Re: xref-query-replace-in-results error message after xref-find-definitions, was: Re: bug#58158: 29.0.50; [overlay] Interval tree iteration considered harmful

[Eli Zaretskii]

> Date: Tue, 11 Oct 2022 14:36:11 +0300
> Cc: emacs-devel <emacs-devel@gnu.org>
> From: Dmitry Gutov <dgutov@yandex.ru>
> 
> Moving from Debbugs here.
> 
> On 11.10.2022 09:37, Eli Zaretskii wrote:
> >> Date: Tue, 11 Oct 2022 05:12:11 +0300
> >> Cc: gerd.moellmann@gmail.com, 58158@debbugs.gnu.org, 
> >> monnier@iro.umontreal.ca
> >> From: Dmitry Gutov <dgutov@yandex.ru>
> >>
> >> What is a "subset of matches"?
> > 
> > Feel free to suggest a less vague description.  The idea is that the
> > list in Xref buffer doesn't show all the references to the identifier,
> > making renaming infeasible.
> 
> How about:
> 
>    Cannot perform replacements in this search's results

This is similar to the original message.  Its problem is that it
states the fact, but doesn't attempt to explain it, and thus doesn't
give a clue what the user did wrong and how to fix that.

> > More generally, what exactly does xref.el test to produce the error
> > message, and how to describe that in user-level terms?
> 
> It tests whether the method xref-match-length returns non-nil for any 
> search results. When they do, it would identify them as "match xrefs" 
> (mentioned in the Commentary).
> 
> But I suppose that clashes with the terminology you prefer to use.

If it's possible to come up with the semantics of xref-match-length or
of "match xrefs", maybe that could be useful.  The commentary just
says the "correspond to search result", which is not very useful for
this purpose.

> > You are saying that 'r' is only useful after M-?, is that right?  The
> > manual says so, but the manual doesn't have to say "the whole truth".
> > The doc string should.
> 
> It works after dired-do-find-regexp and project-find-regexp as well.

So wed cannot say something like "This can only be used after M-?",
sigh...

I still have no idea how to improve the error message.