C++11多线程:Valgrind未初始化的值警告

我使用gcc 8.2.1在Linux下编译了以下虚拟程序:

#include 
#include 
#include 

struct Foo
{
  void start() {
    thread = std::thread(&Foo::run, this);
  }

  void stop() {
    mutex.lock();
    dOne= true;
    mutex.unlock();

    thread.join();
  }

  void run() {
    bool tmp;

    for (;;) {
      mutex.lock();
      tmp = done;
      mutex.unlock();

      if (tmp)
        break;
    }
  }

  std::thread thread;
  std::mutex mutex;
  bool done;
};

int main()
{
  Foo foo;

  std::cout <<"starting...\n";
  foo.start();

  std::cout <<"stopping...\n";
  foo.stop();

  std::cout <<"done\n";
}

如果我随后在valgrind 3.14.0下运行它,我会收到以下警告:

==30060== Thread 2:
==30060== Conditional jump or move depends on uninitialised value(s)
==30060==    at 0x1095F3: Foo::run() (in /.../a.out)
==30060==    by 0x109AAE: void std::__invoke_impl(std::__invoke_memfun_deref, void (Foo::*&&)(), Foo*&&) (in /.../a.out)
==30060==    by 0x109771: std::__invoke_result::type std::__invoke(void (Foo::*&&)(), Foo*&&) (in /.../a.out)
==30060==    by 0x10A012: decltype (__invoke((_S_declval<0ul>)(), (_S_declval<1ul>)())) std::thread::_Invoker >::_M_invoke<0ul, 1ul>(std::_Index_tuple<0ul, 1ul>) (in /.../a.out)
==30060==    by 0x109FB8: std::thread::_Invoker >::operator()() (in /.../a.out)
==30060==    by 0x109F8D: std::thread::_State_impl > >::_M_run() (in /.../a.out)
==30060==    by 0x496A062: execute_native_thread_routine (thread.cc:80)
==30060==    by 0x4894A9C: start_thread (in /usr/lib/libpthread-2.28.so)
==30060==    by 0x4CD7A42: clone (in /usr/lib/libc-2.28.so)

  //...
  std::mutex mutex;
  bool dOne= false; // <--