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

[Eli Zaretskii]

> Date: Mon, 4 Apr 2016 18:58:08 +0200
> From: Anders Lindgren <andlind@gmail.com>
> Cc: 23179@debbugs.gnu.org
> 
>  If nobody steps up to implement your incremental search UI soon, though, 
> we'll most likely release
>  Emacs 25.1 with the current xref UI.
> 
> If xref doesn't provide something similar to tags-search and tags-query 
> replace, I would say that it's more
> likely that Emacs 25.1 will be released with M-, bound to tags-loop-continue 
> -- as this will make both the old
> tags commands and the new xref system work. All we need to do is to find a 
> new binding for
> xref-pop-marker-stack.

We don't want to go back.  That would be a terrible waste of energy
already invested in development, improvements, and documentation of
these new features.  We cannot afford doing that.

Many issues with the xref UI and back-ends were already fixed.  You
raised the issue of the UI that you didn't want to see -- now there's
a proposed solution on the table for that.  Something along those
lines will soon be committed, if no one objects.

Beyond that, I see only one issue remaining to make xref a reasonably
good replacement for etags-based commands: the ability to collect
matches in chunks, so as not to delay the display of the first portion
of matches for too long.  I hope a solution for this will be found
soon enough.

With that problem out of our way, we could safely obsolete tags-search
and tags-query-replace, and leave the key bindings for them for those
who will still want to use them.  (I expect their number to gradually
go down with time.)