* Check if valgrind-detected after-freeing access of PyMethodDef causes macOS Python 3.9 segfaults

* fix: only apply leak on 3.9.0

* fix: faster check

* fix: better naming thanks to @bstaletic

Co-authored-by: Henry Schreiner <henryschreineriii@gmail.com>

* feat: basic typing support

* docs: mention syncing as suggested by @rwgk

* docs: update changelog

* docs: copy of warning in limitations

* fix: ipo should be off for debug or relwithdebinfo

Closes #2587

* docs: slightly more detailed about IPO

* Update pybind11Common.cmake

Fix minor bug in `_add_lflags` that allows a flag to be added more than once.

* docs: some final 2.6.0 updates

* docs: better warning text

Closes #2571; this is defined to share, and unlike DATADIR, is not sometimes overwritten incorrectly for storing CMake files.

* Throw error_already_set in py::len on failing PyObject_Length

* Fix tests to mach error message on PyPy

Shorten PYBIND11_EMBEDDED_MODULE macro implementation by using PYBIND11_CATCH_INIT_EXCEPTIONS (#2579)

* fix: Intel 18+ fully supported

* fix: Intel compiler workaround no longer needed

Followup on #94 now that Intel 18+ is required.

* add support for LLVM compiler

* Update include/pybind11/pybind11.h

__forced_unwind libc++ vs libstdc++

Co-authored-by: Henry Schreiner <HenrySchreinerIII@gmail.com>

Co-authored-by: Henry Schreiner <HenrySchreinerIII@gmail.com>

* Update PGI to 20.9

Update PGI to 20.9

* Update ci.yml

* Update ci.yml

* Update README.rst

* Update ci.yml

Co-authored-by: Henry Schreiner <HenrySchreinerIII@gmail.com>

* docs: FAQ CMake updates

* docs: limitations

* ci: don't over label

* docs: update CHANGELOG, add a bit more structure

* ci: label PRs with more labels, and sooner

* docs: updates from @rwgk

* docs: address @YannickJadoul's points

* Deprecated public constructors of module

* Turn documentation comment of module_::add_object into valid doxygen documentation

* Move definition of PYBIND11_DETAIL_MODULE_STATIC_DEF and PYBIND11_DETAIL_MODULE_CREATE macros up

* Move detail::create_top_level_module to module_::create_extension_module, and unify Python 2 and 3 signature again

* Throw error_already_set if module creation fails in module_::create_extension_module

* Mention module_::create_extension_module in deprecation warning message of module_::module_

* Check scope's __dict__ instead of using hasattr when registering classes and exceptions, to allow registering the same name in a derived class scope

* Extend test_base_and_derived_nested_scope test

* Add tests on error being thrown registering duplicate classes

* Circumvent bug with combination of test_class.py::test_register_duplicate_class and test_factory_constructors.py::test_init_factory_alias

* tests: Don't run tests that often segfault

* tests: drop all cross module gil tests

* tests: try skipping all macOS Python 3.9 tests

* tests: drop macOS Python 3.9

* ci: skip cpptest on Win Py 3.8+

* docs: minor typo caught by @rwgk

* docs: minor cleanup

* ci: fix add-path command

* docs: add example of use in-place

* Update .github/workflows/ci.yml

* fix: PYBIND11_OBJECT could only be used inside the pybind11 namespace (regression)

* docs: add changelog for conversion protection change

* ci: update to Python 3.9