bug#66244: Buffer is modified: Undo after comment-line

bug#66244: Buffer is modified: Undo after comment-line

[Vitaliy Chepelev]

Steps to reproduce:
1) C-x C-; or M-x comment-line
2) C-/ or M-x undo

result: U:@**-

In GNU Emacs 28.2 (build 1, x86_64-pc-linux-gnu, X toolkit) of 2023-07-25

result: U:@---

Tested after removing of ~/.emacs and ~/.emacs.d/

Automatic generated report for emacs version with error:

In GNU Emacs 29.1 (build 1, x86_64-pc-linux-gnu, X toolkit) of
 2023-09-27 built on localhost
Windowing system distributor 'The X.Org Foundation', version 11.0.12101008
System Description: Gentoo Linux

Configured using:
 'configure --prefix=/usr --build=x86_64-pc-linux-gnu
 --host=x86_64-pc-linux-gnu --mandir=/usr/share/man
 --infodir=/usr/share/info --datadir=/usr/share --sysconfdir=/etc
 --localstatedir=/var/lib --datarootdir=/usr/share
 --disable-silent-rules --docdir=/usr/share/doc/emacs-29.1-r1
 --htmldir=/usr/share/doc/emacs-29.1-r1/html --libdir=/usr/lib64
 --program-suffix=-emacs-29 --includedir=/usr/include/emacs-29
 --infodir=/usr/share/info/emacs-29 --localstatedir=/var
 --enable-locallisppath=/etc/emacs:/usr/share/emacs/site-lisp
 --without-compress-install --without-hesiod --without-pop
 --with-file-notification=inotify --with-pdumper --enable-acl
 --without-dbus --without-modules --without-gameuser --with-libgmp
 --without-gpm --without-native-compilation --with-json
 --without-kerberos --without-kerberos5 --without-lcms2 --without-xml2
 --without-mailutils --without-selinux --with-sqlite3 --with-gnutls
 --without-libsystemd --with-threads --with-tree-sitter
 --without-wide-int --with-sound=no --with-zlib --with-x --without-pgtk
 --without-ns --without-gconf --without-gsettings
 --without-toolkit-scroll-bars --with-xpm --with-xft --without-cairo
 --without-harfbuzz --without-libotf --without-m17n-flt
 --with-x-toolkit=lucid --without-xaw3d --with-gif --with-jpeg
 --with-png --with-rsvg --without-tiff --with-webp --without-imagemagick
 --with-dumping=pdumper 'CFLAGS=-O2 -pipe -mno-rdrnd -mno-aes
 -march=ivybridge -msse -msse2 -mmmx -D_FORTIFY_SOURCE=2
 -D_GLIBCXX_ASSERTIONS -fstack-protector-strong -fstack-clash-protection
 -fcf-protection' 'LDFLAGS=-Wl,-O1 -Wl,--as-needed''

Configured features:
ACL FREETYPE GIF GLIB GMP GNUTLS JPEG JSON NOTIFY INOTIFY PDUMPER PNG
RSVG SECCOMP SQLITE3 THREADS TREE_SITTER WEBP X11 XDBE XFT XIM XINPUT2
XPM LUCID ZLIB

Important settings:
  value of $LANG: C.UTF8
  locale-coding-system: utf-8-unix

Major mode: Programming modes - python-mode, python-ts-mode, elisp-mode

Minor modes in effect:
  tooltip-mode: t
  global-eldoc-mode: t
  show-paren-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
  blink-cursor-mode: t
  buffer-read-only: t
  line-number-mode: t
  indent-tabs-mode: t
  transient-mark-mode: t
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t

Load-path shadows:
/home/u/.emacs.d/elpa/transient-0.3.7/transient hides /usr/share/emacs/29.1/lisp/transient

Features:
(shadow sort mail-extr emacsbug message yank-media puny dired
dired-loaddefs rfc822 mml mml-sec epa derived epg rfc6068 epg-config
gnus-util text-property-search time-date mm-decode mm-bodies mm-encode
mail-parse rfc2231 mailabbrev gmm-utils mailheader sendmail rfc2047
rfc2045 ietf-drums mm-util mail-prsvr mail-utils site-gentoo info
package browse-url url url-proxy url-privacy url-expand url-methods
url-history url-cookie generate-lisp-file url-domsuf url-util mailcap
url-handlers url-parse auth-source cl-seq eieio eieio-core cl-macs
password-cache json subr-x map byte-opt gv bytecomp byte-compile
url-vars cl-loaddefs cl-lib rmc iso-transl tooltip cconv eldoc paren
electric uniquify ediff-hook vc-hooks lisp-float-type elisp-mode mwheel
term/x-win x-win term/common-win x-dnd tool-bar dnd fontset image
regexp-opt fringe tabulated-list replace newcomment text-mode lisp-mode
prog-mode register page tab-bar menu-bar rfn-eshadow isearch easymenu
timer select scroll-bar mouse jit-lock font-lock syntax font-core
term/tty-colors frame minibuffer nadvice seq simple cl-generic
indonesian philippine 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 emoji-zwj charscript charprop case-table epa-hook
jka-cmpr-hook help abbrev obarray oclosure cl-preloaded button loaddefs
theme-loaddefs faces cus-face macroexp files window text-properties
overlay sha1 md5 base64 format env code-pages mule custom widget keymap
hashtable-print-readable backquote threads inotify dynamic-setting
font-render-setting x-toolkit xinput2 x multi-tty make-network-process
emacs)

Memory information:
((conses 16 67383 8982)
 (symbols 48 7959 0)
 (strings 32 25056 1635)
 (string-bytes 1 780232)
 (vectors 16 14848)
 (vector-slots 8 206286 10720)
 (floats 8 30 29)
 (intervals 56 356 0)
 (buffers 984 13))

--
Best regards,
Vitaliy Chepelev
Python Middle Data Scientist
https://t.me/vitdata

--
Best regards,
Vitaliy Chepelev
Python Middle Data Scientist
https://t.me/vitdata

bug#66244: Buffer is modified: Undo after comment-line

[Eli Zaretskii]

> From: Vitaliy Chepelev <vitalij@gmx.com>
> Date: Wed, 27 Sep 2023 17:12:37 -0000
> 
> Steps to reproduce:
> 1) C-x C-; or M-x comment-line
> 2) C-/ or M-x undo
> 
> result: U:@**-

Thanks, this is already fixed on the Emacs master branch.