The select and time modules use functions from libm, but do not link against it.* selectmodule.c calls ceil(3) in pyepoll_poll()* timemodule.c calls fmod(3) and floor(3) in floatsleep()

Note: This causes problems at least when running on android, where the system is unable to find the symbols when loading the modules at runtime.

Additionally,* audioop calls floor()* _ctypes_test calls sqrt()Patch attached.

>  audioop_ctypes_test_link_with_libm.patch +                             libraries=['m'])Why not using math_libs here? It would also be nice to add a comment explaining why libm is needed in each module.Can someone please combine both patches?

>>  audioop_ctypes_test_link_with_libm.patch > +                             libraries=['m'])> Why not using math_libs here?math_libs is defined in detect_modules().  But the _ctypes_testextension is defined in a different function: detect_ctypes().The other option, would be to define math_libs=['m'] directly above this line and then use it once.  I didn't think that added clarity, but I'd be happy to do it that way if it fits better with standard style.> It would also be nice to add a comment explaining why libm is needed in each module.Done.> Can someone please combine both patches?Done.

Bump. For revc6930661599b timemodule.c and selectmodule.c no longer calls libm functions, while audioop.c and _ctypes_test.c still do. I have my updated patch here based on previous patches. Note that the introduction of detect_math_libs() is my naive try. Its naming and position in setup.py may need more consideration.Here's the result before and after my patch.Before:shell@GT-N7000:/data/local/tmp $ python3Python 3.6.0a0 (default:6a8fbb97c8d8+, Nov 26 2015, 18:42:29) [GCC 4.9 20140827 (prerelease)] on linuxType "help", "copyright", "credits" or "license" for more information.>>> import select >>> import time>>> import audioopTraceback (most recent call last):  File "<stdin>", line 1, in <module>ImportError: dlopen failed: cannot locate symbol "floor" referenced by "audioop.cpython-36m-arm-linux-gnueabi.so"...>>> import _ctypes_testTraceback (most recent call last):  File "<stdin>", line 1, in <module>ImportError: dlopen failed: cannot locate symbol "sqrt" referenced by "_ctypes_test.cpython-36m-arm-linux-gnueabi.so"...>>> After:shell@GT-N7000:/data/local/tmp $ python3Python 3.6.0a0 (default:c6930661599b+, Nov 26 2015, 19:10:15) [GCC 4.9 20140827 (prerelease)] on linuxType "help", "copyright", "credits" or "license" for more information.>>> import time>>> import selectrTraceback (most recent call last):  File "<stdin>", line 1, in <module>ImportError: No module named 'selectr'>>> import select >>> import audioop>>> import _ctypes_test>>> Tested on Samsung Galaxy Note GT-N7000 with my custom build of CyanogenMod 11.0

Well, the hg revision of Python in two tests are different, because I `hg pull -u` each time I build.

The _datetime module also calls functions in libm: delta_new() usesround() and accum() uses modf().The attached patch updates setup.py for all the modules that use libm.

The approach with a helper function is better. Seehttps://github.com/yan12125/python3-android/blob/038271d/mk/python/modules-link-libm.patch.By the way, I have verified there are no libraries referencing libm functions withhttps://github.com/yan12125/python3-android/blob/cpython-hg/devscripts/import_all.py

New changesetf92fea23161d by Victor Stinner in branch '3.5':setup.py: add missing libm dependencyhttps://hg.python.org/cpython/rev/f92fea23161dNew changeset3a9b47b062b9 by Victor Stinner in branch 'default':Merge 3.5: Issue#21668https://hg.python.org/cpython/rev/3a9b47b062b9

I pushed ext_modules_libm.patch with the helper function proposed by Chi Hsuan Yen inhttps://github.com/yan12125/python3-android/blob/038271d/mk/python/modules-link-libm.patch.Tell me if it's not enough. I hope that it will make CPython a little bit more portable ;-)

The patch should be acknowledged inMisc/NEWS to Chi Hsuan Yen and not to me.

New changesetf76753f26982 by Victor Stinner in branch 'default':Issue#21668: Fix author of the patch.https://hg.python.org/cpython/rev/f76753f26982

New changeset7530caa5ed1a by Victor Stinner in branch 'default':Issue#21668: Add also Chi Hsuan Yen toMisc/ACKShttps://hg.python.org/cpython/rev/7530caa5ed1a

> Xavier de Gaye: "The patch should be acknowledged inMisc/NEWS to Chi Hsuan Yen and not to me."Oh sorry. I see 4 authors in attached patches, I picked the latest. Thank you to all authors for your contribution on this issue ;-) I fixed the author inMisc/NEWS.