: Fixed bytearray.remove() for values greater than 127. Patch byJoe Jevnik.

  • bpo-23640: int.from_bytes() no longer bypasses constructors forsubclasses.

  • bpo-26811: gc.get_objects() no longer contains a broken tuple with NULLpointer.

  • bpo-20120: Use RawConfigParser for .pypirc parsing, removing support forinterpolation unintentionally added with move to Python 3. Behavior nolonger does any interpolation in .pypirc files, matching behavior inPython 2.7 and Setuptools 19.0.

  • bpo-26659: Make the builtin slice type support cycle collection.

  • bpo-26718: super.__init__ no longer leaks memory if called multiple times.NOTE: A direct call of super.__init__ is not endorsed!

  • bpo-25339: PYTHONIOENCODING now has priority over locale in setting theerror handler for stdin and stdout.

  • bpo-26494: Fixed crash on iterating exhausting iterators. Affected classesare generic sequence iterators, iterators of str, bytes, bytearray, list,tuple, set, frozenset, dict, OrderedDict, corresponding views andos.scandir() iterator.

  • bpo-26581: If coding cookie is specified multiple times on a line inPython source code file, only the first one is taken to account.

  • bpo-26464: Fix str.translate() when string is ASCII and first replacementsremoves character, but next replacement uses a non-ASCII character or astring longer than 1 character. Regression introduced in Python 3.5.0.

  • bpo-22836: Ensure exception reports from PyErr_Display() andPyErr_WriteUnraisable() are sensible even when formatting them producessecondary errors. This affects the reports produced bysys.__excepthook__() and when __del__() raises an exception.

  • bpo-26302: Correct behavior to reject comma as a legal character forcookie names.

  • bpo-4806: Avoid masking the original TypeError exception when using star(*) unpacking in function calls. Based on patch by Hagen Fürstenauand Daniel Urban.

  • bpo-27138: Fix the doc comment for FileFinder.find_spec().

  • bpo-26154: Add a new private _PyThreadState_UncheckedGet() function to getthe current Python thread state, but don't issue a fatal error if it isNULL. This new function must be used instead of accessing directly the_PyThreadState_Current variable. The variable is no more exposed sincePython 3.5.1 to hide the exact implementation of atomic C types, to avoidcompiler issues.

  • bpo-26194: Deque.insert() gave odd results for bounded deques that hadreached their maximum size. Now an IndexError will be raised whenattempting to insert into a full deque.

  • bpo-25843: When compiling code, don't merge constants if they are equalbut have a different types. For example,f1,f2=lambda:1,lambda:1.0 is now correctly compiled to two different functions:f1()returns1 (int) andf2() returns1.0 (int), even if1 and1.0 are equal.

  • bpo-22995: [UPDATE] Comment out the one of the pickleability tests in_PyObject_GetState() due to regressions observed in Cython-based projects.

  • bpo-25961: Disallowed null characters in the type name.

  • bpo-25973: Fix segfault when an invalid nonlocal statement binds a namestarting with two underscores.

  • bpo-22995: Instances of extension types with a state that aren'tsubclasses of list or dict and haven't implemented any pickle-relatedmethods (__reduce__, __reduce_ex__, __getnewargs__, __getnewargs_ex__, or__getstate__), can no longer be pickled. Including memoryview.

  • bpo-20440: Massive replacing unsafe attribute setting code with specialmacro Py_SETREF.

  • bpo-25766: Special method __bytes__() now works in str subclasses.

  • bpo-25421: __sizeof__ methods of builtin types now use dynamic basic size.This allows sys.getsize() to work correctly with their subclasses with__slots__ defined.

  • bpo-25709: Fixed problem with in-place string concatenation and utf-8cache.

  • bpo-27147: MentionPEP 420 in the importlib docs.

  • bpo-24097: Fixed crash in object.__reduce__() if slot name is freed inside__getattr__.

  • bpo-24731: Fixed crash on converting objects with special methods__bytes__, __trunc__, and __float__ returning instances of subclasses ofbytes, int, and float to subclasses of bytes, int, and floatcorrespondingly.

  • bpo-26478: Fix semantic bugs when using binary operators with dictionaryviews and tuples.

  • bpo-26171: Fix possible integer overflow and heap corruption inzipimporter.get_data().

  • bpo-25660: Fix TAB key behaviour in REPL with readline.

  • bpo-25887: Raise a RuntimeError when a coroutine object is awaited morethan once.

  • bpo-27243: Update the __aiter__ protocol: instead of returning anawaitable that resolves to an asynchronous iterator, the asynchronousiterator should be returned directly. Doing the former will trigger aPendingDeprecationWarning.

Library

  • bpo-21386: Implement missing IPv4Address.is_global property. It wasdocumented since 07a5610bae9d. Initial patch by Roger Luethi.

  • bpo-20900: distutils register command now decodes HTTP responsescorrectly. Initial patch by ingrid.

  • A new version of typing.py provides several new classes and features:@overload outside stubs, Reversible, DefaultDict, Text, ContextManager,Type[], NewType(), TYPE_CHECKING, and numerous bug fixes (note that someof the new features are not yet implemented in mypy or other staticanalyzers). Also classes forPEP 492 (Awaitable, AsyncIterable,AsyncIterator) have been added (in fact they made it into 3.5.1 but werenever mentioned).

  • bpo-25738: Stop http.server.BaseHTTPRequestHandler.send_error() fromsending a message body for 205 Reset Content. Also, don't send Contentheader fields in responses that don't have a body. Patch by SusumuKoshiba.

  • bpo-21313: Fix the "platform" module to tolerate when sys.version containstruncated build information.

  • bpo-27164: In the zlib module, allow decompressing raw Deflate streamswith a predefined zdict. Based on patch by Xiang Zhang.

  • bpo-24291: Fix wsgiref.simple_server.WSGIRequestHandler to completelywrite data to the client. Previously it could do partial writes andtruncate data. Also, wsgiref.handler.ServerHandler can now handle stdoutdoing partial writes, but this is deprecated.

  • bpo-26809: Add__all__ tostring. Patch by Emanuel Barry.

  • bpo-26373: subprocess.Popen.communicate now correctly ignoresBrokenPipeError when the child process dies before .communicate() iscalled in more/all circumstances.

  • bpo-21776: distutils.upload now correctly handles HTTPError. Initial patchby Claudiu Popa.

  • bpo-27114: Fix SSLContext._load_windows_store_certs fails withPermissionError

  • bpo-18383: Avoid creating duplicate filters when using filterwarnings andsimplefilter. Based on patch by Alex Shkop.

  • bpo-27057: Fix os.set_inheritable() on Android, ioctl() is blocked bySELinux and fails with EACCESS. The function now falls back to fcntl().Patch written by Michał Bednarski.

  • bpo-27014: Fix infinite recursion using typing.py. Thanks to Kalle Tuure!

  • bpo-14132: Fix urllib.request redirect handling when the target only has aquery string. Original fix by Ján Janech.

  • bpo-17214: The "urllib.request" module now percent-encodes non-ASCII bytesfound in redirect target URLs. Some servers send Location header fieldswith non-ASCII bytes, but "http.client" requires the request target to beASCII-encodable, otherwise a UnicodeEncodeError is raised. Based on patchby Christian Heimes.

  • bpo-26892: Honor debuglevel flag in urllib.request.HTTPHandler. Patchcontributed by Chi Hsuan Yen.

  • bpo-22274: In the subprocess module, allow stderr to be redirected tostdout even when stdout is not redirected. Patch by Akira Li.

  • bpo-26807: mock_open 'files' no longer error on readline at end of file.Patch from Yolanda Robla.

  • bpo-25745: Fixed leaking a userptr in curses panel destructor.

  • bpo-26977: Removed unnecessary, and ignored, call to sum of squares helperin statistics.pvariance.

  • bpo-26881: The modulefinder module now supports extended opcode arguments.

  • bpo-23815: Fixed crashes related to directly created instances of types in_tkinter and curses.panel modules.

  • bpo-17765: weakref.ref() no longer silently ignores keyword arguments.Patch by Georg Brandl.

  • bpo-26873: xmlrpc now raises ResponseError on unsupported type tagsinstead of silently return incorrect result.

  • bpo-26711: Fixed the comparison of plistlib.Data with other types.

  • bpo-24114: Fix an uninitialized variable inctypes.util. The bug onlyoccurs on SunOS when the ctypes implementation searches for thecrleprogram. Patch by Xiang Zhang. Tested on SunOS by Kees Bos.

  • bpo-26864: In urllib.request, change the proxy bypass host checkingagainst no_proxy to be case-insensitive, and to not match unrelated hostnames that happen to have a bypassed hostname as a suffix. Patch by XiangZhang.

  • bpo-26634: recursive_repr() now sets __qualname__ of wrapper. Patch byXiang Zhang.

  • bpo-26804: urllib.request will prefer lower_case proxy environmentvariables over UPPER_CASE or Mixed_Case ones. Patch contributed byHans-Peter Jansen.

  • bpo-26837: assertSequenceEqual() now correctly outputs non-stringifieddiffering items (like bytes in the -b mode). This affectsassertListEqual() and assertTupleEqual().

  • bpo-26041: Remove "will be removed in Python 3.7" from deprecationmessages of platform.dist() and platform.linux_distribution(). Patch byKumaripaba Miyurusara Athukorala.

  • bpo-26822: itemgetter, attrgetter and methodcaller objects no longersilently ignore keyword arguments.

  • bpo-26733: Disassembling a class now disassembles class and staticmethods. Patch by Xiang Zhang.

  • bpo-26801: Fix error handling inshutil.get_terminal_size(), catchAttributeError instead ofNameError. Patch written byEmanuel Barry.

  • bpo-24838: tarfile's ustar and gnu formats now correctly calculate nameand link field limits for multibyte character encodings like utf-8.

  • bpo-26717: Stop encoding Latin-1-ized WSGI paths with UTF-8. Patch byAnthony Sottile.

  • bpo-26735: Fixos.urandom() on Solaris 11.3 and newer when readingmore than 1,024 bytes: callgetrandom() multiple times with a limit of1024 bytes per call.

  • bpo-16329: Add .webm to mimetypes.types_map. Patch by Giampaolo Rodola'.

  • bpo-13952: Add .csv to mimetypes.types_map. Patch by Geoff Wilson.

  • bpo-26709: Fixed Y2038 problem in loading binary PLists.

  • bpo-23735: Handle terminal resizing with Readline 6.3+ by installing ourown SIGWINCH handler. Patch by Eric Price.

  • bpo-26586: In http.server, respond with "413 Request header fields toolarge" if there are too many header fields to parse, rather than killingthe connection and raising an unhandled exception. Patch by Xiang Zhang.

  • bpo-22854: Change BufferedReader.writable() and BufferedWriter.readable()to always return False.

  • bpo-25195: Fix a regression in mock.MagicMock. _Call is a subclass oftuple (changeset 3603bae63c13 only works for classes) so we need toimplement __ne__ ourselves. Patch by Andrew Plummer.

  • bpo-26644: Raise ValueError rather than SystemError when a negative lengthis passed to SSLSocket.recv() or read().

  • bpo-23804: Fix SSL recv(0) and read(0) methods to return zero bytesinstead of up to 1024.

  • bpo-26616: Fixed a bug in datetime.astimezone() method.

  • bpo-21925:warnings.formatwarning() now catches exceptions onlinecache.getline(...) to be able to logResourceWarningemitted late during the Python shutdown process.

  • bpo-24266: Ctrl+C during Readline history search now cancels the searchmode when compiled with Readline 7.

  • bpo-26560: Avoid potential ValueError in BaseHandler.start_response.Initial patch by Peter Inglesby.

  • bpo-26569: Fixpyclbr.readmodule() andpyclbr.readmodule_ex()to support importing packages.

  • bpo-26499: Account for remaining Content-Length in HTTPResponse.readline()and read1(). Based on patch by Silent Ghost. Also document thatHTTPResponse now supports these methods.

  • bpo-25320: Handle sockets in directories unittest discovery is scanning.Patch from Victor van den Elzen.

  • bpo-16181: cookiejar.http2time() now returns None if year is higher thandatetime.MAXYEAR.

  • bpo-26513: Fixes platform module detection of Windows Server

  • bpo-23718: Fixed parsing time in week 0 before Jan 1. Original patch byTamás Bence Gedai.

  • bpo-20589: Invoking Path.owner() and Path.group() on Windows now raiseNotImplementedError instead of ImportError.

  • bpo-26177: Fixed the keys() method for Canvas and Scrollbar widgets.

  • bpo-15068: Got rid of excessive buffering in the fileinput module. Thebufsize parameter is no longer used.

  • bpo-2202: Fix UnboundLocalError inAbstractDigestAuthHandler.get_algorithm_impls. Initial patch by MathieuDupuy.

  • bpo-25718: Fixed pickling and copying the accumulate() iterator with totalis None.

  • bpo-26475: Fixed debugging output for regular expressions with the (?x)flag.

  • bpo-26457: Fixed the subnets() methods in IP network classes for the casewhen resulting prefix length is equal to maximal prefix length. Based onpatch by Xiang Zhang.

  • bpo-26385: Remove the file if the internal open() call inNamedTemporaryFile() fails. Patch by Silent Ghost.

  • bpo-26402: Fix XML-RPC client to retry when the server shuts down apersistent connection. This was a regression related to the newhttp.client.RemoteDisconnected exception in 3.5.0a4.

  • bpo-25913: Leading<~ is optional now in base64.a85decode() withadobe=True. Patch by Swati Jaiswal.

  • bpo-26186: Remove an invalid type check in importlib.util.LazyLoader.

  • bpo-26367: importlib.__import__() raises SystemError likebuiltins.__import__() whenlevel is specified but without anaccompanying package specified.

  • bpo-26309: In the "socketserver" module, shut down the request (closingthe connected socket) when verify_request() returns false. Patch by AvivPalivoda.

  • bpo-25995: os.walk() no longer uses FDs proportional to the tree depth.

  • bpo-26117: The os.scandir() iterator now closes file descriptor not onlywhen the iteration is finished, but when it was failed with error.

  • bpo-25911: Restored support of bytes paths in os.walk() on Windows.

  • bpo-26045: Add UTF-8 suggestion to error message when posting anon-Latin-1 string with http.client.

  • bpo-12923: Reset FancyURLopener's redirect counter even if there is anexception. Based on patches by Brian Brazil and Daniel Rocco.

  • bpo-25945: Fixed a crash when unpickle the functools.partial object withwrong state. Fixed a leak in failed functools.partial constructor. "args"and "keywords" attributes of functools.partial have now always types tupleand dict correspondingly.

  • bpo-26202: copy.deepcopy() now correctly copies range() objects withnon-atomic attributes.

  • bpo-23076: Path.glob() now raises a ValueError if it's called with aninvalid pattern. Patch by Thomas Nyberg.

  • bpo-19883: Fixed possible integer overflows in zipimport.

  • bpo-26227: On Windows, getnameinfo(), gethostbyaddr() andgethostbyname_ex() functions of the socket module now decode the hostnamefrom the ANSI code page rather than UTF-8.

  • bpo-26147: xmlrpc now works with strings not encodable with used non-UTF-8encoding.

  • bpo-25935: Garbage collector now breaks reference loops with OrderedDict.

  • bpo-16620: Fixed AttributeError in msilib.Directory.glob().

  • bpo-26013: Added compatibility with broken protocol 2 pickles created inold Python 3 versions (3.4.3 and lower).

  • bpo-25850: Use cross-compilation by default for 64-bit Windows.

  • bpo-17633: Improve zipimport's support for namespace packages.

  • bpo-24705: Fix sysconfig._parse_makefile not expanding ${} vars appearingbefore $() vars.

  • bpo-22138: Fix mock.patch behavior when patching descriptors. Restoreoriginal values after patching. Patch contributed by Sean McCully.

  • bpo-25672: In the ssl module, enable the SSL_MODE_RELEASE_BUFFERS modeoption if it is safe to do so.

  • bpo-26012: Don't traverse into symlinks for** pattern inpathlib.Path.[r]glob().

  • bpo-24120: Ignore PermissionError when traversing a tree withpathlib.Path.[r]glob(). Patch by Ulrich Petri.

  • bpo-25447: fileinput now uses sys.stdin as-is if it does not have a bufferattribute (restores backward compatibility).

  • bpo-25447: Copying the lru_cache() wrapper object now always works,independently from the type of the wrapped object (by returning theoriginal object unchanged).

  • bpo-24103: Fixed possible use after free in ElementTree.XMLPullParser.

  • bpo-25860: os.fwalk() no longer skips remaining directories when erroroccurs. Original patch by Samson Lee.

  • bpo-25914: Fixed and simplified OrderedDict.__sizeof__.

  • bpo-25902: Fixed various refcount issues in ElementTree iteration.

  • bpo-25717: Restore the previous behaviour of tolerating most fstat()errors when opening files. This was a regression in 3.5a1, and stoppedanonymous temporary files from working in special cases.

  • bpo-24903: Fix regression in number of arguments compileall accepts when'-d' is specified. The check on the number of arguments has been droppedcompletely as it never worked correctly anyway.

  • bpo-25764: In the subprocess module, preserve any exception caused byfork() failure when preexec_fn is used.

  • bpo-6478: _strptime's regexp cache now is reset after changing timezonewith time.tzset().

  • bpo-14285: When executing a package with the "python -m package" option,and package initialization fails, a proper traceback is now reported. The"runpy" module now lets exceptions from package initialization pass backto the caller, rather than raising ImportError.

  • bpo-19771: Also in runpy and the "-m" option, omit the irrelevant message". . . is a package and cannot be directly executed" if the package couldnot even be initialized (e.g. due to a bad*.pyc file).

  • bpo-25177: Fixed problem with the mean of very small and very largenumbers. As a side effect, statistics.mean and statistics.variance shouldbe significantly faster.

  • bpo-25718: Fixed copying object with state with boolean value is false.

  • bpo-10131: Fixed deep copying of minidom documents. Based on patch byMarian Ganisin.

  • bpo-25725: Fixed a reference leak in pickle.loads() when unpicklinginvalid data including tuple instructions.

  • bpo-25663: In the Readline completer, avoid listing duplicate globalnames, and search the global namespace before searching builtins.

  • bpo-25688: Fixed file leak in ElementTree.iterparse() raising an error.

  • bpo-23914: Fixed SystemError raised by unpickler on broken pickle data.

  • bpo-25691: Fixed crash on deleting ElementTree.Element attributes.

  • bpo-25624: ZipFile now always writes a ZIP_STORED header for directoryentries. Patch by Dingyuan Wang.

  • Skip getaddrinfo if host is already resolved. Patch by A. Jesse JiryuDavis.

  • bpo-26050: Add asyncio.StreamReader.readuntil() method. Patch by МаркКоренберг.

  • bpo-25924: Avoid unnecessary serialization of getaddrinfo(3) calls on OS Xversions 10.5 or higher. Original patch by A. Jesse Jiryu Davis.

  • bpo-26406: Avoid unnecessary serialization of getaddrinfo(3) calls oncurrent versions of OpenBSD and NetBSD. Patch by A. Jesse Jiryu Davis.

  • bpo-26848: Fix asyncio/subprocess.communicate() to handle empty input.Patch by Jack O'Connor.

  • bpo-27040: Add loop.get_exception_handler method

  • bpo-27041: asyncio: Add loop.create_future method

  • bpo-27223: asyncio: Fix _read_ready and _write_ready to respect_conn_lost. Patch by Łukasz Langa.

  • bpo-22970: asyncio: Fix inconsistency cancelling Condition.wait. Patch byDavid Coles.

IDLE

  • bpo-5124: Paste with text selected now replaces the selection on X11. Thismatches how paste works on Windows, Mac, most modern Linux apps, and ttkwidgets. Original patch by Serhiy Storchaka.

  • bpo-24759: Make clear in idlelib.idle_test.__init__ that the directory isa private implementation of test.test_idle and tool for maintainers.

  • bpo-27196: Stop 'ThemeChanged' warnings when running IDLE tests. Thesepersisted after other warnings were suppressed in #20567. Apply SerhiyStorchaka's update_idletasks solution to four test files. Record thisadditional advice in idle_test/README.txt

  • bpo-20567: Revise idle_test/README.txt with advice about avoiding tkwarning messages from tests. Apply advice to several IDLE tests.

  • bpo-27117: Make colorizer htest and turtledemo work with dark themes. Movecode for configuring text widget colors to a new function.

  • bpo-26673: When tk reports font size as 0, change to size 10. Such fontson Linux prevented the configuration dialog from opening.

  • bpo-21939: Add test for IDLE's percolator. Original patch by SaimadhavHeblikar.

  • bpo-21676: Add test for IDLE's replace dialog. Original patch by SaimadhavHeblikar.

  • bpo-18410: Add test for IDLE's search dialog. Original patch by WestleyMartínez.

  • bpo-21703: Add test for IDLE's undo delegator. Original patch by SaimadhavHeblikar .

  • bpo-27044: Add ConfigDialog.remove_var_callbacks to stop memory leaks.

  • bpo-23977: Add more asserts to test_delegator.

  • bpo-20640: Add tests for idlelib.configHelpSourceEdit. Patch by SaimadhavHeblikar.

  • In the 'IDLE-console differences' section of the IDLE doc, clarify howrunning with IDLE affects sys.modules and the standard streams.

  • bpo-25507: fix incorrect change in IOBinding that prevented printing.Augment IOBinding htest to include all major IOBinding functions.

  • bpo-25905: Revert unwanted conversion of ' to ’ RIGHT SINGLE QUOTATIONMARK in README.txt and open this and NEWS.txt with 'ascii'. Re-encodeCREDITS.txt to utf-8 and open it with 'utf-8'.

Documentation

  • bpo-19489: Moved the search box from the sidebar to the header and footerof each page. Patch by Ammar Askar.

  • bpo-24136: Document the newPEP 448 unpacking syntax of 3.5.

  • bpo-26736: Used HTTPS for external links in the documentation if possible.

  • bpo-6953: Rework the Readline module documentation to group relatedfunctions together, and add more details such as what underlying Readlinefunctions and variables are accessed.

  • bpo-23606: Adds note to ctypes documentation regarding cdll.msvcrt.

  • bpo-25500: Fix documentation to not claim that __import__ is searched forin the global scope.

  • bpo-26014: Update 3.x packaging documentation: * "See also" links to thenew docs are now provided in the legacy pages * links to setuptoolsdocumentation have been updated

Tests

  • bpo-21916: Added tests for the turtle module. Patch by ingrid, GregoryLoyse and Jelle Zijlstra.

  • bpo-26523: The multiprocessing thread pool (multiprocessing.dummy.Pool)was untested.

  • bpo-26015: Added new tests for pickling iterators of mutable sequences.

  • bpo-26325: Added test.support.check_no_resource_warning() to check that noResourceWarning is emitted.

  • bpo-25940: Changed test_ssl to use self-signed.pythontest.net. Thisavoids relying on svn.python.org, which recently changed root certificate.

  • bpo-25616: Tests for OrderedDict are extracted from test_collections intoseparate file test_ordered_dict.

  • bpo-26583: Skip test_timestamp_overflow in test_import if bytecode filescannot be written.

Build

  • bpo-26884: Fix linking extension modules for cross builds. Patch by Xavierde Gaye.

  • bpo-22359: Disable the rules for running _freeze_importlib and pgen whencross-compiling. The output of these programs is normally saved with thesource code anyway, and is still regenerated when doing a native build.Patch by Xavier de Gaye.

  • bpo-27229: Fix the cross-compiling pgen rule for in-tree builds. Patch byXavier de Gaye.

  • bpo-21668: Link audioop, _datetime, _ctypes_test modules to libm, excepton Mac OS X. Patch written by Xavier de Gaye.

  • bpo-25702: A --with-lto configure option has been added that will enablelink time optimizations at build time during a make profile-opt. Somecompilers and toolchains are known to not produce stable code when usingLTO, be sure to test things thoroughly before relying on it. It canprovide a few % speed up over profile-opt alone.

  • bpo-26624: Adds validation of ucrtbase[d].dll version with warning for oldversions.

  • bpo-17603: Avoid error about nonexistent fileblocks.o file by using alower-level check for st_blocks in struct stat.

  • bpo-26079: Fixing the build output folder for tix-8.4.3.6. Patch by BjoernThiel.

  • bpo-26465: Update Windows builds to use OpenSSL 1.0.2g.

  • bpo-24421: Compile Modules/_math.c once, before building extensions.Previously it could fail to compile properly if the math and cmath buildswere concurrent.

  • bpo-25348: Added--pgo and--pgo-job arguments toPCbuild\build.bat for building with Profile-Guided Optimization. TheoldPCbuild\build_pgo.bat script is now deprecated, and simply callsPCbuild\build.bat--pgo%*.

  • bpo-25827: Add support for building with ICC toconfigure, including anew--with-icc flag.

  • bpo-25696: Fix installation of Python on UNIX with make -j9.

  • bpo-26930: Update OS X 10.5+ 32-bit-only installer to build and link withOpenSSL 1.0.2h.

  • bpo-26268: Update Windows builds to use OpenSSL 1.0.2f.

  • bpo-25136: Support Apple Xcode 7's new textual SDK stub libraries.

  • bpo-24324: Do not enable unreachable code warnings when using gcc as theoption does not work correctly in older versions of gcc and has beensilently removed as of gcc-4.5.

Windows

  • bpo-27053: Updates make_zip.py to correctly generate library ZIP file.

  • bpo-26268: Update the prepare_ssl.py script to handle OpenSSL releasesthat don't include the contents of the include directory (that is, 1.0.2eand later).

  • bpo-26071: bdist_wininst created binaries fail to start and find 32bitPython

  • bpo-26073: Update the list of magic numbers in launcher

  • bpo-26065: Excludes venv from library when generating embeddable distro.

  • bpo-17500: Remove unused and outdated icons. (See also:https://github.com/python/pythondotorg/issues/945)

Tools/Demos

  • bpo-26799: Fix python-gdb.py: don't get C types once when the Python codeis loaded, but get C types on demand. The C types can change ifpython-gdb.py is loaded before the Python executable. Patch written byThomas Ilsche.

  • bpo-26271: Fix the Freeze tool to properly use flags passed throughconfigure. Patch by Daniel Shaulov.

  • bpo-26489: Add dictionary unpacking support to Tools/parser/unparse.py.Patch by Guo Ci Teo.

  • bpo-26316: Fix variable name typo in Argument Clinic.

Python 3.5.1 final

Release date: 2015-12-06

Core and Builtins

  • bpo-25709: Fixed problem with in-place string concatenation and utf-8cache.

Windows

  • bpo-25715: Python 3.5.1 installer shows wrong upgrade path and incorrectlogic for launcher detection.

Python 3.5.1 release candidate 1

Release date: 2015-11-22

Core and Builtins

  • bpo-25630: Fix a possible segfault during argument parsing in functionsthat accept filesystem paths.

  • bpo-23564: Fixed a partially broken sanity check in the _posixsubprocessinternals regarding how fds_to_pass were passed to the child. The bug hadno actual impact as subprocess.py already avoided it.

  • bpo-25388: Fixed tokenizer crash when processing undecodable source codewith a null byte.

  • bpo-25462: The hash of the key now is calculated only once in mostoperations in C implementation of OrderedDict.

  • bpo-22995: Default implementation of __reduce__ and __reduce_ex__ nowrejects builtin types with not defined __new__.

  • bpo-25555: Fix parser and AST: fill lineno and col_offset of "arg" nodewhen compiling AST from Python objects.

  • bpo-24802: Avoid buffer overreads when int(), float(), compile(), exec()and eval() are passed bytes-like objects. These objects are notnecessarily terminated by a null byte, but the functions assumed theywere.

  • bpo-24726: Fixed a crash and leaking NULL in repr() of OrderedDict thatwas mutated by direct calls of dict methods.

  • bpo-25449: Iterating OrderedDict with keys with unstable hash now raisesKeyError in C implementations as well as in Python implementation.

  • bpo-25395: Fixed crash when highly nested OrderedDict structures weregarbage collected.

  • bpo-25274: sys.setrecursionlimit() now raises a RecursionError if the newrecursion limit is too low depending at the current recursion depth.Modify also the "lower-water mark" formula to make it monotonic. This markis used to decide when the overflowed flag of the thread state is reset.

  • bpo-24402: Fix input() to prompt to the redirected stdout whensys.stdout.fileno() fails.

  • bpo-24806: Prevent builtin types that are not allowed to be subclassedfrom being subclassed through multiple inheritance.

  • bpo-24848: Fixed a number of bugs in UTF-7 decoding of misformed data.

  • bpo-25280: Import trace messages emitted in verbose (-v) mode are nolonger formatted twice.

  • bpo-25003: On Solaris 11.3 or newer, os.urandom() now uses the getrandom()function instead of the getentropy() function. The getentropy() functionis blocking to generate very good quality entropy, os.urandom() doesn'tneed such high-quality entropy.

  • bpo-25182: The stdprinter (used as sys.stderr before the io module isimported at startup) now uses the backslashreplace error handler.

  • bpo-25131: Make the line number and column offset of set/dict literals andcomprehensions correspond to the opening brace.

  • bpo-25150: Hide the private_Py_atomic_xxx symbols from thepublic Python.h header to fix a compilation error with OpenMP.PyThreadState_GET() becomes an alias to PyThreadState_Get() to avoid ABIincompatibilities.

Library

  • bpo-25626: Change three zlib functions to accept sizes that fit inPy_ssize_t, but internally cap those sizes to UINT_MAX. This resolves aregression in 3.5 where GzipFile.read() failed to read chunks larger than2 or 4 GiB. The change affects the zlib.Decompress.decompress()max_length parameter, the zlib.decompress() bufsize parameter, and thezlib.Decompress.flush() length parameter.

  • bpo-25583: Avoid incorrect errors raised by os.makedirs(exist_ok=True)when the OS gives priority to errors such as EACCES over EEXIST.

  • bpo-25593: Change semantics of EventLoop.stop() in asyncio.

  • bpo-6973: When we know a subprocess.Popen process has died, do not allowthe send_signal(), terminate(), or kill() methods to do anything as theycould potentially signal a different process.

  • bpo-25590: In the Readline completer, only call getattr() once perattribute.

  • bpo-25498: Fix a crash when garbage-collecting ctypes objects created bywrapping a memoryview. This was a regression made in 3.5a1. Based onpatch by Eryksun.

  • bpo-25584: Added "escape" to the __all__ list in the glob module.

  • bpo-25584: Fixed recursive glob() with patterns starting with**.

  • bpo-25446: Fix regression in smtplib's AUTH LOGIN support.

  • bpo-18010: Fix the pydoc web server's module search function to handleexceptions from importing packages.

  • bpo-25554: Got rid of circular references in regular expression parsing.

  • bpo-25510: fileinput.FileInput.readline() now returns b'' instead of '' atthe end if the FileInput was opened with binary mode. Patch by RyosukeIto.

  • bpo-25503: Fixed inspect.getdoc() for inherited docstrings of properties.Original patch by John Mark Vandenberg.

  • bpo-25515: Always use os.urandom as a source of randomness in uuid.uuid4.

  • bpo-21827: Fixed textwrap.dedent() for the case when largest commonwhitespace is a substring of smallest leading whitespace. Based on patchby Robert Li.

  • bpo-25447: The lru_cache() wrapper objects now can be copied and pickled(by returning the original object unchanged).

  • bpo-25390: typing: Don't crash on Union[str, Pattern].

  • bpo-25441: asyncio: Raise error from drain() when socket is closed.

  • bpo-25410: Cleaned up and fixed minor bugs in C implementation ofOrderedDict.

  • bpo-25411: Improved Unicode support in SMTPHandler through better use ofthe email package. Thanks to user simon04 for the patch.

  • bpo-25407: Remove mentions of the formatter module being removed in Python3.6.

  • bpo-25406: Fixed a bug in C implementation of OrderedDict.move_to_end()that caused segmentation fault or hang in iterating after moving severalitems to the start of ordered dict.

  • bpo-25364: zipfile now works in threads disabled builds.

  • bpo-25328: smtpd's SMTPChannel now correctly raises a ValueError if bothdecode_data and enable_SMTPUTF8 are set to true.

  • bpo-25316: distutils raises OSError instead of DistutilsPlatformError whenMSVC is not installed.

  • bpo-25380: Fixed protocol for the STACK_GLOBAL opcode inpickletools.opcodes.

  • bpo-23972: Updates asyncio datagram create method allowing reuseport andreuseaddr socket options to be set prior to binding the socket. Mirroringthe existing asyncio create_server method the reuseaddr option fordatagram sockets defaults to True if the O/S is 'posix' (except if theplatform is Cygwin). Patch by Chris Laws.

  • bpo-25304: Add asyncio.run_coroutine_threadsafe(). This lets you submit acoroutine to a loop from another thread, returning aconcurrent.futures.Future. By Vincent Michel.

  • bpo-25232: Fix CGIRequestHandler to split the query from the URL at thefirst question mark (?) rather than the last. Patch from Xiang Zhang.

  • bpo-24657: Prevent CGIRequestHandler from collapsing slashes in the querypart of the URL as if it were a path. Patch from Xiang Zhang.

  • bpo-24483: C implementation of functools.lru_cache() now calculates key'shash only once.

  • bpo-22958: Constructor and update method of weakref.WeakValueDictionarynow accept the self and the dict keyword arguments.

  • bpo-22609: Constructor of collections.UserDict now accepts the selfkeyword argument.

  • bpo-25111: Fixed comparison of traceback.FrameSummary.

  • bpo-25262: Added support for BINBYTES8 opcode in Python implementation ofunpickler. Highest 32 bits of 64-bit size for BINUNICODE8 and BINBYTES8opcodes no longer silently ignored on 32-bit platforms in Cimplementation.

  • bpo-25034: Fix string.Formatter problem with auto-numbering and nestedformat_specs. Patch by Anthon van der Neut.

  • bpo-25233: Rewrite the guts of asyncio.Queue and asyncio.Semaphore to bemore understandable and correct.

  • bpo-25203: Failed readline.set_completer_delims() no longer left themodule in inconsistent state.

  • bpo-23600: Default implementation of tzinfo.fromutc() was returning wrongresults in some cases.

  • bpo-23329: Allow the ssl module to be built with older versions ofLibreSSL.

  • Prevent overflow in _Unpickler_Read.

  • bpo-25047: The XML encoding declaration written by Element Tree nowrespects the letter case given by the user. This restores the ability towrite encoding names in uppercase like "UTF-8", which worked in Python 2.

  • bpo-25135: Make deque_clear() safer by emptying the deque before clearing.This helps avoid possible reentrancy issues.

  • bpo-19143: platform module now reads Windows version from kernel32.dll toavoid compatibility shims.

  • bpo-25092: Fix datetime.strftime() failure when errno was already set toEINVAL.

  • bpo-23517: Fix rounding in fromtimestamp() and utcfromtimestamp() methodsof datetime.datetime: microseconds are now rounded to nearest with tiesgoing to nearest even integer (ROUND_HALF_EVEN), instead of being roundingtowards minus infinity (ROUND_FLOOR). It's important that these methodsuse the same rounding mode than datetime.timedelta to keep the property:(datetime(1970,1,1) + timedelta(seconds=t)) ==datetime.utcfromtimestamp(t). It also the rounding mode used byround(float) for example.

  • bpo-25155: Fix datetime.datetime.now() and datetime.datetime.utcnow() onWindows to support date after year 2038. It was a regression introduced inPython 3.5.0.

  • bpo-25108: Omitted internal frames in traceback functions print_stack(),format_stack(), and extract_stack() called without arguments.

  • bpo-25118: Fix a regression of Python 3.5.0 in os.waitpid() on Windows.

  • bpo-24684: socket.socket.getaddrinfo() now callsPyUnicode_AsEncodedString() instead of calling the encode() method of thehost, to handle correctly custom string with an encode() method whichdoesn't return a byte string. The encoder of the IDNA codec is now calleddirectly instead of calling the encode() method of the string.

  • bpo-25060: Correctly compute stack usage of the BUILD_MAP opcode.

  • bpo-24857: Comparing call_args to a long sequence now correctly returns aboolean result instead of raising an exception. Patch by A Kaptur.

  • bpo-23144: Make sure that HTMLParser.feed() returns all the data, evenwhen convert_charrefs is True.

  • bpo-24982: shutil.make_archive() with the "zip" format now adds entriesfor directories (including empty directories) in ZIP file.

  • bpo-25019: Fixed a crash caused by setting non-string key of expat parser.Based on patch by John Leitch.

  • bpo-16180: Exit pdb if file has syntax error, instead of trapping user inan infinite loop. Patch by Xavier de Gaye.

  • bpo-24891: Fix a race condition at Python startup if the file descriptorof stdin (0), stdout (1) or stderr (2) is closed while Python is creatingsys.stdin, sys.stdout and sys.stderr objects. These attributes are now setto None if the creation of the object failed, instead of raising anOSError exception. Initial patch written by Marco Paolini.

  • bpo-24992: Fix error handling and a race condition (related to garbagecollection) in collections.OrderedDict constructor.

  • bpo-24881: Fixed setting binary mode in Python implementation of FileIO onWindows and Cygwin. Patch from Akira Li.

  • bpo-25578: Fix (another) memory leak in SSLSocket.getpeercer().

  • bpo-25530: Disable the vulnerable SSLv3 protocol by default when creatingssl.SSLContext.

  • bpo-25569: Fix memory leak in SSLSocket.getpeercert().

  • bpo-25471: Sockets returned from accept() shouldn't appear to benonblocking.

  • bpo-25319: When threading.Event is reinitialized, the underlying conditionshould use a regular lock rather than a recursive lock.

  • bpo-21112: Fix regression in unittest.expectedFailure on subclasses. Patchfrom Berker Peksag.

  • bpo-24764: cgi.FieldStorage.read_multi() now ignores the Content-Lengthheader in part headers. Patch written by Peter Landry and reviewed byPierre Quentel.

  • bpo-24913: Fix overrun error in deque.index(). Found by John Leitch andBryce Darling.

  • bpo-24774: Fix docstring in http.server.test. Patch from Chiu-Hsiang Hsu.

  • bpo-21159: Improve message inconfigparser.InterpolationMissingOptionError. Patch from Łukasz Langa.

  • bpo-20362: Honour TestCase.longMessage correctly in assertRegex. Patchfrom Ilia Kurenkov.

  • bpo-23572: Fixed functools.singledispatch on classes with falsemetaclasses. Patch by Ethan Furman.

  • asyncio: ensure_future() now accepts awaitable objects.

IDLE

  • bpo-15348: Stop the debugger engine (normally in a user process) beforeclosing the debugger window (running in the IDLE process). This preventsthe RuntimeErrors that were being caught and ignored.

  • bpo-24455: Prevent IDLE from hanging when a) closing the shell while thedebugger is active (15347); b) closing the debugger with the [X] button(15348); and c) activating the debugger when already active (24455). Thepatch by Mark Roseman does this by making two changes. 1. Suspend andresume the gui.interaction method with the tcl vwait mechanism intendedfor this purpose (instead of root.mainloop & .quit). 2. In gui.run, allowany existing interaction to terminate first.

  • Change 'The program' to 'Your program' in an IDLE 'kill program?' messageto make it clearer that the program referred to is the currently runninguser program, not IDLE itself.

  • bpo-24750: Improve the appearance of the IDLE editor window status bar.Patch by Mark Roseman.

  • bpo-25313: Change the handling of new built-in text color themes to betteraddress the compatibility problem introduced by the addition of IDLE Dark.Consistently use the revised idleConf.CurrentTheme everywhere in idlelib.

  • bpo-24782: Extension configuration is now a tab in the IDLE Preferencesdialog rather than a separate dialog. The former tabs are now a sortedlist. Patch by Mark Roseman.

  • bpo-22726: Re-activate the config dialog help button with some contentabout the other buttons and the new IDLE Dark theme.

  • bpo-24820: IDLE now has an 'IDLE Dark' built-in text color theme. It ismore or less IDLE Classic inverted, with a cobalt blue background.Strings, comments, keywords, ... are still green, red, orange, ... . Touse it with IDLEs released before November 2015, hit the 'Save as NewCustom Theme' button and enter a new name, such as 'Custom Dark'. Thecustom theme will work with any IDLE release, and can be modified.

  • bpo-25224: README.txt is now an idlelib index for IDLE developers andcurious users. The previous user content is now in the IDLE doc chapter.'IDLE' now means 'Integrated Development and Learning Environment'.

  • bpo-24820: Users can now set breakpoint colors in Settings -> CustomHighlighting. Original patch by Mark Roseman.

  • bpo-24972: Inactive selection background now matches active selectionbackground, as configured by users, on all systems. Found items are nowalways highlighted on Windows. Initial patch by Mark Roseman.

  • bpo-24570: Idle: make calltip and completion boxes appear on Macs affectedby a tk regression. Initial patch by Mark Roseman.

  • bpo-24988: Idle ScrolledList context menus (used in debugger) now work onMac Aqua. Patch by Mark Roseman.

  • bpo-24801: Make right-click for context menu work on Mac Aqua. Patch byMark Roseman.

  • bpo-25173: Associate tkinter messageboxes with a specific widget. For MacOSX, make them a 'sheet'. Patch by Mark Roseman.

  • bpo-25198: Enhance the initial html viewer now used for Idle Help.Properly indent fixed-pitch text (patch by Mark Roseman). Give codesnippet a very Sphinx-like light blueish-gray background. Re-use initialwidth and height set by users for shell and editor. When the Table ofContents (TOC) menu is used, put the section header at the top of thescreen.

  • bpo-25225: Condense and rewrite Idle doc section on text colors.

  • bpo-21995: Explain some differences between IDLE and console Python.

  • bpo-22820: Explain need forprint when running file from Idle editor.

  • bpo-25224: Doc: augment Idle feature list and no-subprocess section.

  • bpo-25219: Update doc for Idle command line options. Some were missing andnotes were not correct.

  • bpo-24861: Most of idlelib is private and subject to change. Useidleib.idle.* to start Idle. See idlelib.__init__.__doc__.

  • bpo-25199: Idle: add synchronization comments for future maintainers.

  • bpo-16893: Replace help.txt with help.html for Idle doc display. The newidlelib/help.html is rstripped Doc/build/html/library/idle.html. It looksbetter than help.txt and will better document Idle as released. Thetkinter html viewer that works for this file was written by Mark Roseman.The now unused EditorWindow.HelpDialog class and helt.txt file aredeprecated.

  • bpo-24199: Deprecate unused idlelib.idlever with possible removal in 3.6.

  • bpo-24790: Remove extraneous code (which also create 2 & 3 conflicts).

Documentation

  • bpo-22558: Add remaining doc links to source code for Python-codedmodules. Patch by Yoni Lavi.

  • bpo-12067: Rewrite Comparisons section in the Expressions chapter of thelanguage reference. Some of the details of comparing mixed types wereincorrect or ambiguous. NotImplemented is only relevant at a lower levelthan the Expressions chapter. Added details of comparing range() objects,and default behaviour and consistency suggestions for user-definedclasses. Patch from Andy Maier.

  • bpo-24952: Clarify the default size argument of stack_size() in the"threading" and "_thread" modules. Patch from Mattip.

  • bpo-23725: Overhaul tempfile docs. Note deprecated status of mktemp. Patchfrom Zbigniew Jędrzejewski-Szmek.

  • bpo-24808: Update the types of some PyTypeObject fields. Patch by JosephWeston.

  • bpo-22812: Fix unittest discovery examples. Patch from Pam McA'Nulty.

Tests

  • bpo-25449: Added tests for OrderedDict subclasses.

  • bpo-25099: Make test_compileall not fail when an entry on sys.path cannotbe written to (commonly seen in administrative installs on Windows).

  • bpo-23919: Prevents assert dialogs appearing in the test suite.

  • PCbuild\rt.bat now accepts an unlimited number of arguments to passalong to regrtest.py. Previously there was a limit of 9.

Build

  • bpo-24915: Add LLVM support for PGO builds and use the test suite togenerate the profile data. Initial patch by Alecsandru Patrascu of Intel.

  • bpo-24910: Windows MSIs now have unique display names.

  • bpo-24986: It is now possible to build Python on Windows without errorswhen external libraries are not available.

Windows

  • bpo-25450: Updates shortcuts to start Python in installation directory.

  • bpo-25164: Changes default all-users install directory to match per-userdirectory.

  • bpo-25143: Improves installer error messages for unsupported platforms.

  • bpo-25163: Display correct directory in installer when using non-defaultsettings.

  • bpo-25361: Disables use of SSE2 instructions in Windows 32-bit build

  • bpo-25089: Adds logging to installer for case where launcher is notselected on upgrade.

  • bpo-25165: Windows uninstallation should not remove launcher if otherversions remain

  • bpo-25112: py.exe launcher is missing icons

  • bpo-25102: Windows installer does not precompile for -O or -OO.

  • bpo-25081: Makes Back button in installer go back to upgrade page whenupgrading.

  • bpo-25091: Increases font size of the installer.

  • bpo-25126: Clarifies that the non-web installer will download somecomponents.

  • bpo-25213: Restores requestedExecutionLevel to manifest to disable UACvirtualization.

  • bpo-25022: Removed very outdated PC/example_nt/ directory.

Tools/Demos

  • bpo-25440: Fix output of python-config --extension-suffix.

Python 3.5.0 final

Release date: 2015-09-13

Build

  • bpo-25071: Windows installer should not require TargetDir parameter wheninstalling quietly.

Python 3.5.0 release candidate 4

Release date: 2015-09-09

Library

  • bpo-25029: Fixes MemoryError in test_strptime.

Build

  • bpo-25027: Reverts partial-static build options and adds vcruntime140.dllto Windows installation.

Python 3.5.0 release candidate 3

Release date: 2015-09-07

Core and Builtins

  • bpo-24305: Prevent import subsystem stack frames from being counted by thewarnings.warn(stacklevel=) parameter.

  • bpo-24912: Prevent __class__ assignment to immutable built-in objects.

  • bpo-24975: Fix AST compilation forPEP 448 syntax.

Library

  • bpo-24917: time_strftime() buffer over-read.

  • bpo-24748: To resolve a compatibility problem found with py2exe andpywin32, imp.load_dynamic() once again ignores previously loaded modulesto support Python modules replacing themselves with extension modules.Patch by Petr Viktorin.

  • bpo-24635: Fixed a bug in typing.py where isinstance([], typing.Iterable)would return True once, then False on subsequent calls.

  • bpo-24989: Fixed buffer overread in BytesIO.readline() if a position isset beyond size. Based on patch by John Leitch.

  • bpo-24913: Fix overrun error in deque.index(). Found by John Leitch andBryce Darling.

Python 3.5.0 release candidate 2

Release date: 2015-08-25

Core and Builtins

  • bpo-24769: Interpreter now starts properly when dynamic loading isdisabled. Patch by Petr Viktorin.

  • bpo-21167: NAN operations are now handled correctly when python iscompiled with ICC even if -fp-model strict is not specified.

  • bpo-24492: A "package" lacking a __name__ attribute when trying to performafrom..import... statement will trigger an ImportError instead ofan AttributeError.

Library

  • bpo-24847: Removes vcruntime140.dll dependency from Tcl/Tk.

  • bpo-24839: platform._syscmd_ver raises DeprecationWarning

  • bpo-24867: Fix Task.get_stack() for 'async def' coroutines

Python 3.5.0 release candidate 1

Release date: 2015-08-09

Core and Builtins

  • bpo-24667: Resize odict in all cases that the underlying dict resizes.

Library

  • bpo-24824: Signatures of codecs.encode() and codecs.decode() now arecompatible with pydoc.

  • bpo-24634: Importing uuid should not try to load libc on Windows

  • bpo-24798: _msvccompiler.py doesn't properly support manifests

  • bpo-4395: Better testing and documentation of binary operators. Patch byMartin Panter.

  • bpo-23973: Update typing.py from GitHub repo.

  • bpo-23004: mock_open() now reads binary data correctly when the type ofread_data is bytes. Initial patch by Aaron Hill.

  • bpo-23888: Handle fractional time in cookie expiry. Patch by ssh.

  • bpo-23652: Make it possible to compile the select module against the libcheaders from the Linux Standard Base, which do not include some EPOLLmacros. Patch by Matt Frank.

  • bpo-22932: Fix timezones in email.utils.formatdate. Patch from DmitryShachnev.

  • bpo-23779: imaplib raises TypeError if authenticator tries to abort. Patchfrom Craig Holmquist.

  • bpo-23319: Fix ctypes.BigEndianStructure, swap correctly bytes. Patchwritten by Matthieu Gautier.

  • bpo-23254: Document how to close the TCPServer listening socket. Patchfrom Martin Panter.

  • bpo-19450: Update Windows and OS X installer builds to use SQLite 3.8.11.

  • bpo-17527: Add PATCH to wsgiref.validator. Patch from Luca Sbardella.

  • bpo-24791: Fix grammar regression for call syntax: 'g(*a or b)'.

IDLE

  • bpo-23672: Allow Idle to edit and run files with astral chars in name.Patch by Mohd Sanad Zaki Rizvi.

  • bpo-24745: Idle editor default font. Switch from Courier toplatform-sensitive TkFixedFont. This should not affect current customizedfont selections. If there is a problem, edit$HOME/.idlerc/config-main.cfg and remove 'fontxxx' entries from[Editor Window]. Patch by Mark Roseman.

  • bpo-21192: Idle editor. When a file is run, put its name in the restartbar. Do not print false prompts. Original patch by Adnan Umer.

  • bpo-13884: Idle menus. Remove tearoff lines. Patch by Roger Serwy.

Documentation

  • bpo-24129: Clarify the reference documentation for name resolution. Thisincludes removing the assumption that readers will be familiar with thename resolution scheme Python used prior to the introduction of lexicalscoping for function namespaces. Patch by Ivan Levkivskyi.

  • bpo-20769: Improve reload() docs. Patch by Dorian Pula.

  • bpo-23589: Remove duplicate sentence from the FAQ. Patch by Yongzhi Pan.

  • bpo-24729: Correct IO tutorial to match implementation regarding encodingparameter to open function.

Tests

  • bpo-24751: When running regrtest with the-w command line option, atest run is no longer marked as a failure if all tests succeed whenre-run.

Python 3.5.0 beta 4

Release date: 2015-07-26

Core and Builtins

  • bpo-23573: Restored optimization of bytes.rfind() and bytearray.rfind()for single-byte argument on Linux.

  • bpo-24569: MakePEP 448 dictionary evaluation more consistent.

  • bpo-24583: Fix crash when set is mutated while being updated.

  • bpo-24407: Fix crash when dict is mutated while being updated.

  • bpo-24619: New approach for tokenizing async/await. As a consequence, itis now possible to have one-line 'async def foo(): await ..' functions.

  • bpo-24687: Plug refleak on SyntaxError in function parameters annotations.

  • bpo-15944: memoryview: Allow arbitrary formats when casting to bytes.Patch by Martin Panter.

Library

  • bpo-23441: rcompleter now prints a tab character instead of displayingpossible completions for an empty word. Initial patch by Martin Sekera.

  • bpo-24683: Fixed crashes in _json functions called with arguments ofinappropriate type.

  • bpo-21697: shutil.copytree() now correctly handles symbolic links thatpoint to directories. Patch by Eduardo Seabra and Thomas Kluyver.

  • bpo-14373: Fixed segmentation fault when gc.collect() is called duringconstructing lru_cache (C implementation).

  • bpo-24695: Fix a regression in traceback.print_exception(). Ifexc_traceback is None we shouldn't print a traceback header like describedin the documentation.

  • bpo-24620: Random.setstate() now validates the value of state lastelement.

  • bpo-22485: Fixed an issue that causedinspect.getsource to returnincorrect results on nested functions.

  • bpo-22153: Improve unittest docs. Patch from Martin Panter and evilzero.

  • bpo-24580: Symbolic group references to open group in re patterns now areexplicitly forbidden as well as numeric group references.

  • bpo-24206: Fixed __eq__ and __ne__ methods of inspect classes.

  • bpo-24631: Fixed regression in the timeit module with multiline setup.

  • bpo-18622: unittest.mock.mock_open().reset_mock would recurse infinitely.Patch from Nicola Palumbo and Laurent De Buyst.

  • bpo-23661: unittest.mock side_effects can now be exceptions again. Thiswas a regression vs Python 3.4. Patch from Ignacio Rossi

  • bpo-24608: chunk.Chunk.read() now always returns bytes, not str.

  • bpo-18684: Fixed reading out of the buffer in the re module.

  • bpo-24259: tarfile now raises a ReadError if an archive is truncatedinside a data segment.

  • bpo-15014: SMTP.auth() and SMTP.login() now support RFC 4954's optionalinitial-response argument to the SMTP AUTH command.

  • bpo-24669: Fix inspect.getsource() for 'async def' functions. Patch by KaiGroner.

  • bpo-24688: ast.get_docstring() for 'async def' functions.

Build

  • bpo-24603: Update Windows builds and OS X 10.5 installer to use OpenSSL1.0.2d.

Python 3.5.0 beta 3

Release date: 2015-07-05

Core and Builtins

  • bpo-24467: Fixed possible buffer over-read in bytearray. The bytearrayobject now always allocates place for trailing null byte and it's buffernow is always null-terminated.

  • Upgrade to Unicode 8.0.0.

  • bpo-24345: Add Py_tp_finalize slot for the stable ABI.

  • bpo-24400: Introduce a distinct type forPEP 492 coroutines; addtypes.CoroutineType, inspect.getcoroutinestate,inspect.getcoroutinelocals; coroutines no longer use CO_GENERATOR flag;sys.set_coroutine_wrapper works only for 'async def' coroutines;inspect.iscoroutine no longer uses collections.abc.Coroutine, it'sintended to test for pure 'async def' coroutines only; add new opcode:GET_YIELD_FROM_ITER; fix generators wrapper used in types.coroutine to beinstance of collections.abc.Generator; collections.abc.Awaitable andcollections.abc.Coroutine can no longer be used to detect generator-basedcoroutines--use inspect.isawaitable instead.

  • bpo-24450: Add gi_yieldfrom to generators and cr_await to coroutines.Contributed by Benno Leslie and Yury Selivanov.

  • bpo-19235: Add new RecursionError exception. Patch by Georg Brandl.

Library

  • bpo-21750: mock_open.read_data can now be read from each instance, as itcould in Python 3.3.

  • bpo-24552: Fix use after free in an error case of the _pickle module.

  • bpo-24514: tarfile now tolerates number fields consisting of onlywhitespace.

  • bpo-19176: Fixed doctype() related bugs in C implementation ofElementTree. A deprecation warning no longer issued by XMLParser subclasswith default doctype() method. Direct call of doctype() now issues awarning. Parser's doctype() now is not called if target's doctype() iscalled. Based on patch by Martin Panter.

  • bpo-20387: Restore semantic round-trip correctness in tokenize/untokenizefor tab-indented blocks.

  • bpo-24456: Fixed possible buffer over-read in adpcm2lin() and lin2adpcm()functions of the audioop module.

  • bpo-24336: The contextmanager decorator now works with functions withkeyword arguments called "func" and "self". Patch by Martin Panter.

  • bpo-24522: Fix possible integer overflow in json accelerator module.

  • bpo-24489: ensure a previously set C errno doesn't disturb cmath.polar().

  • bpo-24408: Fixed AttributeError in measure() and metrics() methods oftkinter.Font.

  • bpo-14373: C implementation of functools.lru_cache() now can be used withmethods.

  • bpo-24347: Set KeyError if PyDict_GetItemWithError returns NULL.

  • bpo-24348: Drop superfluous incref/decref.

  • bpo-24359: Check for changed OrderedDict size during iteration.

  • bpo-24368: Support keyword arguments in OrderedDict methods.

  • bpo-24362: Simplify the C OrderedDict fast nodes resize logic.

  • bpo-24377: Fix a ref leak in OrderedDict.__repr__.

  • bpo-24369: Defend against key-changes during iteration.

Tests

  • bpo-24373: _testmultiphase and xxlimited now use tp_traverse andtp_finalize to avoid reference leaks encountered when combining tp_deallocwith PyType_FromSpec (seebpo-16690 for details)

Documentation

  • bpo-24458: Update documentation to cover multi-phase initialization forextension modules (PEP 489). Patch by Petr Viktorin.

  • bpo-24351: Clarify what is meant by "identifier" in the context ofstring.Template instances.

Build

  • bpo-24432: Update Windows builds and OS X 10.5 installer to use OpenSSL1.0.2c.

Python 3.5.0 beta 2

Release date: 2015-05-31

Core and Builtins

  • bpo-24284: The startswith and endswith methods of the str class no longerreturn True when finding the empty string and the indexes are completelyout of range.

  • bpo-24115: Update uses of PyObject_IsTrue(), PyObject_Not(),PyObject_IsInstance(), PyObject_RichCompareBool() and _PyDict_Contains()to check for and handle errors correctly.

  • bpo-24328: Fix importing one character extension modules.

  • bpo-11205: In dictionary displays, evaluate the key before the value.

  • bpo-24285: Fixed regression that prevented importing extension modulesfrom inside packages. Patch by Petr Viktorin.

Library

  • bpo-23247: Fix a crash in the StreamWriter.reset() of CJK codecs.

  • bpo-24270: Add math.isclose() and cmath.isclose() functions as perPEP 485. Contributed by Chris Barker and Tal Einat.

  • bpo-5633: Fixed timeit when the statement is a string and the setup isnot.

  • bpo-24326: Fixed audioop.ratecv() with non-default weightB argument.Original patch by David Moore.

  • bpo-16991: Add a C implementation of OrderedDict.

  • bpo-23934: Fix inspect.signature to fail correctly for builtin typeslacking signature information. Initial patch by James Powell.

Python 3.5.0 beta 1

Release date: 2015-05-24

Core and Builtins

  • bpo-24276: Fixed optimization of property descriptor getter.

  • bpo-24268: PEP 489: Multi-phase extension module initialization. Patch byPetr Viktorin.

  • bpo-23955: Add pyvenv.cfg option to suppress registry/environment lookupfor generating sys.path on Windows.

  • bpo-24257: Fixed system error in the comparison of fakedtypes.SimpleNamespace.

  • bpo-22939: Fixed integer overflow in iterator object. Patch by ClementRouault.

  • bpo-23985: Fix a possible buffer overrun when deleting a slice from thefront of a bytearray and then appending some other bytes data.

  • bpo-24102: Fixed exception type checking in standard error handlers.

  • bpo-15027: The UTF-32 encoder is now 3x to 7x faster.

  • bpo-23290: Optimize set_merge() for cases where the target is empty.(Contributed by Serhiy Storchaka.)

  • bpo-2292: PEP 448: Additional Unpacking Generalizations.

  • bpo-24096: Make warnings.warn_explicit more robust against mutation of thewarnings.filters list.

  • bpo-23996: Avoid a crash when a delegated generator raises an unnormalizedStopIteration exception. Patch by Stefan Behnel.

  • bpo-23910: Optimize property() getter calls. Patch by Joe Jevnik.

  • bpo-23911: Move path-based importlib bootstrap code to a separate frozenmodule.

  • bpo-24192: Fix namespace package imports.

  • bpo-24022: Fix tokenizer crash when processing undecodable source code.

  • bpo-9951: Added a hex() method to bytes, bytearray, and memoryview.

  • bpo-22906: PEP 479: Change StopIteration handling inside generators.

  • bpo-24017: PEP 492: Coroutines with async and await syntax.

Library

  • bpo-14373: Added C implementation of functools.lru_cache(). Based onpatches by Matt Joiner and Alexey Kachayev.

  • bpo-24230: The tempfile module now accepts bytes for prefix, suffix anddir parameters and returns bytes in such situations (matching the osmodule APIs).

  • bpo-22189: collections.UserString now supports __getnewargs__(),__rmod__(), casefold(), format_map(), isprintable(), and maketrans().Patch by Joe Jevnik.

  • bpo-24244: Prevents termination when an invalid format string isencountered on Windows in strftime.

  • bpo-23973: PEP 484: Add the typing module.

  • bpo-23086: The collections.abc.Sequence() abstract base class addedstart andstop parameters to the index() mixin. Patch by DevinJeanpierre.

  • bpo-20035: Replaced thetkinter._fix module used for setting up theTcl/Tk environment on Windows with a private function in the_tkintermodule that makes no permanent changes to the environment.

  • bpo-24257: Fixed segmentation fault in sqlite3.Row constructor with fakedcursor type.

  • bpo-15836: assertRaises(), assertRaisesRegex(), assertWarns() andassertWarnsRegex() assertments now check the type of the first argument toprevent possible user error. Based on patch by Daniel Wagner-Hall.

  • bpo-9858: Add missing method stubs to _io.RawIOBase. Patch by LauraRupprecht.

  • bpo-22955: attrgetter, itemgetter and methodcaller objects in the operatormodule now support pickling. Added readable and evaluable repr for theseobjects. Based on patch by Josh Rosenberg.

  • bpo-22107: tempfile.gettempdir() and tempfile.mkdtemp() now try again whena directory with the chosen name already exists on Windows as well as onUnix. tempfile.mkstemp() now fails early if parent directory is not valid(not exists or is a file) on Windows.

  • bpo-23780: Improved error message in os.path.join() with single argument.

  • bpo-6598: Increased time precision and random number range inemail.utils.make_msgid() to strengthen the uniqueness of the message ID.

  • bpo-24091: Fixed various crashes in corner cases in C implementation ofElementTree.

  • bpo-21931: msilib.FCICreate() now raises TypeError in the case of a badargument instead of a ValueError with a bogus FCI error number. Patch byJeffrey Armstrong.

  • bpo-13866:quote_via argument added to urllib.parse.urlencode.

  • bpo-20098: New mangle_from policy option for email, default True forcompat32, but False for all other policies.

  • bpo-24211: The email library now supports RFC 6532: it can generateheaders using utf-8 instead of encoded words.

  • bpo-16314: Added support for the LZMA compression in distutils.

  • bpo-21804: poplib now supports RFC 6856 (UTF8).

  • bpo-18682: Optimized pprint functions for builtin scalar types.

  • bpo-22027: smtplib now supports RFC 6531 (SMTPUTF8).

  • bpo-23488: Random generator objects now consume 2x less memory on 64-bit.

  • bpo-1322: platform.dist() and platform.linux_distribution() functions arenow deprecated. Initial patch by Vajrasky Kok.

  • bpo-22486: Added the math.gcd() function. The fractions.gcd() functionnow is deprecated. Based on patch by Mark Dickinson.

  • bpo-24064: Property() docstrings are now writeable. (Patch by BerkerPeksag.)

  • bpo-22681: Added support for the koi8_t encoding.

  • bpo-22682: Added support for the kz1048 encoding.

  • bpo-23796: peek and read1 methods of BufferedReader now raise ValueErrorif they called on a closed object. Patch by John Hergenroeder.

  • bpo-21795: smtpd now supports the 8BITMIME extension whenever the newdecode_data constructor argument is set to False.

  • bpo-24155: optimize heapq.heapify() for better cache performance whenheapifying large lists.

  • bpo-21800: imaplib now supports RFC 5161 (enable), RFC 6855(utf8/internationalized email) and automatically encodes non-ASCIIusernames and passwords to UTF8.

  • bpo-20274: When calling a _sqlite.Connection, it now complains if passedany keyword arguments. Previously it silently ignored them.

  • bpo-20274: Remove ignored and erroneous "kwargs" parameters from threeMETH_VARARGS methods on _sqlite.Connection.

  • bpo-24134: assertRaises(), assertRaisesRegex(), assertWarns() andassertWarnsRegex() checks now emits a deprecation warning when callable isNone or keyword arguments except msg is passed in the context managermode.

  • bpo-24018: Add a collections.abc.Generator abstract base class.Contributed by Stefan Behnel.

  • bpo-23880: Tkinter's getint() and getdouble() now support Tcl_Obj.Tkinter's getdouble() now supports any numbers (in particular int).

  • bpo-22619: Added negative limit support in the traceback module. Based onpatch by Dmitry Kazakov.

  • bpo-24094: Fix possible crash in json.encode with poorly behaved dictsubclasses.

  • bpo-9246: On POSIX, os.getcwd() now supports paths longer than 1025 bytes.Patch written by William Orr.

  • bpo-17445: add difflib.diff_bytes() to support comparison of byte strings(fixes a regression from Python 2).

  • bpo-23917: Fall back to sequential compilation when ProcessPoolExecutordoesn't exist. Patch by Claudiu Popa.

  • bpo-23008: Fixed resolving attributes with boolean value is False inpydoc.

  • Fix asyncio issue 235: LifoQueue and PriorityQueue's put didn't incrementunfinished tasks (this bug was introduced when JoinableQueue was mergedwith Queue).

  • bpo-23908: os functions now reject paths with embedded null character onWindows instead of silently truncating them.

  • bpo-23728: binascii.crc_hqx() could return an integer outside of the range0-0xffff for empty data.

  • bpo-23887: urllib.error.HTTPError now has a proper repr() representation.Patch by Berker Peksag.

  • asyncio: New event loop APIs: set_task_factory() and get_task_factory().

  • asyncio: async() function is deprecated in favour of ensure_future().

  • bpo-24178: asyncio.Lock, Condition, Semaphore, and BoundedSemaphoresupport new 'async with' syntax. Contributed by Yury Selivanov.

  • bpo-24179: Support 'async for' for asyncio.StreamReader. Contributed byYury Selivanov.

  • bpo-24184: Add AsyncIterator and AsyncIterable ABCs to collections.abc.Contributed by Yury Selivanov.

  • bpo-22547: Implement informative __repr__ for inspect.BoundArguments.Contributed by Yury Selivanov.

  • bpo-24190: Implement inspect.BoundArgument.apply_defaults() method.Contributed by Yury Selivanov.

  • bpo-20691: Add 'follow_wrapped' argument toinspect.Signature.from_callable() and inspect.signature(). Contributed byYury Selivanov.

  • bpo-24248: Deprecate inspect.Signature.from_function() andinspect.Signature.from_builtin().

  • bpo-23898: Fix inspect.classify_class_attrs() to support attributes withoverloaded __eq__ and __bool__. Patch by Mike Bayer.

  • bpo-24298: Fix inspect.signature() to correctly unwrap wrappers aroundbound methods.

IDLE

  • bpo-23184: remove unused names and imports in idlelib. Initial patch by AlSweigart.

Tests

  • bpo-21520: test_zipfile no longer fails if the word 'bad' appears anywherein the name of the current directory.

  • bpo-9517: Move script_helper into the support package. Patch by ChristieWilson.

Documentation

  • bpo-22155: Add File Handlers subsection with createfilehandler to tkinterdoc. Remove obsolete example from FAQ. Patch by Martin Panter.

  • bpo-24029: Document the name binding behavior for submodule imports.

  • bpo-24077: Fix typo in man page for -I command option: -s, not -S

Tools/Demos

  • bpo-24000: Improved Argument Clinic's mapping of converters to legacy"format units". Updated the documentation to match.

  • bpo-24001: Argument Clinic converters now use accept={type} instead oftypes={'type'} to specify the types the converter accepts.

  • bpo-23330: h2py now supports arbitrary filenames in #include.

  • bpo-24031: make patchcheck now supports git checkouts, too.

Python 3.5.0 alpha 4

Release date: 2015-04-19

Core and Builtins

  • bpo-22980: Under Linux, GNU/KFreeBSD and the Hurd, C extensions nowinclude the architecture triplet in the extension name, to make it easy totest builds for different ABIs in the same working tree. Under OS X, theextension name now includesPEP 3149-style information.

  • bpo-22631: Added Linux-specific socket constant CAN_RAW_FD_FRAMES. Patchcourtesy of Joe Jevnik.

  • bpo-23731: ImplementPEP 488: removal of .pyo files.

  • bpo-23726: Don't enable GC for user subclasses of non-GC types that don'tadd any new fields. Patch by Eugene Toder.

  • bpo-23309: Avoid a deadlock at shutdown if a daemon thread is abortedwhile it is holding a lock to a buffered I/O object, and the main threadtries to use the same I/O object (typically stdout or stderr). A fatalerror is emitted instead.

  • bpo-22977: Fixed formatting Windows error messages on Wine. Patch byMartin Panter.

  • bpo-23466: %c, %o, %x, and %X in bytes formatting now raise TypeError onnon-integer input.

  • bpo-24044: Fix possible null pointer dereference in list.sort in out ofmemory conditions.

  • bpo-21354: PyCFunction_New function is exposed by python DLL again.

Library

  • bpo-23840: tokenize.open() now closes the temporary binary file on errorto fix a resource warning.

  • bpo-16914: new debuglevel 2 in smtplib adds timestamps to debug output.

  • bpo-7159: urllib.request now supports sending auth credentialsautomatically after the first 401. This enhancement is a superset of theenhancement frombpo-19494 and supersedes that change.

  • bpo-23703: Fix a regression in urljoin() introduced in 901e4e52b20a. Patchby Demian Brecht.

  • bpo-4254: Adds _curses.update_lines_cols(). Patch by Arnon Yaari

  • bpo-19933: Provide default argument for ndigits in round. Patch byVajrasky Kok.

  • bpo-23193: Add a numeric_owner parameter to tarfile.TarFile.extract andtarfile.TarFile.extractall. Patch by Michael Vogt and Eric Smith.

  • bpo-23342: Add a subprocess.run() function than returns a CalledProcessinstance for a more consistent API than the existing call* functions.

  • bpo-21217: inspect.getsourcelines() now tries to compute the start and endlines from the code object, fixing an issue when a lambda function is usedas decorator argument. Patch by Thomas Ballinger and Allison Kaptur.

  • bpo-24521: Fix possible integer overflows in the pickle module.

  • bpo-22931: Allow '[' and ']' in cookie values.

  • The keywords attribute of functools.partial is now always a dictionary.

  • bpo-23811: Add missing newline to the PyCompileError error message. Patchby Alex Shkop.

  • bpo-21116: Avoid blowing memory when allocating a multiprocessing sharedarray that's larger than 50% of the available RAM. Patch by MédéricBoquien.

  • bpo-22982: Improve BOM handling when seeking to multiple positions of awritable text file.

  • bpo-23464: Removed deprecated asyncio JoinableQueue.

  • bpo-23529: Limit the size of decompressed data when reading from GzipFile,BZ2File or LZMAFile. This defeats denial of service attacks usingcompressed bombs (i.e. compressed payloads which decompress to a hugesize). Patch by Martin Panter and Nikolaus Rath.

  • bpo-21859: Added Python implementation of io.FileIO.

  • bpo-23865: close() methods in multiple modules now are idempotent and morerobust at shutdown. If they need to release multiple resources, all arereleased even if errors occur.

  • bpo-23400: Raise same exception on both Python 2 and 3 if sem_open is notavailable. Patch by Davin Potts.

  • bpo-10838: The subprocess now module includes SubprocessError andTimeoutError in its list of exported names for the users wild enough tousefromsubprocessimport*.

  • bpo-23411: Added DefragResult, ParseResult, SplitResult,DefragResultBytes, ParseResultBytes, and SplitResultBytes tourllib.parse.__all__. Patch by Martin Panter.

  • bpo-23881: urllib.request.ftpwrapper constructor now closes the socket ifthe FTP connection failed to fix a ResourceWarning.

  • bpo-23853:socket.socket.sendall() does no more reset the sockettimeout each time data is sent successfully. The socket timeout is now themaximum total duration to send all data.

  • bpo-22721: An order of multiline pprint output of set or dict containingorderable and non-orderable elements no longer depends on iteration orderof set or dict.

  • bpo-15133: _tkinter.tkapp.getboolean() now supports Tcl_Obj and alwaysreturns bool. tkinter.BooleanVar now validates input values (acceptedbool, int, str, and Tcl_Obj). tkinter.BooleanVar.get() now always returnsbool.

  • bpo-10590: xml.sax.parseString() now supports string argument.

  • bpo-23338: Fixed formatting ctypes error messages on Cygwin. Patch byMakoto Kato.

  • bpo-15582: inspect.getdoc() now follows inheritance chains.

  • bpo-2175: SAX parsers now support a character stream of InputSourceobject.

  • bpo-16840: Tkinter now supports 64-bit integers added in Tcl 8.4 andarbitrary precision integers added in Tcl 8.5.

  • bpo-23834: Fix socket.sendto(), use the C Py_ssize_t type to store theresult of sendto() instead of the C int type.

  • bpo-23618:socket.socket.connect() now waits until the connectioncompletes instead of raisingInterruptedError if the connection isinterrupted by signals, signal handlers don't raise an exception and thesocket is blocking or has a timeout.socket.socket.connect() stillraiseInterruptedError for non-blocking sockets.

  • bpo-21526: Tkinter now supports new boolean type in Tcl 8.5.

  • bpo-23836: Fix the faulthandler module to handle reentrant calls to itssignal handlers.

  • bpo-23838: linecache now clears the cache and returns an empty result onMemoryError.

  • bpo-10395: Added os.path.commonpath(). Implemented in posixpath andntpath. Based on patch by Rafik Draoui.

  • bpo-23611: Serializing more "lookupable" objects (such as unbound methodsor nested classes) now are supported with pickle protocols < 4.

  • bpo-13583: sqlite3.Row now supports slice indexing.

  • bpo-18473: Fixed 2to3 and 3to2 compatible pickle mappings. Fixedambiguous reverse mappings. Added many new mappings. Import mapping isno longer applied to modules already mapped with full name mapping.

  • bpo-23485: select.select() is now retried automatically with therecomputed timeout when interrupted by a signal, except if the signalhandler raises an exception. This change is part of thePEP 475.

  • bpo-23752: When built from an existing file descriptor, io.FileIO() nowonly calls fstat() once. Before fstat() was called twice, which was notnecessary.

  • bpo-23704: collections.deque() objects now support __add__, __mul__, and__imul__().

  • bpo-23171: csv.Writer.writerow() now supports arbitrary iterables.

  • bpo-23745: The new email header parser now handles duplicate MIMEparameter names without error, similar to how get_param behaves.

  • bpo-22117: Fix os.utime(), it now rounds the timestamp towards minusinfinity (-inf) instead of rounding towards zero.

  • bpo-23310: Fix MagicMock's initializer to work with __methods__, just likeconfigure_mock(). Patch by Kasia Jachim.

Build

  • bpo-23817: FreeBSD now uses "1.0" in the SOVERSION as other operatingsystems, instead of just "1".

  • bpo-23501: Argument Clinic now generates code into separate files bydefault.

Tests

  • bpo-23799: Added test.support.start_threads() for running and cleaning upmultiple threads.

  • bpo-22390: test.regrtest now emits a warning if temporary files ordirectories are left after running a test.

Tools/Demos

  • bpo-18128: pygettext now uses standard +NNNN format in thePOT-Creation-Date header.

  • bpo-23935: Argument Clinic's understanding of format units acceptingbytes, bytearrays, and buffers is now consistent with both thedocumentation and the implementation.

  • bpo-23944: Argument Clinic now wraps long impl prototypes at column 78.

  • bpo-20586: Argument Clinic now ensures that functions without docstringshave signatures.

  • bpo-23492: Argument Clinic now generates argument parsing code withPyArg_Parse instead of PyArg_ParseTuple if possible.

  • bpo-23500: Argument Clinic is now smarter about generating the "#ifndef"(empty) definition of the methoddef macro: it's only generated once, evenif Argument Clinic processes the same symbol multiple times, and it'semitted at the end of all processing rather than immediately after thefirst use.

C API

  • bpo-23998: PyImport_ReInitLock() now checks for lock allocation error

Python 3.5.0 alpha 3

Release date: 2015-03-28

Core and Builtins

  • bpo-23573: Increased performance of string search operations (str.find,str.index, str.count, the in operator, str.split, str.partition) witharguments of different kinds (UCS1, UCS2, UCS4).

  • bpo-23753: Python doesn't support anymore platforms without stat() orfstat(), these functions are always required.

  • bpo-23681: The -b option now affects comparisons of bytes with int.

  • bpo-23632: Memoryviews now allow tuple indexing (including formulti-dimensional memoryviews).

  • bpo-23192: Fixed generator lambdas. Patch by Bruno Cauet.

  • bpo-23629: Fix the default __sizeof__ implementation for variable-sizedobjects.

Library

  • bpo-14260: The groupindex attribute of regular expression pattern objectnow is non-modifiable mapping.

  • bpo-23792: Ignore KeyboardInterrupt when the pydoc pager is active. Thismimics the behavior of the standard unix pagers, and prevents pipepagerfrom shutting down while the pager itself is still running.

  • bpo-23775: pprint() of OrderedDict now outputs the same representation asrepr().

  • bpo-23765: Removed IsBadStringPtr calls in ctypes

  • bpo-22364: Improved some re error messages using regex for hints.

  • bpo-23742: ntpath.expandvars() no longer loses unbalanced single quotes.

  • bpo-21717: The zipfile.ZipFile.open function now supports 'x' (exclusivecreation) mode.

  • bpo-21802: The reader in BufferedRWPair now is closed even when closingwriter failed in BufferedRWPair.close().

  • bpo-23622: Unknown escapes in regular expressions that consist of'\'and ASCII letter now raise a deprecation warning and will be forbidden inPython 3.6.

  • bpo-23671: string.Template now allows specifying the "self" parameter as akeyword argument. string.Formatter now allows specifying the "self" andthe "format_string" parameters as keyword arguments.

  • bpo-23502: The pprint module now supports mapping proxies.

  • bpo-17530: pprint now wraps long bytes objects and bytearrays.

  • bpo-22687: Fixed some corner cases in breaking words in tetxtwrap. Got ridof quadratic complexity in breaking long words.

  • bpo-4727: The copy module now uses pickle protocol 4 (PEP 3154) andsupports copying of instances of classes whose __new__ method takeskeyword-only arguments.

  • bpo-23491: Added a zipapp module to support creating executable zip filearchives of Python code. Registered ".pyz" and ".pyzw" extensions onWindows for these archives (PEP 441).

  • bpo-23657: Avoid explicit checks for str in zipapp, adding support forpathlib.Path objects as arguments.

  • bpo-23688: Added support of arbitrary bytes-like objects and avoidedunnecessary copying of memoryview in gzip.GzipFile.write(). Original patchby Wolfgang Maier.

  • bpo-23252: Added support for writing ZIP files to unseekable streams.

  • bpo-23647: Increase imaplib's MAXLINE to accommodate modern mailbox sizes.

  • bpo-23539: If body is None, http.client.HTTPConnection.request now setsContent-Length to 0 for PUT, POST, and PATCH headers to avoid 411 errorsfrom some web servers.

  • bpo-22351: The nntplib.NNTP constructor no longer leaves the connectionand socket open until the garbage collector cleans them up. Patch byMartin Panter.

  • bpo-23704: collections.deque() objects now support methods for index(),insert(), and copy(). This allows deques to be registered as aMutableSequence and it improves their substitutability for lists.

  • bpo-23715:signal.sigwaitinfo() andsignal.sigtimedwait() arenow retried when interrupted by a signal not in thesigset parameter, ifthe signal handler does not raise an exception. signal.sigtimedwait()recomputes the timeout with a monotonic clock when it is retried.

  • bpo-23001: Few functions in modules mmap, ossaudiodev, socket, ssl, andcodecs, that accepted only read-only bytes-like object now accept writablebytes-like object too.

  • bpo-23646: If time.sleep() is interrupted by a signal, the sleep is nowretried with the recomputed delay, except if the signal handler raises anexception (PEP 475).

  • bpo-23136: _strptime now uniformly handles all days in week 0, includingDec 30 of previous year. Based on patch by Jim Carroll.

  • bpo-23700: Iterator of NamedTemporaryFile now keeps a reference toNamedTemporaryFile instance. Patch by Bohuslav Kabrda.

  • bpo-22903: The fake test case created by unittest.loader when it failsimporting a test module is now picklable.

  • bpo-22181: On Linux, os.urandom() now uses the new getrandom() syscall ifavailable, syscall introduced in the Linux kernel 3.17. It is morereliable and more secure, because it avoids the need of a file descriptorand waits until the kernel has enough entropy.

  • bpo-2211: Updated the implementation of the http.cookies.Morsel class.Setting attributes key, value and coded_value directly now is deprecated.update() and setdefault() now transform and check keys. Comparing forequality now takes into account attributes key, value and coded_value.copy() now returns a Morsel, not a dict. repr() now contains allattributes. Optimized checking keys and quoting values. Added new tests.Original patch by Demian Brecht.

  • bpo-18983: Allow selection of output units in timeit. Patch by JulianGindi.

  • bpo-23631: Fix traceback.format_list when a traceback has been mutated.

  • bpo-23568: Add rdivmod support to MagicMock() objects. Patch by HåkanLövdahl.

  • bpo-2052: Add charset parameter to HtmlDiff.make_file().

  • bpo-23668: Support os.truncate and os.ftruncate on Windows.

  • bpo-23138: Fixed parsing cookies with absent keys or values in cookiejar.Patch by Demian Brecht.

  • bpo-23051: multiprocessing.Pool methods imap() and imap_unordered() nowhandle exceptions raised by an iterator. Patch by Alon Diamant and DavinPotts.

  • bpo-23581: Add matmul support to MagicMock. Patch by Håkan Lövdahl.

  • bpo-23566: enable(), register(), dump_traceback() anddump_traceback_later() functions of faulthandler now accept filedescriptors. Patch by Wei Wu.

  • bpo-22928: Disabled HTTP header injections in http.client. Original patchby Demian Brecht.

  • bpo-23615: Modules bz2, tarfile and tokenize now can be reloaded withimp.reload(). Patch by Thomas Kluyver.

  • bpo-23605: os.walk() now calls os.scandir() instead of os.listdir(). Theusage of os.scandir() reduces the number of calls to os.stat(). Initialpatch written by Ben Hoyt.

Build

  • bpo-23585: make patchcheck will ensure the interpreter is built.

Tests

  • bpo-23583: Added tests for standard IO streams in IDLE.

  • bpo-22289: Prevent test_urllib2net failures due to ftp connection timeout.

Tools/Demos

  • bpo-22826: The result of open() in Tools/freeze/bkfile.py is now bettercompatible with regular files (in particular it now supports the contextmanagement protocol).

Python 3.5.0 alpha 2

Release date: 2015-03-09

Core and Builtins

  • bpo-23571: PyObject_Call() and PyCFunction_Call() now raise a SystemErrorif a function returns a result and raises an exception. The SystemError ischained to the previous exception.

Library

  • bpo-22524: New os.scandir() function, part of thePEP 471:"os.scandir() function -- a better and faster directory iterator". Patchwritten by Ben Hoyt.

  • bpo-23103: Reduced the memory consumption of IPv4Address and IPv6Address.

  • bpo-21793: BaseHTTPRequestHandler again logs response code as numeric, notas stringified enum. Patch by Demian Brecht.

  • bpo-23476: In the ssl module, enable OpenSSL's X509_V_FLAG_TRUSTED_FIRSTflag on certificate stores when it is available.

  • bpo-23576: Avoid stalling in SSL reads when EOF has been reached in theSSL layer but the underlying connection hasn't been closed.

  • bpo-23504: Added an __all__ to the types module.

  • bpo-23563: Optimized utility functions in urllib.parse.

  • bpo-7830: Flatten nested functools.partial.

  • bpo-20204: Added the __module__ attribute to _tkinter classes.

  • bpo-19980: Improved help() for non-recognized strings. help('') now showsthe help on str. help('help') now shows the help on help(). Originalpatch by Mark Lawrence.

  • bpo-23521: Corrected pure python implementation of timedelta division.Eliminated OverflowError fromtimedelta*float for some floats;Corrected rounding in timedelta true division.

  • bpo-21619: Popen objects no longer leave a zombie after exit in the withstatement if the pipe was broken. Patch by Martin Panter.

  • bpo-22936: Make it possible to show local variables in tracebacks for boththe traceback module and unittest.

  • bpo-15955: Add an option to limit the output size in bz2.decompress().Patch by Nikolaus Rath.

  • bpo-6639: Module-level turtle functions no longer raise TclError afterclosing the window.

  • bpo-814253: Group references and conditional group references now work inlookbehind assertions in regular expressions. (See also:bpo-9179)

  • bpo-23215: Multibyte codecs with custom error handlers that ignores errorsconsumed too much memory and raised SystemError or MemoryError. Originalpatch by Aleksi Torhamo.

  • bpo-5700: io.FileIO() called flush() after closing the file. flush() wasnot called in close() if closefd=False.

  • bpo-23374: Fixed pydoc failure with non-ASCII files when stdout encodingdiffers from file system encoding (e.g. on Mac OS).

  • bpo-23481: Remove RC4 from the SSL module's default cipher list.

  • bpo-21548: Fix pydoc.synopsis() and pydoc.apropos() on modules with emptydocstrings.

  • bpo-22885: Fixed arbitrary code execution vulnerability in the dbm.dumbmodule. Original patch by Claudiu Popa.

  • bpo-23239: ssl.match_hostname() now supports matching of IP addresses.

  • bpo-23146: Fix mishandling of absolute Windows paths with forward slashesin pathlib.

  • bpo-23096: Pickle representation of floats with protocol 0 now is the samefor both Python and C implementations.

  • bpo-19105: pprint now more efficiently uses free space at the right.

  • bpo-14910: Add allow_abbrev parameter to argparse.ArgumentParser. Patch byJonathan Paugh, Steven Bethard, paul j3 and Daniel Eriksson.

  • bpo-21717: tarfile.open() now supports 'x' (exclusive creation) mode.

  • bpo-23344: marshal.dumps() is now 20-25% faster on average.

  • bpo-20416: marshal.dumps() with protocols 3 and 4 is now 40-50% faster onaverage.

  • bpo-23421: Fixed compression in tarfile CLI. Patch by wdv4758h.

  • bpo-23367: Fix possible overflows in the unicodedata module.

  • bpo-23361: Fix possible overflow in Windows subprocess creation code.

  • logging.handlers.QueueListener now takes a respect_handler_level keywordargument which, if set to True, will pass messages to handlers takinghandler levels into account.

  • bpo-19705: turtledemo now has a visual sorting algorithm demo. Originalpatch from Jason Yeo.

  • bpo-23801: Fix issue where cgi.FieldStorage did not always ignore theentire preamble to a multipart body.

Build

  • bpo-23445: pydebug builds now use "gcc -Og" where possible, to make theresulting executable faster.

  • bpo-23686: Update OS X 10.5 installer build to use OpenSSL 1.0.2a.

C API

  • bpo-20204: Deprecation warning is now raised for builtin types without the__module__ attribute.

Windows

  • bpo-23465: ImplementPEP 486 - Make the Python Launcher aware ofvirtual environments. Patch by Paul Moore.

  • bpo-23437: Make user scripts directory versioned on Windows. Patch by PaulMoore.

Python 3.5.0 alpha 1

Release date: 2015-02-08

Core and Builtins

  • bpo-23285: PEP 475 - EINTR handling.

  • bpo-22735: Fix many edge cases (including crashes) involving custom mro()implementations.

  • bpo-22896: Avoid using PyObject_AsCharBuffer(), PyObject_AsReadBuffer()and PyObject_AsWriteBuffer().

  • bpo-21295: Revert some changes (bpo-16795) to AST line numbers andcolumn offsets that constituted a regression.

  • bpo-22986: Allow changing an object's __class__ between a dynamic type andstatic type in some cases.

  • bpo-15859: PyUnicode_EncodeFSDefault(), PyUnicode_EncodeMBCS() andPyUnicode_EncodeCodePage() now raise an exception if the object is not aUnicode object. For PyUnicode_EncodeFSDefault(), it was already the caseon platforms other than Windows. Patch written by Campbell Barton.

  • bpo-21408: The default __ne__() now returns NotImplemented if __eq__()returned NotImplemented. Original patch by Martin Panter.

  • bpo-23321: Fixed a crash in str.decode() when error handler returnedreplacement string longer than malformed input data.

  • bpo-22286: The "backslashreplace" error handlers now works with decodingand translating.

  • bpo-23253: Delay-load ShellExecute[AW] in os.startfile for reduced startupoverhead on Windows.

  • bpo-22038: pyatomic.h now uses stdatomic.h or GCC built-in functions foratomic memory access if available. Patch written by Vitor de Lima andGustavo Temple.

  • bpo-20284: %-interpolation (aka printf) formatting added for bytes andbytearray.

  • bpo-23048: Fix jumping out of an infinite while loop in the pdb.

  • bpo-20335: bytes constructor now raises TypeError when encoding or errorsis specified with non-string argument. Based on patch by Renaud Blanch.

  • bpo-22834: If the current working directory ends up being set to anon-existent directory then import will no longer raise FileNotFoundError.

  • bpo-22869: Move the interpreter startup & shutdown code to a new dedicatedpylifecycle.c module

  • bpo-22847: Improve method cache efficiency.

  • bpo-22335: Fix crash when trying to enlarge a bytearray to 0x7fffffffbytes on a 32-bit platform.

  • bpo-22653: Fix an assertion failure in debug mode when doing a reentrantdict insertion in debug mode.

  • bpo-22643: Fix integer overflow in Unicode case operations (upper, lower,title, swapcase, casefold).

  • bpo-17636: Circular imports involving relative imports are now supported.

  • bpo-22604: Fix assertion error in debug mode when dividing a complexnumber by (nan+0j).

  • bpo-21052: Do not raise ImportWarning when sys.path_hooks or sys.meta_pathare set to None.

  • bpo-16518: Use 'bytes-like object required' in error messages thatpreviously used the far more cryptic "'x' does not support the bufferprotocol.

  • bpo-22470: Fixed integer overflow issues in "backslashreplace","xmlcharrefreplace", and "surrogatepass" error handlers.

  • bpo-22540: speed upPyObject_IsInstance andPyObject_IsSubclass inthe common case that the second argument has metaclasstype.

  • bpo-18711: Add a newPyErr_FormatV function, similar toPyErr_Format but accepting ava_list argument.

  • bpo-22520: Fix overflow checking when generating the repr of a unicodeobject.

  • bpo-22519: Fix overflow checking in PyBytes_Repr.

  • bpo-22518: Fix integer overflow issues in latin-1 encoding.

  • bpo-16324: _charset parameter of MIMEText now also acceptsemail.charset.Charset instances. Initial patch by Claude Paroz.

  • bpo-1764286: Fix inspect.getsource() to support decorated functions. Patchby Claudiu Popa.

  • bpo-18554: os.__all__ includes posix functions.

  • bpo-21391: Use os.path.abspath in the shutil module.

  • bpo-11471: avoid generating a JUMP_FORWARD instruction at the end of anif-block if there is no else-clause. Original patch by Eugene Toder.

  • bpo-22215: Now ValueError is raised instead of TypeError when str or bytesargument contains not permitted null character or byte.

  • bpo-22258: Fix the internal function set_inheritable() on Illumos. Thisplatform exposes the functionioctl(FIOCLEX), but calling it failswith errno is ENOTTY: "Inappropriate ioctl for device". set_inheritable()now falls back to the slowerfcntl() (F_GETFD and thenF_SETFD).

  • bpo-21389: Displaying the __qualname__ of the underlying function in therepr of a bound method.

  • bpo-22206: Using pthread, PyThread_create_key() now sets errno to ENOMEMand returns -1 (error) on integer overflow.

  • bpo-20184: Argument Clinic based signature introspection added for 30 ofthe builtin functions.

  • bpo-22116: C functions and methods (of the 'builtin_function_or_method'type) can now be weakref'ed. Patch by Wei Wu.

  • bpo-22077: Improve index error messages for bytearrays, bytes, lists, andtuples by adding 'or slices'. Added ', not <typename>' for bytearrays.Original patch by Claudiu Popa.

  • bpo-20179: Apply Argument Clinic to bytes and bytearray. Patch by TalEinat.

  • bpo-22082: Clear interned strings in slotdefs.

  • Upgrade Unicode database to Unicode 7.0.0.

  • bpo-21897: Fix a crash with the f_locals attribute with closure variableswhen frame.clear() has been called.

  • bpo-21205: Add a new__qualname__ attribute to generator, thequalified name, and use it in the representation of a generator(repr(gen)). The default name of the generator (__name__attribute) is now get from the function instead of the code. Usegen.gi_code.co_name to get the name of the code.

  • bpo-21669: With the aid of heuristics in SyntaxError.__init__, the parsernow attempts to generate more meaningful (or at least more search enginefriendly) error messages when "exec" and "print" are used as statements.

  • bpo-21642: In the conditional if-else expression, allow an integer writtenwith no space between itself and theelse keyword (e.g.Trueif42elseFalse) to be valid syntax.

  • bpo-21523: Fix over-pessimistic computation of the stack effect of someopcodes in the compiler. This also fixes a quadratic compilation timeissue noticeable when compiling code with a large number of "and" and "or"operators.

  • bpo-21418: Fix a crash in the builtin function super() when called withoutargument and without current frame (ex: embedded Python).

  • bpo-21425: Fix flushing of standard streams in the interactiveinterpreter.

  • bpo-21435: In rare cases, when running finalizers on objects in cyclictrash a bad pointer dereference could occur due to a subtle flaw ininternal iteration logic.

  • bpo-21377: PyBytes_Concat() now tries to concatenate in-place when thefirst argument has a reference count of 1. Patch by Nikolaus Rath.

  • bpo-20355: -W command line options now have higher priority than thePYTHONWARNINGS environment variable. Patch by Arfrever.

  • bpo-21274: Define PATH_MAX for GNU/Hurd in Python/pythonrun.c.

  • bpo-20904: Support setting FPU precision on m68k.

  • bpo-21209: Fix sending tuples to custom generator objects with the yieldfrom syntax.

  • bpo-21193: pow(a, b, c) now raises ValueError rather than TypeError when bis negative. Patch by Josh Rosenberg.

  • bpo-21176: PEP 465: Add the '@' operator for matrix multiplication.

  • bpo-21134: Fix segfault when str is called on an uninitializedUnicodeEncodeError, UnicodeDecodeError, or UnicodeTranslateError object.

  • bpo-19537: Fix PyUnicode_DATA() alignment under m68k. Patch by AndreasSchwab.

  • bpo-20929: Add a type cast to avoid shifting a negative number.

  • bpo-20731: Properly position in source code files even if they are openedin text mode. Patch by Serhiy Storchaka.

  • bpo-20637: Key-sharing now also works for instance dictionaries ofsubclasses. Patch by Peter Ingebretson.

  • bpo-8297: Attributes missing from modules now include the module name inthe error text. Original patch by ysj.ray.

  • bpo-19995: %c, %o, %x, and %X now raise TypeError on non-integer input.

  • bpo-19655: The ASDL parser - used by the build process to generate codefor managing the Python AST in C - was rewritten. The new parser is selfcontained and does not require to carry long the spark.py parser-generatorlibrary; spark.py was removed from the source base.

  • bpo-12546: Allow\x00 to be used as a fill character when using str,int, float, and complex __format__ methods.

  • bpo-20480: Add ipaddress.reverse_pointer. Patch by Leon Weber.

  • bpo-13598: Modify string.Formatter to support auto-numbering ofreplacement fields. It now matches the behavior of str.format() in thisregard. Patches by Phil Elson and Ramchandra Apte.

  • bpo-8931: Make alternate formatting ('#') for type 'c' raise an exception.In versions prior to 3.5, '#' with 'c' had no effect. Now specifying it isan error. Patch by Torsten Landschoff.

  • bpo-23165: Perform overflow checks before allocating memory in the_Py_char2wchar function.

Library

  • bpo-23399: pyvenv creates relative symlinks where possible.

  • bpo-20289: cgi.FieldStorage() now supports the context managementprotocol.

  • bpo-13128: Print response headers for CONNECT requests when debuglevel >0. Patch by Demian Brecht.

  • bpo-15381: Optimized io.BytesIO to make less allocations and copyings.

  • bpo-22818: Splitting on a pattern that could match an empty string nowraises a warning. Patterns that can only match empty strings are nowrejected.

  • bpo-23099: Closing io.BytesIO with exported buffer is rejected now toprevent corrupting exported buffer.

  • bpo-23326: Removed __ne__ implementations. Since fixing default __ne__implementation inbpo-21408 they are redundant.

  • bpo-23363: Fix possible overflow in itertools.permutations.

  • bpo-23364: Fix possible overflow in itertools.product.

  • bpo-23366: Fixed possible integer overflow in itertools.combinations.

  • bpo-23369: Fixed possible integer overflow in_json.encode_basestring_ascii.

  • bpo-23353: Fix the exception handling of generators inPyEval_EvalFrameEx(). At entry, save or swap the exception state even ifPyEval_EvalFrameEx() is called with throwflag=0. At exit, the exceptionstate is now always restored or swapped, not only if why is WHY_YIELD orWHY_RETURN. Patch co-written with Antoine Pitrou.

  • bpo-14099: Restored support of writing ZIP files to tellable butnon-seekable streams.

  • bpo-14099: Writing to ZipFile and reading multiple ZipExtFiles isthreadsafe now.

  • bpo-19361: JSON decoder now raises JSONDecodeError instead of ValueError.

  • bpo-18518: timeit now rejects statements which can't be compiled outside afunction or a loop (e.g. "return" or "break").

  • bpo-23094: Fixed readline with frames in Python implementation of pickle.

  • bpo-23268: Fixed bugs in the comparison of ipaddress classes.

  • bpo-21408: Removed incorrect implementations of __ne__() which didn'treturned NotImplemented if __eq__() returned NotImplemented. The default__ne__() now works correctly.

  • bpo-19996:email.feedparser.FeedParser now handles (malformed)headers with no key rather than assuming the body has started.

  • bpo-20188: Support Application-Layer Protocol Negotiation (ALPN) in thessl module.

  • bpo-23133: Pickling of ipaddress objects now produces more compact andportable representation.

  • bpo-23248: Update ssl error codes from latest OpenSSL git master.

  • bpo-23266: Much faster implementation of ipaddress.collapse_addresses()when there are many non-consecutive addresses.

  • bpo-23098: 64-bit dev_t is now supported in the os module.

  • bpo-21817: When an exception is raised in a task submitted to aProcessPoolExecutor, the remote traceback is now displayed in the parentprocess. Patch by Claudiu Popa.

  • bpo-15955: Add an option to limit output size when decompressing LZMAdata. Patch by Nikolaus Rath and Martin Panter.

  • bpo-23250: In the http.cookies module, capitalize "HttpOnly" and "Secure"as they are written in the standard.

  • bpo-23063: In the distutils' check command, fix parsing of reST with codeor code-block directives.

  • bpo-23209: selectors.BaseSelector.get_key() now raises a RuntimeError ifthe selector is closed. And selectors.BaseSelector.close() now clears itsinternal reference to the selector mapping to break a reference cycle.Initial patch written by Martin Richard. (See also:bpo-23225)

  • bpo-17911: Provide a way to seed the linecache for a PEP-302 modulewithout actually loading the code.

  • bpo-17911: Provide a new object API for traceback, including the abilityto not lookup lines at all until the traceback is actually rendered,without any trace of the original objects being kept alive.

  • bpo-19777: Provide a home() classmethod on Path objects. Contributed byVictor Salgado and Mayank Tripathi.

  • bpo-23206: Makejson.dumps(...,ensure_ascii=False) as fast as thedefault case ofensure_ascii=True. Patch by Naoki Inada.

  • bpo-23185: Add math.inf and math.nan constants.

  • bpo-23186: Add ssl.SSLObject.shared_ciphers() andssl.SSLSocket.shared_ciphers() to fetch the client's list ciphers sent athandshake.

  • bpo-23143: Remove compatibility with OpenSSLs older than 0.9.8.

  • bpo-23132: Improve performance and introspection support of comparisonmethods created by functool.total_ordering.

  • bpo-19776: Add an expanduser() method on Path objects.

  • bpo-23112: Fix SimpleHTTPServer to correctly carry the query string andfragment when it redirects to add a trailing slash.

  • bpo-21793: Added http.HTTPStatus enums (i.e. HTTPStatus.OK,HTTPStatus.NOT_FOUND). Patch by Demian Brecht.

  • bpo-23093: In the io, module allow more operations to work on detachedstreams.

  • bpo-23111: In the ftplib, make ssl.PROTOCOL_SSLv23 the default protocolversion.

  • bpo-22585: On OpenBSD 5.6 and newer, os.urandom() now calls getentropy(),instead of reading /dev/urandom, to get pseudo-random bytes.

  • bpo-19104: pprint now produces evaluable output for wrapped strings.

  • bpo-23071: Added missing names to codecs.__all__. Patch by Martin Panter.

  • bpo-22783: Pickling now uses the NEWOBJ opcode instead of the NEWOBJ_EXopcode if possible.

  • bpo-15513: Added a __sizeof__ implementation for pickle classes.

  • bpo-19858: pickletools.optimize() now aware of the MEMOIZE opcode, canproduce more compact result and no longer produces invalid output if inputdata contains MEMOIZE opcodes together with PUT or BINPUT opcodes.

  • bpo-22095: Fixed HTTPConnection.set_tunnel with default port. The portvalue in the host header was set to "None". Patch by Demian Brecht.

  • bpo-23016: A warning no longer produces an AttributeError when the programis run with pythonw.exe.

  • bpo-21775: shutil.copytree(): fix crash when copying to VFAT. An exceptionhandler assumed that OSError objects always have a 'winerror' attribute.That is not the case, so the exception handler itself raisedAttributeError when run on Linux (and, presumably, any other non-WindowsOS). Patch by Greg Ward.

  • bpo-1218234: Fix inspect.getsource() to load updated source of reloadedmodule. Initial patch by Berker Peksag.

  • bpo-21740: Support wrapped callables in doctest. Patch by Claudiu Popa.

  • bpo-23009: Make sure selectors.EpollSelector.select() works when no FD isregistered.

  • bpo-22959: In the constructor of http.client.HTTPSConnection, prefer thecontext's check_hostname attribute over thecheck_hostname parameter.

  • bpo-22696: Add functionsys.is_finalizing() to know aboutinterpreter shutdown.

  • bpo-16043: Add a default limit for the amount of dataxmlrpclib.gzip_decode will return. This resolvesCVE 2013-1753.

  • bpo-14099: ZipFile.open() no longer reopen the underlying file. Objectsreturned by ZipFile.open() can now operate independently of the ZipFileeven if the ZipFile was created by passing in a file-like object as thefirst argument to the constructor.

  • bpo-22966: Fix __pycache__ pyc file name clobber when pyc_compile is askedto compile a source file containing multiple dots in the source file name.

  • bpo-21971: Update turtledemo doc and add module to the index.

  • bpo-21032: Fixed socket leak if HTTPConnection.getresponse() fails.Original patch by Martin Panter.

  • bpo-22407: Deprecated the use of re.LOCALE flag with str patterns orre.ASCII. It was newer worked.

  • bpo-22902: The "ip" command is now used on Linux to determine MAC addressin uuid.getnode(). Pach by Bruno Cauet.

  • bpo-22960: Add a context argument to xmlrpclib.ServerProxy constructor.

  • bpo-22389: Add contextlib.redirect_stderr().

  • bpo-21356: Make ssl.RAND_egd() optional to support LibreSSL. Theavailability of the function is checked during the compilation. Patchwritten by Bernard Spil.

  • bpo-22915: SAX parser now supports files opened with file descriptor orbytes path.

  • bpo-22609: Constructors and update methods of mapping classes in thecollections module now accept the self keyword argument.

  • bpo-22940: Add readline.append_history_file.

  • bpo-19676: Added the "namereplace" error handler.

  • bpo-22788: Addcontext parameter to logging.handlers.HTTPHandler.

  • bpo-22921: Allow SSLContext to take thehostname parameter even ifOpenSSL doesn't support SNI.

  • bpo-22894: TestCase.subTest() would cause the test suite to be stoppedwhen in failfast mode, even in the absence of failures.

  • bpo-22796: HTTP cookie parsing is now stricter, in order to protectagainst potential injection attacks.

  • bpo-22370: Windows detection in pathlib is now more robust.

  • bpo-22841: Reject coroutines in asyncio add_signal_handler(). Patch byLudovic.Gasc.

  • bpo-19494: Added urllib.request.HTTPBasicPriorAuthHandler. Patch by MatejCepl.

  • bpo-22578: Added attributes to the re.error class.

  • bpo-22849: Fix possible double free in the io.TextIOWrapper constructor.

  • bpo-12728: Different Unicode characters having the same uppercase butdifferent lowercase are now matched in case-insensitive regularexpressions.

  • bpo-22821: Fixed fcntl() with integer argument on 64-bit big-endianplatforms.

  • bpo-21650: Add an--sort-keys option tojson.tool CLI.

  • bpo-22824: Updated reprlib output format for sets to use set literals.Patch contributed by Berker Peksag.

  • bpo-22824: Updated reprlib output format for arrays to display emptyarrays without an unnecessary empty list. Suggested by Serhiy Storchaka.

  • bpo-22406: Fixed the uu_codec codec incorrectly ported to 3.x. Based onpatch by Martin Panter.

  • bpo-17293: uuid.getnode() now determines MAC address on AIX using netstat.Based on patch by Aivars Kalvāns.

  • bpo-22769: Fixed ttk.Treeview.tag_has() when called without arguments.

  • bpo-22417: Verify certificates by default in httplib (PEP 476).

  • bpo-22775: Fixed unpickling of http.cookies.SimpleCookie with protocol 2and above. Patch by Tim Graham.

  • bpo-22776: Brought excluded code into the scope of a try block inSysLogHandler.emit().

  • bpo-22665: Add missing get_terminal_size and SameFileError toshutil.__all__.

  • bpo-6623: Remove deprecated Netrc class in the ftplib module. Patch byMatt Chaput.

  • bpo-17381: Fixed handling of case-insensitive ranges in regularexpressions.

  • bpo-22410: Module level functions in the re module now cache compiledlocale-dependent regular expressions taking into account the locale.

  • bpo-22759: Query methods on pathlib.Path() (exists(), is_dir(), etc.) nowreturn False when the underlying stat call raises NotADirectoryError.

  • bpo-8876: distutils now falls back to copying files when hard linkingdoesn't work. This allows use with special filesystems such as VirtualBoxshared folders.

  • bpo-22217: Implemented reprs of classes in the zipfile module.

  • bpo-22457: Honour load_tests in the start_dir of discovery.

  • bpo-18216: gettext now raises an error when a .mo file has an unsupportedmajor version number. Patch by Aaron Hill.

  • bpo-13918: Provide a locale.delocalize() function which can removelocale-specific number formatting from a string representing a number,without then converting it to a specific type. Patch by Cédric Krier.

  • bpo-22676: Make the pickling of global objects which don't have a__module__ attribute less slow.

  • bpo-18853: Fixed ResourceWarning in shlex.__nain__.

  • bpo-9351: Defaults set with set_defaults on an argparse subparser are nolonger ignored when also set on the parent parser.

  • bpo-7559: unittest test loading ImportErrors are reported as import errorswith their import exception rather than as attribute errors after theimport has already failed.

  • bpo-19746: Make it possible to examine the errors from unittest discoverywithout executing the test suite. The newerrors attribute onTestLoader exposes these non-fatal errors encountered duringdiscovery.

  • bpo-21991: Make email.headerregistry's header 'params' attributes beread-only (MappingProxyType). Previously the dictionary was modifiablebut a new one was created on each access of the attribute.

  • bpo-22638: SSLv3 is now disabled throughout the standard library. It canstill be enabled by instantiating a SSLContext manually.

  • bpo-22641: In asyncio, the default SSL context for client connections isnow created using ssl.create_default_context(), for stronger security.

  • bpo-17401: Include closefd in io.FileIO repr.

  • bpo-21338: Add silent mode for compileall. quiet parameters ofcompile_{dir, file, path} functions now have a multilevel value. Also, -qoption of the CLI now have a multilevel value. Patch by Thomas Kluyver.

  • bpo-20152: Convert the array and cmath modules to Argument Clinic.

  • bpo-18643: Add socket.socketpair() on Windows.

  • bpo-22435: Fix a file descriptor leak when socketserver bind fails.

  • bpo-13096: Fixed segfault in CTypes POINTER handling of large values.

  • bpo-11694: Raise ConversionError in xdrlib as documented. Patch by FilipGruszczyński and Claudiu Popa.

  • bpo-19380: Optimized parsing of regular expressions.

  • bpo-1519638: Now unmatched groups are replaced with empty strings inre.sub() and re.subn().

  • bpo-18615: sndhdr.what/whathdr now return a namedtuple.

  • bpo-22462: Fix pyexpat's creation of a dummy frame to make it appear inexception tracebacks.

  • bpo-21965: Add support for in-memory SSL to the ssl module. Patch byGeert Jansen.

  • bpo-21173: Fix len() on a WeakKeyDictionary when .clear() was called withan iterator alive.

  • bpo-11866: Eliminated race condition in the computation of names for newthreads.

  • bpo-21905: Avoid RuntimeError in pickle.whichmodule() when sys.modules ismutated while iterating. Patch by Olivier Grisel.

  • bpo-11271: concurrent.futures.Executor.map() now takes achunksizeargument to allow batching of tasks in child processes and improveperformance of ProcessPoolExecutor. Patch by Dan O'Reilly.

  • bpo-21883: os.path.join() and os.path.relpath() now raise a TypeError withmore helpful error message for unsupported or mismatched types ofarguments.

  • bpo-22219: The zipfile module CLI now adds entries for directories(including empty directories) in ZIP file.

  • bpo-22449: In the ssl.SSLContext.load_default_certs, consult theenvironmental variables SSL_CERT_DIR and SSL_CERT_FILE on Windows.

  • bpo-22508: The email.__version__ variable has been removed; the email codeis no longer shipped separately from the stdlib, and __version__ hasn'tbeen updated in several releases.

  • bpo-20076: Added non derived UTF-8 aliases to locale aliases table.

  • bpo-20079: Added locales supported in glibc 2.18 to locale alias table.

  • bpo-20218: Added convenience methods read_text/write_text and read_bytes/write_bytes to pathlib.Path objects.

  • bpo-22396: On 32-bit AIX platform, don't expose os.posix_fadvise() noros.posix_fallocate() because their prototypes in system headers are wrong.

  • bpo-22517: When an io.BufferedRWPair object is deallocated, clear itsweakrefs.

  • bpo-22437: Number of capturing groups in regular expression is no longerlimited by 100.

  • bpo-17442: InteractiveInterpreter now displays the full chained tracebackin its showtraceback method, to match the built in interactiveinterpreter.

  • bpo-23392: Added tests for marshal C API that works with FILE*.

  • bpo-10510: distutils register and upload methods now use HTML standardscompliant CRLF line endings.

  • bpo-9850: Fixed macpath.join() for empty first component. Patch by OlegOshmyan.

  • bpo-5309: distutils' build and build_ext commands now accept a-joption to enable parallel building of extension modules.

  • bpo-22448: Improve canceled timer handles cleanup to prevent unboundmemory usage. Patch by Joshua Moore-Oliva.

  • bpo-22427: TemporaryDirectory no longer attempts to clean up twice whenused in the with statement in generator.

  • bpo-22362: Forbidden ambiguous octal escapes out of range 0-0o377 inregular expressions.

  • bpo-20912: Now directories added to ZIP file have correct Unix and MS-DOSdirectory attributes.

  • bpo-21866: ZipFile.close() no longer writes ZIP64 central directoryrecords if allowZip64 is false.

  • bpo-22278: Fix urljoin problem with relative urls, a regression observedafter changes to issue22118 were submitted.

  • bpo-22415: Fixed debugging output of the GROUPREF_EXISTS opcode in the remodule. Removed trailing spaces in debugging output.

  • bpo-22423: Unhandled exception in thread no longer causes unhandledAttributeError when sys.stderr is None.

  • bpo-21332: Ensure thatbufsize=1 in subprocess.Popen() selects linebuffering, rather than block buffering. Patch by Akira Li.

  • bpo-21091: Fix API bug: email.message.EmailMessage.is_attachment is now amethod.

  • bpo-21079: Fix email.message.EmailMessage.is_attachment to return thecorrect result when the header has parameters as well as a value.

  • bpo-22247: Add NNTPError to nntplib.__all__.

  • bpo-22366: urllib.request.urlopen will accept a context object(SSLContext) as an argument which will then be used for HTTPS connection.Patch by Alex Gaynor.

  • bpo-4180: The warnings registries are now reset when the filters aremodified.

  • bpo-22419: Limit the length of incoming HTTP request in wsgiref server to65536 bytes and send a 414 error code for higher lengths. Patchcontributed by Devin Cook.

  • Lax cookie parsing in http.cookies could be a security issue when combinedwith non-standard cookie handling in some web browsers. Reported bySergey Bobrov.

  • bpo-20537: logging methods now accept an exception instance as well as aBoolean value or exception tuple. Thanks to Yury Selivanov for the patch.

  • bpo-22384: An exception in Tkinter callback no longer crashes the programwhen it is run with pythonw.exe.

  • bpo-22168: Prevent turtle AttributeError with non-default Canvas on OS X.

  • bpo-21147: sqlite3 now raises an exception if the request contains a nullcharacter instead of truncating it. Based on patch by Victor Stinner.

  • bpo-13968: The glob module now supports recursive search in subdirectoriesusing the** pattern.

  • bpo-21951: Fixed a crash in Tkinter on AIX when called Tcl command withempty string or tuple argument.

  • bpo-21951: Tkinter now most likely raises MemoryError instead of crash ifthe memory allocation fails.

  • bpo-22338: Fix a crash in the json module on memory allocation failure.

  • bpo-12410: imaplib.IMAP4 now supports the context management protocol.Original patch by Tarek Ziadé.

  • bpo-21270: We now override tuple methods in mock.call objects so that theycan be used as normal call attributes.

  • bpo-16662:load_tests() is now unconditionally run when it is presentin a package's__init__.py.TestLoader.loadTestsFromModule()still accepts use_load_tests, but it is deprecated and ignored. A newkeyword-only attributepattern is added and documented. Patch givenby Robert Collins, tweaked by Barry Warsaw.

  • bpo-22226: First letter no longer is stripped from the "status" key in theresult of Treeview.heading().

  • bpo-19524: Fixed resource leak in the HTTP connection when an invalidresponse is received. Patch by Martin Panter.

  • bpo-20421: Add a .version() method to SSL sockets exposing the actualprotocol version in use.

  • bpo-19546: configparser exceptions no longer expose implementationdetails. Chained KeyErrors are removed, which leads to cleaner tracebacks.Patch by Claudiu Popa.

  • bpo-22051: turtledemo no longer reloads examples to re-run them.Initialization of variables and gui setup should be done in main(), whichis called each time a demo is run, but not on import.

  • bpo-21933: Turtledemo users can change the code font size with a menuselection or control(command) '-' or '+' or control-mousewheel. Originalpatch by Lita Cho.

  • bpo-21597: The separator between the turtledemo text pane and the drawingcanvas can now be grabbed and dragged with a mouse. The code text panecan be widened to easily view or copy the full width of the text. Thecanvas can be widened on small screens. Original patches by Jan Kanis andLita Cho.

  • bpo-18132: Turtledemo buttons no longer disappear when the window isshrunk. Original patches by Jan Kanis and Lita Cho.

  • bpo-22043: time.monotonic() is now always available.threading.Lock.acquire(),threading.RLock.acquire() and socketoperations now use a monotonic clock, instead of the system clock, when atimeout is used.

  • bpo-21527: Add a default number of workers to ThreadPoolExecutor equal to5 times the number of CPUs. Patch by Claudiu Popa.

  • bpo-22216: smtplib now resets its state more completely after a quit. Themost obvious consequence of the previous behavior was a STARTTLS failureduring a connect/starttls/quit/connect/starttls sequence.

  • bpo-22098: ctypes' BigEndianStructure and LittleEndianStructure now definean empty __slots__ so that subclasses don't always get an instance dict.Patch by Claudiu Popa.

  • bpo-22185: Fix an occasional RuntimeError in threading.Condition.wait()caused by mutation of the waiters queue without holding the lock. Patchby Doug Zongker.

  • bpo-22287: On UNIX, _PyTime_gettimeofday() now usesclock_gettime(CLOCK_REALTIME) if available. As a side effect, Python nowdepends on the librt library on Solaris and on Linux (only with glibcolder than 2.17).

  • bpo-22182: Use e.args to unpack exceptions correctly indistutils.file_util.move_file. Patch by Claudiu Popa.

  • The webbrowser module now uses subprocess's start_new_session=True ratherthan a potentially risky preexec_fn=os.setsid call.

  • bpo-22042: signal.set_wakeup_fd(fd) now raises an exception if the filedescriptor is in blocking mode.

  • bpo-16808: inspect.stack() now returns a named tuple instead of a tuple.Patch by Daniel Shahaf.

  • bpo-22236: Fixed Tkinter images copying operations in NoDefaultRoot mode.

  • bpo-2527: Add aglobals argument to timeit functions, in order tooverride the globals namespace in which the timed code is executed. Patchby Ben Roberts.

  • bpo-22118: Switch urllib.parse to use RFC 3986 semantics for theresolution of relative URLs, rather than RFCs 1808 and 2396. Patch byDemian Brecht.

  • bpo-21549: Added the "members" parameter to TarFile.list().

  • bpo-19628: Allow compileall recursion depth to be specified with a -roption.

  • bpo-15696: Add a __sizeof__ implementation for mmap objects on Windows.

  • bpo-22068: Avoided reference loops with Variables and Fonts in Tkinter.

  • bpo-22165: SimpleHTTPRequestHandler now supports undecodable file names.

  • bpo-15381: Optimized line reading in io.BytesIO.

  • bpo-8797: Raise HTTPError on failed Basic Authentication immediately.Initial patch by Sam Bull.

  • bpo-20729: Restored the use of lazy iterkeys()/itervalues()/iteritems() inthe mailbox module.

  • bpo-21448: Changed FeedParser feed() to avoidO(n2)behavior when parsing long line. Original patch by Raymond Hettinger.

  • bpo-22184: The functools LRU Cache decorator factory now gives an earlierand clearer error message when the user forgets the required parameters.

  • bpo-17923: glob() patterns ending with a slash no longer match non-dirs onAIX. Based on patch by Delhallt.

  • bpo-21725: Added support for RFC 6531 (SMTPUTF8) in smtpd.

  • bpo-22176: Update the ctypes module's libffi to v3.1. This release addssupport for the Linux AArch64 and POWERPC ELF ABIv2 little endianarchitectures.

  • bpo-5411: Added support for the "xztar" format in the shutil module.

  • bpo-21121: Don't force 3rd party C extensions to be built with-Werror=declaration-after-statement.

  • bpo-21975: Fixed crash when using uninitialized sqlite3.Row (in particularwhen unpickling pickled sqlite3.Row). sqlite3.Row is now initialized inthe __new__() method.

  • bpo-20170: Convert posixmodule to use Argument Clinic.

  • bpo-21539: Add anexists_ok argument toPathlib.mkdir() to mimicmkdir-p andos.makedirs() functionality. When true, ignoreFileExistsErrors. Patch by Berker Peksag.

  • bpo-22127: Bypass IDNA for pure-ASCII host names in the socket module (inparticular for numeric IPs).

  • bpo-21047: set the default value for theconvert_charrefs argument ofHTMLParser to True. Patch by Berker Peksag.

  • Add an __all__ to html.entities.

  • bpo-15114: the strict mode and argument of HTMLParser, HTMLParser.error,and the HTMLParserError exception have been removed.

  • bpo-22085: Dropped support of Tk 8.3 in Tkinter.

  • bpo-21580: Now Tkinter correctly handles bytes arguments passed to Tk. Inparticular this allows initializing images from binary data.

  • bpo-22003: When initialized from a bytes object, io.BytesIO() now defersmaking a copy until it is mutated, improving performance and memory use onsome use cases. Patch by David Wilson.

  • bpo-22018: On Windows, signal.set_wakeup_fd() now also supports sockets. Aside effect is that Python depends to the WinSock library.

  • bpo-22054: Add os.get_blocking() and os.set_blocking() functions to getand set the blocking mode of a file descriptor (False if the O_NONBLOCKflag is set, True otherwise). These functions are not available onWindows.

  • bpo-17172: Make turtledemo start as active on OS X even when run withsubprocess. Patch by Lita Cho.

  • bpo-21704: Fix build error for _multiprocessing when semaphores are notavailable. Patch by Arfrever Frehtes Taifersar Arahesis.

  • bpo-20173: Convert sha1, sha256, sha512 and md5 to ArgumentClinic. Patchby Vajrasky Kok.

  • Fix repr(_socket.socket) on Windows 64-bit: don't fail with OverflowErroron closed socket. repr(socket.socket) already works fine.

  • bpo-22033: Reprs of most Python implemented classes now contain actualclass name instead of hardcoded one.

  • bpo-21947: The dis module can now disassemble generator-iterator objectsbased on their gi_code attribute. Patch by Clement Rouault.

  • bpo-16133: The asynchat.async_chat.handle_read() method now ignoresBlockingIOError exceptions.

  • bpo-22044: Fixed premature DECREF in call_tzinfo_method. Patch by TomFlanagan.

  • bpo-19884: readline: Disable the meta modifier key if stdout is not aterminal to not write the ANSI sequence"\033[1034h" into stdout. Thissequence is used on some terminal (ex: TERM=xterm-256color") to enablesupport of 8 bit characters.

  • bpo-4350: Removed a number of out-of-dated and non-working for a long timeTkinter methods.

  • bpo-6167: Scrollbar.activate() now returns the name of active element ifthe argument is not specified. Scrollbar.set() now always accepts only 2arguments.

  • bpo-15275: Clean up and speed up the ntpath module.

  • bpo-21888: plistlib's load() and loads() now work if the fmt parameter isspecified.

  • bpo-22032: __qualname__ instead of __name__ is now always used to formatfully qualified class names of Python implemented classes.

  • bpo-22031: Reprs now always use hexadecimal format with the "0x" prefixwhen contain an id in form " at 0x...".

  • bpo-22018: signal.set_wakeup_fd() now raises an OSError instead of aValueError onfstat() failure.

  • bpo-21044: tarfile.open() now handles fileobj with an integer 'name'attribute. Based on patch by Antoine Pietri.

  • bpo-21966: Respect -q command-line option when code module is ran.

  • bpo-19076: Don't pass the redundant 'file' argument to self.error().

  • bpo-16382: Improve exception message of warnings.warn() for bad category.Initial patch by Phil Elson.

  • bpo-21932: os.read() now uses aPy_ssize_t() type instead ofint for the size to support reading more than 2 GB at once. OnWindows, the size is truncated to INT_MAX. As any call to os.read(), theOS may read less bytes than the number of requested bytes.

  • bpo-21942: Fixed source file viewing in pydoc's server mode on Windows.

  • bpo-11259: asynchat.async_chat().set_terminator() now raises a ValueErrorif the number of received bytes is negative.

  • bpo-12523: asynchat.async_chat.push() now raises a TypeError if it doesn'tget a bytes string

  • bpo-21707: Add missing kwonlyargcount argument toModuleFinder.replace_paths_in_code().

  • bpo-20639: calling Path.with_suffix('') allows removing the suffix again.Patch by July Tikhonov.

  • bpo-21714: Disallow the construction of invalid paths usingPath.with_name(). Original patch by Antony Lee.

  • bpo-15014: Added 'auth' method to smtplib to make implementing authmechanisms simpler, and used it internally in the login method.

  • bpo-21151: Fixed a segfault in the winreg module whenNone is passedas aREG_BINARY value to SetValueEx. Patch by John Ehresman.

  • bpo-21090: io.FileIO.readall() does not ignore I/O errors anymore. Before,it ignored I/O errors if at least the first C call read() succeed.

  • bpo-5800: headers parameter of wsgiref.headers.Headers is now optional.Initial patch by Pablo Torres Navarrete and SilentGhost.

  • bpo-21781: ssl.RAND_add() now supports strings longer than 2 GB.

  • bpo-21679: Prevent extraneous fstat() calls during open(). Patch byBohuslav Kabrda.

  • bpo-21863: cProfile now displays the module name of C extension functions,in addition to their own name.

  • bpo-11453: asyncore: emit a ResourceWarning when an unclosed file_wrapperobject is destroyed. The destructor now closes the file if needed. Theclose() method can now be called twice: the second call does nothing.

  • bpo-21858: Better handling of Python exceptions in the sqlite3 module.

  • bpo-21476: Make sure the email.parser.BytesParser TextIOWrapper isdiscarded after parsing, so the input file isn't unexpectedly closed.

  • bpo-20295: imghdr now recognizes OpenEXR format images.

  • bpo-21729: Used the "with" statement in the dbm.dumb module to ensurefiles closing. Patch by Claudiu Popa.

  • bpo-21491: socketserver: Fix a race condition in child processes reaping.

  • bpo-21719: Added thest_file_attributes field to os.stat_result onWindows.

  • bpo-21832: Require named tuple inputs to be exact strings.

  • bpo-21722: The distutils "upload" command now exits with a non-zero returncode when uploading fails. Patch by Martin Dengler.

  • bpo-21723: asyncio.Queue: support any type of number (ex: float) for themaximum size. Patch written by Vajrasky Kok.

  • bpo-21711: support for "site-python" directories has now been removed fromthe site module (it was deprecated in 3.4).

  • bpo-17552: new socket.sendfile() method allowing a file to be sent over asocket by using high-performance os.sendfile() on UNIX. Patch by GiampaoloRodola'.

  • bpo-18039: dbm.dump.open() now always creates a new database when the flaghas the value 'n'. Patch by Claudiu Popa.

  • bpo-21326: Add a new is_closed() method to asyncio.BaseEventLoop.run_forever() and run_until_complete() methods of asyncio.BaseEventLoopnow raise an exception if the event loop was closed.

  • bpo-21766: Prevent a security hole in CGIHTTPServer by URL unquoting pathsbefore checking for a CGI script at that path.

  • bpo-21310: Fixed possible resource leak in failed open().

  • bpo-21256: Printout of keyword args should be in deterministic order in amock function call. This will help to write better doctests.

  • bpo-21677: Fixed chaining nonnormalized exceptions in io close() methods.

  • bpo-11709: Fix the pydoc.help function to not fail when sys.stdin is not avalid file.

  • bpo-21515: tempfile.TemporaryFile now uses os.O_TMPFILE flag is available.

  • bpo-13223: Fix pydoc.writedoc so that the HTML documentation for methodsthat use 'self' in the example code is generated correctly.

  • bpo-21463: In urllib.request, fix pruning of the FTP cache.

  • bpo-21618: The subprocess module could fail to close open fds that wereinherited by the calling process and already higher than POSIX resourcelimits would otherwise allow. On systems with a functioning /proc/self/fdor /dev/fd interface the max is now ignored and all fds are closed.

  • bpo-20383: Introduce importlib.util.module_from_spec() as the preferredway to create a new module.

  • bpo-21552: Fixed possible integer overflow of too long string lengths inthe tkinter module on 64-bit platforms.

  • bpo-14315: The zipfile module now ignores extra fields in the centraldirectory that are too short to be parsed instead of letting astruct.unpack error bubble up as this "bad data" appears in many realworld zip files in the wild and is ignored by other zip tools.

  • bpo-13742: Added "key" and "reverse" parameters to heapq.merge(). (Firstdraft of patch contributed by Simon Sapin.)

  • bpo-21402: tkinter.ttk now works when default root window is not set.

  • bpo-3015:_tkinter.create() now createstkapp object withwantobjects=1 by default.

  • bpo-10203: sqlite3.Row now truly supports sequence protocol. Inparticular it supports reverse() and negative indices. Original patch byClaudiu Popa.

  • bpo-18807: If copying (no symlinks) specified for a venv, then the pythoninterpreter aliases (python, python3) are now created by copying ratherthan symlinking.

  • bpo-20197: Added support for the WebP image type in the imghdr module.Patch by Fabrice Aneche and Claudiu Popa.

  • bpo-21513: Speedup some properties of IP addresses (IPv4Address,IPv6Address) such as .is_private or .is_multicast.

  • bpo-21137: Improve the repr for threading.Lock() and its variants byshowing the "locked" or "unlocked" status. Patch by Berker Peksag.

  • bpo-21538: The plistlib module now supports loading of binary plist fileswhen reference or offset size is not a power of two.

  • bpo-21455: Add a default backlog to socket.listen().

  • bpo-21525: Most Tkinter methods which accepted tuples now accept liststoo.

  • bpo-22166: With the assistance of a new internal _codecs._forget_codechelping function, test_codecs now clears the encoding caches to avoid theappearance of a reference leak

  • bpo-22236: Tkinter tests now don't reuse default root window. New rootwindow is created for every test class.

  • bpo-10744: FixPEP 3118 format strings on ctypes objects with anontrivial shape.

  • bpo-20826: Optimize ipaddress.collapse_addresses().

  • bpo-21487: Optimize ipaddress.summarize_address_range() andipaddress.{IPv4Network,IPv6Network}.subnets().

  • bpo-21486: Optimize parsing of netmasks in ipaddress.IPv4Network andipaddress.IPv6Network.

  • bpo-13916: Disallowed the surrogatepass error handler for non UTF-*encodings.

  • bpo-20998: Fixed re.fullmatch() of repeated single character pattern withignore case. Original patch by Matthew Barnett.

  • bpo-21075: fileinput.FileInput now reads bytes from standard stream ifbinary mode is specified. Patch by Sam Kimbrel.

  • bpo-19775: Add a samefile() method to pathlib Path objects. Initial patchby Vajrasky Kok.

  • bpo-21226: Set up modules properly in PyImport_ExecCodeModuleObject (andfriends).

  • bpo-21398: Fix a unicode error in the pydoc pager when the documentationcontains characters not encodable to the stdout encoding.

  • bpo-16531: ipaddress.IPv4Network and ipaddress.IPv6Network now accept an(address, netmask) tuple argument, so as to easily construct networkobjects from existing addresses.

  • bpo-21156: importlib.abc.InspectLoader.source_to_code() is now astaticmethod.

  • bpo-21424: Simplified and optimized heaqp.nlargest() and nmsmallest() tomake fewer tuple comparisons.

  • bpo-21396: Fix TextIOWrapper(..., write_through=True) to not force aflush() on the underlying binary stream. Patch by akira.

  • bpo-18314: Unlink now removes junctions on Windows. Patch by Kim Gräsman

  • bpo-21088: Bugfix for curses.window.addch() regression in 3.4.0. Inporting to Argument Clinic, the first two arguments were reversed.

  • bpo-21407: _decimal: The module now supports function signatures.

  • bpo-10650: Remove the non-standard 'watchexp' parameter from theDecimal.quantize() method in the Python version. It had never beenpresent in the C version.

  • bpo-21469: Reduced the risk of false positives in robotparser by checkingto make sure that robots.txt has been read or does not exist prior toreturning True in can_fetch().

  • bpo-19414: Have the OrderedDict mark deleted links as unusable. This givesan early failure if the link is deleted during iteration.

  • bpo-21421: Add __slots__ to the MappingViews ABC. Patch by Josh Rosenberg.

  • bpo-21101: Eliminate double hashing in the C speed-up code forcollections.Counter().

  • bpo-21321: itertools.islice() now releases the reference to the sourceiterator when the slice is exhausted. Patch by Anton Afanasyev.

  • bpo-21057: TextIOWrapper now allows the underlying binary stream's read()or read1() method to return an arbitrary bytes-like object (such as amemoryview). Patch by Nikolaus Rath.

  • bpo-20951: SSLSocket.send() now raises either SSLWantReadError orSSLWantWriteError on a non-blocking socket if the operation would block.Previously, it would return 0. Patch by Nikolaus Rath.

  • bpo-13248: removed previously deprecated asyncore.dispatcher __getattr__cheap inheritance hack.

  • bpo-9815: assertRaises now tries to clear references to local variables inthe exception's traceback.

  • bpo-19940: ssl.cert_time_to_seconds() now interprets the given time stringin the UTC timezone (as specified in RFC 5280), not the local timezone.

  • bpo-13204: Calling sys.flags.__new__ would crash the interpreter, now itraises a TypeError.

  • bpo-19385: Make operations on a closed dbm.dumb database always raise thesame exception.

  • bpo-21207: Detect when the os.urandom cached fd has been closed orreplaced, and open it anew.

  • bpo-21291: subprocess's Popen.wait() is now thread safe so that multiplethreads may be calling wait() or poll() on a Popen instance at the sametime without losing the Popen.returncode value.

  • bpo-21127: Path objects can now be instantiated from str subclassinstances (such asnumpy.str_).

  • bpo-15002: urllib.response object to use _TemporaryFileWrapper (and_TemporaryFileCloser) facility. Provides a better way to handle filedescriptor close. Patch contributed by Christian Theune.

  • bpo-12220: mindom now raises a custom ValueError indicating it doesn'tsupport spaces in URIs instead of letting a 'split' ValueError bubble up.

  • bpo-21068: The ssl.PROTOCOL* constants are now enum members.

  • bpo-21276: posixmodule: Don't define USE_XATTRS on KFreeBSD and the Hurd.

  • bpo-21262: New method assert_not_called for Mock. It raises AssertionErrorif the mock has been called.

  • bpo-21238: New keyword argumentunsafe to Mock. It raisesAttributeError incase of an attribute startswith assert or assret.

  • bpo-20896: ssl.get_server_certificate() now uses PROTOCOL_SSLv23, notPROTOCOL_SSLv3, for maximum compatibility.

  • bpo-21239: patch.stopall() didn't work deterministically when the samename was patched more than once.

  • bpo-21203: Updated fileConfig and dictConfig to remove inconsistencies.Thanks to Jure Koren for the patch.

  • bpo-21222: Passing name keyword argument to mock.create_autospec nowworks.

  • bpo-21197: Add lib64 -> lib symlink in venvs on 64-bit non-OS X POSIX.

  • bpo-17498: Some SMTP servers disconnect after certain errors, violatingstrict RFC conformance. Instead of losing the error code when we issuethe subsequent RSET, smtplib now returns the error code and defers raisingthe SMTPServerDisconnected error until the next command is issued.

  • bpo-17826: setting an iterable side_effect on a mock function created bycreate_autospec now works. Patch by Kushal Das.

  • bpo-7776: FixHost: header and reconnection when usinghttp.client.HTTPConnection.set_tunnel(). Patch by Nikolaus Rath.

  • bpo-20968: unittest.mock.MagicMock now supports division. Patch byJohannes Baiter.

  • bpo-21529: Fix arbitrary memory access in JSONDecoder.raw_decode with anegative second parameter. Bug reported by Guido Vranken. (See also:CVE 2014-4616)

  • bpo-21169: getpass now handles non-ascii characters that the input streamencoding cannot encode by re-encoding using the replace error handler.

  • bpo-21171: Fixed undocumented filter API of the rot13 codec. Patch byBerker Peksag.

  • bpo-20539: Improved math.factorial error message for large positive inputsand changed exception type (OverflowError -> ValueError) for largenegative inputs.

  • bpo-21172: isinstance check relaxed from dict to collections.Mapping.

  • bpo-21155: asyncio.EventLoop.create_unix_server() now raises a ValueErrorif path and sock are specified at the same time.

  • bpo-21136: Avoid unnecessary normalization of Fractions resulting frompower and other operations. Patch by Raymond Hettinger.

  • bpo-17621: Introduce importlib.util.LazyLoader.

  • bpo-21076: signal module constants were turned into enums. Patch byGiampaolo Rodola'.

  • bpo-20636: Improved the repr of Tkinter widgets.

  • bpo-19505: The items, keys, and values views of OrderedDict now supportreverse iteration using reversed().

  • bpo-21149: Improved thread-safety in logging cleanup during interpretershutdown. Thanks to Devin Jeanpierre for the patch.

  • bpo-21058: Fix a leak of file descriptor intempfile.NamedTemporaryFile(), close the file descriptor ifio.open() fails

  • bpo-21200: Return None from pkgutil.get_loader() when __spec__ is missing.

  • bpo-21013: Enhance ssl.create_default_context() when used for server sidesockets to provide better security by default.

  • bpo-20145:assertRaisesRegex andassertWarnsRegex now raise aTypeError if the second argument is not a string or compiled regex.

  • bpo-20633: Replace relative import by absolute import.

  • bpo-20980: Stop wrapping exception when using ThreadPool.

  • bpo-21082: In os.makedirs, do not set the process-wide umask. Note thischanges behavior of makedirs when exist_ok=True.

  • bpo-20990: Fix issues found by pyflakes for multiprocessing.

  • bpo-21015: SSL contexts will now automatically select an elliptic curvefor ECDH key exchange on OpenSSL 1.0.2 and later, and otherwise default to"prime256v1".

  • bpo-21000: Improve the command-line interface of json.tool.

  • bpo-20995: Enhance default ciphers used by the ssl module to enable bettersecurity and prioritize perfect forward secrecy.

  • bpo-20884: Don't assume that __file__ is defined on importlib.__init__.

  • bpo-21499: Ignore __builtins__ in several test_importlib.test_api tests.

  • bpo-20627: xmlrpc.client.ServerProxy is now a context manager.

  • bpo-19165: The formatter module now raises DeprecationWarning instead ofPendingDeprecationWarning.

  • bpo-13936: Remove the ability of datetime.time instances to be consideredfalse in boolean contexts.

  • bpo-18931: selectors module now supports /dev/poll on Solaris. Patch byGiampaolo Rodola'.

  • bpo-19977: When theLC_TYPE locale is the POSIX locale (C locale),sys.stdin andsys.stdout are now using thesurrogateescape error handler, instead of thestrict errorhandler.

  • bpo-20574: Implement incremental decoder for cp65001 code (Windows codepage 65001, Microsoft UTF-8).

  • bpo-20879: Delay the initialization of encoding and decoding tables forbase32, ascii85 and base85 codecs in the base64 module, and delay theinitialization of the unquote_to_bytes() table of the urllib.parse module,to not waste memory if these modules are not used.

  • bpo-19157: Include the broadcast address in the usuable hosts for IPv6 inipaddress.

  • bpo-11599: When an external command (e.g. compiler) fails, distutils nowprints out the whole command line (instead of just the command name) ifthe environment variable DISTUTILS_DEBUG is set.

  • bpo-4931: distutils should not produce unhelpful "error: None" messagesanymore. distutils.util.grok_environment_error is kept but doc-deprecated.

  • bpo-20875: Prevent possible gzip "'read' is not defined" NameError. Patchby Claudiu Popa.

  • bpo-11558:email.message.Message.attach now returns a more usefulerror message ifattach is called on a message for whichis_multipart is False.

  • bpo-20283: RE pattern methods now accept the string keyword parameters asdocumented. The pattern and source keyword parameters are left asdeprecated aliases.

  • bpo-20778: Fix modulefinder to work with bytecode-only modules.

  • bpo-20791: copy.copy() now doesn't make a copy when the input is a bytesobject. Initial patch by Peter Otten.

  • bpo-19748: On AIX, time.mktime() now raises an OverflowError for yearoutsize range [1902; 2037].

  • bpo-19573: inspect.signature: Use enum for parameter kind constants.

  • bpo-20726: inspect.signature: Make Signature and Parameter picklable.

  • bpo-17373: Add inspect.Signature.from_callable method.

  • bpo-20378: Improve repr of inspect.Signature and inspect.Parameter.

  • bpo-20816: Fix inspect.getcallargs() to raise correct TypeError formissing keyword-only arguments. Patch by Jeremiah Lowin.

  • bpo-20817: Fix inspect.getcallargs() to fail correctly if more than 3arguments are missing. Patch by Jeremiah Lowin.

  • bpo-6676: Ensure a meaningful exception is raised when attempting to parsemore than one XML document per pyexpat xmlparser instance. (Originalpatches by Hirokazu Yamamoto and Amaury Forgeot d'Arc, with suggestedwording by David Gutteridge)

  • bpo-21117: Fix inspect.signature to better support functools.partial. Dueto the specifics of functools.partial implementation,positional-or-keyword arguments passed as keyword arguments becomekeyword-only.

  • bpo-20334: inspect.Signature and inspect.Parameter are now hashable.Thanks to Antony Lee for bug reports and suggestions.

  • bpo-15916: doctest.DocTestSuite returns an empty unittest.TestSuiteinstead of raising ValueError if it finds no tests

  • bpo-21209: Fix asyncio.tasks.CoroWrapper to workaround a bug in yield-fromimplementation in CPythons prior to 3.4.1.

  • asyncio: Add gi_{frame,running,code} properties to CoroWrapper (upstreambpo-163).

  • bpo-21311: Avoid exception in _osx_support with non-standard compilerconfigurations. Patch by John Szakmeister.

  • bpo-11571: Ensure that the turtle window becomes the topmost window whenlaunched on OS X.

  • bpo-21801: Validate that __signature__ is None or an instance ofSignature.

  • bpo-21923: Prevent AttributeError indistutils.sysconfig.customize_compiler due to possible uninitialized_config_vars.

  • bpo-21323: Fix http.server to again handle scripts in CGI subdirectories,broken by the fix for securitybpo-19435. Patch by Zach Byrne.

  • bpo-22733: Fix ffi_prep_args not zero-extending argument values correctlyon 64-bit Windows.

  • bpo-23302: Default to TCP_NODELAY=1 upon establishing an HTTPConnection.Removed use of hard-coded MSS as it's an optimization that's no longerneeded with Nagle disabled.

IDLE

  • bpo-20577: Configuration of the max line length for the FormatParagraphextension has been moved from the General tab of the Idle preferencesdialog to the FormatParagraph tab of the Config Extensions dialog. Patchby Tal Einat.

  • bpo-16893: Update Idle doc chapter to match current Idle and add newinformation.

  • bpo-3068: Add Idle extension configuration dialog to Options menu. Changesare written to HOME/.idlerc/config-extensions.cfg. Original patch by TalEinat.

  • bpo-16233: A module browser (File : Class Browser, Alt+C) requires aneditor window with a filename. When Class Browser is requested otherwise,from a shell, output window, or 'Untitled' editor, Idle no longer displaysan error box. It now pops up an Open Module box (Alt+M). If a valid nameis entered and a module is opened, a corresponding browser is also opened.

  • bpo-4832: Save As to type Python files automatically adds .py to the nameyou enter (even if your system does not display it). Some systemsautomatically add .txt when type is Text files.

  • bpo-21986: Code objects are not normally pickled by the pickle module. Tomatch this, they are no longer pickled when running under Idle.

  • bpo-17390: Adjust Editor window title; remove 'Python', move version toend.

  • bpo-14105: Idle debugger breakpoints no longer disappear when inserting ordeleting lines.

  • bpo-17172: Turtledemo can now be run from Idle. Currently, the entry is onthe Help menu, but it may move to Run. Patch by Ramchandra Apt and LitaCho.

  • bpo-21765: Add support for non-ascii identifiers to HyperParser.

  • bpo-21940: Add unittest for WidgetRedirector. Initial patch by SaimadhavHeblikar.

  • bpo-18592: Add unittest for SearchDialogBase. Patch by Phil Webster.

  • bpo-21694: Add unittest for ParenMatch. Patch by Saimadhav Heblikar.

  • bpo-21686: add unittest for HyperParser. Original patch by SaimadhavHeblikar.

  • bpo-12387: Add missing upper(lower)case versions of default Windows keybindings for Idle so Caps Lock does not disable them. Patch by RogerSerwy.

  • bpo-21695: Closing a Find-in-files output window while the search is stillin progress no longer closes Idle.

  • bpo-18910: Add unittest for textView. Patch by Phil Webster.

  • bpo-18292: Add unittest for AutoExpand. Patch by Saihadhav Heblikar.

  • bpo-18409: Add unittest for AutoComplete. Patch by Phil Webster.

  • bpo-21477: htest.py - Improve framework, complete set of tests. Patches bySaimadhav Heblikar

  • bpo-18104: Add idlelib/idle_test/htest.py with a few sample tests to beginconsolidating and improving human-validated tests of Idle. Change otherfiles as needed to work with htest. Running the module as __main__ runsall tests.

  • bpo-21139: Change default paragraph width to 72, thePEP 8recommendation.

  • bpo-21284: Paragraph reformat test passes after user changes reformatwidth.

  • bpo-17654: Ensure IDLE menus are customized properly on OS X fornon-framework builds and for all variants of Tk.

  • bpo-23180: Rename IDLE "Windows" menu item to "Window". Patch by AlSweigart.

Build

  • bpo-15506: Use standard PKG_PROG_PKG_CONFIG autoconf macro in theconfigure script.

  • bpo-22935: Allow the ssl module to be compiled if openssl doesn't supportSSL 3.

  • bpo-22592: Drop support of the Borland C compiler to build Python. Thedistutils module still supports it to build extensions.

  • bpo-22591: Drop support of MS-DOS, especially of the DJGPP compiler(MS-DOS port of GCC).

  • bpo-16537: Check whether self.extensions is empty in setup.py. Patch byJonathan Hosmer.

  • bpo-22359: Remove incorrect uses of recursive make. Patch by JonasWagner.

  • bpo-21958: Define HAVE_ROUND when building with Visual Studio 2013 andabove. Patch by Zachary Turner.

  • bpo-18093: the programs that embed the CPython runtime are now in aseparate "Programs" directory, rather than being kept in the Modulesdirectory.

  • bpo-15759: "make suspicious", "make linkcheck" and "make doctest" in Doc/now display special message when and only when there are failures.

  • bpo-21141: The Windows build process no longer attempts to find Perl,instead relying on OpenSSL source being configured and ready to build.ThePCbuild\build_ssl.py script has been re-written and re-named toPCbuild\prepare_ssl.py, and takes care of configuring OpenSSL sourcefor both 32 and 64 bit platforms. OpenSSL sources obtained fromsvn.python.org will always be pre-configured and ready to build.

  • bpo-21037: Add a build option to enable AddressSanitizer support.

  • bpo-19962: The Windows build process now creates "python.bat" in the rootof the source tree, which passes all arguments through to the mostrecently built interpreter.

  • bpo-21285: Refactor and fix curses configure check to always search in ancursesw directory.

  • bpo-15234: For BerkeleyDB and Sqlite, only add the found library andinclude directories if they aren't already being searched. This avoids anexplicit runtime library dependency.

  • bpo-17861: Tools/scripts/generate_opcode_h.py automatically regeneratesInclude/opcode.h from Lib/opcode.py if the latter gets any change.

  • bpo-20644: OS X installer build support for documentation build changes in3.4.1: assume externally supplied sphinx-build is available in /usr/bin.

  • bpo-20022: Eliminate use of deprecated bundlebuilder in OS X builds.

  • bpo-15968: Incorporated Tcl, Tk, and Tix builds into the Windows buildsolution.

  • bpo-17095: Fix Modules/Setupshared support.

  • bpo-21811: Anticipated fixes to support OS X versions > 10.9.

  • bpo-21166: Prevent possible segfaults and other random failures of python--generate-posix-vars in pybuilddir.txt build target.

  • bpo-18096: Fix library order returned by python-config.

  • bpo-17219: Add library build dir for Python extension cross-builds.

  • bpo-22919: Windows build updated to support VC 14.0 (Visual Studio 2015),which will be used for the official release.

  • bpo-21236: Build _msi.pyd with cabinet.lib instead of fci.lib

  • bpo-17128: Use private version of OpenSSL for OS X 10.5+ installer.

C API

  • bpo-14203: Remove obsolete support for view==NULL in PyBuffer_FillInfo(),bytearray_getbuffer(), bytesiobuf_getbuffer() and array_buffer_getbuf().All functions now raise BufferError in that case.

  • bpo-22445: PyBuffer_IsContiguous() now implements precise contiguitytests, compatible with NumPy's NPY_RELAXED_STRIDES_CHECKING compilationflag. Previously the function reported false negatives for corner cases.

  • bpo-22079: PyType_Ready() now checks that statically allocated type has nodynamically allocated bases.

  • bpo-22453: Removed non-documented macro PyObject_REPR().

  • bpo-18395: Rename_Py_char2wchar() toPy_DecodeLocale(),rename_Py_wchar2char() toPy_EncodeLocale(), and documentthese functions.

  • bpo-21233: Add new C functions: PyMem_RawCalloc(), PyMem_Calloc(),PyObject_Calloc(), _PyObject_GC_Calloc(). bytes(int) is now usingcalloc() instead ofmalloc() for large objects which is faster anduse less memory.

  • bpo-20942: PyImport_ImportFrozenModuleObject() no longer sets __file__ tomatch what importlib does; this affects _frozen_importlib as well as anymodule loaded using imp.init_frozen().

Documentation

  • bpo-19548: Update the codecs module documentation to better cover thedistinction between text encodings and other codecs, together with otherclarifications. Patch by Martin Panter.

  • bpo-22394: Doc/Makefile now supportsmakevenvPYTHON=../python tocreate a venv for generating the documentation, e.g.,makehtmlPYTHON=venv/bin/python3.

  • bpo-21514: The documentation of the json module now refers to new JSON RFC7159 instead of obsoleted RFC 4627.

  • bpo-21777: The binary sequence methods on bytes and bytearray are nowdocumented explicitly, rather than assuming users will be able to derivethe expected behaviour from the behaviour of the corresponding strmethods.

  • bpo-6916: undocument deprecated asynchat.fifo class.

  • bpo-17386: Expanded functionality of theDoc/make.bat script to makeit much more comparable toDoc/Makefile.

  • bpo-21312: Update the thread_foobar.h template file to include newerthreading APIs. Patch by Jack McCracken.

  • bpo-21043: Remove the recommendation for specific CA organizations and tomention the ability to load the OS certificates.

  • bpo-20765: Add missing documentation for PurePath.with_name() andPurePath.with_suffix().

  • bpo-19407: New package installation and distribution guides based on thePython Packaging Authority tools. Existing guides have been retained aslegacy links from the distutils docs, as they still contain some requiredreference material for tool developers that isn't recorded anywhere else.

  • bpo-19697: Document cases where __main__.__spec__ is None.

Tests

  • bpo-18982: Add tests for CLI of the calendar module.

  • bpo-19548: Added some additional checks to test_codecs to ensure thatstatements in the updated documentation remain accurate. Patch by MartinPanter.

  • bpo-22838: All test_re tests now work with unittest test discovery.

  • bpo-22173: Update lib2to3 tests to use unittest test discovery.

  • bpo-16000: Convert test_curses to use unittest.

  • bpo-21456: Skip two tests in test_urllib2net.py if _ssl module notpresent. Patch by Remi Pointel.

  • bpo-20746: Fix test_pdb to run in refleak mode (-R). Patch by Xavier deGaye.

  • bpo-22060: test_ctypes has been somewhat cleaned up and simplified; it nowuses unittest test discovery to find its tests.

  • bpo-22104: regrtest.py no longer holds a reference to the suite of testsloaded from test modules that don't define test_main().

  • bpo-22111: Assorted cleanups in test_imaplib. Patch by Milan Oberkirch.

  • bpo-22002: Addedload_package_tests function to test.support and usedit to implement/augment test discovery in test_asyncio, test_email,test_importlib, test_json, and test_tools.

  • bpo-21976: Fix test_ssl to accept LibreSSL version strings. Thanks toWilliam Orr.

  • bpo-21918: Converted test_tools from a module to a package containingseparate test files for each tested script.

  • bpo-9554: Use modern unittest features in test_argparse. Initial patch byDenver Coneybeare and Radu Voicilas.

  • bpo-20155: Changed HTTP method names in failing tests in test_httpserversso that packet filtering software (specifically Windows Base FilteringEngine) does not interfere with the transaction semantics expected by thetests.

  • bpo-19493: Refactored the ctypes test package to skip tests explicitlyrather than silently.

  • bpo-18492: All resources are now allowed when tests are not run byregrtest.py.

  • bpo-21634: Fix pystone micro-benchmark: use floor division instead of truedivision to benchmark integers instead of floating-point numbers. Setpystone version to 1.2. Patch written by Lennart Regebro.

  • bpo-21605: Added tests for Tkinter images.

  • bpo-21493: Added test for ntpath.expanduser(). Original patch by ClaudiuPopa.

  • bpo-19925: Added tests for the spwd module. Original patch by VajraskyKok.

  • bpo-21522: Added Tkinter tests for Listbox.itemconfigure(),PanedWindow.paneconfigure(), and Menu.entryconfigure().

  • bpo-17756: Fix test_code test when run from the installed location.

  • bpo-17752: Fix distutils tests when run from the installed location.

  • bpo-18604: Consolidated checks for GUI availability. All platforms now atleast check whether Tk can be instantiated when the GUI resource isrequested.

  • bpo-21275: Fix a socket test on KFreeBSD.

  • bpo-21223: Pass test_site/test_startup_imports when some of the extensionsare built as builtins.

  • bpo-20635: Added tests for Tk geometry managers.

  • Add test case for freeze.

  • bpo-20743: Fix a reference leak in test_tcl.

  • bpo-21097: Move test_namespace_pkgs into test_importlib.

  • bpo-21503: Use test_both() consistently in test_importlib.

  • bpo-20939: Avoid various network test failures due to new redirect ofhttp://www.python.org/ tohttps://www.python.org: usehttp://www.example.com instead.

  • bpo-20668: asyncio tests no longer rely on tests.txt file. (Patch byVajrasky Kok)

  • bpo-21093: Prevent failures of ctypes test_macholib on OS X if a copy oflibz exists in $HOME/lib or /usr/local/lib.

  • bpo-22770: Prevent some Tk segfaults on OS X when running gui tests.

  • bpo-23211: Workaround test_logging failure on some OS X 10.6 systems.

  • bpo-23345: Prevent test_ssl failures with large OpenSSL patch level values(like 0.9.8zc).

Tools/Demos

  • bpo-22314: pydoc now works when the LINES environment variable is set.

  • bpo-22615: Argument Clinic now supports the "type" argument for the intconverter. This permits using the int converter with enums and typedefs.

  • bpo-20076: The makelocalealias.py script no longer ignores UTF-8 mapping.

  • bpo-20079: The makelocalealias.py script now can parse the SUPPORTED filefrom glibc sources and supports command line options for source paths.

  • bpo-22201: Command-line interface of the zipfile module now correctlyextracts ZIP files with directory entries. Patch by Ryan Wilson.

  • bpo-22120: For functions using an unsigned integer return converter,Argument Clinic now generates a cast to that type for the comparison to -1in the generated code. (This suppresses a compilation warning.)

  • bpo-18974: Tools/scripts/diff.py now uses argparse instead of optparse.

  • bpo-21906: Make Tools/scripts/md5sum.py work in Python 3. Patch by ZacharyWare.

  • bpo-21629: Fix Argument Clinic's "--converters" feature.

  • Add support foryieldfrom to 2to3.

  • Add support for thePEP 465 matrix multiplication operator to 2to3.

  • bpo-16047: Fix module exception list and __file__ handling in freeze.Patch by Meador Inge.

  • bpo-11824: Consider ABI tags in freeze. Patch by Meador Inge.

  • bpo-20535: PYTHONWARNING no longer affects the run_tests.py script. Patchby Arfrever Frehtes Taifersar Arahesis.

Windows

  • bpo-23260: Update Windows installer

  • The bundled version of Tcl/Tk has been updated to 8.6.3. The most visibleresult of this change is the addition of new native file dialogs whenrunning on Windows Vista or newer. See Tcl/Tk's TIP 432 for moreinformation. Also, this version of Tcl/Tk includes support for Windows10.

  • bpo-17896: The Windows build scripts now expect external library sourcesto be inPCbuild\..\externals rather thanPCbuild\..\...

  • bpo-17717: The Windows build scripts now use a copy of NASM pulled fromsvn.python.org to build OpenSSL.

  • bpo-21907: Improved the batch scripts provided for building Python.

  • bpo-22644: The bundled version of OpenSSL has been updated to 1.0.1j.

  • bpo-10747: Use versioned labels in the Windows start menu. Patch by OliveKilburn.

  • bpo-22980: .pyd files with a version and platform tag (for example,".cp35-win32.pyd") will now be loaded in preference to those without tags.

(For information about older versions, consult the HISTORY file.)