text: //===----------------------------------------------------------------------===//
  //
  //                     The LLVM Compiler Infrastructure
  //
  // This file is dual licensed under the MIT and the University of Illinois Open
  // Source Licenses. See LICENSE.TXT for details.
  //
  //===----------------------------------------------------------------------===//
  //
  // UNSUPPORTED: libcpp-has-no-threads
  // UNSUPPORTED: c++98, c++03
  
  // There's currently no release of OS X whose dylib contains the patch for
  // PR38682. Since the fix for future<void> is in the dylib, this test may fail.
  // UNSUPPORTED: apple-darwin
  
  // This test is designed to cause and allow TSAN to detect a race condition
  // in std::async, as reported in https://bugs.llvm.org/show_bug.cgi?id=38682.
  
  #include <cassert>
  #include <functional>
  #include <future>
  #include <numeric>
  #include <vector>
  
  
  static int worker(std::vector<int> const& data) {
    return std::accumulate(data.begin(), data.end(), 0);
  }
  
  static int& worker_ref(int& i) { return i; }
  
  static void worker_void() { }
  
  int main() {
    // future<T>
    {
      std::vector<int> const v{1, 2, 3, 4, 5, 6, 7, 8, 9, 10};
      for (int i = 0; i != 20; ++i) {
        std::future<int> fut = std::async(std::launch::async, worker, v);
        int answer = fut.get();
        assert(answer == 55);
      }
    }
  
    // future<T&>
    {
      for (int i = 0; i != 20; ++i) {
        std::future<int&> fut = std::async(std::launch::async, worker_ref, std::ref(i));
        int& answer = fut.get();
        assert(answer == i);
      }
    }
  
    // future<void>
    {
      for (int i = 0; i != 20; ++i) {
        std::future<void> fut = std::async(std::launch::async, worker_void);
        fut.get();
      }
    }
  }
  