gh-157649: Merge test_cppext into test_cext by vstinner · Pull Request #158176 · python/cpython

vstinner · 2026-09-25T16:06:17Z

test_cext now uses a single virtual environment for all tests. It makes the test way faster since creating a virtual environment is quite slow.
Add Py_TARGET_ABI3T test on C++.
Move macro tests from module exec function to test_macros().
Call Py_BEGIN_CRITICAL_SECTION() on a fresh dictionary object, rather than on the module.
Rename some environment variables to always use "CPYTHON_TEST_" prefix.
Replace support.MS_WINDOWS with MSVC to be more explicit.
Move macro tests to test_macros().

Issue: Py_CLEAR/Py_SETREF() regression on the main branch with C++: SEGV with simple numpy program #157649

* test_cext now uses a single virtual environment for all tests. It makes the test way faster since creating a virtual environment is quite slow. * Add Py_TARGET_ABI3T test on C++. * Move macro tests from module exec function to test_macros(). * Call Py_BEGIN_CRITICAL_SECTION() on a fresh dictionary object, rather than on the module. * Rename some environment variables to always use "CPYTHON_TEST_" prefix. * Replace support.MS_WINDOWS with MSVC to be more explicit. * Move macro tests to test_macros().

bedevere-bot · 2026-09-25T16:09:57Z

🤖 New build scheduled with the buildbot fleet by @vstinner for commit 18d8ef5 🤖

Results will be shown at:

https://buildbot.python.org/all/#/grid?branch=refs%2Fpull%2F158176%2Fmerge

If you want to schedule another build, you need to add the 🔨 test-with-buildbots label again.

bedevere-bot · 2026-09-25T16:37:21Z

🤖 New build scheduled with the buildbot fleet by @vstinner for commit 8ee942f 🤖

Results will be shown at:

https://buildbot.python.org/all/#/grid?branch=refs%2Fpull%2F158176%2Fmerge

If you want to schedule another build, you need to add the 🔨 test-with-buildbots label again.

vstinner · 2026-09-25T16:40:02Z

test_cext and test_cppext had a lot of duplicated code with only minor differences. Merging the two tests makes sure that most code is shared between C and C++ tests to keep code consistent.

For example, this PR adds PyUnicode tests in C and adds Py_TARGET_ABI3T tests in C++.

vstinner · 2026-09-25T20:51:05Z

test_cext fails on macOS:

ERROR: test_build (test.test_cext.TestPublicCpp.test_build)
ERROR: test_build_intel_asm (test.test_cext.TestPublicCpp.test_build_intel_asm)

Example:

Building wheels for collected packages: internal__test_cppext
  Building wheel for internal__test_cppext (pyproject.toml): started
  Running command Building wheel for internal__test_cppext (pyproject.toml)
  Language: C++
  Source: extension.cpp
  CC env var: 'gcc'
  CXX env var: <missing>
  CFLAGS env var: <missing>
  CPPFLAGS env var: <missing>
  CXXFLAGS env var: <missing>
  extra_compile_args: ['-Werror', '-DMODULE_NAME=_test_cppext', '-pedantic-errors', '-Wno-long-long']
  running bdist_wheel
  running build
  running build_ext
  building '_test_cppext' extension
  creating build/temp.macosx-13.7-x86_64-cpython-316t-pydebug
  /usr/bin/clang++ -fno-omit-frame-pointer -mno-omit-leaf-frame-pointer -fno-strict-overflow -Wsign-compare -g -Og -Wall -I/Users/buildbot/buildarea/pull_request.itamaro-macos-intel-aws.nogil/build/build/test_python_98426æ/tempcwd/env/include -I/Users/buildbot/buildarea/pull_request.itamaro-macos-intel-aws.nogil/build/Include -I/Users/buildbot/buildarea/pull_request.itamaro-macos-intel-aws.nogil/build -c extension.cpp -o build/temp.macosx-13.7-x86_64-cpython-316t-pydebug/extension.o -Werror -DMODULE_NAME=_test_cppext -pedantic-errors -Wno-long-long
  In file included from extension.cpp:3:
  In file included from ./extension.c:16:
  In file included from /Users/buildbot/buildarea/pull_request.itamaro-macos-intel-aws.nogil/build/Include/Python.h:72:
  In file included from /Users/buildbot/buildarea/pull_request.itamaro-macos-intel-aws.nogil/build/Include/pymem.h:103:
  /Users/buildbot/buildarea/pull_request.itamaro-macos-intel-aws.nogil/build/Include/cpython/pymem.h:28:39: error: commas at the end of enumerator lists are a C++11 extension [-Werror,-Wc++11-extensions]
      PYMEM_ALLOCATOR_MIMALLOC_DEBUG = 8,
                                        ^
  In file included from extension.cpp:3:
  In file included from ./extension.c:16:
  In file included from /Users/buildbot/buildarea/pull_request.itamaro-macos-intel-aws.nogil/build/Include/Python.h:79:
  In file included from /Users/buildbot/buildarea/pull_request.itamaro-macos-intel-aws.nogil/build/Include/object.h:742:
  /Users/buildbot/buildarea/pull_request.itamaro-macos-intel-aws.nogil/build/Include/cpython/object.h:476:36: error: commas at the end of enumerator lists are a C++11 extension [-Werror,-Wc++11-extensions]
      PyRefTracer_TRACKER_REMOVED = 2,
                                     ^
  In file included from extension.cpp:3:
  In file included from ./extension.c:16:
  In file included from /Users/buildbot/buildarea/pull_request.itamaro-macos-intel-aws.nogil/build/Include/Python.h:99:
  In file included from /Users/buildbot/buildarea/pull_request.itamaro-macos-intel-aws.nogil/build/Include/dictobject.h:113:
  /Users/buildbot/buildarea/pull_request.itamaro-macos-intel-aws.nogil/build/Include/cpython/dictobject.h:90:27: error: commas at the end of enumerator lists are a C++11 extension [-Werror,-Wc++11-extensions]
      PY_FOREACH_DICT_EVENT(PY_DEF_EVENT)
                            ^
  In file included from extension.cpp:3:
  In file included from ./extension.c:16:
  In file included from /Users/buildbot/buildarea/pull_request.itamaro-macos-intel-aws.nogil/build/Include/Python.h:106:
  /Users/buildbot/buildarea/pull_request.itamaro-macos-intel-aws.nogil/build/Include/cpython/funcobject.h:142:27: error: commas at the end of enumerator lists are a C++11 extension [-Werror,-Wc++11-extensions]
      PY_FOREACH_FUNC_EVENT(PY_DEF_EVENT)
                            ^
  In file included from extension.cpp:3:
  In file included from ./extension.c:16:
  In file included from /Users/buildbot/buildarea/pull_request.itamaro-macos-intel-aws.nogil/build/Include/Python.h:110:
  /Users/buildbot/buildarea/pull_request.itamaro-macos-intel-aws.nogil/build/Include/cpython/code.h:236:27: error: commas at the end of enumerator lists are a C++11 extension [-Werror,-Wc++11-extensions]
      PY_FOREACH_CODE_EVENT(PY_DEF_EVENT)
                            ^
  In file included from extension.cpp:3:
  In file included from ./extension.c:16:
  In file included from /Users/buildbot/buildarea/pull_request.itamaro-macos-intel-aws.nogil/build/Include/Python.h:129:
  /Users/buildbot/buildarea/pull_request.itamaro-macos-intel-aws.nogil/build/Include/cpython/context.h:36:28: error: commas at the end of enumerator lists are a C++11 extension [-Werror,-Wc++11-extensions]
      Py_CONTEXT_SWITCHED = 1,
                             ^
  6 errors generated.
  error: command '/usr/bin/clang++' failed with exit code 1

It seems like clang++ uses a C++ version older than C++11 by default. It's likely the old Apple clang++ which uses gnu++98 by default. I changed the two affected TestPublicCpp tests to use C++11 by default on macOS.

It's unclear to me why the same passed on macOS before this change. But I don't have access to macOS, so I cannot investigate. Well, my change should fix macOS support.

vstinner · 2026-09-25T20:52:25Z

!buildbot x86-64 MacOS

bedevere-bot · 2026-09-25T20:52:28Z

🤖 New build scheduled with the buildbot fleet by @vstinner for commit ee31df3 🤖

Results will be shown at:

https://buildbot.python.org/all/#/grid?branch=refs%2Fpull%2F158176%2Fmerge

The command will test the builders whose names match following regular expression: x86-64 MacOS

The builders matched are:

x86-64 macOS PR
x86-64 MacOS Intel NoGIL PR
x86-64 MacOS Intel ASAN NoGIL PR

vstinner · 2026-09-25T21:19:47Z

!buildbot AMD64 Fedora Stable

bedevere-bot · 2026-09-25T21:19:51Z

🤖 New build scheduled with the buildbot fleet by @vstinner for commit ee31df3 🤖

Results will be shown at:

https://buildbot.python.org/all/#/grid?branch=refs%2Fpull%2F158176%2Fmerge

The command will test the builders whose names match following regular expression: AMD64 Fedora Stable

The builders matched are:

AMD64 Fedora Stable LTO + PGO PR
AMD64 Fedora Stable LTO PR
AMD64 Fedora Stable PR
AMD64 Fedora Stable Clang PR
AMD64 Fedora Stable Clang Installed PR
AMD64 Fedora Stable Refleaks PR

vstinner added the skip news label Sep 25, 2026

bedevere-app Bot mentioned this pull request Sep 25, 2026

Py_CLEAR/Py_SETREF() regression on the main branch with C++: SEGV with simple numpy program #157649

Open

bedevere-app Bot added the awaiting core review label Sep 25, 2026

vstinner added the 🔨 test-with-buildbots Test PR w/ buildbots; report in status section label Sep 25, 2026

bedevere-bot removed the 🔨 test-with-buildbots Test PR w/ buildbots; report in status section label Sep 25, 2026

vstinner added 2 commits September 25, 2026 18:26

Remove test_cppext from Makefile TESTSUBDIRS

52dc9ec

Skip test_cext on WASI (need subprocess)

8ee942f

vstinner requested review from AA-Turner, emmatyping, erlend-aasland and itamaro as code owners September 25, 2026 16:29

vstinner added the 🔨 test-with-buildbots Test PR w/ buildbots; report in status section label Sep 25, 2026

bedevere-bot removed the 🔨 test-with-buildbots Test PR w/ buildbots; report in status section label Sep 25, 2026

vstinner added 2 commits September 25, 2026 22:40

test.pythoninfo logs C++ compiler version

dd81873

On macOS, use C++11 by default

ee31df3

test.pythoninfo: log CC/CXX command

2a88c6e

vstinner enabled auto-merge (squash) September 25, 2026 22:00

vstinner merged commit b71989d into python:main Sep 25, 2026
52 checks passed

vstinner deleted the merge_test_cext branch September 25, 2026 22:31

bedevere-app Bot removed the awaiting core review label Sep 25, 2026

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gh-157649: Merge test_cppext into test_cext - #158176

gh-157649: Merge test_cppext into test_cext#158176
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