title: Qt connect crash when using lambda function
body: <p>Code is here</p>
  
  <pre><code>void A::fun()
  {
      QAction* act = new QAction(this);
      QAction* act2 = new QAction(this);
      connect(act, QAction::triggered, [this, &amp;act2]() {...; act2.setDisable(true);}
                                // crash when &amp;act2 is used to capture the variable
                                // but it is okay using act2 to capture the variable
  }
  </code></pre>
  
  <p>What is the reason? Thanks.</p>