* Testing

* Similar fix for std::vector

* Fix infinite recursion check:

1) Apply to is_copy_assignable additionally
2) Check infinite recursion for map-like types

* style: pre-commit fixes

* Optional commit that demonstrates the limitations of this PR

* Fix positioning of container bindings

The bindings were previously in a block that was only activated if numpy
was available.

* Suggestions from code review: API side

* Suggestions from code review: Test side

* Suggestions from code review

1) Renaming: is_recursive_container and
   MutuallyRecursiveContainerPair(MV|VM)
2) Avoid ambiguous specializations of is_recursive_container

* Some little fixes

* Reordering of structs

* Add recursive checks for is_move_constructible

* Static testing for pybind11 type traits

* More precise checking of recursive types

Instead of a trait `is_recursive_container`, use a trait
`recursive_container_traits` with dependent type
`recursive_container_traits::type_to_check_recursively`.
So, instead of just checking if a type is recursive and then trying to
somehow deal with it, recursively-defined traits such as
is_move_constructible can now directly ask this trait where the
recursion should proceed.

* Review suggestions

1. Use std::conditional
2. Fix typo

* Remove leftover include from test

---------

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

updates:
- [github.com/pre-commit/mirrors-mypy: v1.1.1 → v1.2.0](https://github.com/pre-commit/mirrors-mypy/compare/v1.1.1...v1.2.0)
- [github.com/pre-commit/mirrors-clang-format: v16.0.0 → v16.0.2](https://github.com/pre-commit/mirrors-clang-format/compare/v16.0.0...v16.0.2

)

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

Bumps [pypa/gh-action-pypi-publish](https://github.com/pypa/gh-action-pypi-publish) from 1.8.5 to 1.8.6.
- [Release notes](https://github.com/pypa/gh-action-pypi-publish/releases)
- [Commits](https://github.com/pypa/gh-action-pypi-publish/compare/v1.8.5...v1.8.6

)

---
updated-dependencies:
- dependency-name: pypa/gh-action-pypi-publish
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

* Inject -stdlib=libc++ on macOS only when it's supported, close #4637.

On macOS, by default, pybind11 currently unconditionally set the compiler
flag "-stdlib=libc++" in Pybind11Extension.__init__(), regardless of which
compiler is used. This flag is required for clang, but is invalid for GCC.
If GCC is used, it causes compilation failures in all Python projects that
use pybind11, with the error message:

    arm64-apple-darwin22-gcc: error: unrecognized command-line option -stdlib=libc++.

This commit uses has_flag() to detect whether "-stdlib=libc++" on macOS,
and injects this flag from build_ext.build_extensions(), rather than
setting it unconditionally.

Signed-off-by: Yifeng Li <tomli@tomli.me>

* revert: just remove flags

---------

Signed-off-by: Yifeng Li <tomli@tomli.me>
Co-authored-by: Henry Schreiner <HenrySchreinerIII@gmail.com>

Signed-off-by: Henry Schreiner <henryschreineriii@gmail.com>

* chore(deps): update pre-commit hooks

updates:
- [github.com/psf/black: 23.1.0 → 23.3.0](https://github.com/psf/black/compare/23.1.0...23.3.0)
- [github.com/Lucas-C/pre-commit-hooks: v1.4.2 → v1.5.1](https://github.com/Lucas-C/pre-commit-hooks/compare/v1.4.2...v1.5.1)
- [github.com/charliermarsh/ruff-pre-commit: v0.0.254 → v0.0.260](https://github.com/charliermarsh/ruff-pre-commit/compare/v0.0.254...v0.0.260)
- [github.com/PyCQA/pylint: v2.16.4 → v3.0.0a6](https://github.com/PyCQA/pylint/compare/v2.16.4...v3.0.0a6)
- [github.com/pre-commit/mirrors-mypy: v1.0.1 → v1.1.1](https://github.com/pre-commit/mirrors-mypy/compare/v1.0.1...v1.1.1)
- [github.com/codespell-project/codespell: v2.2.2 → v2.2.4](https://github.com/codespell-project/codespell/compare/v2.2.2...v2.2.4)
- [github.com/pre-commit/mirrors-clang-format: v15.0.7 → v16.0.0](https://github.com/pre-commit/mirrors-clang-format/compare/v15.0.7...v16.0.0

)

* style: pre-commit fixes

* style: fix issues

* Update tests/test_call_policies.py

* Update tests/test_call_policies.py

* fix: ignore code in file

* style: pre-commit fixes

---------

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

Use `std::hash<std::type_index>`, `std::equal_to<std::type_index>` everywhere **except when libc++ is in use** (#4319)

* Try using `std::hash<std::type_index>`, `std::equal_to<std::type_index>` everywhere.

From PR #4316 we know that types in the unnamed namespace in different translation units do not compare equal, as desired.

But do types in named namespaces compare equal, as desired?

* Revert "Try using `std::hash<std::type_index>`, `std::equal_to<std::type_index>` everywhere."

This reverts commit a06949a9265014b3c581396c4f37c45ccc03dea6.

* Use "our own name-based hash and equality functions" for `std::type_index` only under macOS, based on results shown under https://github.com/pybind/pybind11/pull/4316#issuecomment-1305097879

* Patch in PR #4313: Minimal reproducer for clash when binding types defined in the unnamed namespace.

* test_unnamed_namespace_b xfail for clang

* `PYBIND11_INTERNALS_VERSION 5`

* Add a note to docs/classes.rst

* For compatibility with Google-internal testing, test_unnamed_namespace_a & test_unnamed_namespace_b need to work when imported in any order.

* Trying "__GLIBCXX__ or Windows", based on observations from Google-internal testing.

* Try _LIBCPP_VERSION

* Account for libc++ behavior in tests and documentation.

* Adjust expectations for Windows Clang (and make code less redundant).

* Add WindowsClang to ci.yml

Added block transferred from PR #4321

* Add clang-latest to name that appears in the GitHub Actions web view.

* Tweak the note in classes.rst again.

* Add `pip install --upgrade pip`, Show env, cosmetic changes

Already tested under PR #4321

* Add macos_brew_install_llvm to ci.yml

Added block transferred from PR #4324

* `test_cross_module_exception_translator` xfail 'Homebrew Clang'

* Revert back to base version of .github/workflows/ci.yml (the ci.yml changes were merged under #4323 and #4326)

* Fixes for ruff

* Make updated condition in internals.h dependent on ABI version.

* Remove PYBIND11_TEST_OVERRIDE when testing with PYBIND11_INTERNALS_VERSION=10000000

* Selectively exercise cmake `-DPYBIND11_TEST_OVERRIDE`: ubuntu, macos, windows

Extra work added to quick jobs, based on timings below, to not increase the GHA start-to-last-job-finished time.

```
Duration
^              Number of pytest runs
^              ^ Job identifier
^              ^ ^
0:03:48.024227 1 1___3___Clang_3.6___C++11___x64.txt
0:03:58.992814 1 2___3___Clang_3.7___C++11___x64.txt
0:04:25.758942 1 1___3.7___Debian___x86____Install.txt
0:04:50.148276 1 4___3___Clang_7___C++11___x64.txt
0:04:55.784558 1 13___3___Clang_15___C++20___x64.txt
0:04:57.048754 1 6___3___Clang_dev___C++11___x64.txt
0:05:00.485181 1 7___3___Clang_5___C++14___x64.txt
0:05:03.744964 1 2___3___almalinux8___x64.txt
0:05:06.222752 1 5___3___Clang_9___C++11___x64.txt
0:05:11.767022 1 2___3___GCC_7___C++17__x64.txt
0:05:18.634930 1 2___3.11__deadsnakes____x64.txt
0:05:22.810995 1 1___3___GCC_7___C++11__x64.txt
0:05:25.275317 1 12___3___Clang_14___C++20___x64.txt
0:05:32.058174 1 5___3___GCC_10___C++17__x64.txt
0:05:39.381351 1 7___3___GCC_12___C++20__x64.txt
0:05:40.502252 1 8___3___Clang_10___C++17___x64.txt
0:05:59.344905 1 3___3___Clang_3.9___C++11___x64.txt
0:06:10.825147 1 6___3___GCC_11___C++20__x64.txt
0:06:20.655443 1 3___3___almalinux9___x64.txt
0:06:22.472061 1 3___3___GCC_8___C++14__x64.txt
0:06:42.647406 1 11___3___Clang_13___C++20___x64.txt
0:06:53.352720 1 1___3.10___CUDA_11.7___Ubuntu_22.04.txt
0:07:07.357801 1 2___3.7___MSVC_2019___x86_-DCMAKE_CXX_STANDARD=14.txt
0:07:09.057603 1 1___3___centos7___x64.txt
0:07:15.546282 1 1___3.8___MSVC_2019__Debug____x86_-DCMAKE_CXX_STANDARD=17.txt
0:07:22.566022 1 4___3___GCC_8___C++17__x64.txt
0:08:13.592674 1 2___3.9___MSVC_2019__Debug____x86_-DCMAKE_CXX_STANDARD=20.txt
0:08:16.422768 1 9___3___Clang_11___C++20___x64.txt
0:08:21.168457 1 3___3.8___MSVC_2019___x86_-DCMAKE_CXX_STANDARD=17.txt
0:08:27.129468 1 10___3___Clang_12___C++20___x64.txt
0:09:35.045470 1 1___3.10___windows-latest___clang-latest.txt
0:09:57.361843 1 1___3.9___MSVC_2022_C++20___x64.txt
0:10:35.187767 1 1___3.6___MSVC_2019___x86.txt
0:11:14.691200 4 2___3.9___ubuntu-20.04___x64.txt
0:11:37.701167 1 1_macos-latest___brew_install_llvm.txt
0:11:38.688299 4 4___3.11___ubuntu-20.04___x64.txt
0:11:52.720216 1 4___3.9___MSVC_2019___x86_-DCMAKE_CXX_STANDARD=20.txt
0:13:23.456591 4 6___pypy-3.8___ubuntu-20.04___x64_-DPYBIND11_FINDPYTHON=ON.txt
0:13:25.863592 2 1___3___ICC_latest___x64.txt
0:13:32.411758 3 9___3.9___windows-2022___x64.txt
0:13:45.473377 4 3___3.10___ubuntu-20.04___x64.txt
0:13:55.366447 4 5___pypy-3.7___ubuntu-20.04___x64.txt
0:13:57.969502 3 10___3.10___windows-2022___x64.txt
0:14:19.837475 3 11___3.11___windows-2022___x64.txt
0:14:33.316770 4 1___3.6___ubuntu-20.04___x64_-DPYBIND11_FINDPYTHON=ON_-DCMA.txt
0:15:34.449278 4 22___3.6___windows-2019___x64_-DPYBIND11_FINDPYTHON=ON.txt
0:16:25.189055 2 1___3.9-dbg__deadsnakes____Valgrind___x64.txt
0:17:20.956667 4 15___3.6___macos-latest___x64.txt
0:17:27.513891 4 23___3.9___windows-2019___x64.txt
0:17:58.783286 3 8___3.6___windows-2022___x64.txt
0:18:25.917828 4 7___pypy-3.9___ubuntu-20.04___x64.txt
0:19:17.399820 3 13___pypy-3.8___windows-2022___x64.txt
0:19:45.002122 3 12___pypy-3.7___windows-2022___x64.txt
0:20:03.201926 4 16___3.9___macos-latest___x64.txt
0:20:15.415178 4 17___3.10___macos-latest___x64.txt
0:20:20.263216 4 20___pypy-3.8___macos-latest___x64.txt
0:20:31.998226 3 1___3___windows-latest___mingw64.txt
0:20:40.812286 4 18___3.11___macos-latest___x64.txt
0:22:47.714749 4 19___pypy-3.7___macos-latest___x64.txt
0:23:04.435859 3 2___3___windows-latest___mingw32.txt
0:25:48.719597 3 14___pypy-3.9___windows-2022___x64.txt
0:26:01.211688 4 21___pypy-3.9___macos-latest___x64.txt
0:28:19.971015 1 1___3___CentOS7__PGI_22.9___x64.txt
```

* Update skipif for Python 3.12a7 (the WIP needs to be handled in a separate PR).

2. Selectively exercise cmake `-DPYBIND11_TEST_OVERRIDE`: ubuntu, macos, windows

Extra work added to quick jobs, based on timings below, to not increase the GHA start-to-last-job-finished time.

```
Duration
^              Number of pytest runs
^              ^ Job identifier
^              ^ ^
0:03:48.024227 1 1___3___Clang_3.6___C++11___x64.txt
0:03:58.992814 1 2___3___Clang_3.7___C++11___x64.txt
0:04:25.758942 1 1___3.7___Debian___x86____Install.txt
0:04:50.148276 1 4___3___Clang_7___C++11___x64.txt
0:04:55.784558 1 13___3___Clang_15___C++20___x64.txt
0:04:57.048754 1 6___3___Clang_dev___C++11___x64.txt
0:05:00.485181 1 7___3___Clang_5___C++14___x64.txt
0:05:03.744964 1 2___3___almalinux8___x64.txt
0:05:06.222752 1 5___3___Clang_9___C++11___x64.txt
0:05:11.767022 1 2___3___GCC_7___C++17__x64.txt
0:05:18.634930 1 2___3.11__deadsnakes____x64.txt
0:05:22.810995 1 1___3___GCC_7___C++11__x64.txt
0:05:25.275317 1 12___3___Clang_14___C++20___x64.txt
0:05:32.058174 1 5___3___GCC_10___C++17__x64.txt
0:05:39.381351 1 7___3___GCC_12___C++20__x64.txt
0:05:40.502252 1 8___3___Clang_10___C++17___x64.txt
0:05:59.344905 1 3___3___Clang_3.9___C++11___x64.txt
0:06:10.825147 1 6___3___GCC_11___C++20__x64.txt
0:06:20.655443 1 3___3___almalinux9___x64.txt
0:06:22.472061 1 3___3___GCC_8___C++14__x64.txt
0:06:42.647406 1 11___3___Clang_13___C++20___x64.txt
0:06:53.352720 1 1___3.10___CUDA_11.7___Ubuntu_22.04.txt
0:07:07.357801 1 2___3.7___MSVC_2019___x86_-DCMAKE_CXX_STANDARD=14.txt
0:07:09.057603 1 1___3___centos7___x64.txt
0:07:15.546282 1 1___3.8___MSVC_2019__Debug____x86_-DCMAKE_CXX_STANDARD=17.txt
0:07:22.566022 1 4___3___GCC_8___C++17__x64.txt
0:08:13.592674 1 2___3.9___MSVC_2019__Debug____x86_-DCMAKE_CXX_STANDARD=20.txt
0:08:16.422768 1 9___3___Clang_11___C++20___x64.txt
0:08:21.168457 1 3___3.8___MSVC_2019___x86_-DCMAKE_CXX_STANDARD=17.txt
0:08:27.129468 1 10___3___Clang_12___C++20___x64.txt
0:09:35.045470 1 1___3.10___windows-latest___clang-latest.txt
0:09:57.361843 1 1___3.9___MSVC_2022_C++20___x64.txt
0:10:35.187767 1 1___3.6___MSVC_2019___x86.txt
0:11:14.691200 4 2___3.9___ubuntu-20.04___x64.txt
0:11:37.701167 1 1_macos-latest___brew_install_llvm.txt
0:11:38.688299 4 4___3.11___ubuntu-20.04___x64.txt
0:11:52.720216 1 4___3.9___MSVC_2019___x86_-DCMAKE_CXX_STANDARD=20.txt
0:13:23.456591 4 6___pypy-3.8___ubuntu-20.04___x64_-DPYBIND11_FINDPYTHON=ON.txt
0:13:25.863592 2 1___3___ICC_latest___x64.txt
0:13:32.411758 3 9___3.9___windows-2022___x64.txt
0:13:45.473377 4 3___3.10___ubuntu-20.04___x64.txt
0:13:55.366447 4 5___pypy-3.7___ubuntu-20.04___x64.txt
0:13:57.969502 3 10___3.10___windows-2022___x64.txt
0:14:19.837475 3 11___3.11___windows-2022___x64.txt
0:14:33.316770 4 1___3.6___ubuntu-20.04___x64_-DPYBIND11_FINDPYTHON=ON_-DCMA.txt
0:15:34.449278 4 22___3.6___windows-2019___x64_-DPYBIND11_FINDPYTHON=ON.txt
0:16:25.189055 2 1___3.9-dbg__deadsnakes____Valgrind___x64.txt
0:17:20.956667 4 15___3.6___macos-latest___x64.txt
0:17:27.513891 4 23___3.9___windows-2019___x64.txt
0:17:58.783286 3 8___3.6___windows-2022___x64.txt
0:18:25.917828 4 7___pypy-3.9___ubuntu-20.04___x64.txt
0:19:17.399820 3 13___pypy-3.8___windows-2022___x64.txt
0:19:45.002122 3 12___pypy-3.7___windows-2022___x64.txt
0:20:03.201926 4 16___3.9___macos-latest___x64.txt
0:20:15.415178 4 17___3.10___macos-latest___x64.txt
0:20:20.263216 4 20___pypy-3.8___macos-latest___x64.txt
0:20:31.998226 3 1___3___windows-latest___mingw64.txt
0:20:40.812286 4 18___3.11___macos-latest___x64.txt
0:22:47.714749 4 19___pypy-3.7___macos-latest___x64.txt
0:23:04.435859 3 2___3___windows-latest___mingw32.txt
0:25:48.719597 3 14___pypy-3.9___windows-2022___x64.txt
0:26:01.211688 4 21___pypy-3.9___macos-latest___x64.txt
0:28:19.971015 1 1___3___CentOS7__PGI_22.9___x64.txt
```

To support the use case captured in the new test_vector_unique_ptr_member.cpp

Bumps [jwlawson/actions-setup-cmake](https://github.com/jwlawson/actions-setup-cmake) from 1.13 to 1.14.
- [Release notes](https://github.com/jwlawson/actions-setup-cmake/releases)
- [Commits](https://github.com/jwlawson/actions-setup-cmake/compare/v1.13...v1.14

)

---
updated-dependencies:
- dependency-name: jwlawson/actions-setup-cmake
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

To support the use case captured in the new test_vector_unique_ptr_member.cpp

* Alternative approach to #3807 that supports an important PyCLIF use case: `Base` not specified in `classh<Derived>` statement, but passing Derived as Base works anyway.

* NOtest_multiple_inheritance_getattr in test_class_sh_void_ptr_capsule.py (quick experiment)

* Revert "NOtest_multiple_inheritance_getattr in test_class_sh_void_ptr_capsule.py (quick experiment)"

This reverts commit e8f0749b895ad941221316a5fa43d873a2b00397.

* Special handling of pybind11 objects to side-step try_as_void_ptr_capsule_get_pointer __getattr__ issues.

* Inspect `internals.registered_types_py` in `type_is_pybind11_class_()`

* Remove debug code in tests subdir.

* Clean up the modified `try_as_void_ptr_capsule_get_pointer()` implementation and new helper functions.

Bumps [pypa/gh-action-pypi-publish](https://github.com/pypa/gh-action-pypi-publish) from 1.8.4 to 1.8.5.
- [Release notes](https://github.com/pypa/gh-action-pypi-publish/releases)
- [Commits](https://github.com/pypa/gh-action-pypi-publish/compare/v1.8.4...v1.8.5

)

---
updated-dependencies:
- dependency-name: pypa/gh-action-pypi-publish
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

* Avoid dangling pointers.

* Add test for const ptr

* Fix test failures.

* Fix ClangTidy

* fix emplace_back

Bumps [pypa/gh-action-pypi-publish](https://github.com/pypa/gh-action-pypi-publish) from 1.8.3 to 1.8.4.
- [Release notes](https://github.com/pypa/gh-action-pypi-publish/releases)
- [Commits](https://github.com/pypa/gh-action-pypi-publish/compare/v1.8.3...v1.8.4

)

---
updated-dependencies:
- dependency-name: pypa/gh-action-pypi-publish
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

* ci: Python 3.12 optional testing

Signed-off-by: Henry Schreiner <henryschreineriii@gmail.com>

* Skip test_flaky_exception_failure_point_init() for Python 3.12.0a6 (similar to https://github.com/google/pywrapcc/commit/af5c6536aba77b1db99bb16995d3a684351efb93#diff-f46006e3f43ffb1dd5d6862005427f6620f4dcfb1fa2f883d8482550069eeecc

).

* Disable tests/test_embed/test_interpreter.cpp (broken with Python 3.12.0alpha6)

```
free(): invalid pointer

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
test_embed is a Catch v2.13.9 host application.
Run with -? for options

-------------------------------------------------------------------------------
Custom PyConfig
-------------------------------------------------------------------------------
/home/runner/work/pybind11/pybind11/tests/test_embed/test_interpreter.cpp:175
...............................................................................

/home/runner/work/pybind11/pybind11/tests/test_embed/test_interpreter.cpp:179: FAILED:
  {Unknown expression after the reported line}
due to a fatal error condition:
  SIGABRT - Abort (abnormal termination) signal

===============================================================================
test cases:    6 |    5 passed | 1 failed
assertions: 1518 | 1517 passed | 1 failed
```

---------

Signed-off-by: Henry Schreiner <henryschreineriii@gmail.com>
Co-authored-by: Ralf W. Grosse-Kunstleve <rwgk@google.com>

* Introduce `get_python_state_dict()`

* Conditional version bump for Python 3.12+

* Shuffle subexpressions to make the condition easier to understand (no change to logic).

* Make pybind11 ABI version 5 the minimum for Python 3.12+ (as suggested by @Lalaland)

* Add back condition for PYPY_VERSION, but keep it open for future PyPy versions.

* Fall back to simple `|| defined(PYPY_VERSION)`. `PY_VERSION_HEX` does not appear to be meaningful with PyPy.

* bugfix: allow noexcept lambdas in CPP17. Fix #4565

* Remove unused code from test case

* Fix clang-tidy error

* Address reviewer comment

* use C++17 syntax to get rid of recursive template instantiations for concatenating type signatures (#4587)

* Apply descr.h `src_loc` change (smart_holder PR #4022) to code added with master PR #4587

* Add test_class_sh_property_non_owning to CMakeLists.txt (fixes oversight in PR #4586)

* Resolve clang-tidy errors.

* clang-tidy auto fix

---------

Co-authored-by: Konstantin Bespalov <kos5tya@yandex.ru>

use C++17 syntax to get rid of recursive template instantiations for concatenating type signatures (#4587)

* Add test_class_sh_property_non_owning.cpp,py

Failing:

```
__________________________________________________________ test_persistent_holder __________________________________________________________

    def test_persistent_holder():
        h = m.DataFieldsHolder(2)
>       c = h.vec_at(0).core_fld
E       RuntimeError: Non-owning holder (loaded_as_shared_ptr).

h          = <pybind11_tests.class_sh_property_non_owning.DataFieldsHolder object at 0x7fabab516470>

test_class_sh_property_non_owning.py:6: RuntimeError
__________________________________________________________ test_temporary_holder ___________________________________________________________

    def test_temporary_holder():
        d = m.DataFieldsHolder(2).vec_at(1)
>       c = d.core_fld
E       RuntimeError: Non-owning holder (loaded_as_shared_ptr).

d          = <pybind11_tests.class_sh_property_non_owning.DataField object at 0x7fabab548770>

test_class_sh_property_non_owning.py:13: RuntimeError
```

* Introduce `shared_ptr_from_python(responsible_parent)` and use in all `property_cpp_function`s with `const shared_ptr<T> &` arguments.

Tests are incomplete.

* Complete tests.

* Add comment for `smart_holder_type_caster_load<T>::shared_ptr_from_python`

Bumps [pypa/gh-action-pypi-publish](https://github.com/pypa/gh-action-pypi-publish) from 1.8.1 to 1.8.3.
- [Release notes](https://github.com/pypa/gh-action-pypi-publish/releases)
- [Commits](https://github.com/pypa/gh-action-pypi-publish/compare/v1.8.1...v1.8.3

)

---
updated-dependencies:
- dependency-name: pypa/gh-action-pypi-publish
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

* docs: changelog for 2.10.4

Signed-off-by: Henry Schreiner <henryschreineriii@gmail.com>

* Apply suggestions from code review

* Update docs/changelog.rst

---------

Signed-off-by: Henry Schreiner <henryschreineriii@gmail.com>