title: Expression has no effect warning
body: <p>I have a callback function which gets called when a hardware interrupt is generated. But when I build my code I am getting "expression has no effect"</p>
  
  <pre><code>void registerCallBack(int originator,uint32* cbackFunction)
  {
      Originator[originator].callback = cbackFunction;
  }
  
  // interrupt calls the following function
  void callbackFunction(int originator)
  {
  
      Originator[originator].callback;  // throwing warning here
  }
  </code></pre>