~read_lock() = default;
/* "Not copyable" and "not moveable" Mutex requirements. */
- read_lock(read_lock const&) = delete;
+ read_lock(const read_lock&) = delete;
read_lock(read_lock&&) = delete;
read_lock& operator=(read_lock&&) = delete;
read_lock& operator=(const read_lock&) = delete;