title: Qt: field has incomplete type
body: <p>Can't compile my class.
  Getting error:
  error: field 'filename' has incomplete type</p>
  
  <p>If I change <code>QString filename</code> to <code>QString *filename</code>, error goes off.. but I need to have <code>QString filename</code>.</p>
  
  <p>process.h:</p>
  
  <pre><code>#ifndef PROCESS_H
  #define PROCESS_H
  
  #include &lt;QString&gt;
  
  class Process
  {
  public:
      int pid;
      QString filename;
      Process(int pid, QString filename);
  };
  
  #endif // PROCESS_H
  </code></pre>
  
  <p>process.cpp:</p>
  
  <pre><code>#include "process.h"
  
  Process::Process(int pid, QString filename)
  {
      this-&gt;pid = pid;
      this-&gt;filename = filename;
  }
  </code></pre>
  
  <p>What's wrong?</p>