cc -pthread  -Wall -Wextra -Werror=implicit-function-declaration pthread/pthread_getcpuclockid.c -o pthread/pthread_getcpuclockid -D_GNU_SOURCE -D_BSD_SOURCE -D_ALL_SOURCE -D_DEFAULT_SOURCE  -lm -lpthread  -liconv
pthread/pthread_getcpuclockid.c:20:16: error: call to undeclared function 'pthread_getcpuclockid'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
   20 |         if ( (errno = pthread_getcpuclockid(pthread_self(), &clock_id)) )
      |                       ^
pthread/pthread_getcpuclockid.c:20:16: note: did you mean 'pthread_getspecific'?
/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/pthread.h:367:17: note: 'pthread_getspecific' declared here
  367 | void* _Nullable pthread_getspecific(pthread_key_t);
      |                 ^
1 error generated.