Detects when a mutex is used before it’s initialized.

pthread_mutex_t.md

Use the pthread_once(_:_:) function to ensure that initialization is called before a mutex is used.

static pthread_once_t once = PTHREAD_ONCE_INIT;
static pthread_mutex_t mutex;
void init() {    
    pthread_mutex_init(&mutex, NULL);
}
void performWork() {
    pthread_once(&once, init); // Correct
    pthread_mutex_lock(&mutex);
    // ...
    pthread_mutex_unlock(&mutex);
}