* fix: Make gil_safe_call_once thread-safe in free-threaded CPython
The "is_initialized_" flags is not protected by the GIL in free-threaded
Python, so it needs to be an atomic field.
Fixes#5245
* style: pre-commit fixes
* Apply changes from code review
---------
Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
This fixes a PyTorch build error (using the Google-internal toolchain):
```
In file included from third_party/py/torch/torch/csrc/distributed/c10d/init.cpp:15:
In file included from third_party/py/torch/torch/csrc/distributed/c10d/PyProcessGroup.hpp:4:
In file included from third_party/py/torch/torch/csrc/jit/python/pybind_utils.h:7:
In file included from third_party/pybind11/include/pybind11/complex.h:14:
In file included from third_party/pybind11/include/pybind11/pybind11.h:14:
In file included from third_party/pybind11/include/pybind11/detail/class.h:14:
In file included from third_party/pybind11/include/pybind11/detail/../attr.h:16:
third_party/pybind11/include/pybind11/detail/../cast.h:856:19: error: static assertion failed due to requirement 'std::is_base_of<pybind11::detail::type_caster_base<c10::intrusive_ptr<c10d::Store, c10::detail::intrusive_target_default_null_type<c10d::Store>>>, pybind11::detail::type_caster<c10::intrusive_ptr<c10d::Store, c10::detail::intrusive_target_default_null_type<c10d::Store>>, void>>::value': Holder classes are only supported for custom types
856 | static_assert(std::is_base_of<base, type_caster<type>>::value,
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
third_party/pybind11/include/pybind11/detail/../cast.h:982:48: note: in instantiation of template class 'pybind11::detail::copyable_holder_caster<c10::intrusive_ptr<c10d::Store>, std::shared_ptr<c10::intrusive_ptr<c10d::Store>>>' requested here
982 | class type_caster<std::shared_ptr<T>> : public copyable_holder_caster<T, std::shared_ptr<T>> {};
| ^
third_party/crosstool/v18/stable/src/libcxx/include/__type_traits/is_base_of.h:22:91: note: in instantiation of template class 'pybind11::detail::type_caster<std::shared_ptr<c10::intrusive_ptr<c10d::Store>>>' requested here
22 | struct _LIBCPP_TEMPLATE_VIS is_base_of : public integral_constant<bool, __is_base_of(_Bp, _Dp)> {};
| ^
third_party/pybind11/include/pybind11/detail/../cast.h:1382:30: note: in instantiation of template class 'std::is_base_of<pybind11::detail::type_caster_generic, pybind11::detail::type_caster<std::shared_ptr<c10::intrusive_ptr<c10d::Store>>>>' requested here
1382 | detail::enable_if_t<std::is_base_of<type_caster_generic, make_caster<Return>>::value, void>> {
| ^
third_party/pybind11/include/pybind11/pybind11.h:287:19: note: during template argument deduction for class template partial specialization 'return_value_policy_override<Return, detail::enable_if_t<std::is_base_of<type_caster_generic, make_caster<Return>>::value, void>>' [with Return = std::shared_ptr<c10::intrusive_ptr<c10d::Store>>]
287 | = return_value_policy_override<Return>::policy(call.func.policy);
| ^
third_party/pybind11/include/pybind11/pybind11.h:287:19: note: in instantiation of template class 'pybind11::detail::return_value_policy_override<std::shared_ptr<c10::intrusive_ptr<c10d::Store>>>' requested here
third_party/pybind11/include/pybind11/pybind11.h:269:55: note: while substituting into a lambda expression here
269 | rec->impl = [](function_call &call) -> handle {
| ^
third_party/pybind11/include/pybind11/pybind11.h:147:9: note: in instantiation of function template specialization 'pybind11::cpp_function::initialize<(lambda at third_party/pybind11/include/pybind11/pybind11.h:1714:17), std::shared_ptr<c10::intrusive_ptr<c10d::Store>>, pybind11::handle, pybind11::is_method>' requested here
147 | initialize(
| ^
third_party/pybind11/include/pybind11/pybind11.h:1713:20: note: in instantiation of function template specialization 'pybind11::cpp_function::cpp_function<(lambda at third_party/pybind11/include/pybind11/pybind11.h:1714:17), pybind11::is_method, void>' requested here
1713 | return cpp_function(
| ^
third_party/pybind11/include/pybind11/pybind11.h:1964:54: note: in instantiation of function template specialization 'pybind11::property_cpp_function<c10d::DistributedBackendOptions, c10::intrusive_ptr<c10d::Store>>::read<c10::intrusive_ptr<c10d::Store> c10d::DistributedBackendOptions::*, 0>' requested here
1964 | property_cpp_function<type, D>::read(pm, *this),
| ^
third_party/py/torch/torch/csrc/distributed/c10d/init.cpp:945:8: note: in instantiation of function template specialization 'pybind11::class_<c10d::DistributedBackendOptions>::def_readwrite<c10d::DistributedBackendOptions, c10::intrusive_ptr<c10d::Store>>' requested here
945 | .def_readwrite("store", &::c10d::DistributedBackendOptions::store)
| ^
1 error generated.
```
NO SegFault 20.04 C++11 Debug all tests, even in first pass after git clean -fdx
BUT then suddenly SegFaults not reproducible anymore even with MinSizeRel!?
Current thread 0x00007f6c7165e740 (most recent call first):
File "/mounted_pybind11/tests/test_class_sh_shared_ptr_copy_move.py", line 9 in test_shptr_copy
line 9:
lst = m.test_ShPtr_copy()
This line was added after last observed SegFault
del mth
* Disable all tests in test_class_sh_property_non_owning.py
* Disable only `test_properties()` in test_class_sh_shared_ptr_copy_move.py
* Go back to original .github/workflows/ci.yml
