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 // void swap(unique_lock& u);
17 
18 #include <mutex>
19 #include <cassert>
20 
21 struct mutex
22 {
lockmutex23     void lock() {}
unlockmutex24     void unlock() {}
25 };
26 
27 mutex m;
28 
main()29 int main()
30 {
31     std::unique_lock<mutex> lk1(m);
32     std::unique_lock<mutex> lk2;
33     lk1.swap(lk2);
34     assert(lk1.mutex() == nullptr);
35     assert(lk1.owns_lock() == false);
36     assert(lk2.mutex() == &m);
37     assert(lk2.owns_lock() == true);
38 }
39