New Features:

• pybind11 now supports compiling for NumPy 2. Most code shouldn't change (see upgrade-guide-2.12 for details). However, if you experience issues you can define PYBIND11_NUMPY_1_ONLY to disable the new support for now, but this will be removed in the future. #5050
• pybind11/gil_safe_call_once.h was added (it needs to be included explicitly). The primary use case is GIL-safe initialization of C++ static variables. #4877
• Support move-only iterators in py::make_iterator, py::make_key_iterator, py::make_value_iterator. #4834
• Two simple py::set_error() functions were added and the documentation was updated accordingly. In particular, py::exception<>::operator() was deprecated (use one of the new functions instead). The documentation for py::exception<> was further updated to not suggest code that may result in undefined behavior. #4772

Bug fixes:

• Removes potential for Undefined Behavior during process teardown. #4897
• Improve compatibility with the nvcc compiler (especially CUDA 12.1/12.2). #4893
• pybind11/numpy.h now imports NumPy's multiarray and _internal submodules with paths depending on the installed version of NumPy (for compatibility with NumPy 2). #4857
• Builtins collections names in docstrings are now consistently rendered in lowercase (list, set, dict, tuple), in accordance with PEP 585. #4833
• Added py::typing::Iterator<T>, py::typing::Iterable<T>. #4832
• Render py::function as Callable in docstring. #4829
• Also bump PYBIND11_INTERNALS_VERSION for MSVC, which unlocks two new features without creating additional incompatibilities. #4819
• Guard against crashes/corruptions caused by modules built with different MSVC versions. #4779
• A long-standing bug in the handling of Python multiple inheritance was fixed. See PR #4762 for the rather complex details. #4762
• Fix bind_map with using declarations. #4952
• Qualify py::detail::concat usage to avoid ADL selecting one from somewhere else, such as modernjson's concat. #4955
• Use new PyCode API on Python 3.12+. #4916
• Minor cleanup from warnings reported by Clazy. #4988
• Remove typing and duplicate class_ for KeysView/ValuesView/ItemsView. #4985
• Use PyObject_VisitManagedDict() and PyObject_ClearManagedDict() on Python 3.13 and newer. #4973
• Update make_static_property_type() to make it compatible with Python 3.13. #4971

• Render typed iterators for make_iterator, make_key_iterator, make_value_iterator. #4876
• Add several missing type name specializations. #5073
• Change docstring render for py::buffer, py::sequence and py::handle (to Buffer, Sequence, Any). #4831
• Fixed base_enum.__str__ docstring. #4827
• Enforce single line docstring signatures. #4735
• Special 'typed' wrappers now available in typing.h to annotate tuple, dict, list, set, and function. #4259
• Create handle_type_name specialization to type-hint variable length tuples. #5051

• Setting PYBIND11_FINDPYTHON to OFF will force the old FindPythonLibs mechanism to be used. #5042
• Skip empty PYBIND11_PYTHON_EXECUTABLE_LAST for the first cmake run. #4856
• Fix FindPython mode exports & avoid pkg_resources if importlib.metadata available. #4941
• Python_ADDITIONAL_VERSIONS (classic search) now includes 3.12. #4909
• pybind11.pc is now relocatable by default as long as install destinations are not absolute paths. #4830
• Correctly detect CMake FindPython removal when used as a subdirectory. #4806
• Don't require the libs component on CMake 3.18+ when using PYBIND11_FINDPYTHON (fixes manylinux builds). #4805
• pybind11_strip is no longer automatically applied when CMAKE_BUILD_TYPE is unset. #4780
• Support DEBUG_POSFIX correctly for debug builds. #4761
• Hardcode lto/thin lto for Emscripten cross-compiles. #4642
• Upgrade maximum supported CMake version to 3.27 to fix CMP0148 warnings. #4786

Documentation:

• Small fix to grammar in functions.rst. #4791
• Remove upper bound in example pyproject.toml for setuptools. #4774

CI:

• CI: Update NVHPC to 23.5 and Ubuntu 20.04. #4764
• Test on PyPy 3.10. #4714

Other:

• Use Ruff formatter instead of Black. #4912
• An assert() was added to help Coverty avoid generating a false positive. #4817