bug#44611: Prefix arg for xref-goto-xref

[Eli Zaretskii]

> From: Juri Linkov <juri@linkov.net>
> Cc: dgutov@yandex.ru,  joaotavora@gmail.com,  44611@debbugs.gnu.org
> Date: Tue, 22 Dec 2020 23:20:37 +0200
> 
> >> Should these cases use different modes with different buffer names?
> >
> > I think it's a slippery slope to take a minor very specialized mode
> > and start adding variants to it.  But if you insist on having TAB go
> > to the next candidate, perhaps we will have no other choice than to
> > take that path.
> 
> There are already two different modes: the first is
> defined by the user option xref-show-definitions-function
> (by default, xref--show-defs-buffer), the second is defined by
> xref-show-xrefs-function (by default, xref--show-xref-buffer).
> 
> It's fine to use TAB to bury the output buffer in the first case,
> but not in the second case.

I'm okay with this distinction, provided we decide that we will try to
keep only these two variants, as much as possible.