10.43.4 atomic_compare_exchange_weak_explicit

ISO C23 specification:
https://www.open-std.org/jtc1/sc22/wg14/www/docs/n3220.pdf section 7.17.7.4.

POSIX specification:
https://pubs.opengroup.org/onlinepubs/9799919799/functions/atomic_compare_exchange_weak_explicit.html

Gnulib module: —

Portability problems fixed by Gnulib:

Portability problems not fixed by Gnulib: