23.0.60; C-x v v in an ordinary file throws strange error

23.0.60; C-x v v in an ordinary file throws strange error

[David Kastrup]

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 pressed C-x v v in a buffer associated with a file not under version
control.

The backtrace is

Debugger entered--Lisp error: (error "Selecting deleted buffer")
  vc-deduce-fileset(nil t)
  vc-next-action(nil)
  call-interactively(vc-next-action nil nil)



In GNU Emacs 23.0.60.3 (i686-pc-linux-gnu, GTK+ Version 2.12.0)
 of 2008-02-08 on lisa
Windowing system distributor `The X.Org Foundation', version 11.0.10300000
configured using `configure  '--prefix=/usr/local/emacs-21' '--without-toolkit-scroll-bars''

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

Major mode: Debugger

Minor modes in effect:
  shell-dirtrack-mode: t
  TeX-PDF-mode: t
  server-mode: t
  desktop-save-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
  blink-cursor-mode: t
  global-auto-composition-mode: t
  auto-composition-mode: t
  auto-compression-mode: t
  line-number-mode: t

Recent input:

C-g <switch-frame> C-x v v C-x v v M-x s e t - v a 
r <tab> <return> d e b u g - o n <tab> e r <tab> <return> 
t <return> C-x v v M-x r e p o r t - e m <tab> <re
turn>

Recent messages:
Quit [3 times]
vc-next-action: Selecting deleted buffer [2 times]
Entering debugger...

-- 
David Kastrup

Re: 23.0.60; C-x v v in an ordinary file throws strange error

[Eric Hanchrow]

This sounds dimly familiar; I think the fix is to call buffer-live-p
instead of merely checking that the isn't nil (note that the following
three patches are somewhat disorganized; I think one patch obviates
another, but you get the idea):

    git show d92d80884f25a3d58d2a799c3426d498dadbc6a6
    commit d92d80884f25a3d58d2a799c3426d498dadbc6a6
    Author: Eric Hanchrow <offby1@blarg.net>
    Date:   Fri Feb 15 15:01:00 2008 -0800

        (and x (buffer-live-p x)) => (buffer-live-p x)

    diff --git a/lisp/vc.el b/lisp/vc.el
    index 584b58d..ec59361 100644
    --- a/lisp/vc.el
    +++ b/lisp/vc.el
    @@ -1354,8 +1354,7 @@ Otherwise, throw an error."
                  (list (vc-status-current-file)))))
            ((vc-backend buffer-file-name)
             (list buffer-file-name))
    -	((and vc-parent-buffer
    -              (buffer-live-p vc-parent-buffer)
    +	((and (buffer-live-p vc-parent-buffer)
                   (or (buffer-file-name vc-parent-buffer)
                       (with-current-buffer vc-parent-buffer
                         vc-dired-mode)))
    @@ -1389,8 +1388,7 @@ Otherwise, throw an error."
        ((eq major-mode 'vc-status-mode)
         (set-buffer (find-file-noselect (vc-status-current-file))))
        (t
    -    (while (and vc-parent-buffer
    -                (buffer-live-p vc-parent-buffer)
    +    (while (and (buffer-live-p vc-parent-buffer)
                    ;; Avoid infinite looping when vc-parent-buffer and
                    ;; current buffer are the same buffer.
                    (not (eq vc-parent-buffer (current-buffer))))
    07:36:29 [erich@debian emacs-via-git]$ git show d20791cd96cf39e630e85b3b77cee4eb945a3783
    commit d20791cd96cf39e630e85b3b77cee4eb945a3783
    Author: Eric Hanchrow <erich@erich-dev.Kasayka.local>
    Date:   Fri Feb 15 14:26:00 2008 -0800

        vc-deduce-fileset: similarly to dfbfd942, call buffer-live-p

    diff --git a/lisp/vc.el b/lisp/vc.el
    index 102eeef..584b58d 100644
    --- a/lisp/vc.el
    +++ b/lisp/vc.el
    @@ -1354,9 +1354,11 @@ Otherwise, throw an error."
                  (list (vc-status-current-file)))))
            ((vc-backend buffer-file-name)
             (list buffer-file-name))
    -	((and vc-parent-buffer (or (buffer-file-name vc-parent-buffer)
    -				   (with-current-buffer vc-parent-buffer
    -				     vc-dired-mode)))
    +	((and vc-parent-buffer
    +              (buffer-live-p vc-parent-buffer)
    +              (or (buffer-file-name vc-parent-buffer)
    +                  (with-current-buffer vc-parent-buffer
    +                    vc-dired-mode)))
             (progn
               (set-buffer vc-parent-buffer)
               (vc-deduce-fileset)))
    07:36:46 [erich@debian emacs-via-git]$ git show dfbfd942
    commit dfbfd942a3c3e667a6f7b09f2d52f91e541a8b01
    Author: Stefan Monnier <monnier@cs.yale.edu>
    Date:   Sun Jan 6 16:02:38 2008 +0000

        (vc-ensure-vc-buffer): Check liveness of vc-parent-buffer.

    diff --git a/lisp/ChangeLog b/lisp/ChangeLog
    index c8e3dc4..4a874b5 100644
    --- a/lisp/ChangeLog
    +++ b/lisp/ChangeLog
    @@ -1,3 +1,7 @@
    +2008-01-06  Stefan Monnier  <monnier@iro.umontreal.ca>
    +
    +	* vc.el (vc-ensure-vc-buffer): Check liveness of vc-parent-buffer.
    +
     2008-01-06  Dan Nicolaescu  <dann@ics.uci.edu>

            * vc.el (vc-status-fileinfo): New defstruct.
    diff --git a/lisp/vc.el b/lisp/vc.el
    index 9e5df68..61a2c67 100644
    --- a/lisp/vc.el
    +++ b/lisp/vc.el
    @@ -1310,6 +1310,7 @@ Otherwise, throw an error."
       (if vc-dired-mode
           (set-buffer (find-file-noselect (dired-get-filename)))
         (while (and vc-parent-buffer
    +                (buffer-live-p vc-parent-buffer)
                    ;; Avoid infinite looping when vc-parent-buffer and
                    ;; current buffer are the same buffer.
                    (not (eq vc-parent-buffer (current-buffer))))

-- 
None of the ... actors do anything we couldn't do if we looked
like them.
        -- Roger Ebert, reviewing "The Chronicles Of Riddick"