bug#4209: 23.1; Emacs 23.1 regression in re-search-forward

[Christopher J. Madsen]

I've found a regression in Emacs 23.1 (versus Emacs 22.3).  I've
narrowed it down to this test case:

;--- re-bug.el starts here
(set-buffer (get-buffer-create "*Test Buffer*"))

(insert "\xC2\x4C\xEF\x77\xC6\x69\x8C\x0A")

(goto-char (point-min))

(message "looking-at: %s" (looking-at "\\`\xC2\x4C\xEF\x77\xC6\x69\x8C\x0A"))

(message "re-search-forward: %s"
         (re-search-forward "\\`\xC2\x4C\xEF\x77\xC6\x69\x8C\x0A" 100 t))
;--- re-bug.el ends here

Then at the command line:

$ emacs-22 --batch -Q -l re-bug.el
looking-at: t
re-search-forward: 9

$ emacs-23 --batch -Q -l re-bug.el
looking-at: t
re-search-forward: nil


As you can see, looking-at succeeds in both versions, but
re-search-forward fails in Emacs 23.  I don't know why.  It seems like
the functions should either both succeed or both fail.


For comparison, here's the version of Emacs 22 that I'm using:
GNU Emacs 22.3.1 (i686-pc-linux-gnu, GTK+ Version 2.12.11)
 of 2009-04-06 on byte
Windowing system distributor `The X.Org Foundation', version 11.0.10503000
configured using `configure  '--prefix=/usr' '--host=i686-pc-linux-gnu' 
'--mandir=/usr/share/man' '--infodir=/usr/share/info' '--datadir=/usr/share' 
'--sysconfdir=/etc' '--localstatedir=/var/lib' '--program-suffix=-emacs-22' 
'--infodir=/usr/share/info/emacs-22' '--without-carbon' '--with-sound' 
'--with-x' '--with-toolkit-scroll-bars' '--with-jpeg' '--with-tiff' 
'--with-gif' '--with-png' '--with-xpm' '--with-x-toolkit=gtk' 
'--without-hesiod' '--without-kerberos' '--without-kerberos5' 
'--build=i686-pc-linux-gnu' 'build_alias=i686-pc-linux-gnu' 
'host_alias=i686-pc-linux-gnu' 'CFLAGS=-march=prescott -O2 -pipe' 
'LDFLAGS=-Wl,-O1''


And this is the Emacs 23 information:

In GNU Emacs 23.1.1 (i686-pc-linux-gnu, GTK+ Version 2.16.5)
 of 2009-08-10 on byte
Windowing system distributor `The X.Org Foundation', version 11.0.10503000
configured using `configure  '--prefix=/usr' '--host=i686-pc-linux-gnu' 
'--mandir=/usr/share/man' '--infodir=/usr/share/info' '--datadir=/usr/share' 
'--sysconfdir=/etc' '--localstatedir=/var/lib' '--program-suffix=-emacs-23' 
'--infodir=/usr/share/info/emacs-23' '--with-sound' '--with-x' 
'--with-toolkit-scroll-bars' '--with-gif' '--with-jpeg' '--with-png' 
'--with-rsvg' '--with-tiff' '--with-xpm' '--without-xft' '--without-libotf' 
'--without-m17n-flt' '--with-x-toolkit=gtk' '--without-hesiod' 
'--without-kerberos' '--without-kerberos5' '--with-gpm' '--with-dbus' 
'--build=i686-pc-linux-gnu' 'build_alias=i686-pc-linux-gnu' 
'host_alias=i686-pc-linux-gnu' 'CFLAGS=-march=core2 -O2 -pipe' 
'LDFLAGS=-Wl,-O1''

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.utf8
  value of $XMODIFIERS: nil
  locale-coding-system: utf-8-unix
  default-enable-multibyte-characters: t

Major mode: Fundamental