bug#6870: Make vc-root-diff work in more modes

[Lars Magne Ingebrigtsen]

Stefan Monnier <monnier@iro.umontreal.ca> writes:

> It's only reasonable in buffers where default-directory is really
> meaningful.  E.g. in *Help* or *info* it's likely not going to do you
> much good.
> So feel free to add more major modes (rather than just `dired'), but
> I don't think using (vc-responsible-backend default-directory)
> everywhere is a good idea.

What about all buffers that have file names?  A la

(and (buffer-file-name)
     (vc-responsible-backend default-directory))

or something along those lines...
     
-- 
(domestic pets only, the antidote for overdose, milk.)
  bloggy blog http://lars.ingebrigtsen.no/