cc -O2 -pipe -pthread  -Wall -Wextra -Werror -Wno-error=deprecated -Wno-error=deprecated-declarations unistd/_POSIX2_SYMLINKS.c -o unistd/_POSIX2_SYMLINKS -D_POSIX_C_SOURCE=202405L  -lm -lpthread -lrt  -lstdthreads -lcrypt
unistd/_POSIX2_SYMLINKS.c:3:17: error: use of undeclared identifier '_POSIX2_SYMLINKS'
    3 | int const foo = _POSIX2_SYMLINKS;
      |                 ^
1 error generated.