title: How do I get Doxygen to expand macros from include files?
body: <p>I have a number of multiline macros defined in a file called macros.h. In my doxyfile, I've got</p>
  
  <pre><code>ENABLE_PREPROCESSING   = YES
  MACRO_EXPANSION        = YES
  EXPAND_ONLY_PREDEF     = NO
  PREDEFINED             =
  EXPAND_AS_DEFINED      =
  SKIP_FUNCTION_MACROS   = NO
  </code></pre>
  
  <p>yet Doxygen still will not expand the macros in any source file that includes macros.h. I ran "doxygen -d Preprocessor doxyfile" to see the output of the preprocessor, and it outputs messages like:</p>
  
  <pre><code>#include macros.h: not found or already included! skipping...
  </code></pre>