cc -O2 -pipe  -pthread  -Wall -Wextra -Werror -Wno-error=deprecated -Wno-error=deprecated-declarations time/clock_nanosleep.c -o time/clock_nanosleep -D_POSIX_C_SOURCE=202405L  -lm -lpthread 
time/clock_nanosleep.c:5:74: error: use of undeclared identifier 'clock_nanosleep'
int (*foo)(clockid_t, int, const struct timespec *, struct timespec *) = clock_nanosleep;
                                                                         ^
1 error generated.