Subject: Unhelpful error message whilst byte-compiling a function.
From: Alan Mackenzie <[email-masked]>
To: [email-masked]
Date: Wed, 8 Sep 2021 20:37:45 +0000
List-Id: <debbugs-submit.debbugs.gnu.org>

Hello, Emacs

I'm working on Emacs 28.  Not emacs -Q, but it shouldn't matter.

I'm working on a function which begins thus:

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
(defun jit-lock--run-functions-new (beg end &optional last-fun)
  (let ((tight-beg nil) (tight-end nil) ; The region we have fully fontified.
        (loose-beg beg) (loose-end end)) ; The maximum region we have fontified
                                        ; with at least some of
                                        ; `jit-lock-functions'.
    (run-hook-wrapped
     'jit-lock-functions
......
......
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

On doing M-x compile-defun on this function, I get as sum total of the
output in *Compile-Log* this:

Buffer jit-lock.el:416:1: Error: Wrong number of arguments: #<subr
macroexp--warn-wrap>, 3

..  I don't know what this means.  Line 416 is the line where the defun
starts.  I don't have `macroexp--warn-wrap' anywhere in my source code,
it's not clear to what form 3 arguments are being wrongly passed, or
where.

Emacs compilation messages should not be so obscure.  This message
should be so formulated that I can see immediately what needs fixing.

#########################################################################

Second curiosity.  I can evaluate that defun form, and when I do C-h C-f
on it, I get:

jit-lock--run-functions-new is a Lisp closure in `jit-lock.el'.

A "closure" for crying out loud.  It's a FUNCTION, created by defun.
Calling a function a "closure" seems very pretentious and somewhat
patronising.  Not all users will know what it means.

Was there some discussion on emacs-devel which I somehow missed, where
this was agreed to?  If not, can we restore this word to "function",
please?

-- 
Alan Mackenzie (Nuremberg, Germany).