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 // <mutex>
11 
12 // template <class Mutex> class unique_lock;
13 
14 // mutex_type *mutex() const;
15 
16 #include <mutex>
17 #include <cassert>
18 
19 std::mutex m;
20 
21 int main()
22 {
23     std::unique_lock<std::mutex> lk0;
24     assert(lk0.mutex() == nullptr);
25     std::unique_lock<std::mutex> lk1(m);
26     assert(lk1.mutex() == &m);
27     lk1.unlock();
28     assert(lk1.mutex() == &m);
29 }
30