Re: My usage of imenu is broken.

[Alan Mackenzie <acm@muc.de>]

Hello, Eli.

On Tue, May 28, 2024 at 14:34:21 +0300, Eli Zaretskii wrote:
> > Date: Tue, 28 May 2024 10:53:18 +0000
> > From: Alan Mackenzie <acm@muc.de>

> > Hello, Emacs.

> > imenu no longer works for me.  The imenu page in the Emacs manual says

> >     the command [imenu] always displays the whole list of valid names.  

> > This is not true.  When I type C-c i (my binding for imenu) I see no
> > such list.

> AFAIK, this never worked literally as the manual says.  I went as far
> back as Emacs 23, and I don't see it.

> > When I additionally type TAB I still see no such list.

> I do see the list after TAB.  So I guess the devil is in the details
> (which file you were visiting, under what major mode, etc.) -- details
> you haven't provided...

> > All I see is *Rescan*, Function, and Variable.  I think the manual
> > should be fixed.

> Let's first understand why it doesn't work for you as it does for me.

I now understand what's happening.  Stefan M committed a patch some while
ago, the effect of which is to force users who've set up their
auto-mode-alist for CC Mode to use c-ts-mode, etc., instead.  It is in a
subroutine of normal-mode where this subterfuge occurs.

Yesterday, I'd reverted src/eval.c (which normally gets loaded via
desktop), and Stefan's patch converted it to c-ts-mode without me being
aware of this.

So my problem was being in c-ts-mode, for which all these things I don't
like about imenu are apparently normal.  It's one more reason for me to
carry on using CC Mode.

I'd wrongly jumped to the conclusion that what I was seeing was due to
recent changes in imenu.el, so apologies to yourself and those who
amended imenu.el.

> > The manual talks about "flatten"ing without explaining what this means.
> > The NEWS item doesn't explain it either.  I think this should be fixed.

> Sadly, it is quite pointless to complain about deficiencies of
> documentation in most cases, because no one which is in the position
> to fix that is listening or can be bothered!

:-(  Yes.  Maybe I should fix it myself.  Substandard documentation was
one of the things which led to the fall of XEmacs.

[ .... ]

> > How do I get the old behaviour back, please?  Why doesn't the NEWS item
> > say how to get back the old behaviour?

> Old behavior in what Emacs version, please?  (In fact, you don't even
> say in which version the above misbehavior happened to you, which I
> find unexpected from you.)

Sorry, I was in master, but not in emacs -Q.

[ .... ]

The bug "fix" and its patch which caused all this trouble were:

Bug#69191 New var `major-mode-remap-defaults`, for packages.

commit 2b5d43081a30f816dd38a16c7b5bfbad712a779b
Author: Stefan Monnier <monnier@iro.umontreal.ca>
Date:   Sun Mar 3 23:08:16 2024 -0500

    (major-mode-remap(-defaults)): New var and function (bug#69191)

I don't understand what major-mode-remap and major-mode-remap-defaults
are for.  They would appear to be duplicating and confusing the mechanism
of auto-mode-alist, and seem unnecessary.  It seems clear they are too
difficult to use.

I would favour reverting that patch, and thus restore the preference of
users for CC Mode.

Stefan, your comments, please.

-- 
Alan Mackenzie (Nuremberg, Germany).