bug#53215: 27.2; unexpected scroll at invisible text

bug#53215: 27.2; unexpected scroll at invisible text

[awrhygty]

Evaluate the following form and type 'C-f'.
The point moves to invisible text and the buffer scrolls up as if
recenter('C-l') is done.
Same things happen on other lines if the end of buffer is not displayed
in the current window.

(let ((buf (generate-new-buffer "tmp")))
  (switch-to-buffer buf)
  (setq truncate-lines nil)
  (dotimes (i (1+ (- ?~ ?!)))
    (insert (format "%d " i))
    (insert (propertize " " 'invisible t))
    (insert-char (+ ?! i) (window-width))
    (insert ?\n))
  (goto-line 20)
  (redisplay)
  (forward-line)
  (skip-chars-forward "^ "))



In GNU Emacs 27.2 (build 1, x86_64-w64-mingw32)
 of 2021-03-26 built on CIRROCUMULUS
Repository revision: deef5efafb70f4b171265b896505b92b6eef24e6
Repository branch: HEAD
Windowing system distributor 'Microsoft Corp.', version 10.0.19043
System Description: Microsoft Windows 10 Pro (v10.0.2009.19043.1415)

Recent messages:

Configured using:
 'configure --without-dbus --host=x86_64-w64-mingw32
 --without-compress-install 'CFLAGS=-O2 -static''

Configured features:
XPM JPEG TIFF GIF PNG RSVG SOUND NOTIFY W32NOTIFY ACL GNUTLS LIBXML2
HARFBUZZ ZLIB TOOLKIT_SCROLL_BARS MODULES THREADS JSON PDUMPER LCMS2 GMP

Important settings:
  value of $LANG: JPN
  locale-coding-system: cp932

Major mode: Lisp Interaction

Minor modes in effect:
  tooltip-mode: t
  global-eldoc-mode: t
  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
  line-number-mode: t
  transient-mark-mode: t

Load-path shadows:
None found.

Features:
(misearch multi-isearch gnutls network-stream nsm mailalias smtpmail
auth-source cl-seq eieio eieio-core cl-macs eieio-loaddefs json map
tabify help-mode pp shadow sort mail-extr emacsbug message rmc puny
dired dired-loaddefs format-spec rfc822 mml easymenu mml-sec
password-cache epa derived epg epg-config gnus-util rmail rmail-loaddefs
text-property-search time-date subr-x seq byte-opt gv bytecomp
byte-compile cconv mm-decode mm-bodies mm-encode mail-parse rfc2231
mailabbrev gmm-utils mailheader cl-loaddefs cl-lib sendmail rfc2047
rfc2045 ietf-drums mm-util mail-prsvr mail-utils term/bobcat japan-util
tooltip eldoc electric uniquify ediff-hook vc-hooks lisp-float-type
mwheel dos-w32 ls-lisp disp-table term/w32-win w32-win w32-vars
term/common-win tool-bar dnd fontset image regexp-opt fringe
tabulated-list replace newcomment text-mode elisp-mode lisp-mode
prog-mode register page tab-bar menu-bar rfn-eshadow isearch timer
select scroll-bar mouse jit-lock font-lock syntax facemenu font-core
term/tty-colors frame minibuffer cl-generic cham georgian utf-8-lang
misc-lang vietnamese tibetan thai tai-viet lao korean japanese eucjp-ms
cp51932 hebrew greek romanian slovak czech european ethiopic indian
cyrillic chinese composite charscript charprop case-table epa-hook
jka-cmpr-hook help simple abbrev obarray cl-preloaded nadvice loaddefs
button faces cus-face macroexp files text-properties overlay sha1 md5
base64 format env code-pages mule custom widget hashtable-print-readable
backquote threads w32notify w32 lcms2 multi-tty make-network-process
emacs)

Memory information:
((conses 16 62844 10393)
 (symbols 48 7261 0)
 (strings 32 20539 1285)
 (string-bytes 1 653910)
 (vectors 16 13463)
 (vector-slots 8 238422 21754)
 (floats 8 25 286)
 (intervals 56 624 189)
 (buffers 1000 15))

bug#53215: 27.2; unexpected scroll at invisible text

[Lars Ingebrigtsen]

awrhygty@outlook.com writes:

> Evaluate the following form and type 'C-f'.
> The point moves to invisible text and the buffer scrolls up as if
> recenter('C-l') is done.

Yup; I can reproduce this behaviour in Emacs 29, too.

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no

bug#53215: 27.2; unexpected scroll at invisible text

[Eli Zaretskii]

> From: awrhygty@outlook.com
> Date: Thu, 13 Jan 2022 02:21:06 +0900
> 
> Evaluate the following form and type 'C-f'.
> The point moves to invisible text and the buffer scrolls up as if
> recenter('C-l') is done.
> Same things happen on other lines if the end of buffer is not displayed
> in the current window.
> 
> (let ((buf (generate-new-buffer "tmp")))
>   (switch-to-buffer buf)
>   (setq truncate-lines nil)
>   (dotimes (i (1+ (- ?~ ?!)))
>     (insert (format "%d " i))
>     (insert (propertize " " 'invisible t))
>     (insert-char (+ ?! i) (window-width))
>     (insert ?\n))
>   (goto-line 20)
>   (redisplay)
>   (forward-line)
>   (skip-chars-forward "^ "))

Thanks, should be fixed now on the master branch.