cc -pthread -Wall -Wextra -Werror=implicit-function-declaration pthread/pthread_mutexattr_setrobust.c -o pthread/pthread_mutexattr_setrobust -D_GNU_SOURCE -D_BSD_SOURCE -D_ALL_SOURCE -D_DEFAULT_SOURCE -lm -lpthread -liconv pthread/pthread_mutexattr_setrobust.c:12:16: error: call to undeclared function 'pthread_mutexattr_setrobust'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration] 12 | if ( (errno = pthread_mutexattr_setrobust(&attr, PTHREAD_MUTEX_ROBUST)) ) | ^ pthread/pthread_mutexattr_setrobust.c:12:51: error: use of undeclared identifier 'PTHREAD_MUTEX_ROBUST' 12 | if ( (errno = pthread_mutexattr_setrobust(&attr, PTHREAD_MUTEX_ROBUST)) ) | ^ pthread/pthread_mutexattr_setrobust.c:15:16: error: call to undeclared function 'pthread_mutexattr_getrobust'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration] 15 | if ( (errno = pthread_mutexattr_getrobust(&attr, &robustness)) ) | ^ pthread/pthread_mutexattr_setrobust.c:17:21: error: use of undeclared identifier 'PTHREAD_MUTEX_ROBUST' 17 | if ( robustness != PTHREAD_MUTEX_ROBUST ) | ^ 4 errors generated.