title: Qt Creator's intellisense grays out #ifdef _DEBUG blocks even though Debug build is selected
body: <p>When I have in my code an <code>#ifdef</code> like this</p>
  
  <pre><code>#ifdef _DEBUG
      printf("This is a debug build");
  #endif
  </code></pre>
  
  <p>Qt Creator grays out the <code>printf</code> even though it is a debug build, and when I run it <code>"This is a debug build"</code> gets printed.</p>
  
  <p>It seems that the intellisense isn't seeing the preprocessor defines that will be passed to the compiler via the command line (i.e. <code>-D_DEBUG</code>) instead of being defined in the header/source files.</p>