Don't mark old extra memory dead before calling realloc(). realloc() can fail
and realloc() must not touch the original buffer on failure.

So mark old extra memory dead only on success if the new buffer did not move
(has the same address).

cases, so _PyUnicodeWriter_Dealloc() can be called after finish.

_PyBytes_Resize(&v, new_size) sets v to NULL on error, so v cannot be used
anymore. Replace "Py_DECREF(v); v = NULL;" with "Py_CLEAR(v);".

failure.

(MemoryError).

(MemoryError).

for a framework install, the python shared library is installed in
the frameworkinstallstructure target, not in altbininstall.

so _PyUnicodeWriter_Dealloc() can be called on the writer after finish.

(in load_args()), ex: MemoryError.

PyWeakref_NewRef() failure (ex: MemoryError).

PyUnicode_DecodeUTF8() failure (ex: MemoryError).

(MemoryError).

is negative

Replace strdup() with _PyMem_RawStrdup() or _PyMem_Strdup(), depending if the
GIL is held or not.

Issue #18227: pyexpat now uses a static XML_Memory_Handling_Suite. cElementTree uses the same approach since at least Python 2.6

Modules/posixmodule.c: In function 'posix_sendfile':
Modules/posixmodule.c:7700: warning: ISO C90 forbids mixed declarations and code

Replace malloc() with PyMem_Malloc() when the GIL is held, or with
PyMem_RawMalloc() otherwise.

* Replace malloc() with PyMem_RawMalloc()
* Replace PyMem_Malloc() with PyMem_RawMalloc() where the GIL is not held.
* _Py_char2wchar() now returns a buffer allocated by PyMem_RawMalloc(), instead
  of PyMem_Malloc()

PyMem_Malloc() or PyObject_Malloc().

For example, PyCFunction_Fini() calls PyObject_GC_Del() which calls
PyObject_FREE().

* Add comment explaining the endpoint checks
* Only do the checks in a debug build
* Simplify newblock() to only require a length argument
  and leave the link updates to the calling code.
* Also add comment for the freelisting logic.