bug#69271: 30.0.50; Strange interaction between :inverse-video overlay face and calendar today face

bug#69271: 30.0.50; Strange interaction between :inverse-video overlay face and calendar today face

[Ihor Radchenko]

Originally reported in
https://list.orgmode.org/orgmode/CALEYq09=JKfzRY26fohLPYz7_2mnvhg_LGsjnQwQKov5SbqkYg@mail.gmail.com/

Steps to reproduce:

1. emacs -Q
2. Insert the following code into *scratch* buffer


(defface yant/test '((t :foreground "red" :weight bold)) "")
(defface yant/test-inv '((t :foreground "red"  :inverse-video t)) "")
(require 'calendar)

;; (dotimes (_ 5)
;;   (let* ((mark-calendar
;; 	  (lambda ()
;; 	    (calendar-mark-visible-date
;; 	     (read (format-time-string "(%m %d %Y)"))
;; 	     'yant/test)))
;; 	 (calendar-today-visible-hook))
;;     (add-hook 'calendar-today-visible-hook mark-calendar)
;;     (calendar)
;;     (setq cursor-type nil)
;;     (let ((ov (make-overlay (1- (point)) (1+ (point)))))
;;       (overlay-put ov 'face 'yant/test-inv)))
;;   (read-char "Observe overlay obeying inverse-video. Press any key")
;;   (kill-buffer calendar-buffer))
(dotimes (_ 50)
  (let* ((mark-calendar
	  (lambda ()
	    (calendar-mark-visible-date
	     (read (format-time-string "(%m %d %Y)"))
	     (list :foreground "red" :weight 'bold))))
	 (calendar-today-visible-hook))
    (add-hook 'calendar-today-visible-hook mark-calendar)
    (calendar)
    (setq cursor-type nil)
    (let ((ov (make-overlay (1- (point)) (1+ (point)))))
      (overlay-put ov 'face 'yant/test-inv)))
  (read-char "Observe overlay sometimes *not* obeying inverse-video. Press any key")
  (kill-buffer calendar-buffer))

3. M-x eval-buffer <RET>
4. Observe today date in the calendar fontified inconsistently as the
   code is executed multiple times.

In GNU Emacs 30.0.50 (build 1, x86_64-pc-linux-gnu, GTK+ Version
 3.24.41, cairo version 1.18.0) of 2024-02-18 built on localhost
Repository revision: 951379a0983ea66b1396d07628bb726f033ea24b
Repository branch: master
Windowing system distributor 'The X.Org Foundation', version 11.0.12101011
System Description: Gentoo Linux

Configured using:
 'configure JAVAC=/etc/java-config-2/current-system-vm/bin/javac'

-- 
Ihor Radchenko // yantar92,
Org mode contributor,
Learn more about Org mode at <https://orgmode.org/>.
Support Org development at <https://liberapay.com/org-mode>,
or support my work at <https://liberapay.com/yantar92>

bug#69271: 30.0.50; Strange interaction between :inverse-video overlay face and calendar today face

[Eli Zaretskii]

> From: Ihor Radchenko <yantar92@posteo.net>
> Date: Mon, 19 Feb 2024 12:14:28 +0000
> 
> 1. emacs -Q
> 2. Insert the following code into *scratch* buffer
> 
> 
> (defface yant/test '((t :foreground "red" :weight bold)) "")
> (defface yant/test-inv '((t :foreground "red"  :inverse-video t)) "")
> (require 'calendar)
> 
> ;; (dotimes (_ 5)
> ;;   (let* ((mark-calendar
> ;; 	  (lambda ()
> ;; 	    (calendar-mark-visible-date
> ;; 	     (read (format-time-string "(%m %d %Y)"))
> ;; 	     'yant/test)))
> ;; 	 (calendar-today-visible-hook))
> ;;     (add-hook 'calendar-today-visible-hook mark-calendar)
> ;;     (calendar)
> ;;     (setq cursor-type nil)
> ;;     (let ((ov (make-overlay (1- (point)) (1+ (point)))))
> ;;       (overlay-put ov 'face 'yant/test-inv)))
> ;;   (read-char "Observe overlay obeying inverse-video. Press any key")
> ;;   (kill-buffer calendar-buffer))
> (dotimes (_ 50)
>   (let* ((mark-calendar
> 	  (lambda ()
> 	    (calendar-mark-visible-date
> 	     (read (format-time-string "(%m %d %Y)"))
> 	     (list :foreground "red" :weight 'bold))))
> 	 (calendar-today-visible-hook))
>     (add-hook 'calendar-today-visible-hook mark-calendar)
>     (calendar)
>     (setq cursor-type nil)
>     (let ((ov (make-overlay (1- (point)) (1+ (point)))))
>       (overlay-put ov 'face 'yant/test-inv)))
>   (read-char "Observe overlay sometimes *not* obeying inverse-video. Press any key")
>   (kill-buffer calendar-buffer))
> 
> 3. M-x eval-buffer <RET>
> 4. Observe today date in the calendar fontified inconsistently as the
>    code is executed multiple times.

This code places two overlays on the same text, with each overlay
defining a foreground color.  So which one "wins" is basically random,
unless you give each overlay a priority to make that deterministic.

I tried a simpler recipe:

  emacs -Q
  M-x load-library RET calendar RET
  C-x b foo RET
  C-u 30 a RET
  M-: (defface yant/test-inv '((t :foreground "red"  :inverse-video t)) "") RET
  M-: (setq ov1 (make-overlay 24 26)) RET
  M-: (overlay-put ov1 'face (calendar-make-temp-face (list :foreground "red" :weight 'bold))) RET
  M-: (setq ov2 (make-overlay 24 26)) RET
  M-: (overlay-put ov2 'face 'yant/test-inv) RET

This produced text with red background, according to the yant/test-inv
face.  But if you define the overlays in the opposite order, you get
the red bold foreground instead.  If you now give each overlay a
priority, you can control which face shows: the one whose overlay has
the higher priority.

Maybe I'm missing something, but I see no bug here.

bug#69271: 30.0.50; Strange interaction between :inverse-video overlay face and calendar today face

[Ihor Radchenko]

Eli Zaretskii <eliz@gnu.org> writes:

>
> This produced text with red background, according to the yant/test-inv
> face.  But if you define the overlays in the opposite order, you get
> the red bold foreground instead.  If you now give each overlay a
> priority, you can control which face shows: the one whose overlay has
> the higher priority.
>
> Maybe I'm missing something, but I see no bug here.

You are indeed right.
I fixed this priority race on Org mode side.
https://git.savannah.gnu.org/cgit/emacs/org-mode.git/commit/?id=67d937248
Thanks!

-- 
Ihor Radchenko // yantar92,
Org mode contributor,
Learn more about Org mode at <https://orgmode.org/>.
Support Org development at <https://liberapay.com/org-mode>,
or support my work at <https://liberapay.com/yantar92>

bug#69271: 30.0.50; Strange interaction between :inverse-video overlay face and calendar today face

[Eli Zaretskii]

tags 69271 notabug
close 69271
thanks

> From: Ihor Radchenko <yantar92@posteo.net>
> Cc: 69271@debbugs.gnu.org
> Date: Wed, 21 Feb 2024 11:18:22 +0000
> 
> Eli Zaretskii <eliz@gnu.org> writes:
> 
> >
> > This produced text with red background, according to the yant/test-inv
> > face.  But if you define the overlays in the opposite order, you get
> > the red bold foreground instead.  If you now give each overlay a
> > priority, you can control which face shows: the one whose overlay has
> > the higher priority.
> >
> > Maybe I'm missing something, but I see no bug here.
> 
> You are indeed right.
> I fixed this priority race on Org mode side.
> https://git.savannah.gnu.org/cgit/emacs/org-mode.git/commit/?id=67d937248
> Thanks!

Thanks, I'm therefore closing this bug report.