chore: prepare for the 2.6.2 release

[henryiii]

Minor missing functionality added:

• enum: add missing Enum.value property. #2739
• Allow thread termination to be avoided during shutdown for CPython 3.7+ via .disarm for gil_scoped_acquire/gil_scoped_release. #2657

Fixed or improved behavior in a few special cases:

• Fix bug where the constructor of object subclasses would not throw on being passed a Python object of the wrong type. #2701
• The type_caster for integers does not convert Python objects with __int__ anymore with noconvert or during the first round of trying overloads. #2698
• When casting to a C++ integer, __index__ is always called and not considered as conversion, consistent with Python 3.8+. #2801

Build improvements:

• Setup helpers: extra_compile_args and extra_link_args automatically set by Pybind11Extension are now prepended, which allows them to be overridden by user-set extra_compile_args and extra_link_args. #2808
• Setup helpers: Don't trigger unused parameter warning. #2735
• CMake: Support running with --warn-uninitialized active. #2806
• CMake: Avoid error if included from two submodule directories. #2804
• CMake: Fix STATIC / SHARED being ignored in FindPython mode. #2796
• CMake: Respect the setting for CMAKE_CXX_VISIBILITY_PRESET if defined. #2793
• CMake: Fix issue with FindPython2/FindPython3 not working with pybind11::embed. #2662
• CMake: mixing local and installed pybind11's would prioritize the installed one over the local one (regression in 2.6.0). #2716

Bug fixes:

• Fixed segfault in multithreaded environments when using scoped_ostream_redirect. #2675
• Leave docstring unset when all docstring-related options are disabled, rather than set an empty string. #2745
• The module key in builtins that pybind11 uses to store its internals changed from std::string to a python str type (more natural on Python 2, no change on Python 3). #2814
• Fixed assertion error related to unhandled (later overwritten) exception in CPython 3.8 and 3.9 debug builds. #2685
• Fix py::gil_scoped_acquire assert with CPython 3.9 debug build. #2683
• Fix issue with a test failing on PyTest 6.2. #2741

Warning fixes:

• Fix warning modifying constructor parameter 'flag' that shadows a field of 'set_flag' [-Wshadow-field-in-constructor-modified]. #2780
• Suppressed some deprecation warnings about old-style __init__/__setstate__ in the tests. #2759

Valgrind work:

• Fix invalid access when calling a pybind11 __init__ on a non-pybind11 class instance. #2755
• Fixed various minor memory leaks in pybind11's test suite. #2758
• Resolved memory leak in cpp_function initialization when exceptions occurred. #2756
• Added a Valgrind build, checking for leaks and memory-related UB, to CI. #2746

Compiler support:

• Intel compiler was not activating C++14 support due to a broken define. #2679
• Support ICC and NVIDIA HPC SDK in C++17 mode. #2729
• Support Intel OneAPI compiler (ICC 20.2) and add to CI. #2573

[YannickJadoul]

Wow, this was autogenerated, I hope? This is just the changelog as it will be?

[henryiii]

Ehh, partially. I want to make it fully automated, but gave up on messing with the regex to pick out the first block, will work on it later. This is the result of pandoc + a few quick manips in VI. ([\ -> [, - to * , and set textwidth=300 followed by gq on blocks of bullets (since Github cares about line breaks in markdown, and it affects release notes).

[henryiii]

And, yes, this is markdown I can copy and paste into release notes. :)

[YannickJadoul]

Ah, that's great! :-)

[YannickJadoul]

Not an approval you urgently need, but ... here you go

[henryiii]

Thinking about dropping AppVeyor, now that we have Github actions testing MSVC 2015... One of the AppVeyor tests hung up. If it's Appveyor's fault, I'm interested in dropping it. If it's our fault, then not so much...

[henryiii]

It seems to have died on test_gil_scoped, which is worrisome.

[henryiii]

It's fine now. I've added pytest-timeout (just for AppVeyor) just in case it happens again, we might get some debugging info then (if a job times out, you get absolutely nothing. If pytest-timeout does, you often get a nice traceback to see where it died. Might not work for a compiled piece, but better than no chance at all!)

[YannickJadoul]

test_gil_scoped

Probably still linked to #2754?

[henryiii]

A GHA MSVC job stalled this time.

[henryiii]

It's out! Bumped brew too. Homebrew/homebrew-core#69840