cc -O2 -pipe -pthread  -Wall -Wextra -Werror -Wno-error=deprecated -Wno-error=deprecated-declarations unistd/_SC_THREAD_ROBUST_PRIO_PROTECT.c -o unistd/_SC_THREAD_ROBUST_PRIO_PROTECT -D_POSIX_C_SOURCE=202405L  -lm -lpthread -lrt  -lstdthreads -lcrypt
unistd/_SC_THREAD_ROBUST_PRIO_PROTECT.c:2:17: error: use of undeclared identifier '_SC_THREAD_ROBUST_PRIO_PROTECT'
    2 | int const foo = _SC_THREAD_ROBUST_PRIO_PROTECT;
      |                 ^
1 error generated.