title: qDebug() not showing const std::string&
body: <p>I am trying to use some vector data's name with <code>struct</code>. I am trying to get see which name in <code>qDebug()</code></p>
  
  <p>To be more clear: </p>
  
  <pre><code>const std::string&amp; testName = "asdfqwer";
  qDebug() &lt;&lt; testName;
  </code></pre>
  
  <p>It gives en error message in build:</p>
  
  <pre><code>Error: no match for 'operator&lt;&lt;' in 'qDebug()() &lt;&lt; testName'
  </code></pre>
  
  <p>I don't have options to change <code>const std::string&amp;</code> type. Could you please help me to solve this issue without changing type? </p>