[Bug driver/57951] New: -MG doesn't work with -MD

[f.heckenbach@fh-soft.de]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57951

            Bug ID: 57951
           Summary: -MG doesn't work with -MD
           Product: gcc
           Version: 4.7.2
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: driver
          Assignee: unassigned at gcc dot gnu.org
          Reporter: f.heckenbach@fh-soft.de

This was reported as Debian bug #593086 several years ago ...

% gcc -MD -MG foo.c
cc1: error: -MG may only be used with -M or -MM

(Contents of source file don't matter.)

According to the manual

  `-MD' is equivalent to `-M -MF FILE', except that `-E' is not implied.

so I figure it should work. (It did in previous versions, e.g. 4.1.2)

There seems to be no work-around since "-M" implies "-E".

I guess the driver only needs to be told that "-MD" is also OK for "-MG" to
work since it implies "-M".