bug#56683: 29.0.50; long lines fix doesn't work correctly when lines are truncated

[Andrey Listopadov]

I'm using emacs with `truncate-lines` set to `t` in my init.el.  After
the merge of #56393 I've rebuilt Emacs, and started testing the fix.
I've noticed, that when lines are truncated, opening dictionary.json
from the #45898 and pressing C-e doesn't move you to the end of the
line, but stops somewhere inside it.  E.g. with the default window width
of Emacs -Q, I can see the following portion of the line

←, "hu": ["index"]}, "examples": [["en C la indicoj aperas inter ortajkrampoj, →

Arrows shown in the fringe indicate that there are more to the line on
the right side.

As a side question, does these optimizations work with truncated lines?
As far as I can tell Emacs is not as responsive as when the lines are
wrapped, but I don't know how to measure this precisely.

In GNU Emacs 29.0.50 (build 1, x86_64-pc-linux-gnu, GTK+ Version 3.24.30, cairo 
version 1.17.4)
 of 2022-07-21 built on toolbox
Repository revision: 4a4fcf628e1e4c8db47cd62fa5617b662fa8b5d6
Repository branch: master
System Description: Fedora Linux 36 (Workstation Edition)

Configured using:
 'configure --without-compress-install --with-native-compilation
 --with-pgtk --with-mailutils --prefix=/home/alist/.local'

Configured features:
ACL CAIRO DBUS FREETYPE GIF GLIB GMP GNUTLS GPM GSETTINGS HARFBUZZ JPEG
JSON LCMS2 LIBOTF LIBSELINUX LIBXML2 MODULES NATIVE_COMP NOTIFY INOTIFY
PDUMPER PGTK PNG RSVG SECCOMP SOUND THREADS TIFF TOOLKIT_SCROLL_BARS XIM
GTK3 ZLIB

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

Major mode: Lisp Interaction

Minor modes in effect:
  tooltip-mode: t
  global-eldoc-mode: t
  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:
(comp comp-cstr warnings rx cl-seq cl-macs gv cl-extra bytecomp
byte-compile cconv help-mode pp 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 subr-x 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 rmc
iso-transl tooltip eldoc paren electric uniquify ediff-hook vc-hooks
lisp-float-type elisp-mode mwheel term/pgtk-win pgtk-win term/common-win
pgtk-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 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 dynamic-setting system-font-setting font-render-setting cairo
gtk pgtk lcms2 multi-tty make-network-process native-compile emacs)

Memory information:
((conses 16 82646 9587)
 (symbols 48 7091 6)
 (strings 32 19214 1773)
 (string-bytes 1 656752)
 (vectors 16 15347)
 (vector-slots 8 284088 17444)
 (floats 8 173 66)
 (intervals 56 698 7)
 (buffers 992 13))

--
Andrey Listopadov