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 // <shared_mutex>
11 
12 // template <class Mutex> class shared_lock;
13 
14 // mutex_type* release() noexcept;
15 
16 #include <shared_mutex>
17 #include <cassert>
18 
19 #if _LIBCPP_STD_VER > 11
20 
21 struct mutex
22 {
23     static int lock_count;
24     static int unlock_count;
lock_sharedmutex25     void lock_shared() {++lock_count;}
unlock_sharedmutex26     void unlock_shared() {++unlock_count;}
27 };
28 
29 int mutex::lock_count = 0;
30 int mutex::unlock_count = 0;
31 
32 mutex m;
33 
34 #endif  // _LIBCPP_STD_VER > 11
35 
main()36 int main()
37 {
38 #if _LIBCPP_STD_VER > 11
39     std::shared_lock<mutex> lk(m);
40     assert(lk.mutex() == &m);
41     assert(lk.owns_lock() == true);
42     assert(mutex::lock_count == 1);
43     assert(mutex::unlock_count == 0);
44     assert(lk.release() == &m);
45     assert(lk.mutex() == nullptr);
46     assert(lk.owns_lock() == false);
47     assert(mutex::lock_count == 1);
48     assert(mutex::unlock_count == 0);
49     static_assert(noexcept(lk.release()), "release must be noexcept");
50 #endif  // _LIBCPP_STD_VER > 11
51 }
52