bug#19468: 25.0.50; UI inconveniences with M-.

[Eli Zaretskii]

> From: Stefan Monnier <monnier@IRO.UMontreal.CA>
> Cc: Eli Zaretskii <eliz@gnu.org>, 19468@debbugs.gnu.org
> Date: Mon, 27 Apr 2015 18:54:05 -0400
> 
> > - If I do have a tags table loaded, it's likely for a different project than
> >   Emacs.  This is most likely true for the majority of our users.
> 
> I really think the etags backend should only return data when the TAGS
> file is in one of the parents of the current directory.

That goes back to the "working on several projects" discussion of
yore.  Specifically, you might be working on two related packages
(e.g., one calls the other) that live in two different directories.

> And it should also be able to keep several independent TAGS tables
> opened for different projects in different directory trees.

It already does that.

> > I think Eli (and everyone like-minded) should advise elisp-xref-find and
> > xref-identifier-completion-table-function instead, inside their init script,
> > like suggested by Daniel in another thread.
> 
> It seems a common enough request that we should accommodate
> them better. At the very least provide a minor mode which sets up
> such advice.

User options if possible, minor modes if not, yes.