cc -pthread  -Wall -Wextra -Werror=implicit-function-declaration time/timer_getoverrun.c -o time/timer_getoverrun -D_GNU_SOURCE -D_BSD_SOURCE -D_ALL_SOURCE -D_DEFAULT_SOURCE  -lm -lpthread  -liconv
time/timer_getoverrun.c:8:8: error: unknown type name 'timer_t'; did you mean 'time_t'?
    8 | static 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_getoverrun.c:15:18: error: call to undeclared function 'timer_getoverrun'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
   15 |         if ( (overrun = timer_getoverrun(timer)) < 0 )
      |                         ^
time/timer_getoverrun.c:37:7: error: call to undeclared function 'timer_create'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
   37 |         if ( timer_create(CLOCK_MONOTONIC, &event, &timer) < 0 )
      |              ^
time/timer_getoverrun.c:49:20: error: variable has incomplete type 'struct itimerspec'
   49 |         struct itimerspec its =
      |                           ^
time/timer_getoverrun.c:49:9: note: forward declaration of 'struct itimerspec'
   49 |         struct itimerspec its =
      |                ^
time/timer_getoverrun.c:54:7: error: call to undeclared function 'timer_settime'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
   54 |         if ( timer_settime(timer, TIMER_ABSTIME, &its, NULL) < 0 )
      |              ^
time/timer_getoverrun.c:54:28: error: use of undeclared identifier 'TIMER_ABSTIME'
   54 |         if ( timer_settime(timer, TIMER_ABSTIME, &its, NULL) < 0 )
      |                                   ^
time/timer_getoverrun.c:63:7: error: call to undeclared function 'clock_nanosleep'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
   63 |         if ( clock_nanosleep(CLOCK_MONOTONIC, TIMER_ABSTIME, &expiration,
      |              ^
time/timer_getoverrun.c:63:40: error: use of undeclared identifier 'TIMER_ABSTIME'
   63 |         if ( clock_nanosleep(CLOCK_MONOTONIC, TIMER_ABSTIME, &expiration,
      |                                               ^
8 errors generated.