libcxx/test/std/thread/thread.jthread/joinable.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, c++14, c++17
  11 // XFAIL: availability-synchronization_library-missing
  12
  13 // [[nodiscard]] bool joinable() const noexcept;
  14
  15 #include <atomic>
  16 #include <cassert>
  17 #include <concepts>
  18 #include <thread>
  19 #include <type_traits>
  20
  21 #include "make_test_thread.h"
  22 #include "test_macros.h"
  23
  24 static_assert(noexcept(std::declval<const std::jthread&>().joinable()));
  25
  26 int main(int, char**) {
  27   // Default constructed
  28   {
  29     const std::jthread jt;
  30     std::same_as<bool> decltype(auto) result = jt.joinable();
  31     assert(!result);
  32   }
  33
  34   // Non-default constructed
  35   {
  36     const std::jthread jt                    = support::make_test_jthread([] {});
  37     std::same_as<bool> decltype(auto) result = jt.joinable();
  38     assert(result);
  39   }
  40
  41   // Non-default constructed
  42   // the thread of execution has not finished
  43   {
  44     std::atomic_bool done                    = false;
  45     const std::jthread jt                    = support::make_test_jthread([&done] { done.wait(false); });
  46     std::same_as<bool> decltype(auto) result = jt.joinable();
  47     done                                     = true;
  48     done.notify_all();
  49     assert(result);
  50   }
  51
  52   return 0;
  53 }