1 //===----------------------------------------------------------------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // UNSUPPORTED: libcpp-has-no-threads
10 
11 // <mutex>
12 
13 // template <class Mutex> class unique_lock;
14 
15 // void swap(unique_lock& u);
16 
17 #include <mutex>
18 #include <cassert>
19 
20 struct mutex
21 {
22     void lock() {}
23     void unlock() {}
24 };
25 
26 mutex m;
27 
28 int main(int, char**)
29 {
30     std::unique_lock<mutex> lk1(m);
31     std::unique_lock<mutex> lk2;
32     lk1.swap(lk2);
33     assert(lk1.mutex() == nullptr);
34     assert(lk1.owns_lock() == false);
35     assert(lk2.mutex() == &m);
36     assert(lk2.owns_lock() == true);
37 
38   return 0;
39 }
40