cc -O2 -pipe  -pthread  -Wall -Wextra -Werror=implicit-function-declaration spawn/posix_spawnattr_setschedparam.c -o spawn/posix_spawnattr_setschedparam -D_GNU_SOURCE -D_BSD_SOURCE -D_ALL_SOURCE -D_DEFAULT_SOURCE  -lm -lpthread 
spawn/posix_spawnattr_setschedparam.c:28:7: error: call to undeclared function 'sched_getparam'; ISO C99 and later do not support implicit function declarations [-Werror,-Wimplicit-function-declaration]
   28 |         if ( sched_getparam(0, &param) < 0 )
      |              ^
1 error generated.