bug#46469: [External] : bug#46469: 27.1; `isearch-del-char' should move point further back

[Augusto Stoffel <arstoffel@gmail.com>]

Re the idea that we can't change the behavior of an old command: if
taken too seriously, this principle would imply that the standard Emacs
UI can never improve; I'm glad this is not the case.  Also,
`isearch-del-char' changed from one obscure key to another obscure key
in Emacs 27.  So clearly things can change.

Re this being a personal preference: I wouldn't bother to send a patch
if I thought so.  As already mentioned, lots of programs copied Emacs's
incremental search, and apparently all changed how DEL works in a
similar way.  This indicates that the patched `isearch-del-char' is what
most people expect (but I'm not suggesting to bind it to DEL, just have
it around for those who want it).

With all that said, could we discuss the merits of the change itself?

If it has a real drawback in comparison with the current
`isearch-del-char', then it would be fine to add a defcustom.  But I
suspect that 3 alternative ways to delete characters from a search
string is a bit over the top.  We can probably come up with a solid
default behavior here.

I already explained my rationale for wanting the change: I mistype
things, but I never hit ‘C-s’ by mistake.  So I want a way to undo just
what I typed.  The current `iserach-del-char' does something slightly
different.  Refer to my third message in this thread for details.

Is there a case where the current behavior is much more convenient
and/or takes the search to a state that can't be easily reproduced by
the patched version?

Thanks,
Augusto