bug#11912: 24.1; 'M' in Dired on a symlink does not refresh the display

[Eli Zaretskii]

On a system that supports symlinks, do this:

 emacs -Q
 C-x d RET

Go to any file and type

 S foobar RET

This creates a symlink named 'foobar' to the file on whose line you
were when you typed S.  Now go to the line of 'foobar' and type this:

 M 0444 RET

Emacs says "Redisplaying...done", but the mode bits of the target of
the symlink do not reflect the change.  Type 'g', and they will.

>From a cursory look at the code (dired-do-redisplay), it sounds like
Dired assumes that the file to be refreshed is necessarily on the
current line (or marked).  This is false for symlinks and the 'M'
command (and probably a few others, like 'O'), because the file that
changes is the target of the symlink.

I think this bug was in Emacs since about forever; I tried as far back
as Emacs 22.1, and the problem was still there.


In GNU Emacs 24.1.1 (i386-mingw-nt5.1.2600)
 of 2012-06-11 on HOME-C4E4A596F7
Windowing system distributor `Microsoft Corp.', version 5.1.2600
Configured using:
 `configure --with-gcc (3.4)'

Important settings:
  value of $LC_ALL: nil
  value of $LC_COLLATE: nil
  value of $LC_CTYPE: nil
  value of $LC_MESSAGES: nil
  value of $LC_MONETARY: nil
  value of $LC_NUMERIC: nil
  value of $LC_TIME: nil
  value of $LANG: ENU
  value of $XMODIFIERS: nil
  locale-coding-system: cp1255
  default enable-multibyte-characters: t

Major mode: Mail

Minor modes in effect:
  diff-auto-refine-mode: t
  flyspell-mode: t
  desktop-save-mode: t
  show-paren-mode: t
  display-time-mode: t
  tooltip-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
  temp-buffer-resize-mode: t
  line-number-mode: t
  abbrev-mode: t

Recent input:
n SPC t h e SPC n e t . <return> <right> <up> <C-left> 
<C-left> <C-right> SPC W i n d o w s M-q <down> <down> 
<up> <up> <up> <C-left> <C-left> <C-left> <C-left> 
l i b f f i SPC M-q <down> <down> <down> <C-home> C-c 
C-s <help-echo> <help-echo> <help-echo> <help-echo> 
<help-echo> <switch-frame> d <next> <next> <next> <prior> 
<next> <next> <next> <prior> <C-home> <C-end> <prior> 
<prior> <prior> <prior> <prior> d d <next> d d <next> 
d d d d d d <next> d d <next> d d d d d d d d d d d 
d <next> d <next> <next> d <next> d d d d d d d d d 
d d d SPC o <up> <up> <down> <return> d d d d d SPC 
d d C-z C-z C-z C-z C-z C-z C-z C-z C-z C-z <next> 
<next> SPC SPC SPC SPC SPC SPC SPC SPC SPC SPC SPC 
<prior> SPC SPC SPC SPC SPC SPC SPC SPC SPC <prior> 
<prior> <prior> <next> <next> <next> <next> <next> 
<next> <next> <next> <next> <next> <next> <next> <next> 
<next> <next> <next> <prior> <prior> <prior> <prior> 
<prior> C-r e g g e <M-left> <next> d d d d d SPC d 
SPC d d d d d SPC d d d d d n d SPC d d d d d d d d 
d n d d d d d d d d SPC d d d d <down> n SPC d d d 
d d d d d d d d d d d d d SPC d d SPC d SPC d d SPC 
d SPC d d d d d d d d C-z C-z C-z C-z C-z C-z C-z C-z 
C-z C-z d C-x C-s <switch-frame> M-x r e p o r t <tab> 
<return>

Recent messages:
Sending email done
Sending...done
Mark set [2 times]
Showing message 3132
Showing message 3132...done
Added to d:/usr/eli/rmail/TEXINFO.rmail
Mark saved where search started
No following nondeleted message
Saving file d:/usr/eli/rmail/INBOX...
Wrote d:/usr/eli/rmail/INBOX [2 times]

Load-path shadows:
None found.

Features:
(shadow emacsbug multi-isearch network-stream starttls tls smtpmail
auth-source eieio assoc gnus-util password-cache mailalias sendmail
rmailout tcl nxml-uchnm rng-xsd xsd-regexp rng-cmpct rng-nxml
rng-valid rng-loc rng-uri rng-parse nxml-parse rng-match rng-dt
rng-util rng-pttrn nxml-ns nxml-mode nxml-outln nxml-rap nxml-util
nxml-glyph nxml-enc xmltok sgml-mode conf-mode newcomment parse-time
generic ld-script sh-script executable vc-git arc-mode archive-mode
diff-mode dired-x dired make-mode tar-mode vc-cvs face-remap org-wl
org-w3m org-vm org-rmail org-mhe org-mew org-irc org-jsinfo org-infojs
org-html org-exp ob-exp org-exp-blocks find-func org-agenda org-info
org-gnus org-docview org-bibtex bibtex org-bbdb org byte-opt warnings
bytecomp byte-compile cconv macroexp advice help-fns advice-preload
ob-emacs-lisp ob-tangle ob-ref ob-lob ob-table org-footnote org-src
ob-comint ob-keys ob ob-eval org-pcomplete pcomplete comint ansi-color
ring org-list org-faces org-compat org-entities org-macs noutline
outline easy-mmode cal-menu calendar cal-loaddefs flyspell texinfo
jka-compr autorevert info vc-bzr cc-mode cc-fonts cc-guess cc-menus
cc-cmds cc-styles cc-align cc-engine cc-vars cc-defs regexp-opt qp
rmailsum rmailmm message format-spec rfc822 mml mml-sec mm-decode
mm-bodies mm-encode mailabbrev gmm-utils mailheader mail-parse rfc2231
rmail rfc2047 rfc2045 ietf-drums mm-util mail-prsvr mail-utils desktop
server filecache mairix cus-edit easymenu cus-start cus-load wid-edit
saveplace midnight ispell generic-x paren battery time time-date
tooltip ediff-hook vc-hooks lisp-float-type mwheel dos-w32 disp-table
ls-lisp w32-win w32-vars tool-bar dnd fontset image fringe lisp-mode
register page menu-bar rfn-eshadow timer select scroll-bar mouse
jit-lock font-lock syntax facemenu font-core frame cham georgian
utf-8-lang misc-lang vietnamese tibetan thai tai-viet lao korean
japanese hebrew greek romanian slovak czech european ethiopic indian
cyrillic chinese case-table epa-hook jka-cmpr-hook help simple abbrev
minibuffer loaddefs button faces cus-face files text-properties
overlay sha1 md5 base64 format env code-pages mule custom widget
hashtable-print-readable backquote make-network-process multi-tty
emacs)