bug#19466: 25.0.50; xref-find-def doesn't find C functions

[Dmitry Gutov]

On 12/30/2014 08:05 PM, Stefan Monnier wrote:
> > Isn't it possible to _prefer_ the symbols that are consistent with the
> > major mode, but not entirely discard the other possible candidates?
>
> Indeed there should be a way to use the tags.el backend (or other
> similar whole-project systems like GNU global, ...) instead of the
> major mode's backend.

In general, a minor mode would do that (set project-specific 
xref-find-function and friends, etc), probably using a system like 
projectile to determine the current project kind.

We could do something specific for Emacs sources, but if using lisp/TAGS 
is preferred over find-func by the same developers who work on C 
sources, maybe emacs-lisp-mode shouldn't make any changes in xref-* 
variables for them. An boolean option would be the simplest solution.