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 // <shared_mutex>
13 
14 // template <class Mutex> class shared_lock;
15 
16 // mutex_type* release() noexcept;
17 
18 #include <shared_mutex>
19 #include <cassert>
20 
21 #if _LIBCPP_STD_VER > 11
22 
23 struct mutex
24 {
25     static int lock_count;
26     static int unlock_count;
lock_sharedmutex27     void lock_shared() {++lock_count;}
unlock_sharedmutex28     void unlock_shared() {++unlock_count;}
29 };
30 
31 int mutex::lock_count = 0;
32 int mutex::unlock_count = 0;
33 
34 mutex m;
35 
36 #endif  // _LIBCPP_STD_VER > 11
37 
main()38 int main()
39 {
40 #if _LIBCPP_STD_VER > 11
41     std::shared_lock<mutex> lk(m);
42     assert(lk.mutex() == &m);
43     assert(lk.owns_lock() == true);
44     assert(mutex::lock_count == 1);
45     assert(mutex::unlock_count == 0);
46     assert(lk.release() == &m);
47     assert(lk.mutex() == nullptr);
48     assert(lk.owns_lock() == false);
49     assert(mutex::lock_count == 1);
50     assert(mutex::unlock_count == 0);
51     static_assert(noexcept(lk.release()), "release must be noexcept");
52 #endif  // _LIBCPP_STD_VER > 11
53 }
54