cc -O2 -pipe  -pthread  -Wall -Wextra -Werror=implicit-function-declaration pthread/pthread_setschedprio.c -o pthread/pthread_setschedprio -D_GNU_SOURCE -D_BSD_SOURCE -D_ALL_SOURCE -D_DEFAULT_SOURCE  -lm -lpthread 
pthread/pthread_setschedprio.c:20:16: error: call to undeclared function 'pthread_setschedprio'; ISO C99 and later do not support implicit function declarations [-Werror,-Wimplicit-function-declaration]
   20 |         if ( (errno = pthread_setschedprio(pthread_self(), priority)) /*&&
      |                       ^
pthread/pthread_setschedprio.c:20:16: note: did you mean 'pthread_setschedparam'?
/usr/include/pthread.h:292:6: note: 'pthread_setschedparam' declared here
  292 | int             pthread_setschedparam(pthread_t, int,
      |                 ^
1 error generated.