cc -pthread  -Wall -Wextra -Werror=implicit-function-declaration pthread/pthread_condattr_setclock.c -o pthread/pthread_condattr_setclock -D_GNU_SOURCE -D_BSD_SOURCE -D_ALL_SOURCE -D_DEFAULT_SOURCE  -lm -lpthread  -liconv
pthread/pthread_condattr_setclock.c:13:16: error: call to undeclared function 'pthread_condattr_getclock'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
   13 |         if ( (errno = pthread_condattr_getclock(&attr, &clock_id)) )
      |                       ^
pthread/pthread_condattr_setclock.c:13:16: note: did you mean 'pthread_condattr_destroy'?
/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/pthread.h:324:5: note: 'pthread_condattr_destroy' declared here
  324 | int pthread_condattr_destroy(pthread_condattr_t *);
      |     ^
pthread/pthread_condattr_setclock.c:17:16: error: call to undeclared function 'pthread_condattr_setclock'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
   17 |         if ( (errno = pthread_condattr_setclock(&attr, CLOCK_MONOTONIC)) )
      |                       ^
2 errors generated.