Subject: bug#46727: 27.1; Only the first function from prefix-command-echo-keystrokes-functions is used

From: Lars Ingebrigtsen <[email-masked]>
Date: Wed, 24 Feb 2021 17:42:03 +0100

Miha Rihtaršič <[email-masked]> writes:

> Greetings.
>
> Looking at the function internal-echo-keystrokes-prefix, it is heavily
> implied that all functions from
> `prefix-command-echo-keystrokes-functions` should be used and their
> return values concatenated. This isn't the case, however, because
> `run-hook-wrapped` aborts on first non-nil returned value. The following
> simple patch fixes this.

[...]

>              (run-hook-wrapped 'prefix-command-echo-keystrokes-functions
> -                              (lambda (fun) (push (funcall fun) strs)))
> +                              (lambda (fun) (push (funcall fun) strs) nil))

Thanks.

I poked around in the code, and I think your interpretation here must be
correct, and I've applied your patch to Emacs 28.  (Besides, `push' has
an undefined return value...  and always returns non-nil, so the old
code would, as you said, never use more than the first function in
`prefix-command-echo-keystrokes-functions'.)

This change was small enough to apply without assigning copyright to the
FSF, but for future patches you want to submit, it might make sense to
get the paperwork started now, so that subsequent patches can be applied
speedily. Would you be willing to sign such paperwork?

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no