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 
12 // <mutex>
13 
14 // template <class Mutex> class unique_lock;
15 
16 // template <class Mutex>
17 //   void swap(unique_lock<Mutex>& x, unique_lock<Mutex>& y);
18 
19 #include <mutex>
20 #include <cassert>
21 
22 struct mutex
23 {
lockmutex24     void lock() {}
unlockmutex25     void unlock() {}
26 };
27 
28 mutex m;
29 
main()30 int main()
31 {
32     std::unique_lock<mutex> lk1(m);
33     std::unique_lock<mutex> lk2;
34     swap(lk1, lk2);
35     assert(lk1.mutex() == nullptr);
36     assert(lk1.owns_lock() == false);
37     assert(lk2.mutex() == &m);
38     assert(lk2.owns_lock() == true);
39 }
40