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 // <mutex> 11 12 // template <class Mutex> class unique_lock; 13 14 // explicit operator bool() const; 15 16 #include <mutex> 17 #include <cassert> 18 19 std::mutex m; 20 main()21int main() 22 { 23 std::unique_lock<std::mutex> lk0; 24 assert(static_cast<bool>(lk0) == false); 25 std::unique_lock<std::mutex> lk1(m); 26 assert(static_cast<bool>(lk1) == true); 27 lk1.unlock(); 28 assert(static_cast<bool>(lk1) == false); 29 } 30