cc -O2 -pipe  -pthread  -Wall -Wextra -Werror -Wno-error=deprecated -Wno-error=deprecated-declarations sched/sched_rr_get_interval.c -o sched/sched_rr_get_interval -D_POSIX_C_SOURCE=202405L  -lm -lpthread 
sched/sched_rr_get_interval.c:6:40: error: use of undeclared identifier 'sched_rr_get_interval'
int (*foo)(pid_t, struct timespec *) = sched_rr_get_interval;
                                       ^
1 error generated.