* Replace _Py_ALIGN_AS(V) by _Py_ALIGNED_DEF(N, T)
This is now a common façade for the various `_Alignas` alternatives,
which behave in interesting ways -- see the source comment.
The new macro (and MSVC's `__declspec(align)`) should not be used
on a variable/member declaration that includes a struct declaraton.
A workaround is to separate the struct definition.
Do that for `PyASCIIObject.state`.
* Specify minimum PyGC_Head and PyObject alignment
As documented in InternalDocs/garbage_collector.md, the garbage collector
stores flags in the least significant two bits of the _gc_prev pointer
in struct PyGC_Head. Consequently, this pointer is only capable of storing
a location that's aligned to a 4-byte boundary.
Encode this requirement using _Py_ALIGNED_DEF.
This patch fixes a segfault in m68k, which was previously investigated
by Adrian Glaubitz here:
https://lists.debian.org/debian-68k/2024/11/msg00020.htmlhttps://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1087600
Original patch (using the GCC-only Py_ALIGNED) by Finn Thain.
Co-authored-by: Finn Thain <fthain@linux-m68k.org>
Co-authored-by: Victor Stinner <vstinner@python.org>
Co-authored-by: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
The Python C API
================
The C API is divided into these sections:
1. ``Include/``: Limited API
2. ``Include/cpython/``: CPython implementation details
3. ``Include/cpython/``, names with the ``PyUnstable_`` prefix: API that can
change between minor releases
4. ``Include/internal/``, and any name with ``_`` prefix: The internal API
Information on changing the C API is available `in the developer guide`_
.. _in the developer guide: https://devguide.python.org/c-api/
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