bug#2497: 23.0.91; Fails to read UTF-8 on Win2k

[Eli Zaretskii <eliz@gnu.org>]

> From: Stefan Monnier <monnier@iro.umontreal.ca>
> Cc: 2497@emacsbugs.donarmstrong.com,  uwe.siart@tum.de
> Date: Fri, 27 Feb 2009 23:40:01 -0500
> 
> >> It works with "C-x RET c utf-8 RET" immediately prior to "C-x C-f".
> >> > If it does, then the problem is with guessing the encoding, not with
> >> > decoding it.
> >> That's also my impression.
> >> > Also, what is the default value of buffer-file-coding-system, and was
> >> > it the same in 23.0.90?
> >> iso-latin-1-dos in 23.0.90 and in 23.0.91.
> > Then you shouldn't expect Emacs to guess UTF-8 encoding correctly in
> > every single instance.  Distinguishing between UTF-8 and Latin-1 is
> 
> The guessing shouldn't give priority to buffer-file-coding-system.
> Instead we have the set-coding-system-priority instead.

Please give me some credit: I said ``the _default_value_ of
buffer-file-coding-system''.  That default tells volumes about the
coding-system priorities.

> And IIUC utf-8 should always have a pretty high priority

With today's CVS on a Windows XP machine I get this:

  M-: (coding-system-priority-list) RET
  =>  (iso-latin-1 utf-8 iso-2022-7bit iso-2022-7bit-lock iso-2022-8bit-ss2 emacs-mule raw-text iso-2022-jp in-is13194-devanagari chinese-iso-8bit utf-8-auto utf-8-with-signature utf-16 utf-16be-with-signature utf-16le-with-signature utf-16be utf-16le japanese-shift-jis undecided)

So UTF-8 is indeed ``pretty high'', but lower than the locale's
default.

> So this still looks like a real bug.

Perhaps it is, but I didn't know Emacs 23 can reliably distinguish
between Latin-1 and UTF-8, even when UTF-8 sequences are present in
the text.  Can we do that reliably?  Perhaps Handa-san can shed some
light on this.