cc -pthread  -Wall -Wextra -Werror=implicit-function-declaration time/timer_settime.c -o time/timer_settime -D_GNU_SOURCE -D_BSD_SOURCE -D_ALL_SOURCE -D_DEFAULT_SOURCE  -lm -lpthread  -liconv
time/timer_settime.c:30:2: error: unknown type name 'timer_t'; did you mean 'time_t'?
   30 |         timer_t timer;
      |         ^~~~~~~
      |         time_t
/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/sys/_types/_time_t.h:31:33: note: 'time_t' declared here
   31 | typedef __darwin_time_t         time_t;
      |                                 ^
time/timer_settime.c:31:7: error: call to undeclared function 'timer_create'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
   31 |         if ( timer_create(CLOCK_MONOTONIC, &event, &timer) < 0 )
      |              ^
time/timer_settime.c:33:20: error: variable has incomplete type 'struct itimerspec'
   33 |         struct itimerspec its = { .it_value = { .tv_sec = 0, .tv_nsec = 1 } };
      |                           ^
time/timer_settime.c:33:9: note: forward declaration of 'struct itimerspec'
   33 |         struct itimerspec its = { .it_value = { .tv_sec = 0, .tv_nsec = 1 } };
      |                ^
time/timer_settime.c:34:7: error: call to undeclared function 'timer_settime'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
   34 |         if ( timer_settime(timer, 0, &its, NULL) < 0 )
      |              ^
4 errors generated.