`file-coding-system-alist' and shift_jis coding issue

[William]

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 address@hidden mailing list.

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

Hi,

When visiting a file with shift_jis encoding, emacs-snapshot is unable
to recoganize it automatically. Hence, i tried to use `C-x RET r'
(namely, M-x revert-buffer-with-coding-system) to force it to decode
buffer using shift_jis.

While, in the following two cases, case1 fails, case2 succeeds. Their
only difference is case2 has specified a default encoding in
`file-coding-system-alist' rather than `undecided'. Is the difference
the expected behaviour?


1) $ emacs-snapshot -Q

2) $ emacs-snapshot -Q
  Then eval this in *scratch* buffer before visiting the file,

(setq file-coding-system-alist
     ' (("\\.dz\\'" no-conversion . no-conversion)
        ("\\.g?z\\(~\\|\\.~[0-9]+~\\)?\\'" no-conversion . no-conversion)
        ("\\.tgz\\'" no-conversion . no-conversion)
        ("\\.tbz\\'" no-conversion . no-conversion)
        ("\\.bz2\\'" no-conversion . no-conversion)
        ("\\.Z\\(~\\|\\.~[0-9]+~\\)?\\'" no-conversion . no-conversion)
        ("\\.elc\\'" emacs-mule . emacs-mule)
        ("\\.utf\\(-8\\)?\\'" . utf-8)
        ("\\(\\`\\|/\\)loaddefs.el\\'" raw-text . raw-text-unix)
        ("\\.tar\\'" no-conversion . no-conversion)
        ("\\.po[tx]?\\'\\|\\.po\\." . po-find-file-coding-system)
        ("\\.\\(tex\\|ltx\\|dtx\\|drv\\)\\'" .
latexenc-find-file-coding-system)
        ;; the only changes
        ;; ("" undecided))
        ("" utf-8 . utf-8)))

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/22.0.90/etc/DEBUG for instructions.


In GNU Emacs 22.0.90.1 (powerpc-unknown-linux-gnu, X toolkit, Xaw3d scroll bars)
of 2006-10-28 on malo, modified by Debian
(Debian emacs-snapshot package, version 1:20061027-1)
X server distributor `The X.Org Foundation', version 11.0.70101000
configured using `configure '--build' 'powerpc-linux-gnu' '--host'
'powerpc-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/22.0.90/site-lisp:/usr/local/share/emacs/site-lisp:/usr/share/emacs/22.0.90/site-lisp:/usr/share/emacs/site-lisp:/usr/share/emacs/22.0.90/leim'
'--with-x=yes' '--with-x-toolkit=athena' '--with-toolkit-scroll-bars'
'CFLAGS=-DDEBIAN -DSITELOAD_PURESIZE_EXTRA=5000 -g -O2'
'build_alias=powerpc-linux-gnu' 'host_alias=powerpc-linux-gnu''

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: zh_CN.UTF-8
 locale-coding-system: utf-8
 default-enable-multibyte-characters: t

Major mode: Emacs-Lisp

Minor modes in effect:
 eldoc-mode: t
 which-function-mode: t
 darcs-mode: t
 less-minor-mode: t
 page-break-mode: t
 outline-minor-mode: t
 erc-spelling-mode: t
 erc-fill-mode: t
 erc-stamp-mode: t
 erc-match-mode: t
 erc-autojoin-mode: t
 erc-smiley-mode: t
 erc-readonly-mode: t
 recentf-mode: t
 display-time-mode: t
 global-auto-revert-mode: t
 show-paren-mode: t
 shell-dirtrack-mode: t
 tooltip-mode: t
 mouse-wheel-mode: t
 file-name-shadow-mode: t
 global-font-lock-mode: t
 font-lock-mode: t
 blink-cursor-mode: t
 unify-8859-on-encoding-mode: t
 utf-translate-cjk-mode: t
 auto-compression-mode: t
 column-number-mode: t
 line-number-mode: t
 transient-mark-mode: t
 fast-lock-mode: t

Recent input:
e s <return> j j f f G C-c m C-c C-g C-c C-v c v C--
C-c v C-c C-g C-c v C-c m r y j j g C-x k <return>
C-x C-f t e s <return> g C-x <return> r s h i <tab>
<return> y j j f f G g C-x b . x C-r C-r <return> C-x
C-f C-x b C-g C-x b s t a <return> C-a M-K M-x e m
a <tab> r e <tab> <tab> DEL C-a C-k r e p o <tab> <tab>
r <tab> b u <tab> <tab> <return>

Recent messages:
Mark set [2 times]
Revert buffer from file
/home/william/remote/studio/svn/vce2jp/test/doc/test? (y or n)
Mark set [2 times]
Quit
byte-code: Command attempted to use minibuffer while in minibuffer
Quit [2 times]
byte-code: Buffer is read-only: #<buffer .xwl-emacs-standard.el>
Making completion list...
Loading emacsbug...done
call-interactively: Text is read-only

--
William

We come to bury DOS, not to praise it.
(Paul Vojta, address@hidden, paraphrasing a quote of Shakespeare)