title: gcc dump resolved defines
body: <p>I have code like</p>
  
  <pre><code>#define ONE 1
  #define TWO 2
  #define SUM (ONE+TWO)
  </code></pre>
  
  <p>How do I dump SUM as "3", the resolved value, in gcc 4.3+?</p>
  
  <p><code>gcc -dM -E foo.h</code> only seems to dump it as is. How do I get the actual value like it's inserted on compilation stage?</p>