* feat!: drop support for Python 3.8
The minimum supported version is now Python 3.9. pybind11 v3.0 was the last
release that supports Python 3.8. The deprecation note said that support goes
away in 3.1.
Remove the code paths that this makes dead:
- the `_PyObject_Vectorcall` fallback in `cast.h`
- the `frame->f_code` and `frame->f_back` fallbacks in `pytypes.h`
- the `PyFrame_FastToLocals` path in `get_type_override`
- the conditional `Py_VISIT(Py_TYPE(self))` in `tp_traverse`
- `PYBIND11_PYCONFIG_SUPPORT_PY_VERSION_HEX`, the pre-PyConfig interpreter
init, and the `widen_chars` helpers in `embed.h`
Assisted-by: ClaudeCode:claude-opus-5
* ci(appveyor): use Python 3.9
The AppVeyor job set `PYTHON: 38`, which makes the path `C:\Python38`.
The image gives Python 3.9.13 as `C:\Python39`.
Assisted-by: ClaudeCode:claude-opus-5
* feat!: require MSVC 2019 or newer
Python 3.9 is the new minimum, so MSVC 2017 is no longer needed. Raise the
compile-time floor to _MSC_VER 1920 and remove the workarounds that only
applied below it: std::launder, fold expressions, weak_from_this, aligned
new/delete, the C4100 warning helper, and the func_handle syntax error.
AppVeyor now builds with Visual Studio 2019.
Assisted-by: ClaudeCode:claude-opus-5
* fix(appveyor): build against the Python that has the test packages
CMake 4 has no FindPythonLibs, so pybind11 uses FindPython. FindPython reads
the registry before PATH and selected `C:\Python314-x64`, but the test packages
go into the Python on PATH. Pass `Python_ROOT_DIR` to name the correct one.
Also set `CMAKE_ARCH`. It was never set, so the architecture came from the
generator. Visual Studio 2017 defaults to Win32, but Visual Studio 2019
defaults to x64, which made this x86 job build 64-bit code.
Assisted-by: ClaudeCode:claude-opus-5
* fix(appveyor): give the linker Python's libs directory
The build compiled but failed to link with LNK1104 on a bare `python39.lib`.
That name comes from the `#pragma comment(lib, ...)` in pyconfig.h, so the
linker needs the directory. CMake 4 has no FindPythonLibs, and FindPython does
not add it for this Debug x86 build. Put it on LIB instead.
The directory listing is temporary, to confirm the library is present.
Assisted-by: ClaudeCode:claude-opus-5
* fix(appveyor): link the release Python library in Debug
The image ships python39_d.lib next to python39.lib, so FindPython picks the
debug import library for a Debug build. pybind11 undefines _DEBUG around
Python.h, so pyconfig.h asks for python39.lib instead and the link failed with
LNK1104. Name the release library for the debug slot.
Setting LIB does not work, because MSBuild replaces it from the toolset, and it
would link both import libraries.
Assisted-by: ClaudeCode:claude-opus-5
* chore(appveyor): print link settings to debug LNK1104
Revert the two attempted fixes. Neither changed the failure: setting LIB does
not survive MSBuild, and naming the release library for Python_LIBRARY_DEBUG
had no effect.
Print the Python cache entries and the link settings of a generated project
file instead, to see what the linker really gets. Temporary.
Assisted-by: ClaudeCode:claude-opus-5
* fix(appveyor): take the release Python library in Debug
The generated project file linked C:\Python39\libs\python39_d.lib in the Debug
configuration, because the image ships debug binaries next to the release ones.
pybind11 undefines _DEBUG around Python.h, so pyconfig.h asks for python39.lib
in a #pragma comment(lib), which nothing on the link line satisfies and no
library directory holds. Map Debug to the release artifacts.
Assisted-by: ClaudeCode:claude-opus-5
* chore(appveyor): drop the temporary link diagnostic
Assisted-by: ClaudeCode:claude-opus-5
* fix(tests): guard the unraisable warning filter for pytest < 6
The distro pytest in the Clang and GCC Docker jobs has no
PytestUnraisableExceptionWarning, so an unconditional filterwarnings
mark makes pytest fail with an INTERNALERROR after the tests pass.
Assisted-by: ClaudeCode:claude-opus-5
Claude-Session: https://claude.ai/code/session_01Aimf6HuSz1vLRwBnbxmCTc
* docs: address review items on version hints, embed docs, and a PyPy xfail
Extend Python_ADDITIONAL_VERSIONS through 3.15, describe the PyConfig
behavior of initialize_interpreter, and drop the stale Python 3.8 wording
from the PyPy xfail reason.
Assisted-by: ClaudeCode:claude-opus-5
* Update README.rst
Co-authored-by: Ralf W. Grosse-Kunstleve <rwgkio@gmail.com>
---------
Co-authored-by: Ralf W. Grosse-Kunstleve <rwgkio@gmail.com>
* fix(ci): pin the discovered Python to the venv/setup-python interpreter
The manylinux/musllinux images added Python 3.15 and dropped 3.13t;
FindPython's version scan then picked /usr/local/bin/python3.15 over
the uv-created venv (Python_ROOT_DIR is only a hint). Similarly, the
macOS and Windows 3.14t jobs picked a system 3.14 over setup-python's
free-threaded interpreter. Pin the interpreter explicitly in both
places, and drop the 3.13t manylinux jobs.
Assisted-by: ClaudeCode:claude-fable-5
* ci: use setup-python's python-path output instead of a locate step
Assisted-by: ClaudeCode:claude-fable-5
* Apply suggestions from code review
Co-authored-by: Ralf W. Grosse-Kunstleve <rwgkio@gmail.com>
---------
Co-authored-by: Ralf W. Grosse-Kunstleve <rwgkio@gmail.com>
* Add failback implementation of `PyCriticalSection_BeginMutex` for Python 3.13t
* Add comment for Python version
* Use `_PyCriticalSection_BeginSlow`
* Add forward declaration
* Fix forward declaration
* Remove always true condition `defined(PY_VERSION_HEX)`
* Detect musllinux
* Add manylinux test
* Use direct mutex locking for Python 3.13t
`_PyCriticalSection_BeginSlow` is a private CPython function not exported
on Linux. For Python < 3.14.0rc1, use direct `mutex.lock()`/`mutex.unlock()`
instead of critical section APIs.
* Empty commit to trigger CI
* Empty commit to trigger CI
* Empty commit to trigger CI
* Run apt update before apt install
* Remove unnecessary prefix
* Add manylinux test with Python 3.13t
* Simplify pycritical_section with std::unique_lock fallback for Python < 3.14
* Fix potential deadlock in make_iterator_impl for Python 3.13t
Refactor pycritical_section into a unified class with internal version
checks instead of using a type alias fallback. Skip locking in
make_iterator_impl for Python < 3.14.0rc1 to avoid deadlock during
type registration, as pycritical_section cannot release the mutex
during Python callbacks without PyCriticalSection_BeginMutex.
* Add reference for xfail message
* Improve C++ test infrastructure and disable hanging test
This commit improves the C++ test infrastructure to ensure test output
is visible in CI logs, and disables a test that hangs on free-threaded
Python 3.14+.
Changes:
## CI/test infrastructure improvements
- .github/workflows: Added `timeout-minutes: 3` to all C++ test steps
to prevent indefinite hangs.
- tests/**/CMakeLists.txt: Added `USES_TERMINAL` to C++ test targets
(cpptest, test_cross_module_rtti, test_pure_cpp) to ensure output is
shown immediately rather than buffered and possibly lost on crash/timeout.
- tests/test_with_catch/catch.cpp: Added a custom Catch2 progress reporter
with timestamps, Python version info, and a SIGTERM handler to make test
execution and failures clearly visible in CI logs.
## Disabled hanging test
- The "Move Subinterpreter" test is disabled on free-threaded Python 3.14+
due to a hang in Py_EndInterpreter() when the subinterpreter is destroyed
from a different thread than it was created on. Work on fixing the
underlying issue will continue under PR #5940.
Context: We were in the dark for months (since we started testing with
Python 3.14t) because CI logs gave no clue about the root cause of hangs.
This led to ignoring intermittent hangs (mostly on macOS). Our hand was
forced only with the Python 3.14.1 release, when hangs became predictable
on all platforms.
For the full development history of these changes, see PR #5933.
* Add test summary to progress reporter
Print the total number of test cases and assertions at the end of the
test run, making it easy to spot if tests are disabled or added.
Example output:
[ PASSED ] 20 test cases, 1589 assertions.
* Add PYBIND11_CATCH2_SKIP_IF macro to skip tests at runtime
Catch2 v2 doesn't have native skip support (v3 does with SKIP()).
This macro allows tests to be skipped with a visible message while
still appearing in the test list.
Use this for the Move Subinterpreter test on free-threaded Python 3.14+
so it shows as skipped rather than being conditionally compiled out.
Example output:
[ RUN ] Move Subinterpreter
[ SKIPPED ] Skipped on free-threaded Python 3.14+ (see PR #5940)
[ OK ] Move Subinterpreter
* Fix clang-tidy bugprone-macro-parentheses warning in PYBIND11_CATCH2_SKIP_IF
Occasionally a test will get stuck and run for 6 hours until Github cancels the workflow.
This reduces the timeout to 90 minutes to not waste resources.
Pybind11's tests seem to run in 30 minutes so this should be plenty of time.
* test: Added test case for visibility of common symbols across shared libraries
* style: pre-commit fixes
* tests: cmake target name fix
* tests: Added visibility test to ci
* tests: set the default visibility to hidden
* prototype/proof-of-concept fix: PYBIND11_EXPORT_GUARDED_DELETE
* Fix silly oversight: actually use PYBIND11_EXPORT_GUARDED_DELETE
* Update struct_smart_holder.h
* style: pre-commit fixes
* Update include/pybind11/detail/struct_smart_holder.h
* Update struct_smart_holder.h
* ci: fix addition to reusable-standard.yml
* Update CMakeLists.txt
* refactor: rename tests to test_cross_module_rtti
Signed-off-by: Henry Schreiner <henryschreineriii@gmail.com>
---------
Signed-off-by: Henry Schreiner <henryschreineriii@gmail.com>
Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Co-authored-by: Henry Schreiner <HenrySchreinerIII@gmail.com>
Co-authored-by: Ralf W. Grosse-Kunstleve <rgrossekunst@nvidia.com>
