gh-135906: Use _PyObject_CAST in internal CPython headers by clin1234 · Pull Request #135892 · python/cpython · GitHub

Fixes build errors encountered in python-greenlet/greenlet#450 when building greenlet against CPython 3.14.0b3 free-threaded. Resolves #135906

Issue: Use _PyObject_CAST in internal headers #135906

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looks good

I see some similar issues elsewhere:

cpython/Include/internal/pycore_freelist.h

Line 88 in 642e5df

PyObject *op = _PyFreeList_PopNoStats(fl);

cpython/Include/internal/pycore_weakref.h

Line 63 in 642e5df

PyObject *obj = FT_ATOMIC_LOAD_PTR(ref->wr_object);

cpython/Include/internal/pycore_weakref.h

Line 90 in 642e5df

PyObject *obj = FT_ATOMIC_LOAD_PTR(ref->wr_object);

Theoretically, we could test for this by including internal headers in test_cppext, but I haven't decided whether I think that's a good idea yet. I'm worried that we're going to be encouraging people to use the private API. Which APIs does Greenlet need?

…CWq.rst Co-authored-by: Peter Bierma <zintensitydev@gmail.com>

I see some similar issues elsewhere:

cpython/Include/internal/pycore_freelist.h

Line 88 in 642e5df

PyObject *op = _PyFreeList_PopNoStats(fl);

cpython/Include/internal/pycore_weakref.h

Line 63 in 642e5df

PyObject *obj = FT_ATOMIC_LOAD_PTR(ref->wr_object);

cpython/Include/internal/pycore_weakref.h

Line 90 in 642e5df

PyObject *obj = FT_ATOMIC_LOAD_PTR(ref->wr_object);

Theoretically, we could test for this by including internal headers in test_cppext, but I haven't decided whether I think that's a good idea yet. I'm worried that we're going to be encouraging people to use the private API. Which APIs does Greenlet need?

This:

https://github.com/python-greenlet/greenlet/blob/b24e39c992e1758032bd913bf7c03d239c29480b/src/greenlet/TGreenlet.hpp#L30-L37

Ok. For 3.15, please open an issue requesting that those private APIs be exposed as unstable APIs.

Ok. For 3.15, please open an issue requesting that those private APIs be exposed as unstable APIs.

They don't need to open a new issue. This is a known issue with Cython reporting it as well #130931

I would be happy to merge this (I won't block it). However, we should have some way to make sure we don't regress. pycore_interpframe.h seems to be used by greenlet and Cython which makes it a big enough use case.

I think including pycore_interpframe.h (or pycore_interp_structs.h) in test_cppext would work as a good regression test.

I think including pycore_interpframe.h (or pycore_interp_structs.h) in test_cppext would work as a good regression test.

I wrote test_cppext to test the public C API (headers). Please don't include the internal C API in test_cppext, or add new tests.

Co-authored-by: Victor Stinner <vstinner@python.org>

Hm, why not? Wouldn't it be easier if we were able to catch regressions immediately instead of Cython or Greenlet complaining to us later?

I mean that I would prefer to leave existing test_cppext unchanged. But you can add new tests on the internal C API if you want.

I wrote #136247 to test the internal C API in test_cext.

So far, I failed to test the internal C API with C++, I get many compiler errors from mimalloc headers and I'm not sure how to handle them.

I think we can ignore mimalloc. Nobody--even Cython--is using that with the internal headers.

I think we can ignore mimalloc. Nobody--even Cython--is using that with the internal headers.

mimalloc is included indirectly by many internal headers such as pycore_interp.h.

This change on its own looks good to me. We'll figure out testing this in #136247.

LGTM

Thanks @clin1234 for the PR, and @ZeroIntensity for merging it 🌮🎉.. I'm working now to backport this PR to: 3.14.
🐍🍒⛏🤖 I'm not a witch! I'm not a witch!

…35892) Fixes build errors encountered in python-greenlet/greenlet#450 when building greenlet on the free-threaded build. --------- (cherry picked from commit fe187fa) Co-authored-by: Charlie Lin <tuug@gmx.us> Co-authored-by: Peter Bierma <zintensitydev@gmail.com> Co-authored-by: Victor Stinner <vstinner@python.org>

GH-136392 is a backport of this pull request to the 3.14 branch.

GH-136392) gh-135906: Use `_PyObject_CAST` in internal headers (GH-135892) Fixes build errors encountered in python-greenlet/greenlet#450 when building greenlet on the free-threaded build. --------- (cherry picked from commit fe187fa) Co-authored-by: Charlie Lin <tuug@gmx.us> Co-authored-by: Peter Bierma <zintensitydev@gmail.com> Co-authored-by: Victor Stinner <vstinner@python.org>

…135892) Fixes build errors encountered in python-greenlet/greenlet#450 when building greenlet on the free-threaded build. --------- Co-authored-by: Peter Bierma <zintensitydev@gmail.com> Co-authored-by: Victor Stinner <vstinner@python.org>

clin1234 added 2 commits June 24, 2025 13:24

Use _Py_STATIC_CAST in _Py_TryXGetStackRef

b471043

Use _Py_STATIC_CAST in Include/internal/pycore_object.h

e205e0a

clin1234 requested a review from Fidget-Spinner as a code owner June 24, 2025 13:32

bedevere-app Bot added the awaiting review label Jun 24, 2025

clin1234 mentioned this pull request Jun 24, 2025

Build failure with 3.14.0b3 free-threaded python-greenlet/greenlet#450

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ZeroIntensity reviewed Jun 24, 2025

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ZeroIntensity added the build The build process and cross-build label Jun 24, 2025

clin1234 mentioned this pull request Jun 25, 2025

Use _PyObject_CAST in internal headers #135906

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de9016c

clin1234 changed the title Use _Py_STATIC_CAST in internal CPython headers Use _PyObject_CAST in internal CPython headers Jun 25, 2025

clin1234 added 2 commits June 25, 2025 01:06

Use _PyObject_CAST in Include/internal/pycore_object.h

b54a5db

Use _PyObject_CAST for one function

7bbfa8c

clin1234 changed the title Use _PyObject_CAST in internal CPython headers gh-135906: Use _PyObject_CAST in internal CPython headers Jun 25, 2025

auvipy approved these changes Jun 25, 2025

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Comment thread Misc/NEWS.d/next/C_API/2025-06-25-01-03-10.gh-issue-135906.UBrCWq.rst Outdated

Update Misc/NEWS.d/next/C_API/2025-06-25-01-03-10.gh-issue-135906.UBr…

62eb149

…CWq.rst Co-authored-by: Peter Bierma <zintensitydev@gmail.com>

vstinner reviewed Jul 3, 2025

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Comment thread Include/internal/pycore_stackref.h Outdated

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Comment thread Misc/NEWS.d/next/C_API/2025-06-25-01-03-10.gh-issue-135906.UBrCWq.rst

Update Include/internal/pycore_stackref.h

2e909b3

Co-authored-by: Victor Stinner <vstinner@python.org>

ZeroIntensity approved these changes Jul 7, 2025

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bedevere-app Bot added awaiting merge and removed awaiting core review labels Jul 7, 2025

ZeroIntensity added the needs backport to 3.14 bugs and security fixes label Jul 7, 2025

ZeroIntensity requested a review from vstinner July 7, 2025 16:05

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ZeroIntensity merged commit fe187fa into python:main Jul 7, 2025

bedevere-app Bot removed the awaiting merge label Jul 7, 2025

bedevere-app Bot removed the needs backport to 3.14 bugs and security fixes label Jul 7, 2025

clin1234 deleted the cpp_trivial branch July 7, 2025 17:03

gh-135906: Use _PyObject_CAST in internal CPython headers by clin1234 · Pull Request #135892 · python/cpython · GitHub

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gh-135906: Use _PyObject_CAST in internal CPython headers - #135892

gh-135906: Use _PyObject_CAST in internal CPython headers#135892ZeroIntensity merged 7 commits intopython:mainpython/cpython:mainfrom clin1234:cpp_trivialclin1234/cpython:cpp_trivialCopy head branch name to clipboard

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gh-135906: Use _PyObject_CAST in internal CPython headers#135892
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