tree 9b968f764a91c4d12fb24b457791985ab9444f5e
parent e9664b064e188a538ddbd6b9268dba6f624b50ae
author Fabian Keßler <fabian_kessler@gmx.de> 1714514918 +0200
committer Copybara-Service <copybara-worker@google.com> 1714515288 -0700

Add basic char*_t support for libc (partial WG14 N2653) (#90360)

This PR implements a part of WG14 N2653:
 - Define C23 char8_t
 - Define C11 char16_t
 - Define C11 char32_t

 Missing goals are:
- The type of UTF-8 character literals is changed from unsigned char to
char8_t. (Since UTF-8 character literals already have type unsigned
char, this is not a semantic change).
- New mbrtoc8() and c8rtomb() functions declared in <uchar.h> enable
conversions between multibyte characters and UTF-8.
    - A new ATOMIC_CHAR8_T_LOCK_FREE macro.
    - A new atomic_char8_t typedef name.

GitOrigin-RevId: cd7a7a56fc73c73855036f77a4f69ea90c75c27a