Subject: bug#66764: closed (Re: bug#66764: 29.1; Emacs scrolls for "(goto-char (point-max))" instead of jumping)

From: [email-masked] (GNU bug Tracking System)
Date: Mon, 15 Jan 2024 13:31:02 +0000

Your bug report

#66764: 29.1; Emacs scrolls for "(goto-char (point-max))" instead of jumping

which was filed against the emacs package, has been closed.

The explanation is attached below, along with your original report.
If you require more details, please reply to [email-masked].

-- 
66764: https://debbugs.gnu.org/cgi/bugreport.cgi?bug=66764
GNU Bug Tracking System
Contact [email-masked] with problems

Subject: Re: bug#66764: 29.1; Emacs scrolls for "(goto-char (point-max))" instead of jumping
From: Gregory Heytings <[email-masked]>
To: Eli Zaretskii <[email-masked]>
Cc: [email-masked], [email-masked]
Date: Mon, 15 Jan 2024 13:30:04 +0000
List-Id: <debbugs-submit.debbugs.gnu.org>

>> I was AFK between the moment your previous post arrived and now.  Just 
>> done (5bb5590dec).
>
> Thanks.  Should we now close this bug?
>

Yes, I don't think there's anything more to do here.

>> Is there any chance the (cosmetic) change in 9e9e11648d could be 
>> cherry-picked from master to emacs-29?  I had forgotten they were only 
>> on master, and my eyes were hurting when I read that part of the code 
>> while debugging it.
>
> Yes, okay.
>

Thanks, done (53b5b77010).

Subject: 29.1; Emacs scrolls for "(goto-char (point-max))" instead of jumping
From: Geza Herman <[email-masked]>
To: [email-masked]
Date: Thu, 26 Oct 2023 19:04:42 +0200
List-Id: <debbugs-submit.debbugs.gnu.org>

The bug is, that in certain circumstances, emacs moves the point by 
using some kind of scrolling for "(goto-char (point-max))", instead of 
just jumping.

Repro:

- create a file using the little C program at the end (it produces a 
large text to stdout, you'll need to redirect it to some file)

- open the file with "emacs -Q generated.txt"

- with M-:, execute this:

    (progn
      (setq scroll-conservatively 101)
      (font-lock-add-keywords nil '(((lambda (bound)) (1 'error prepend 
t))) t)
      (goto-char (point-max)))

Notice that emacs doesn't jump to the end immediately as usual, but it 
does some kind of very fast scrolling.

(With long-line-threshold set to nil, the issue doesn't happen)

In my real case, a much smaller file produces this problem. Also, Emacs 
doesn't go to the end of the file, but stops somewhere in the middle (I 
was unable to reproduce this issue with a simple configuration). So to 
go to the end of the file I have to run "(goto-char (point-max))" 
multiple times. Interestingly, "M->" works fine. But if I remove the 
recenter call at the end of "end-of-buffer", it also has this odd behavior.

Here is the C program:

#include <stdio.h>
#include <stdlib.h>

int main() {
     for (int i=0; i<200000; i++) {
         int len = 100 + (rand()&0x7f);
         if (i==5000) len = 60000;
         for (int j=0; j<len; j++) {
             printf("x");
         }
         printf("\n");
     }
}

In GNU Emacs 29.1 (build 1, x86_64-pc-linux-gnu, GTK+ Version 3.24.38,
  cairo version 1.16.0) of 2023-08-30, modified by Debian built on
  x86-csail-01
Windowing system distributor 'The X.Org Foundation', version 11.0.12101008
System Description: Debian GNU/Linux trixie/sid

Configured using:
  'configure --build x86_64-linux-gnu --prefix=/usr
  --sharedstatedir=/var/lib --libexecdir=/usr/libexec
  --localstatedir=/var/lib --infodir=/usr/share/info
  --mandir=/usr/share/man --with-libsystemd --with-pop=yes
  --enable-locallisppath=/etc/emacs:/usr/local/share/emacs/29.1/site-lisp:/usr/local/share/emacs/site-lisp:/usr/share/emacs/29.1/site-lisp:/usr/share/emacs/site-lisp
  --with-sound=alsa --without-gconf --with-mailutils
  --with-native-compilation --build x86_64-linux-gnu --prefix=/usr
  --sharedstatedir=/var/lib --libexecdir=/usr/libexec
  --localstatedir=/var/lib --infodir=/usr/share/info
  --mandir=/usr/share/man --with-libsystemd --with-pop=yes
  --enable-locallisppath=/etc/emacs:/usr/local/share/emacs/29.1/site-lisp:/usr/local/share/emacs/site-lisp:/usr/share/emacs/29.1/site-lisp:/usr/share/emacs/site-lisp
  --with-sound=alsa --without-gconf --with-mailutils
  --with-native-compilation --with-cairo --with-x=yes
  --with-x-toolkit=gtk3 --with-toolkit-scroll-bars 'CFLAGS=-g -O2
  -ffile-prefix-map=/build/reproducible-path/emacs-29.1+1=. 
-fstack-protector-strong
  -Wformat -Werror=format-security -Wall' 'CPPFLAGS=-Wdate-time
  -D_FORTIFY_SOURCE=2' LDFLAGS=-Wl,-z,relro'

Configured features:
ACL CAIRO DBUS FREETYPE GIF GLIB GMP GNUTLS GPM GSETTINGS HARFBUZZ JPEG
JSON LCMS2 LIBOTF LIBSELINUX LIBSYSTEMD LIBXML2 M17N_FLT MODULES
NATIVE_COMP NOTIFY INOTIFY PDUMPER PNG RSVG SECCOMP SOUND SQLITE3
THREADS TIFF TOOLKIT_SCROLL_BARS TREE_SITTER WEBP X11 XDBE XIM XINPUT2
XPM GTK3 ZLIB

Important settings:
   value of $LC_ALL: C.UTF-8
   value of $LANG: en_US.UTF-8
   value of $XMODIFIERS: @im=ibus
   locale-coding-system: utf-8-unix

Major mode: Text

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
   font-lock-mode: t
   blink-cursor-mode: 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:
None found.

Features:
(shadow sort mail-extr emacsbug message mailcap yank-media puny dired
dired-loaddefs rfc822 mml mml-sec password-cache 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 comp comp-cstr
warnings icons subr-x rx cl-seq cl-macs gv cl-extra help-mode
cl-loaddefs cl-lib bytecomp byte-compile 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 dbusbind inotify lcms2
dynamic-setting system-font-setting font-render-setting cairo
move-toolbar gtk x-toolkit xinput2 x multi-tty make-network-process
native-compile emacs)

Memory information:
((conses 16 100665 12371)
  (symbols 48 7141 0)
  (strings 32 26857 2252)
  (string-bytes 1 845777)
  (vectors 16 20215)
  (vector-slots 8 367701 18494)
  (floats 8 50 17)
  (intervals 56 2211 0)
  (buffers 984 12))