Nov 7, 2023 · Nov 7, 2023 · Nov 7, 2023
diff --git a/Doc/whatsnew/3.13.rst b/Doc/whatsnew/3.13.rst
  (as has always been the case for an executing frame).
  (Contributed by Irit Katriel in :gh:`79932`.)

 * Assignment to a function's ``__code__`` attribute where the new code
  object's type does not match the function's type, is deprecated. The
  different types are: plain function, generator, async generator and
  coroutine.
  (Contributed by Irit Katriel in :gh:`81137`.)


 Pending Removal in Python 3.14
 ------------------------------
diff --git a/Lib/test/test_funcattrs.py b/Lib/test/test_funcattrs.py
 importtypes
 importtyping
 importunittest
 importwarnings


 defglobal_function():
 test.__code__=self.b.__code__
 self.assertEqual(test(),3)# self.b always returns 3, arbitrarily

 deftest_invalid___code___assignment(self):
 defA():pass
 defB():yield
 asyncdefC():yield
 asyncdefD(x):awaitx

 forsrcin [A,B,C,D]:
 fordstin [A,B,C,D]:
 ifsrc==dst:
 continue

 assertsrc.__code__.co_flags!=dst.__code__.co_flags
 prev=dst.__code__
 try:
 withself.assertWarnsRegex(DeprecationWarning,'code object of non-matching type'):
 dst.__code__=src.__code__
 finally:
 withwarnings.catch_warnings():
 warnings.filterwarnings('ignore','',DeprecationWarning)
 dst.__code__=prev

 deftest___globals__(self):
 self.assertIs(self.b.__globals__,globals())
 self.cannot_set_attr(self.b,'__globals__',2,
diff --git a/Misc/NEWS.d/next/Core and Builtins/2023-11-07-12-59-02.gh-issue-81137.qFpJCY.rst b/Misc/NEWS.d/next/Core and Builtins/2023-11-07-12-59-02.gh-issue-81137.qFpJCY.rst
 Deprecate assignment to a function's ``__code__`` field when the new code
 object is of a mismatched type (e.g., from a generator to a plain function).
diff --git a/Objects/funcobject.c b/Objects/funcobject.c
 nclosure,nfree);
 return-1;
    }

 PyObject*func_code=PyFunction_GET_CODE(op);
 intold_flags= ((PyCodeObject*)func_code)->co_flags;
 intnew_flags= ((PyCodeObject*)value)->co_flags;
 intmask=CO_GENERATOR |CO_COROUTINE |CO_ASYNC_GENERATOR;
 if ((old_flags&mask)!= (new_flags&mask)) {
 if (PyErr_Warn(PyExc_DeprecationWarning,
 "Assigning a code object of non-matching type is deprecated "
 "(e.g., from a generator to a plain function)")<0)
        {
 return-1;
        }
    }

 handle_func_event(PyFunction_EVENT_MODIFY_CODE,op,value);
 _PyFunction_SetVersion(op,0);
 Py_XSETREF(op->func_code,Py_NewRef(value));
Original file line number	Diff line number	Diff line change
Expand Up		@@ -401,6 +401,12 @@ Deprecated
		(as has always been the case for an executing frame).
		(Contributed by Irit Katriel in :gh:`79932`.)

		* Assignment to a function's ``__code__`` attribute where the new code
		object's type does not match the function's type, is deprecated. The
		different types are: plain function, generator, async generator and
		coroutine.
		(Contributed by Irit Katriel in :gh:`81137`.)


		Pending Removal in Python 3.14
		------------------------------
Expand Down
Original file line number	Diff line number	Diff line change
Expand Up		@@ -2,6 +2,7 @@
		importtypes
		importtyping
		importunittest
		importwarnings


		defglobal_function():
Expand DownExpand Up		@@ -70,6 +71,27 @@ def test(): pass
		test.__code__=self.b.__code__
		self.assertEqual(test(),3)# self.b always returns 3, arbitrarily

		deftest_invalid___code___assignment(self):
		defA():pass
		defB():yield
		asyncdefC():yield
		asyncdefD(x):awaitx

		forsrcin [A,B,C,D]:
		fordstin [A,B,C,D]:
		ifsrc==dst:
		continue

		assertsrc.__code__.co_flags!=dst.__code__.co_flags
		prev=dst.__code__
		try:
		withself.assertWarnsRegex(DeprecationWarning,'code object of non-matching type'):
		dst.__code__=src.__code__
		finally:
		withwarnings.catch_warnings():
		warnings.filterwarnings('ignore','',DeprecationWarning)
		dst.__code__=prev

		deftest___globals__(self):
		self.assertIs(self.b.__globals__,globals())
		self.cannot_set_attr(self.b,'__globals__',2,
Expand Down
Original file line number	Diff line number	Diff line change
		@@ -0,0 +1,2 @@
		Deprecate assignment to a function's ``__code__`` field when the new code
		object is of a mismatched type (e.g., from a generator to a plain function).
Original file line number	Diff line number	Diff line change
Expand Up		@@ -557,6 +557,20 @@ func_set_code(PyFunctionObject op, PyObject value, void *Py_UNUSED(ignored))
		nclosure,nfree);
		return-1;
		}

		PyObject*func_code=PyFunction_GET_CODE(op);
		intold_flags= ((PyCodeObject*)func_code)->co_flags;
		intnew_flags= ((PyCodeObject*)value)->co_flags;
		intmask=CO_GENERATOR \|CO_COROUTINE \|CO_ASYNC_GENERATOR;
		if ((old_flags&mask)!= (new_flags&mask)) {
		if (PyErr_Warn(PyExc_DeprecationWarning,
		"Assigning a code object of non-matching type is deprecated "
		"(e.g., from a generator to a plain function)")<0)
		{
		return-1;
		}
		}

		handle_func_event(PyFunction_EVENT_MODIFY_CODE,op,value);
		_PyFunction_SetVersion(op,0);
		Py_XSETREF(op->func_code,Py_NewRef(value));
Expand Down