libcxx/test/std/thread/thread.mutex/thread.lock/thread.lock.shared/thread.lock.shared.obs/op_bool.pass.cpp

   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: no-threads
  10 // UNSUPPORTED: c++03, c++11
  11
  12 // <shared_mutex>
  13
  14 // template <class Mutex> class shared_lock;
  15
  16 // explicit operator bool() const noexcept;
  17
  18 #include <shared_mutex>
  19 #include <cassert>
  20 #include <type_traits>
  21
  22 #include "test_macros.h"
  23
  24 struct M {
  25     void lock_shared() {}
  26     void unlock_shared() {}
  27 };
  28
  29 int main(int, char**)
  30 {
  31     static_assert(std::is_constructible<bool, std::shared_lock<M>>::value, "");
  32     static_assert(!std::is_convertible<std::shared_lock<M>, bool>::value, "");
  33
  34     M m;
  35     std::shared_lock<M> lk0;
  36     assert(static_cast<bool>(lk0) == false);
  37     std::shared_lock<M> lk1(m);
  38     assert(static_cast<bool>(lk1) == true);
  39     lk1.unlock();
  40     assert(static_cast<bool>(lk1) == false);
  41     ASSERT_NOEXCEPT(static_cast<bool>(lk0));
  42
  43     return 0;
  44 }