title: qDebug not showing __FILE__,__LINE__
body: <p>According to qlogging.h</p>
  
  <pre><code>#define qDebug QMessageLogger(__FILE__, __LINE__, Q_FUNC_INFO).debug
  </code></pre>
  
  <p>but when I use like this, file,line,function name not show.</p>
  
  <pre><code>qDebug()&lt;&lt; "abc"; // only show abc;
  qDebug()&lt;&lt; "";    // show nothing;
  </code></pre>
  
  <p>I search for a while, it seems no one had my problem like above.</p>
  
  <p>I use ubuntu14.04,g++ version 4.8.2, qt5.3 build from git.</p>