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 lock_guard;
14 
15 // lock_guard(mutex_type& m, adopt_lock_t);
16 
17 #include <mutex>
18 #include <cstdlib>
19 #include <cassert>
20 
21 #include "test_macros.h"
22 
23 std::mutex m;
24 
25 int main(int, char**) {
26   {
27     m.lock();
28     std::lock_guard<std::mutex> lg(m, std::adopt_lock);
29     assert(m.try_lock() == false);
30   }
31 
32   m.lock();
33   m.unlock();
34 
35   return 0;
36 }
37