macros and defines used in file

[Brian Dessent]

J?drzej Dudkiewicz wrote:

> So, my question is - is there a way to force cpp or gcc (As I believe
> gcc has internal preprocessor, which can do a little more that
> standalone cpp?) to show defines and macros used during file
> preprocessing, even those, who aren't used because '#if' branching
> forbade it? Or is there any other, clever method to do what I want?
> (Clever as in "not by hand" :] ).

Can't you just diff the preprocessed source with and without
COMPONENT_NAME defined?  If the output is identical then its presence
cannot possibly have any semantic effect.

Brian