bug#6212: 23.2; ^S^Q^@ --error--> Wrong type argument: characterp, 67108896

[Trent W. Buck]

Attempting to insert a literal ^@ control character worked in 23.1.
In 23.2, it results in an error: Wrong type argument: characterp,
67108896

I am typing C-q C-SPC, in Emacs in Screen in linux's fbcon.  Since ^@ is
the zeroth character, perhaps this is an off-by-one or overflow error
somewhere.  The same error occurs when typing C-q C-@.

The use case is to find high-bit (non-ASCII) characters in a file of
indeterminate Windows codepage encoding.  I normally type C-M-s [^ C-q
C-SPC -~] (since ^@ and ~ are the bounds of the ASCII character set).
This no longer works.

In GNU Emacs 23.2.1 (x86_64-pc-linux-gnu)
 of 2010-05-16 on barber, modified by Debian
configured using `configure  '--build' 'x86_64-linux-gnu' '--build' 
'x86_64-linux-gnu' '--prefix=/usr' '--sharedstatedir=/var/lib' 
'--libexecdir=/usr/lib' '--localstatedir=/var/lib' '--infodir=/usr/share/info' 
'--mandir=/usr/share/man' '--with-pop=yes' 
'--enable-locallisppath=/etc/emacs23:/etc/emacs:/usr/local/share/emacs/23.2/site-lisp:/usr/local/share/emacs/site-lisp:/usr/share/emacs/23.2/site-lisp:/usr/share/emacs/site-lisp:/usr/share/emacs/23.2/leim'
 '--with-x=no' '--without-gconf' 'build_alias=x86_64-linux-gnu' 
'CFLAGS=-DDEBIAN -g -O2' 'LDFLAGS=-g' 'CPPFLAGS=''

Important settings:
  value of $LC_ALL: nil
  value of $LC_COLLATE: C
  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_AU.utf8
  value of $XMODIFIERS: nil
  locale-coding-system: utf-8-unix
  default enable-multibyte-characters: t

Major mode: Fundamental

Minor modes in effect:
  xterm-mouse-mode: t
  ido-everywhere: t
  savehist-mode: t
  icomplete-mode: t
  partial-completion-mode: t
  show-paren-mode: t
  delete-selection-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  font-lock-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t
  column-number-mode: t
  line-number-mode: t
  transient-mark-mode: t

Recent input:
C-s C-q C-@ ESC x r e p o r t SPC e m a c s SPC b u 
g RET

Recent messages:
Loading /etc/emacs/site-start.d/50haskell-mode.el (source)...
Loading /usr/share/emacs/site-lisp/haskell-mode/haskell-site-file.el 
(source)...done
Loading /etc/emacs/site-start.d/50haskell-mode.el (source)...done
Loading /etc/emacs/site-start.d/50paredit-el.el (source)...done
Loading /etc/emacs/site-start.d/50psvn.el (source)...done
Loading /etc/emacs/site-start.d/50puppet-el.el (source)...done
Loading /etc/emacs/site-start.d/50w3m-el-snapshot.el (source)...done
Loading /etc/emacs/site-start.d/51debian-el.el (source)...done
Ido mode enabled
For information about GNU Emacs and the GNU system, type C-h C-a.
isearch-process-search-char: Wrong type argument: characterp, 67108896

Load-path shadows:
/usr/share/emacs/site-lisp/haskell-mode/inf-haskell hides 
/usr/share/emacs/23.2/site-lisp/haskell-mode/inf-haskell
/usr/share/emacs/site-lisp/haskell-mode/haskell-site-file hides 
/usr/share/emacs/23.2/site-lisp/haskell-mode/haskell-site-file
/usr/share/emacs/site-lisp/haskell-mode/haskell-simple-indent hides 
/usr/share/emacs/23.2/site-lisp/haskell-mode/haskell-simple-indent
/usr/share/emacs/site-lisp/haskell-mode/haskell-mode hides 
/usr/share/emacs/23.2/site-lisp/haskell-mode/haskell-mode
/usr/share/emacs/site-lisp/haskell-mode/haskell-indentation hides 
/usr/share/emacs/23.2/site-lisp/haskell-mode/haskell-indentation
/usr/share/emacs/site-lisp/haskell-mode/haskell-indent hides 
/usr/share/emacs/23.2/site-lisp/haskell-mode/haskell-indent
/usr/share/emacs/site-lisp/haskell-mode/haskell-hugs hides 
/usr/share/emacs/23.2/site-lisp/haskell-mode/haskell-hugs
/usr/share/emacs/site-lisp/haskell-mode/haskell-ghci hides 
/usr/share/emacs/23.2/site-lisp/haskell-mode/haskell-ghci
/usr/share/emacs/site-lisp/haskell-mode/haskell-font-lock hides 
/usr/share/emacs/23.2/site-lisp/haskell-mode/haskell-font-lock
/usr/share/emacs/site-lisp/haskell-mode/haskell-doc hides 
/usr/share/emacs/23.2/site-lisp/haskell-mode/haskell-doc
/usr/share/emacs/site-lisp/haskell-mode/haskell-decl-scan hides 
/usr/share/emacs/23.2/site-lisp/haskell-mode/haskell-decl-scan
/usr/share/emacs/site-lisp/haskell-mode/haskell-cabal hides 
/usr/share/emacs/23.2/site-lisp/haskell-mode/haskell-cabal
/usr/share/emacs/site-lisp/haskell-mode/haskell-c hides 
/usr/share/emacs/23.2/site-lisp/haskell-mode/haskell-c
/usr/share/emacs/23.2/site-lisp/puppet-el/puppet-mode hides 
/usr/share/emacs/site-lisp/puppet-mode
/usr/share/emacs/23.2/site-lisp/debian-startup hides 
/usr/share/emacs/site-lisp/debian-startup
/usr/share/emacs23/site-lisp/dictionaries-common/flyspell hides 
/usr/share/emacs/23.2/lisp/textmodes/flyspell
/usr/share/emacs23/site-lisp/dictionaries-common/ispell hides 
/usr/share/emacs/23.2/lisp/textmodes/ispell

Features:
(shadow sort mail-extr message sendmail regexp-opt ecomplete rfc822 mml
easymenu mml-sec password-cache mm-decode mm-bodies mm-encode mailcap
mail-parse rfc2231 rfc2047 rfc2045 qp ietf-drums mailabbrev nnheader
gnus-util netrc time-date mm-util mail-prsvr gmm-utils wid-edit
mailheader canlock sha1 hex-util hashcash mail-utils emacsbug
multi-isearch jka-compr edmacro kmacro xt-mouse ido savehist icomplete
complete paren delsel saveplace debian-el debian-el-loaddefs w3m-load
emacs-goodies-el emacs-goodies-custom emacs-goodies-loaddefs easy-mmode
dpkg-dev-el dpkg-dev-el-loaddefs ediff-hook vc-hooks lisp-float-type
lisp-mode register page menu-bar rfn-eshadow timer select mldrag mouse
jit-lock font-lock syntax facemenu font-core frame cham georgian
utf-8-lang misc-lang vietnamese tibetan thai tai-viet lao korean
japanese hebrew greek romanian slovak czech european ethiopic indian
cyrillic chinese case-table epa-hook jka-cmpr-hook help simple abbrev
loaddefs button minibuffer faces cus-face files text-properties overlay
md5 base64 format env code-pages mule custom widget
hashtable-print-readable backquote make-network-process dbusbind
multi-tty emacs)