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 // FLAKY_TEST.
12 
13 // <mutex>
14 
15 // template <class Mutex> class lock_guard;
16 
17 // explicit lock_guard(mutex_type& m);
18 
19 // template<class _Mutex> lock_guard(lock_guard<_Mutex>)
20 //     -> lock_guard<_Mutex>;  // C++17
21 
22 #include <mutex>
23 #include <thread>
24 #include <cstdlib>
25 #include <cassert>
26 
27 #include "test_macros.h"
28 
29 std::mutex m;
30 
31 typedef std::chrono::system_clock Clock;
32 typedef Clock::time_point time_point;
33 typedef Clock::duration duration;
34 typedef std::chrono::milliseconds ms;
35 typedef std::chrono::nanoseconds ns;
36 
37 void f()
38 {
39     time_point t0 = Clock::now();
40     time_point t1;
41     {
42     std::lock_guard<std::mutex> lg(m);
43     t1 = Clock::now();
44     }
45     ns d = t1 - t0 - ms(250);
46     assert(d < ms(200));  // within 200ms
47 }
48 
49 int main(int, char**)
50 {
51     m.lock();
52     std::thread t(f);
53     std::this_thread::sleep_for(ms(250));
54     m.unlock();
55     t.join();
56 
57 #ifdef __cpp_deduction_guides
58     std::lock_guard lg(m);
59     static_assert((std::is_same<decltype(lg), std::lock_guard<decltype(m)>>::value), "" );
60 #endif
61 
62   return 0;
63 }
64