title: How to tell where a header file is included from?
body: <p>How can I tell where g++ was able to find an include file?  Basically if I</p>
  
  <pre><code>#include &lt;foo.h&gt;
  </code></pre>
  
  <p>g++ will scan the search path, using any include options to add or alter the path.  But, at the end of days, is there a way I can tell the absolute path of foo.h that g++ chose to compile?  Especially relevant if there is more than one foo.h in the myriad of search paths.</p>
  
  <p>Short of a way of accomplishing that... is there a way to get g++ to tell me what its final search path is after including defaults and all include options?</p>