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Make wrapped C++ functions pickleable (#5580)

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* Backport of https://github.com/google/pybind11clif/pull/30099

* Add back `PYBIND11_WARNING_DISABLE_CLANG("-Wcast-function-type-mismatch")`

macos-13 • brew install llvm

```
/Users/runner/work/pybind11/pybind11/include/pybind11/detail/function_record_pyobject.h:40:26: error: cast from 'PyObject *(*)(PyObject *, PyObject *, PyObject *)' (aka '_object *(*)(_object *, _object *, _object *)') to 'PyCFunction' (aka '_object *(*)(_object *, _object *)') converts to incompatible function type [-Werror,-Wcast-function-type-mismatch]
   40 |     = {{"__reduce_ex__", (PyCFunction) reduce_ex_impl, METH_VARARGS | METH_KEYWORDS, nullptr},
      |                          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
```

* Remove obsolete `PY_VERSION_HEX >= 0x03080000` (discovered by gh-henryiii)
This commit is contained in:
Ralf W. Grosse-Kunstleve
2025-03-28 11:50:37 -07:00
committed by GitHub
parent 8f00d1eea0
commit e7e5d6e5bb
9 changed files with 294 additions and 88 deletions
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45
tests/test_pickling.py
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@@ -9,18 +9,41 @@ import env
from pybind11_tests import pickling as m
def test_pickle_simple_callable():
def test_assumptions():
assert pickle.HIGHEST_PROTOCOL >= 0
@pytest.mark.parametrize("protocol", range(pickle.HIGHEST_PROTOCOL + 1))
def test_pickle_simple_callable(protocol):
assert m.simple_callable() == 20220426
if env.PYPY:
serialized = pickle.dumps(m.simple_callable)
deserialized = pickle.loads(serialized)
assert deserialized() == 20220426
else:
# To document broken behavior: currently it fails universally with
# all C Python versions.
with pytest.raises(TypeError) as excinfo:
pickle.dumps(m.simple_callable)
assert re.search("can.*t pickle .*[Cc]apsule.* object", str(excinfo.value))
serialized = pickle.dumps(m.simple_callable, protocol=protocol)
assert b"pybind11_tests.pickling" in serialized
assert b"simple_callable" in serialized
deserialized = pickle.loads(serialized)
assert deserialized() == 20220426
assert deserialized is m.simple_callable
# UNUSUAL: function record pickle roundtrip returns a module, not a function record object:
if not env.PYPY:
assert (
pickle.loads(pickle.dumps(m.simple_callable.__self__, protocol=protocol))
is m
)
# This is not expected to create issues because the only purpose of
# `m.simple_callable.__self__` is to enable pickling: the only method it has is
# `__reduce_ex__`. Direct access for any other purpose is not supported.
# Note that `repr(m.simple_callable.__self__)` shows, e.g.:
# `<pybind11_detail_function_record_v1__gcc_libstdcpp_cxxabi1018 object at 0x...>`
# It is considered to be as much an implementation detail as the
# `pybind11::detail::function_record` C++ type is.
# @rainwoodman suggested that the unusual pickle roundtrip behavior could be
# avoided by changing `reduce_ex_impl()` to produce, e.g.:
# `"__import__('importlib').import_module('pybind11_tests.pickling').simple_callable.__self__"`
# as the argument for the `eval()` function, and adding a getter to the
# `function_record_PyTypeObject` that returns `self`. However, the additional code complexity
# for this is deemed warranted only if the unusual pickle roundtrip behavior actually
# creates issues.
@pytest.mark.parametrize("cls_name", ["Pickleable", "PickleableNew"])