Re: What's happened to M-<tab> `completion-at-point'?

[Eli Zaretskii]

> From: Tassilo Horn <tsdh@gnu.org>
> Cc: Alan Mackenzie <acm@muc.de>, emacs-devel@gnu.org
> Date: Wed, 04 May 2022 21:16:42 +0200
> 
> Eli Zaretskii <eliz@gnu.org> writes:
> 
> >> I think I've found the problem.  A new version of ncurses was
> >> installed on my machine on 2022-05-01.  It contains a version of
> >> terminfo, specifically /etc/terminfo/l/linux.
> >> 
> >> The new version is ncurses-6.3_p20211106.  The old version was
> >> ncurses-6.2_p20210619.
> >> 
> >> So, possibly we need to amend Emacs (? src/term.c) to work properly
> >> on this version of the Linux console.
> >
> > Amend how?  I still don't understand where did <backtab> come from.
> > If you do understand, can you describe that?
> 
> I never use the Linux console (unless something is severely broken) but
> can confirm Alan's observation.  With emacs -Q -nw , all of M-TAB, ESC
> TAB, and C-M-i say <backtab> is undefined.  That happens with emacs 27,
> 28, and the current master.  I also have ncurses 6.3 which ships with
> tons of files below /usr/share/terminfo/ including the l/linux Alan
> mentioned.

My point is that if <backtab> comes from outside of Emacs, there's
nothing we can do about it.

But Alan's report says that "C-h l" tells a different story: that
Emacs got "ESC TAB".  In which case I find it hard to understand how
ncurses or the terminfo database could be involved.  I'm probably
missing something.