title: invalid application of 'sizeof' to incomplete type 'QImage'
body: <p>This happens even on a <strong>newly created</strong> Qt Creator project. It's a Qt Widgets Application. When I try to compile it using the Qt 5.4.2 MinGW toolchain I get this error:</p>
  
  <pre>..\..\..\Qt\5.4\mingw491_32\include/QtCore/qtypeinfo.h:178:31: error: invalid application of 'sizeof' to incomplete type 'QImage'
           isLarge = (sizeof(TYPE)>sizeof(void*)), \
                                 ^
  </pre>
  
  <p>If I compile it using the other toolchain I have installed (Qt 5.4.2 VS2008), the same project <strong>compiles without any errors</strong>.</p>
  
  <p>So I assume this is a problem with the configuration of the MinGW toolchain.</p>
  
  <p>Full compiler output - <a href="http://pastebin.com/kUW6Ss6v" rel="nofollow">http://pastebin.com/kUW6Ss6v</a>.</p>
  
  <p>Is this a problem with the MinGW toolchain, and how do I fix it?</p>
  
  <p><strong>Edit:</strong> I created a minimal example that reproduces the error:</p>
  
  <pre><code>#include &lt;QImage&gt;
  int main(int argc, char *argv[]) {
      return 0;
  }
  </code></pre>
  
  <p>This fails under the MinGW toolchain with the same error, but compiles under the VS2008 toolchain.</p>