Subject: bug#66570: 29.1; Regression when printing option set with value of wrong type

From: Eli Zaretskii <[email-masked]>
Date: Mon, 23 Oct 2023 17:53:58 +0300

tags 66570 wontfix
close 66570
thanks

> From: Drew Adams <[email-masked]>
> Date: Sun, 15 Oct 2023 21:25:00 +0000
> 
> emacs -Q
> 
> Evaluate (customize-set-variable 'fill-column nil).
> 
> No message or error about improver value (just as in previous releases).

Emacs 29 has setopt, so you should use that instead.  It will display
a warning when a variable is set to a value that it doesn't support.

Or use the command customize-option.

> C-h v fill-column
> 
> An error is raised, but the *Compile-Log* message doesn't say what
> function raised the error:
> 
> z:/path/to/Emacs-29.1.2/share/emacs/29.1/lisp/emacs-lisp/cl-print.elc:
> Error: Wrong type argument: number-or-marker-p, nil

Yes.  Actually, errors start popping up before that, because the value
of fill-column is bogus.  Just don't do that (and use setopt to make
sure you don't inadvertently set a variable to a bad value).

I don't think we should do anything here, as this is a clear cockpit
error that can nowadays be avoided by using a different API.

So I'm closing this bug.