1 //===----------------------------------------------------------------------===//
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file is dual licensed under the MIT and the University of Illinois Open
6 // Source Licenses. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // UNSUPPORTED: libcpp-has-no-threads
11 // UNSUPPORTED: c++98, c++03, c++11
12 
13 // <shared_mutex>
14 
15 // template <class Mutex> class shared_lock;
16 
17 // mutex_type *mutex() const noexcept;
18 
19 #include <shared_mutex>
20 #include <cassert>
21 
22 std::shared_timed_mutex m;
23 
main()24 int main()
25 {
26     std::shared_lock<std::shared_timed_mutex> lk0;
27     assert(lk0.mutex() == nullptr);
28     std::shared_lock<std::shared_timed_mutex> lk1(m);
29     assert(lk1.mutex() == &m);
30     lk1.unlock();
31     assert(lk1.mutex() == &m);
32     static_assert(noexcept(lk0.mutex()), "mutex() must be noexcept");
33 }
34