Location-aware tags?

[Lars Magne Ingebrigtsen]

It's possible that this functionality exists, and I'm just unaware of
it, but wouldn't it be nice if `M-.' could be location-aware instead of
global?

That is, if I'm in ~/src/emacs/emacs-24/lisp and I hit `M-.', it would
use the TAGS file in ~/src/emacs/emacs-24.  If I'm in
~/src/emacs/trunk/src, it would use the TAGS file in ~/src/emacs/trunk.
And so on.

Especially when dealing with branches that have (basically) the same
symbols, just adding more tags files to the search list doesn't help.
You can almost get away with it when you're editing totally separate
projects, but even then you're occasionally popped to the wrong place.

So I'm proposing to add a new variable `tags-use-auto-tags' or
something, that would make `M-.' always look for the nearest TAGS file
upwards in the directory structure, and then switch to that file before
looking up the symbol.

Unless somebody has a better idea.

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