title: Where is stdarg.h?
body: <p>On my system (Mac OS 10.6) <em>/usr/include/stdarg.h</em> is:</p>
  
  <pre><code>/* This file is public domain.  */
  /* GCC uses its own copy of this header */
  #if defined(__GNUC__)
  #include_next &lt;stdarg.h&gt;
  #elif defined(__MWERKS__)
  #include "mw_stdarg.h"
  #else
  #error "This header only supports __MWERKS__."
  #endif
  </code></pre>
  
  <p>So, if GCC uses its own copy of <em>stdarg.h</em>, where is it? I have no idea on what
  that <code>#include_next</code> means (maybe a GCC extension?), nor something about
  "MWERKS" (a compiler?).</p>