[qt/clang/llvm-project]: Summary of bulk changes made

Git repository change summary for qt/clang/llvm-project
Pushed by mirror-service into branch 'upstream/users/aokblast/libcxx/fix_odr_on_clang_module'.
Changed from 0000000000000000000000000000000000000000 to 164de49e3b7ab9fc2924c4808dd6d23d12e7aadd
Acknowledgement was received that this change introduces only existing code that has been pushed to another public open source repository.

This change contains the following new commits:

Git commit 164de49e3b7ab9fc2924c4808dd6d23d12e7aadd by ShengYi Hung on 13/08/2026 at 14:36..
[libcxx] Fix ODR violation in FreeBSD path

When building stdcxx clang module, it include cwchar and trigger
inclusion of wchar.h in libcxx, which expand inline function of
__libcpp_wcschr. However, wchar.h includes __mbstate_t, which include
wchar.h again. This causes __libcpp_wcschr exposes to
std_private_mbstate_t and create ODR violation.

It doesn't happen on other platforms as we don't instantiate
__libcpp_wcschr as _LIBCPP_WCHAR_H_HAS_CONST_OVERLOADS is defined.

To fix it, we creates a stub macro _LIBCPP_WCHAR_H_SYSTEM_HEADER_ONLY to
make wchar.h instantiation is not happens when building
std_private_mbstate_t module.
https://invent.kde.org/qt/clang/llvm-project/-/commit/164de49e3b7ab9fc2924c4808dd6d23d12e7aadd