Re: info-lookup-alist mangled, breaks C-h S

[Tassilo Horn]

Eli Zaretskii <eliz@gnu.org> writes:

Hi Eli,

>> FWIW, the problematic entry doesn't seem to come from some external
>> package, at least I can reproduce the error using
>> 
>>   1. emacs -Q
>>   2. M-x fundamental-mode RET in *stratch*
>>   3. C-h S
>> 
>> with GNU Emacs 29.0.50 of 2022-01-03.  The step 2 above is needed
>> because `C-h S' in an emacs-lisp-mode or lisp-interaction-mode buffer
>> works just fine whereas I get the error in fundamental-mode or
>> Info-mode.  I can't reproduce with emacs 27 or 28.
>
> Does the patch below give good results?

Yes, it does, thanks!

Bye,
Tassilo

> diff --git a/lisp/info-look.el b/lisp/info-look.el
> index e6f267d..9224aa3 100644
> --- a/lisp/info-look.el
> +++ b/lisp/info-look.el
> @@ -347,7 +347,10 @@ info-lookup-select-mode
>  
>  (defun info-lookup-change-mode (topic)
>    (let* ((completions (mapcar (lambda (arg)
> -                             (cons (symbol-name (car arg)) (car arg)))
> +                                (let ((mode-spec (car arg)))
> +                                  (and (consp mode-spec)
> +                                       (setq mode-spec (car mode-spec)))
> +                               (cons (symbol-name mode-spec) mode-spec)))
>                             (info-lookup->topic-value topic)))
>        (mode (completing-read
>               (format "Use %s help mode: " topic)