bug#47603: closed (comint sets '(rear-nonsticky t) on entire prompt, disabling 'cursor-intangible)

[GNU bug Tracking System]

Your message dated Mon, 12 Apr 2021 22:49:55 -0400
with message-id <jwv35vu7vcf.fsf-monnier+emacs@gnu.org>
and subject line Re: bug#47603: comint sets '(rear-nonsticky t) on entire 
prompt, disabling 'cursor-intangible
has caused the debbugs.gnu.org bug report #47603,
regarding comint sets '(rear-nonsticky t) on entire prompt, disabling 
'cursor-intangible
to be marked as done.

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-- 
47603: http://debbugs.gnu.org/cgi/bugreport.cgi?bug=47603
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--- Begin Message --- Subject: comint sets '(rear-nonsticky t) on entire prompt, disabling 'cursor-intangible Date: Mon, 5 Apr 2021 14:07:17 -0400

Comint sets ‘(rear-nonsticky t) on the entire detected prompt text, which prevents `cursor-intangible from functioning correctly when applied to the prompt.  As Stefan put it:

I suspect the issue comes from the difference between `get-pos-property` and `get-char-property`: positions (like `point`) are not placed on a character but between two characters.  But text properties only apply to characters.  So the properties that are "on a position" are based on what properties would a character inherit if it where inserted at that position.

By default text properties are front-nonstick and rear-sticky, so basically a position gets its properties from the char right before it. But if you set (rear-nonsticky t), then you get no properties at all at that position.

This causes issues when "applying (rear-nonsticky t) a bit too generously, e.g. to all the chars in the prompt rather than only to the last one."

--- End Message ---

> --- Begin Message ---
>
>
>
> Subject: 
>
> Re: bug#47603: comint sets '(rear-nonsticky t) on entire prompt, disabling 'cursor-intangible
>
>
>
>
> Date: 
>
> Mon, 12 Apr 2021 22:49:55 -0400
>
>
>
>
> User-agent: 
>
> Gnus/5.13 (Gnus v5.13) Emacs/28.0.50 (gnu/linux)
>
>
>
>
> > Comint sets ‘(rear-nonsticky t) on the entire detected prompt text, which
> > prevents `cursor-intangible from functioning correctly when applied to the
> > prompt.  As Stefan put it:
>
> I fixed it a while back but forgot the `font-lock-face` property in the
> list of properties to add to `rear-nonstick` so I just added the
> patch below to `master`.
> I believe this should now do it.
>
>
>         Stefan
>
>
> diff --git a/lisp/comint.el b/lisp/comint.el
> index 2745c5a26f..b90e6354d8 100644
> --- a/lisp/comint.el
> +++ b/lisp/comint.el
> @@ -1797,6 +1797,9 @@ comint-add-to-input-history
>                         (min size (- comint-input-ring-size size)))))
>      (ring-insert comint-input-ring cmd)))
>  
> +(defconst comint--prompt-rear-nonsticky
> +  '(field inhibit-line-move-field-capture read-only font-lock-face))
> +
>  (defun comint-send-input (&optional no-newline artificial)
>    "Send input to process.
>  After the process output mark, sends all text from the process mark to
> @@ -1916,8 +1919,8 @@ comint-send-input
>              (unless (or no-newline comint-use-prompt-regexp)
>                ;; Cover the terminating newline
>                (add-text-properties end (1+ end)
> -                                   '(rear-nonsticky
> -                                     (field inhibit-line-move-field-capture 
> read-only)
> +                                   `(rear-nonsticky
> +                                     ,comint--prompt-rear-nonsticky
>                                       field boundary
>                                       inhibit-line-move-field-capture t)))))
>  
> @@ -2124,10 +2127,10 @@ comint-output-filter
>             (unless comint-use-prompt-regexp
>                (with-silent-modifications
>                  (add-text-properties comint-last-output-start (point)
> -                                     '(front-sticky
> +                                     `(rear-nonsticky
> +                                      ,comint--prompt-rear-nonsticky
> +                                      front-sticky
>                                        (field inhibit-line-move-field-capture)
> -                                      rear-nonsticky
> -                                      (field inhibit-line-move-field-capture 
> read-only)
>                                        field output
>                                        inhibit-line-move-field-capture t))))
>  
> @@ -2157,8 +2160,8 @@ comint-output-filter
>                                                'font-lock-face
>                                                'comint-highlight-prompt)
>               (add-text-properties prompt-start (point)
> -                                  '(rear-nonsticky
> -                                    (field inhibit-line-move-field-capture 
> read-only))))
> +                                  `(rear-nonsticky
> +                                    ,comint--prompt-rear-nonsticky)))
>             (goto-char saved-point)))))))
>  
>  (defun comint-preinput-scroll-to-bottom ()
>
>
>
> --- End Message ---