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
22struct mutex
23{
24    void lock() {}
25    void unlock() {}
26};
27
28mutex m;
29
30int 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