bug#65347: 29.1; Underscore in query replace prevents case-matching

[Eli Zaretskii]

> From: Spencer Baugh <sbaugh@janestreet.com>
> Cc: 65347@debbugs.gnu.org,  monnier@iro.umontreal.ca
> Date: Fri, 18 Aug 2023 15:14:46 -0400
> 
> > What are "symbols" in this context?
> 
> Strings made up of symbol constituents as defined by the current
> major-mode's syntax table.  The normal definition of symbols.

Then you are talking about something very different from "words".

> > Capitalization issues with program code are conceptually different
> > from those with human-readable text.  You are basically talking about
> > refactoring, not about text replacement.  So the use cases that are of
> > interest to you are not well supported by query-replace, because it
> > doesn't target them.  It could well mean that you will need a custom
> > replace-match function.  Insisting on replace-match to support these
> > cases is not necessarily wise, from where I stand.
> 
> Hm, that's fair.  Although I would bet that the majority of usage of
> query-replace is with program code, since the majority of Emacs usage is
> with program code.

That's profoundly not true!  Emacs is used with human-readable text
not less, and maybe more, than with program source code.  I'm typing
this email in Emacs; I'm routinely making changes to our documentation
in Emacs -- these and others are all frequent text-editing activities.

> So features which make query-replace work better with code are still
> useful.

No, we need a real refactoring in Emacs!  Using M-% as poor-man's
refactoring is fine, but pretending that it _is_ refactoring, and
adding minor extensions to it that are motivated by refactoring, is
simply wrong!  It will likely complicate the text-oriented replacement
we have already, and will always fall short of decent refactoring
capabilities.

We should work on adding refactoring instead of tweaking M-% and M-*
in these directions.

> Another feature that could support this would be to allow defining
> multiple query/replacement pairs, and applying them together across the
> file or across multiple files, querying as we go.  Then "foo" could be
> replaced with "bar" and "Foo" with "Bar".  That kind of simultaneous
> replacement is something I've definitely wanted before.

IMO, this makes little or no sense in human-readable text; it does
make sense in the refactoring context.  So let's add refactoring
capabilities to Emacs, and leave M-% for text.