bug#16274: 24.3.50; Error in post-command-hook (icomplete-post-command-hook): (invalid-function ("..." ...))

[charles@aurox.ch (Charles A. Roelli)]

Ping!  I hope to fix this for emacs-26 if it's possible.  It also
solves Bug#28898.

> Date: Sun, 22 Oct 2017 17:06:35 +0200
> From: charles@aurox.ch (Charles A. Roelli)
> 
> > From: Stefan Monnier <monnier@iro.umontreal.ca>
> > Date: Fri, 03 Jan 2014 23:51:48 -0500
> > 
> > > So far, my best guess is still that in
> > > (completion-try-completion name comps nil (length name) md)
> > > the list COMPS is for some reason being treated as a function (the
> > > second argument can of course be either).
> > 
> > Oh, you mean that the error could come from the fact that `md' goes with
> > `candidates', so some code might assume that the completion table is
> > a function based on the `md' data, whereas we passed `comps' which is
> > a list of strings?
> > 
> > Hmm... that sounds plausible.
> 
> This seems to be the mistake.  If you pass nil instead of `md' (as in
> the patch below), then there's no more problem.
> 
> diff --git a/lisp/icomplete.el b/lisp/icomplete.el
> index 038f58f..38be657 100644
> --- a/lisp/icomplete.el
> +++ b/lisp/icomplete.el
> @@ -395,7 +395,7 @@ icomplete-completions
>                  ;; If the `comps' are 0-based, the result should be
>                  ;; the same with `comps'.
>                  (completion-try-completion
> -                 name comps nil (length name) md)))
> +                 name comps nil (length name) nil)))
>  	     (most (if (consp most-try) (car most-try)
>                       (if most-try (car comps) "")))
>               ;; Compare name and most, so we can determine if name is
> 
> Alternatively, this part of `completion--nth-completion' could be
> updated to respond to `completio--unquote-requote' in the completion
> metadata when `table' is not a function:
> 
>          (when (completion-metadata-get metadata 'completion--unquote-requote)
>            (cl-assert (functionp table))
>            (let ((new (funcall table string point 'completion--unquote)))
> 
> (No idea if that would make sense.)
> 
> I was using this recipe for testing:
> 
> > Date: Fri, 30 Jan 2015 14:25:04 +0000
> > From: Jeremy Moore <jmoore@ieee.org>
> > 
> > Hi folks,
> > 
> > I get a similar error by following this sequence in 24.4.1:
> > 1. emacs -Q
> > 2. M-x icomplete-mode
> > 3. M-x set-variable icomplete-show-matches-on-no-input t
> > 4. C-x C-f C-a C-k
> > 
> > Version and settings are below.
> > 
> > Regards,
> > Jeremy
> > 
> > In GNU Emacs 24.4.1 (i686-pc-mingw32)
> > of 2014-10-24 on LEG570
> > Windowing system distributor `Microsoft Corp.', version 6.1.7601
> > Configured using:
> > `configure --prefix=/c/usr'