I have a number of multiline macros defined in a file called macros.h. In my doxyfile, I've got
ENABLE_PREPROCESSING = YES
MACRO_EXPANSION = YES
EXPAND_ONLY_PREDEF = NO
PREDEFINED =
EXPAND_AS_DEFINED =
SKIP_FUNCTION_MACROS = NO
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:
#include macros.h: not found or already included! skipping...