title: Does Q_UNUSED have any side effects?
body: <p>Given the following piece of code:</p>
  
  <pre><code>void test(int var)
  {
       Q_UNUSED(var);
  #ifdef SOMETHING
       printf("%d",var);
       //do something else with var...
  #endif
  }
  </code></pre>
  
  <p>Would the <code>Q_UNUSED</code> macro have any effect if I actually use the 'var' variable in some scenario (like in the example above), or it has no effect at all when I suppress compiler warnings for unused variables?</p>
  
  <p>So far I observe it has no effect, but I would like to make sure.</p>