GNU bug report logs - #70436
30.0.50; Fail to enter the debugger when using prin1 (instead of cl-prin1)

Previous Next

Full log

Message #10 received at 70436 <at> debbugs.gnu.org (full text, mbox):

From: Eli Zaretskii <eliz <at> gnu.org>
To: Bruno Barbier <brubar.cs <at> gmail.com>,
 Stefan Monnier <monnier <at> iro.umontreal.ca>
Cc: 70436 <at> debbugs.gnu.org
Subject: Re: bug#70436: 30.0.50;
 Fail to enter the debugger when using prin1 (instead of cl-prin1)
Date: Sat, 20 Apr 2024 11:24:11 +0300

> From: Bruno Barbier <brubar.cs <at> gmail.com>
> Date: Wed, 17 Apr 2024 15:29:14 +0200
> 
> When setting debugger-print-function to prin1, Emacs 30.0.50 may fail
> to enter the debugger.
> 
> Emacs displays something like:
> 
>     Entering debugger...
>     make-text-button: Args out of range: 67, 3000
> 
> 
> The correct behavior is to enter the debugger, with something like this:
> 
>     Debugger entered--Lisp error: (wrong-type-argument stringp nil)
>       #f(compiled-function (&rest args) "Start a program in a subprocess.  ...
>       ...
>       make-process(:name "mandatory" :command "ls" :stderr err-buf)
> 
> The problem doesn't occur with Emacs 29.3.
> 
> To manually reproduce, execute the following code block in a new Emacs
> (started with '-Q'):
> 
>   #+begin_src elisp
>     (progn 
>       (setq debugger-print-function 'prin1)
>       
>       (defun my-useless-advice (fun &rest args)
>          (apply fun args))
> 
>       (advice-add 'make-process :around #'my-useless-advice)
> 
>       (make-process :name "mandatory"
>                     :command "ls"
>                     :stderr 'err-buf))
>   #+end_src
>   
> It seems that backtrace.el prints using prin1, but infers where the
> button should be using cl-prin1.
> 
> My personal workaround is to stop setting debugger-print-function to
> prin1 (I customized it a few years ago because I found that cl-prin1 was
> really slow at the time, I guess it shouldn't be the case anymore).

Stefan, is this supposed to be supported?

Previous Next

GNU bug tracking system
Copyright (C) 1999 Darren O. Benham, 1997,2003 nCipher Corporation Ltd, 1994-97 Ian Jackson.