cc -pthread  -Wall -Wextra -Werror=implicit-function-declaration pthread/pthread_barrier_wait.c -o pthread/pthread_barrier_wait -D_GNU_SOURCE -D_BSD_SOURCE -D_ALL_SOURCE -D_DEFAULT_SOURCE  -lm -lpthread  -liconv
pthread/pthread_barrier_wait.c:8:8: error: unknown type name 'pthread_barrier_t'
    8 | static pthread_barrier_t barrier;
      |        ^
pthread/pthread_barrier_wait.c:14:16: error: call to undeclared function 'pthread_barrier_wait'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
   14 |         if ( (errno = pthread_barrier_wait(&barrier)) &&
      |                       ^
pthread/pthread_barrier_wait.c:15:16: error: use of undeclared identifier 'PTHREAD_BARRIER_SERIAL_THREAD'
   15 |              errno != PTHREAD_BARRIER_SERIAL_THREAD )
      |                       ^
pthread/pthread_barrier_wait.c:22:2: error: unknown type name 'pthread_barrierattr_t'; did you mean 'pthread_mutexattr_t'?
   22 |         pthread_barrierattr_t attr;
      |         ^~~~~~~~~~~~~~~~~~~~~
      |         pthread_mutexattr_t
/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/sys/_pthread/_pthread_mutexattr_t.h:31:38: note: 'pthread_mutexattr_t' declared here
   31 | typedef __darwin_pthread_mutexattr_t pthread_mutexattr_t;
      |                                      ^
pthread/pthread_barrier_wait.c:23:16: error: call to undeclared function 'pthread_barrierattr_init'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
   23 |         if ( (errno = pthread_barrierattr_init(&attr)) )
      |                       ^
pthread/pthread_barrier_wait.c:23:16: note: did you mean 'pthread_mutexattr_init'?
/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/pthread.h:431:5: note: 'pthread_mutexattr_init' declared here
  431 | int pthread_mutexattr_init(pthread_mutexattr_t *);
      |     ^
pthread/pthread_barrier_wait.c:25:16: error: call to undeclared function 'pthread_barrier_init'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
   25 |         if ( (errno = pthread_barrier_init(&barrier, &attr, 2)) )
      |                       ^
pthread/pthread_barrier_wait.c:30:16: error: call to undeclared function 'pthread_barrier_wait'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
   30 |         if ( (errno = pthread_barrier_wait(&barrier)) &&
      |                       ^
pthread/pthread_barrier_wait.c:31:16: error: use of undeclared identifier 'PTHREAD_BARRIER_SERIAL_THREAD'
   31 |              errno != PTHREAD_BARRIER_SERIAL_THREAD )
      |                       ^
8 errors generated.