33 Thread support library [thread]

33.4 Mutual exclusion [thread.mutex]

33.4.4 Locks [thread.lock]

33.4.4.4 Class template shared_­lock [thread.lock.shared]

33.4.4.4.4 shared_­lock observers [thread.lock.shared.obs]

bool owns_lock() const noexcept;

explicit operator bool() const noexcept;

mutex_type* mutex() const noexcept;