cc -pthread  -Wall -Wextra -Werror=implicit-function-declaration spawn/posix_spawnattr_setschedpolicy.c -o spawn/posix_spawnattr_setschedpolicy -D_GNU_SOURCE -D_BSD_SOURCE -D_ALL_SOURCE -D_DEFAULT_SOURCE -lm -lpthread -lnetwork -lbsd -latomic
spawn/posix_spawnattr_setschedpolicy.c: In function 'main':
spawn/posix_spawnattr_setschedpolicy.c:28:24: error: implicit declaration of function 'sched_getscheduler' [-Werror=implicit-function-declaration]
   28 |         if ( (policy = sched_getscheduler(0)) < 0 &&
      |                        ^~~~~~~~~~~~~~~~~~
spawn/posix_spawnattr_setschedpolicy.c:34:55: error: 'POSIX_SPAWN_SETSCHEDULER' undeclared (first use in this function); did you mean 'POSIX_SPAWN_SETSIGDEF'?
   34 |         if ( (errno = posix_spawnattr_setflags(&attr, POSIX_SPAWN_SETSCHEDULER)) )
      |                                                       ^~~~~~~~~~~~~~~~~~~~~~~~
      |                                                       POSIX_SPAWN_SETSIGDEF
spawn/posix_spawnattr_setschedpolicy.c:34:55: note: each undeclared identifier is reported only once for each function it appears in
spawn/posix_spawnattr_setschedpolicy.c:36:23: error: implicit declaration of function 'posix_spawnattr_setschedpolicy'; did you mean 'posix_spawnattr_setsigdefault'? [-Werror=implicit-function-declaration]
   36 |         if ( (errno = posix_spawnattr_setschedpolicy(&attr, policy)) )
      |                       ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      |                       posix_spawnattr_setsigdefault
cc1: some warnings being treated as errors