bug#40788: 28.0.50; Error running timer ‘custom-magic-reset’

bug#40788: 28.0.50; Error running timer ‘custom-magic-reset’

[David Ponce]

Hello,

Here is the recipe for an error I encounter when using customize with
2 windows in the same frame:

emacs -Q
M-x pop-to-buffer RET *Message*
M-x customize-variable RET blink-cursor-alist

At this point the *scratch* buffer is on top window and the customize
buffer on bottom.

Click on 'INS' button and insert a new Key/Value pair
Clict on 'State' button, then 'Set for Current Session'

Then click somewhere in the *scratch* buffer, then click on the 'DEL'
button in the customize buffer to delete the value previously entered.

At this point custom try to redraw the 'State' button in the *scratch*
buffer instead of the customize buffer! In this case, because the
*scratch* buffer is shorter than the position of the State button, it
fails with the error:

Error running timer ‘custom-magic-reset’: (args-out-of-range #<buffer
*scratch*> #<marker (moves after insertion) at 287 in *Customize Option:
Blink Cursor Alist*> #<marker at 294 in *Customize Option: Blink Cursor
Alist*>)

This error can be severe because, if in place of the *scratch* buffer
you were editing a file big enough to include the position of the 'State'
button, the 'State' button is drawn in your file without you realizing it!
And if you ever realize it, this change cannot be undone!

Thanks!

In GNU Emacs 28.0.50 (build 32, x86_64-pc-linux-gnu, GTK+ Version 3.24.13, cairo version 1.16.0)
  of 2020-04-23 built
Repository revision: 7b15cc3ebb45e50ac5faf3bbc2a813afffdaa418
Repository branch: master
Windowing system distributor 'Fedora Project', version 11.0.12006000
System Description: Fedora 31 (KDE Plasma)

Recent messages:
Mark set
Creating customization items...
Creating customization items ...done
Creating customization setup...done
Mark set
Beginning of buffer
Mark set [2 times]
scroll-up-command: End of buffer

Configured using:
  'configure --prefix=/home/dponce --with-cairo
  PKG_CONFIG_PATH=/usr/local/lib/pkgconfig:/usr/lib/pkgconfig'

Configured features:
XPM JPEG TIFF GIF PNG RSVG CAIRO SOUND DBUS GSETTINGS GLIB NOTIFY
INOTIFY LIBSELINUX GNUTLS LIBXML2 FREETYPE HARFBUZZ M17N_FLT LIBOTF ZLIB
TOOLKIT_SCROLL_BARS GTK3 X11 XDBE XIM MODULES THREADS LIBSYSTEMD JSON
PDUMPER LCMS2 GMP

Important settings:
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   value of $LANG: fr_FR.UTF-8
   locale-coding-system: utf-8-unix

Major mode: Messages

Minor modes in effect:
   tooltip-mode: t
   global-eldoc-mode: t
   electric-indent-mode: t
   mouse-wheel-mode: t
   tool-bar-mode: t
   menu-bar-mode: t
   file-name-shadow-mode: t
   global-font-lock-mode: t
   font-lock-mode: t
   blink-cursor-mode: t
   auto-composition-mode: t
   auto-encryption-mode: t
   auto-compression-mode: t
   buffer-read-only: t
   line-number-mode: t
   transient-mark-mode: t

Load-path shadows:
None found.

Features:
(shadow sort mail-extr emacsbug message rmc puny dired dired-loaddefs
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Memory information:
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  (symbols 48 10003 1)
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bug#40788: 28.0.50; Error running timer ‘custom-magic-reset’

[David PONCE]

Hello again,

Below is a possible patch that seems to have fixed the issue for me.
But I am not sure the approach is correct 

Thanks!

diff --git a/installs/emacs/lisp/cus-edit.el b/emacs.d/cus-edit.el
index d3d17fd..eec7ef0 100644
--- a/installs/emacs/lisp/cus-edit.el
+++ b/emacs.d/cus-edit.el
@@ -2217,9 +2217,16 @@ and `face'."
;; commands like `M-u' (that work on a region in the buffer)
;; will upcase the wrong part of the buffer, since more text has
;; been inserted before point.
- (run-with-idle-timer 0.0 nil #'custom-magic-reset widget)
+ (run-with-idle-timer 0.0 nil #'custom-magic-reset-async (current-buffer) widget)
(apply 'widget-default-notify widget args))))

+(defun custom-magic-reset-async (buffer widget)
+ "Redraw the :custom-magic property of WIDGET.
+Called asynchronously thru an idle timer, ensure redrawing will happen in the
+origin custom BUFFER."
+ (set-buffer buffer)
+ (custom-magic-reset widget))
+
(defun custom-redraw (widget)
"Redraw WIDGET with current settings."
(let ((line (count-lines (point-min) (point)))

bug#40788: 28.0.50; Error running timer ‘custom-magic-reset’

[Robert Pluim]

>>>>> On Thu, 23 Apr 2020 19:39:26 +0200 (CEST), David PONCE <da_vid@orange.fr> said:

    David> Hello again,
    David> Below is a possible patch that seems to have fixed the issue for me.
    David> But I am not sure the approach is correct 

Rather than defining a new function, you can add an argument to the
existing one. Something like (untested)

diff --git a/lisp/cus-edit.el b/lisp/cus-edit.el
index d3d17fda7a..93012b134f 100644
--- a/lisp/cus-edit.el
+++ b/lisp/cus-edit.el
@@ -2102,11 +2102,12 @@ custom-magic-value-create
 	(insert " "))
       (widget-put widget :children children))))
 
-(defun custom-magic-reset (widget)
+(defun custom-magic-reset (widget &optional buffer)
   "Redraw the :custom-magic property of WIDGET."
-  (let ((magic (widget-get widget :custom-magic)))
-    (when magic
-      (widget-value-set magic (widget-value magic)))))
+  (with-current-buffer (or buffer (current-buffer))
+    (let ((magic (widget-get widget :custom-magic)))
+      (when magic
+        (widget-value-set magic (widget-value magic))))))
 
 ;;; The `custom' Widget.
 
@@ -2217,7 +2218,7 @@ custom-notify
       ;; commands like `M-u' (that work on a region in the buffer)
       ;; will upcase the wrong part of the buffer, since more text has
       ;; been inserted before point.
-      (run-with-idle-timer 0.0 nil #'custom-magic-reset widget)
+      (run-with-idle-timer 0.0 nil #'custom-magic-reset widget (current-buffer))
       (apply 'widget-default-notify widget args))))
 
 (defun custom-redraw (widget)

bug#40788: 28.0.50; Error running timer ‘custom-magic-reset’

[David Ponce]

On 24/04/2020 13:56, Robert Pluim wrote:
>>>>>> On Thu, 23 Apr 2020 19:39:26 +0200 (CEST), David PONCE <da_vid@orange.fr> said:
> 
>      David> Hello again,
>      David> Below is a possible patch that seems to have fixed the issue for me.
>      David> But I am not sure the approach is correct
> 
> Rather than defining a new function, you can add an argument to the
> existing one. Something like (untested)

Hi Robert,

Sure, your patch is better :-)
I tested it, and I confirm it fixes the issue :-)
I also tested the below variant, because it seems to me that it is not
necessary to set the buffer when magic is nil, as there is nothing to do.

Please feel free to apply which version looks better to you.
Thanks!

diff --git a/home/dponce/installs/emacs/lisp/cus-edit.el b/cus-edit.el
index d3d17fd..490d905 100644
--- a/home/dponce/installs/emacs/lisp/cus-edit.el
+++ b/cus-edit.el
@@ -2102,11 +2102,12 @@ and `face'."
  	(insert " "))
        (widget-put widget :children children))))
  
-(defun custom-magic-reset (widget)
+(defun custom-magic-reset (widget &optional buffer)
    "Redraw the :custom-magic property of WIDGET."
    (let ((magic (widget-get widget :custom-magic)))
      (when magic
-      (widget-value-set magic (widget-value magic)))))
+      (with-current-buffer (or buffer (current-buffer))
+        (widget-value-set magic (widget-value magic))))))
  
  ;;; The `custom' Widget.
  
@@ -2217,7 +2218,7 @@ and `face'."
        ;; commands like `M-u' (that work on a region in the buffer)
        ;; will upcase the wrong part of the buffer, since more text has
        ;; been inserted before point.
-      (run-with-idle-timer 0.0 nil #'custom-magic-reset widget)
+      (run-with-idle-timer 0.0 nil #'custom-magic-reset widget (current-buffer))
        (apply 'widget-default-notify widget args))))
  
  (defun custom-redraw (widget)

bug#40788: 28.0.50; Error running timer ‘custom-magic-reset’

[Robert Pluim]

>>>>> On Fri, 24 Apr 2020 17:56:42 +0200, David Ponce <da_vid@orange.fr> said:

    David> On 24/04/2020 13:56, Robert Pluim wrote:
    >>>>>>> On Thu, 23 Apr 2020 19:39:26 +0200 (CEST), David PONCE <da_vid@orange.fr> said:
    David> Hello again,
    David> Below is a possible patch that seems to have fixed the issue for me.
    David> But I am not sure the approach is correct
    >> Rather than defining a new function, you can add an argument to the
    >> existing one. Something like (untested)

    David> Hi Robert,

    David> Sure, your patch is better :-)
    David> I tested it, and I confirm it fixes the issue :-)
    David> I also tested the below variant, because it seems to me that it is not
    David> necessary to set the buffer when magic is nil, as there is nothing to do.

    David> Please feel free to apply which version looks better to you.
    David> Thanks!

Thanks for testing. Eli, would this be OK to go into emacs-27 ? The
bug causes unintended changes to buffers unrelated to customize.

    David> diff --git a/home/dponce/installs/emacs/lisp/cus-edit.el b/cus-edit.el
    David> index d3d17fd..490d905 100644
    David> --- a/home/dponce/installs/emacs/lisp/cus-edit.el
    David> +++ b/cus-edit.el
    David> @@ -2102,11 +2102,12 @@ and `face'."
    David>  	(insert " "))
    David>        (widget-put widget :children children))))
    David>  -(defun custom-magic-reset (widget)
    David> +(defun custom-magic-reset (widget &optional buffer)
    David>    "Redraw the :custom-magic property of WIDGET."
    David>    (let ((magic (widget-get widget :custom-magic)))
    David>      (when magic
    David> -      (widget-value-set magic (widget-value magic)))))
    David> +      (with-current-buffer (or buffer (current-buffer))
    David> +        (widget-value-set magic (widget-value magic))))))
    David>    ;;; The `custom' Widget.
    David>  @@ -2217,7 +2218,7 @@ and `face'."
    David>        ;; commands like `M-u' (that work on a region in the buffer)
    David>        ;; will upcase the wrong part of the buffer, since more text has
    David>        ;; been inserted before point.
    David> -      (run-with-idle-timer 0.0 nil #'custom-magic-reset widget)
    David> +      (run-with-idle-timer 0.0 nil #'custom-magic-reset widget (current-buffer))
    David>        (apply 'widget-default-notify widget args))))
    David>    (defun custom-redraw (widget)

bug#40788: 28.0.50; Error running timer ‘custom-magic-reset’

[Eli Zaretskii]

> From: Robert Pluim <rpluim@gmail.com>
> Date: Tue, 21 Jul 2020 10:39:26 +0200
> Cc: 40788@debbugs.gnu.org
> 
>     David> Please feel free to apply which version looks better to you.
>     David> Thanks!
> 
> Thanks for testing. Eli, would this be OK to go into emacs-27 ? The
> bug causes unintended changes to buffers unrelated to customize.

Yes, OK.

Thanks.

bug#40788: 28.0.50; Error running timer ‘custom-magic-reset’

[Robert Pluim]

>>>>> On Tue, 21 Jul 2020 17:20:11 +0300, Eli Zaretskii <eliz@gnu.org> said:

    >> From: Robert Pluim <rpluim@gmail.com>
    >> Date: Tue, 21 Jul 2020 10:39:26 +0200
    >> Cc: 40788@debbugs.gnu.org
    >> 
    David> Please feel free to apply which version looks better to you.
    David> Thanks!
    >> 
    >> Thanks for testing. Eli, would this be OK to go into emacs-27 ? The
    >> bug causes unintended changes to buffers unrelated to customize.

    Eli> Yes, OK.

Done as 4db3235fd8

Closing.

Thanks

Robert