Ediff frequently crashes emacs.

[Peter Seibel]

Symptoms:

I will be ediffing two buffers as a result of invoking this function:

  (defun p4-diff (&optional version)
    "p4 diff the file visited by the current buffer with a version in the depot.
  If called with a prefix arg, diffs against that version; otherwise diffs
  versus the latest version."
    (interactive "P")
    (ediff-buffers
     (current-buffer)
     (p4-make-diff-buffer (p4-print-to-buffer (p4-filename version)))))

Here are the functions it calls:

    (defun p4-make-diff-buffer (buf)
      ; this is redundant but safer than only doing it when
      ; p4-diff-buffers is nil
      (add-hook 'ediff-quit-hook 'p4-cleanup-diff-buffers)
      (setq p4-diff-buffers (cons buf p4-diff-buffers))
      buf)

    (defun p4-print-to-buffer (filename)
      (let* ((buf (p4-get-cleared-buffer (concat filename "<depot>"))))
        (shell-command (concat "p4 print -q " filename) buf)
        buf))

    (defun p4-filename (&optional version)
      (let ((base-filename (file-name-nondirectory buffer-file-name)))
        (if version 
            (concat base-filename "#" (number-to-string version))
          base-filename)))

At seemingly random times executing any ediff command such as by
hitting 'n' or 'p' or (this latest time) 'b' to move a change from
buffer b to buffer a, it will cause emacs to exit with no warning. (I
have confirm-kill-emacs set to y-or-n-p). Othertimes it won't crash
emacs but instead will seemingly hang it--my cursor changes to a watch
and emacs does not respond to C-g or 'q' to quit ediff. I've tried to
reproduce this by ediffing the same files and it doesn't always happen.

-Peter

In GNU Emacs 21.3.50.1 (i686-pc-linux-gnu, X toolkit, Xaw3d scroll bars)
 of 2004-10-23 on xeon
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.iso885915
  locale-coding-system: iso-latin-9
  default-enable-multibyte-characters: t

Major mode: Apropos

Minor modes in effect:
  mouse-wheel-mode: t
  global-font-lock-mode: t
  font-lock-mode: t
  unify-8859-on-encoding-mode: t
  utf-translate-cjk-mode: t
  line-number-mode: t

Recent input:
M-x m e c <tab> <backspace> <backspace> <backspace> 
e m a c <tab> b u <tab> <backspace> <tab> <tab> <backspace> 
<tab> C-g C-h a b u g <return> M-x e m <tab> a c <tab> 
- s u <backspace> <backspace> <backspace> s u b <tab> 
<M-backspace> <tab> <M-backspace> s u b <tab> C-x o 
C-s s s M-x r e p <tab> o r t <tab> <return>

Recent messages:
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