bug#38731: 27.0.50; Unexpected redisplay behaviour. Cursor can’t be moved to end of line.

[HaiJun Zhang <netjune@outlook.com>]

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In GNU Emacs 27.0.50 (build 1, x86_64-apple-darwin17.7.0, NS appkit-1561.61 Version 10.13.6 (Build 17G10021))
 of 2019-12-23 built on jundeMac
Repository revision: 3ee8ee8476fef2a5e8159f7597e36e0953295ce2
Repository branch: mod
Windowing system distributor ‘Apple', version 10.3.1561
System Description: Mac OS X 10.13.6

Reproduction steps:
1. emacs -Q
2. open the test file in attachment(a.cpp)
3. M-x toggle-truncate-lines
4. M-x global-hl-line
5. shrink the width of the emacs window so that the longest line(#12) can’t be fully visible
6. go to line 12 and press C-e to goto end of line
7. the cursor is not at the end of line and you can’t move the cursor to end of line



Recent messages:
For information about GNU Emacs and the GNU system, type C-h C-a.
Truncate long lines enabled
Global Hl-Line mode enabled
next-line: End of buffer
delete-backward-char: Text is read-only
funcall-interactively: End of buffer [3 times]

Configured using:
 ‘configure —with-ns '--enable-locallisppath=/Library/Application
 Support/Emacs/${version}/site-lisp:/Library/Application
 Support/Emacs/site-lisp’ --with-modules --disable-acl
 —without-makeinfo CFLAGS=-O2’

Configured features:
RSVG GLIB NOTIFY KQUEUE GNUTLS LIBXML2 ZLIB TOOLKIT_SCROLL_BARS NS
MODULES THREADS PDUMPER LCMS2 GMP

Important settings:
  value of $LANG: zh_CN.UTF-8
  locale-coding-system: utf-8-unix

Major mode: C++//l

Minor modes in effect:
  global-hl-line-mode: t
  tooltip-mode: t
  global-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
  abbrev-mode: t

Load-path shadows:
None found.

Features:
(shadow sort mail-extr emacsbug message rmc puny dired dired-loaddefs
format-spec rfc822 mml 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 sendmail rfc2047
rfc2045 ietf-drums mm-util mail-prsvr mail-utils cus-start cus-load
hl-line vc-git diff-mode easy-mmode cc-mode cc-fonts easymenu cc-guess
cc-menus cc-cmds cc-styles cc-align cc-engine cc-vars cc-defs
cl-loaddefs cl-lib china-util tooltip eldoc electric uniquify ediff-hook
vc-hooks lisp-float-type mwheel term/ns-win ns-win ucs-normalize
mule-util 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 kqueue cocoa ns lcms2 multi-tty make-network-process
emacs)

Memory information:
((conses 16 80300 14394)
 (symbols 48 9922 0)
 (strings 32 24946 2210)
 (string-bytes 1 886243)
 (vectors 16 14651)
 (vector-slots 8 229697 4904)
 (floats 8 23 40)
 (intervals 56 259 0)
 (buffers 1000 12))


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[-- Attachment #2: a.cpp --]
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#include <stdio.h>

int main(int argc, char **argv)
{
	printf("hello world\n");

	if(1)
	{
		if(1)
		{
			if(a long long variable -name fffffffffffff ) {
				// printf("------------ very long line .......", foobar())

				foo();
			}
		}
	}

	return 0;
}