* Add type_caster<std::monostate> for std::variant

Add type_caster<std::monostate>, allowing std::variant<std::monostate, ...>

* Add  variant<std::monostate, ...> test methods

* Add std::monostate tests

* Update test_stl.py

Remove erroneous extra tests

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* Update test fn name

* And update the doc() test

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updates:
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The docs were not 100% the same as we advertise with our
tooling function: most users do not want to strip symbols
in Debug builds.

updates:
- [github.com/asottile/pyupgrade: v2.31.0 → v2.31.1](https://github.com/asottile/pyupgrade/compare/v2.31.0...v2.31.1)
- [github.com/sirosen/texthooks: 0.2.2 → 0.3.1](https://github.com/sirosen/texthooks/compare/0.2.2...0.3.1)
- [github.com/hadialqattan/pycln: v1.2.4 → v1.2.5](https://github.com/hadialqattan/pycln/compare/v1.2.4...v1.2.5)
- [github.com/pre-commit/mirrors-mypy: v0.931 → v0.940](https://github.com/pre-commit/mirrors-mypy/compare/v0.931...v0.940)
- [github.com/mgedmin/check-manifest: 0.47 → 0.48](https://github.com/mgedmin/check-manifest/compare/0.47...0.48

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* PYBIND11_OBJECT_CVT should use namespace for error_already_set()

This change makes the macro usable outside of pybind11 namespace.

* added test for use of PYBIND11_OBJECT_CVT for classes in external to pybind11 namespaces

* Extended test_pytypes.cpp and test_pytest.py

The added test defines a dummy function that takes a custom-defined class external::float_
that uses PYBIND11_OBJECT_CVT

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* fixed issues pointed out by CI

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* fixed memory leak in default constructor

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Nearly every call site of cast_op<T> uses an r-value reference.

Except stl.h variant_caster::load_alternative for handling std::variant.

Fix that.

* Fixes issue

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* Fix lint error

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* Fix flake8

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* Fix test

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* Fix clang tidy

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* Fix again

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* Fix test

* Add comments

* Try fix Valgrind

* Resolve comments

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The docs were not 100% the same as we advertise with our
tooling function: most users do not want to strip symbols
in Debug builds.

updates:
- [github.com/asottile/pyupgrade: v2.31.0 → v2.31.1](https://github.com/asottile/pyupgrade/compare/v2.31.0...v2.31.1)
- [github.com/sirosen/texthooks: 0.2.2 → 0.3.1](https://github.com/sirosen/texthooks/compare/0.2.2...0.3.1)
- [github.com/hadialqattan/pycln: v1.2.4 → v1.2.5](https://github.com/hadialqattan/pycln/compare/v1.2.4...v1.2.5)
- [github.com/pre-commit/mirrors-mypy: v0.931 → v0.940](https://github.com/pre-commit/mirrors-mypy/compare/v0.931...v0.940)
- [github.com/mgedmin/check-manifest: 0.47 → 0.48](https://github.com/mgedmin/check-manifest/compare/0.47...0.48

)

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* PYBIND11_OBJECT_CVT should use namespace for error_already_set()

This change makes the macro usable outside of pybind11 namespace.

* added test for use of PYBIND11_OBJECT_CVT for classes in external to pybind11 namespaces

* Extended test_pytypes.cpp and test_pytest.py

The added test defines a dummy function that takes a custom-defined class external::float_
that uses PYBIND11_OBJECT_CVT

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

* fixed issues pointed out by CI

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* fixed memory leak in default constructor

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* Reproducer for https://github.com/pybind/pybind11/issues/3788

Expected to build & run as-is. Uncommenting reproduces the infinite recursion.

* Moving try_as_void_ptr_capsule() to the end of load_impl()

* Moving new test into the existing test_class_sh_void_ptr_capsule

* Experiment

* Remove comments and simplify the test cases.

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* Test out Python 3.11 migration

* Clean up a bit

* Remove todo

* Test workaround

* Fix potential bug uncovered in 3.11

* Try to fix it more

* last ditch fix

* Revert. Tp-traverse isn't the problem

* Test workaround

* Try this hack

* Revert MRO changes

* Use f_back properly

* Qualify auto

* Update include/pybind11/pybind11.h

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* Simplify code slightly

* Ensure co_varnames decref if dict_getitem throws

* Eager decref f_code

Co-authored-by: Henry Schreiner <HenrySchreinerIII@gmail.com>
Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

* Use sysconfig in Python >= 3.10

Rely on sysconfig for installation paths for Python >= 3.10. distutils
has been deprecated and will be removed.

Fixes: #3677

* Explicitly select the posix_prefix scheme for platinclude on Debian

Debian's default scheme is posix_local, for installing locally-built
packages to /usr/local/.  We want to find the Python headers in /usr/,
so search posix_prefix.

* chore: minor fixes for newer PyPys

* ci: fix issue with PyPy

updates:
- [github.com/Lucas-C/pre-commit-hooks: v1.1.12 → v1.1.13](https://github.com/Lucas-C/pre-commit-hooks/compare/v1.1.12...v1.1.13)
- [github.com/hadialqattan/pycln: v1.2.0 → v1.2.4](https://github.com/hadialqattan/pycln/compare/v1.2.0...v1.2.4

)

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* cast: Qualify symbol usage in PYBIND11_TYPE_CASTER

Permits using macro outside of pybind11::detail

* fixup! review

* Add bytearray to string cast, testcase and rename load_bytes to load_raw

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* New bytearray test case and convert failure to pybind11_fail

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* Fix merge comments

* Actually fix merge comments

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* Assert early if AsString fails

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* [pre-commit.ci] pre-commit autoupdate

updates:
- [github.com/hadialqattan/pycln: v1.1.0 → v1.2.0](https://github.com/hadialqattan/pycln/compare/v1.1.0...v1.2.0)
- [github.com/pre-commit/mirrors-clang-format: v13.0.0 → v13.0.1](https://github.com/pre-commit/mirrors-clang-format/compare/v13.0.0...v13.0.1

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* Update .pre-commit-config.yaml

* ci: specify which windows image to use

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* Clear local internals after finalizing interpreter

* Add descriptive comments

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* Clear Python error state if pybind11::weakref() fails.

The weakref() constructor calls pybind11_fail() without clearing any
Python interpreter error state. If a client catches the C++ exception
thrown by pybind11_fail(), the Python interpreter will be left in an
error state.

* Add test case for failing to create weakref

* Add Debug asserts for pybind11 fail

* Make error handling more pythonic

* Does this fix PyPy?

* Adapt test to PyPy differences

* Simplify test to remove redundancy

Co-authored-by: Aaron Gokaslan <skylion.aaron@gmail.com>

* Removing C++20 condition for MSVC is_template_base_of decltype workaround.

* `-DDOWNLOAD_EIGEN=ON` for MSVC 2022 C++20

* `-DDOWNLOAD_EIGEN=ON` for MSVC 2019 C++20

* `-DPYBIND11_WERROR=OFF` for MSVC C++20 (2019, 2020)

* Restoring `defined(PYBIND11_CPP20)` in common.h

* pragma warning(disable : 5054) in eigen.h

* Reverting `-DPYBIND11_WERROR=OFF` changes.

* fix: add pylint and fix issue

* chore: add pylint to pre-commit

* fix: local variable warning surfaced mistake in intree

updates:
- [github.com/Lucas-C/pre-commit-hooks: v1.1.11 → v1.1.12](https://github.com/Lucas-C/pre-commit-hooks/compare/v1.1.11...v1.1.12

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