GNU bug report logs - #76748
31.0.50; `unload-feature' unbinds NEW-ALIAS and BASE-VARIABLE of variable alias

Previous Next

Full log

Message #8 received at 76748 <at> debbugs.gnu.org (full text, mbox):

From: Eli Zaretskii <eliz <at> gnu.org>
To: Jens Schmidt <jschmidt4gnu <at> vodafonemail.de>,
 Stefan Monnier <monnier <at> iro.umontreal.ca>
Cc: 76748 <at> debbugs.gnu.org
Subject: Re: bug#76748: 31.0.50;
 `unload-feature' unbinds NEW-ALIAS and BASE-VARIABLE of variable alias
Date: Wed, 05 Mar 2025 14:33:49 +0200

> Date: Tue, 04 Mar 2025 21:57:18 +0100
> From:  Jens Schmidt via "Bug reports for GNU Emacs,
>  the Swiss army knife of text editors" <bug-gnu-emacs <at> gnu.org>
> 
> 1. `defalias' on builtin variable, like in vhdl-mode.el:
> 
>      ./progmodes/vhdl-mode.el:2331:  (defvaralias 'vhdl-last-input-event 'last-input-event)
> 
>    Start with "emacs -Q", then execute with C-j in *scratch*:
> 
>      (require 'vhdl-mode)
>      vhdl-mode
> 
>      (unload-feature 'vhdl-mode)
>      =>
>      Lisp error: (error "Built-in variables may not be unbound")
>        makunbound(vhdl-last-input-event)
>        #f(compiled-function (x) #<bytecode -0x15f00789bdf1ec4b>)(vhdl-last-input-event)
>        apply(#f(compiled-function (x) #<bytecode -0x15f00789bdf1ec4b>) vhdl-last-input-event nil)
>        loadhist-unload-element(vhdl-last-input-event)
>        unload-feature(vhdl-mode)
> 
> 2. `define-obsolete-variable-alias' on non-builtin, like this:
> 
>      ./net/shr.el:164:(define-obsolete-variable-alias 'shr-external-browser 'browse-url-secondary-browser-function "27.1")
> 
>    Start with "emacs -Q", then execute with C-j in *scratch*:
> 
>      (require 'browse-url)
>      browse-url
> 
>      browse-url-secondary-browser-function
>      browse-url-default-browser
> 
>      (require 'shr)
>      shr
> 
>      (unload-feature 'shr)
>      nil
> 
>      browse-url-secondary-browser-function
>      => Lisp error: (void-variable browse-url-secondary-browser-function)
> 
> My understanding is that `unload-feature' in
> 
> case 1. tries to unbind BASE-VARIABLE of the alias, and not NEW-ALIAS,
> and fails to do so and in
> 
> case 2. unbinds both CURRENT-NAME and OBSOLETE-NAME.
> 
> I would expect that in these cases `unload-feature' should unbind
> NEW-ALIAS/OBSOLETE-NAME from the feature being unloaded, but leave
> BASE-VARIABLE/CURRENT-NAME unchanged.  (Except of course if both items
> of the alias originate from the same feature.)

Stefan, any suggestions?

Previous Next

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