title: stack object Qt signal and parameter as reference
body: <p>May I have a "dangling reference" with the following code (in an eventual slot connected to the myQtSignal)?</p>
  
  <pre><code>class Test : public QObject
  {
      Q_OBJECT
  
  signals:
      void myQtSignal(const FooObject&amp; obj);
  
  public:
      void sendSignal(const FooObject&amp; fooStackObject)
      {
          emit  myQtSignal(fooStackObject);
      }
  };
  
  void f()
  {
      FooObject fooStackObject;
      Test t;
      t.sendSignal(fooStackObject);
  }
  
  int main()
  {
      f();
      std::cin.ignore();
      return 0;
  }
  </code></pre>
  
  <p>Particularly if emit and slot are not executed in the same thread.</p>