bug#23179: 25.0.92; Restore `M-,' to continue etags search

[Dmitry Gutov]

On 04/04/2016 01:44 AM, John Wiegley wrote:

> I realize it all sounds very natural to you, Dmitry, because you designed it.

This advantage clearly should be the most convincing, but you've skipped 
the other one: non-proliferation of new query-replace commands.

> However, accept that is not as natural to everyone else.  I too want a command
> that lets me immediately jump to the first hit, rather than populating a very
> large search results list only to visit it.  There is value in
> tags-query-replace.

First hit of what? We already have three different commands which search 
for different things, and return replace-able results.

If we want the xref UI to be reusable, that would bring new search 
commands in the future. Do you want each of them to come with a 
corresponding query-replace command?

> The fact that the xref.el API makes this now hard to do is a deficiency in
> that API, not an indication that we shouldn't be doing it. Let's fix the API
> -- which is still considered experimental. Your generator suggestion sounds
> like a good approach.

Sure, I'm all for that.