bug#1135: marked as done (23.0.60; (expand-file-name ".." "/") produces surprising results)

[don@donarmstrong.com (Emacs bug Tracking System)]

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Your message dated Thu, 16 Oct 2008 14:01:06 -0400
with message-id <87ljwo1kt9.fsf@cyd.mit.edu>
and subject line Re: bug#1135: 23.0.60; (expand-file-name ".." "/") produces surprising results
has caused the Emacs bug report #1135,
regarding 23.0.60; (expand-file-name ".." "/") produces surprising results
to be marked as done.

This means that you claim that the problem has been dealt with.
If this is not the case it is now your responsibility to reopen the
bug report if necessary, and/or fix the problem forthwith.

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immediately.)


-- 
1135: http://emacsbugs.donarmstrong.com/cgi-bin/bugreport.cgi?bug=1135
Emacs Bug Tracking System
Contact don@donarmstrong.com with problems

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From: Daniel Pittman <daniel@rimspace.net>
To: emacs-pretest-bug@gnu.org
Subject: 23.0.60; (expand-file-name ".." "/") produces surprising results
Date: Fri, 10 Oct 2008 14:41:55 +1100
Message-ID: <87k5chce0s.fsf@rimspace.net>


Please write in English if possible, because the Emacs maintainers
usually do not have translators to read other languages for them.

Your bug report will be posted to the emacs-pretest-bug@gnu.org mailing list.

Please describe exactly what actions triggered the bug
and the precise symptoms of the bug:


I use some code that uses (setq dir (expand-file-name ".." dir)) to walk
up a directory tree to the root.  This works fine on the local disk, but
has some surprising results -- infinite loop -- on Tramp files.

I debugged this down to the unexpected (to me) behaviour of

    (expand-file-name ".." "/")
    => "/.."

    (expand-file-name ".." "/..")
    => "/"

This was causing the code, which checked if the current and previous
result of (expand-file-name ".." dir) were the same, to go into an
infinite loop cycling between those two values...


I would have expected that the result was:

    (expand-file-name ".." "/")
    => "/"

Regards,
        Daniel


If Emacs crashed, and you have the Emacs process in the gdb debugger,
please include the output from the following gdb commands:
    `bt full' and `xbacktrace'.
If you would like to further debug the crash, please read the file
/usr/share/emacs/23.0.60/etc/DEBUG for instructions.


In GNU Emacs 23.0.60.1 (x86_64-pc-linux-gnu, GTK+ Version 2.12.9)
 of 2008-03-20 on yellow, modified by Debian
 (emacs-snapshot package, version 1:20080228-1ubuntu1)
Windowing system distributor `The X.Org Foundation', version 11.0.10400090
configured using `configure  '--build' 'x86_64-linux-gnu' '--host' 'x86_64-linux-gnu' '--prefix=/usr' '--sharedstatedir=/var/lib' '--libexecdir=/usr/lib' '--localstatedir=/var' '--infodir=/usr/share/info' '--mandir=/usr/share/man' '--with-pop=yes' '--enable-locallisppath=/etc/emacs-snapshot:/etc/emacs:/usr/local/share/emacs/23.0.60/site-lisp:/usr/local/share/emacs/site-lisp:/usr/share/emacs/23.0.60/site-lisp:/usr/share/emacs/site-lisp:/usr/share/emacs/23.0.60/leim' '--with-x=yes' '--with-x-toolkit=gtk' '--enable-font-backend' 'build_alias=x86_64-linux-gnu' 'host_alias=x86_64-linux-gnu' 'CFLAGS=-DDEBIAN -DSITELOAD_PURESIZE_EXTRA=5000 -g -O2' 'LDFLAGS=-g -Wl,--as-needed' 'CPPFLAGS=''

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: en_AU.UTF-8
  value of $XMODIFIERS: nil
  locale-coding-system: utf-8-unix
  default-enable-multibyte-characters: t

Major mode: Emacs-Lisp

Minor modes in effect:
  eldoc-mode: t
  highlight-parentheses-mode: t
  flyspell-mode: t
  shell-dirtrack-mode: t
  show-paren-mode: t
  tooltip-mode: t
  mouse-wheel-mode: t
  menu-bar-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  font-lock-mode: t
  global-auto-composition-mode: t
  auto-composition-mode: t
  auto-compression-mode: t
  column-number-mode: t
  line-number-mode: t
  transient-mark-mode: t

Recent input:
c c c c c d d d d d d d d d c c c c c c c c c c c c 
c c C-x k <return> C-x C-f <up> <return> c c c c c 
c c c c c c c c c c c c c c c c c c c c c c c c c c 
c c c c c c c c c c c c c c c c c c c c c c c c c c 
c c c c c c c c c c c c c c c c c c c c c c c c c c 
c c c c c c c c c c c c c c d d d d d d d d d d d c 
c c c q C-/ C-/ C-M-x C-x k <return> M-: ( e x p a 
n d - f i l e - n a m e SPC " . . " S-SPC " / " ) <return> 
M-: <up> C-e <left> <left> <left> <left> <right> <right> 
. p . <backspace> <backspace> . <return> <tab> C-h 
f e x p a n d - f i l / <tab> <backspace> <tab> <return> 
<switch-frame> SPC n q C-s g n u <down> <down> <down> 
<down> <return> SPC C-k C-k C-k C-k q p p g n SPC SPC 
n n n <switch-frame> <switch-frame> <switch-frame> 
<switch-frame> <switch-frame> <switch-frame> <C-tab> 
C-p C-p C-p C-f C-f C-f C-f C-f C-f C-f C-f C-f C-SPC 
M-f M-f M-f <C-insert> <switch-frame> <switch-frame> 
<switch-frame> <switch-frame> <switch-frame> M-x r 
e p o r t <tab> C-g <switch-frame> M-x C-g M-x r e 
p o r t - e m <tab> b <tab> <return>

Recent messages:
Reading active file from archive via nnfolder...done
Checking new news...done
Retrieving newsgroup: nntp+enki:gmane.emacs.devel...
Fetching headers for nntp+enki:gmane.emacs.devel...done
Suppressing duplicates...done
Scoring...done
Generating summary...done
Mark set
Auto-saving...done
Quit
Quit



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From: Chong Yidong <cyd@stupidchicken.com>
To: Daniel Pittman <daniel@rimspace.net>
Cc: 1135-done@emacsbugs.donarmstrong.com
Subject: Re: bug#1135: 23.0.60; (expand-file-name ".." "/") produces surprising results
Date: Thu, 16 Oct 2008 14:01:06 -0400
Message-ID: <87ljwo1kt9.fsf@cyd.mit.edu>

> My suggestion would be the documentation approach

I checked in a slightly different doc fix.  Thanks for reporting the
bug.