[Bug preprocessor/48865] New: It would be useful to have a way to check the value of a #define at preprocessing time

[bero at arklinux dot org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=48865

           Summary: It would be useful to have a way to check the value of
                    a #define at preprocessing time
           Product: gcc
           Version: 4.7.0
            Status: UNCONFIRMED
          Severity: enhancement
          Priority: P3
         Component: preprocessor
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: bero@arklinux.org


When debugging compile failures in huge projects that heavily (ab)use
preprocessor macros, it would be useful to have a way to output the value of a
preprocessor token, e.g. something like

#define XYZ 42 // buried deep inside some header
#warning XYZ is ##XYZ

should say
XYZ is 42

or, better yet:
XYZ is 42 (defined in something.h:123, included from somethingelse.h:456,
included from stillsomethingelse.h:789)