cc -pthread  -Wall -Wextra -Werror=implicit-function-declaration sched/sched_getscheduler.c -o sched/sched_getscheduler -D_GNU_SOURCE -D_BSD_SOURCE -D_ALL_SOURCE -D_DEFAULT_SOURCE  -lm -lpthread  -liconv
sched/sched_getscheduler.c:10:15: error: call to undeclared function 'sched_getscheduler'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
   10 |         int policy = sched_getscheduler(0);
      |                      ^
1 error generated.