bug#5981: 24.0.50; Attempt to set a constant symbol: enable-multibyte-characters

bug#5981: 24.0.50; Attempt to set a constant symbol: enable-multibyte-characters

[Eli Zaretskii]

This bug report will be sent to the Free Software Foundation,
not to your local site managers!
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 bug-gnu-emacs@gnu.org mailing list,
and to the gnu.emacs.bug news group.

Please describe exactly what actions triggered the bug
and the precise symptoms of the bug.  If you can, give
a recipe starting from `emacs -Q':

With today's trunk, trying to display the HELLO file, like this:

  emacs -Q
  C-h H

Causes Emacs to signal an error:

   Attempt to set a constant symbol: enable-multibyte-characters


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'.
For information about debugging Emacs, please read the file
d:/gnu/bzr/emacs/trunk/etc/DEBUG.


In GNU Emacs 24.0.50.1 (i386-mingw-nt5.1.2600)
 of 2010-04-20 on HOME-C4E4A596F7
Windowing system distributor `Microsoft Corp.', version 5.1.2600
configured using `configure --with-gcc (3.4)'

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: ENU
  value of $XMODIFIERS: nil
  locale-coding-system: cp1255
  default enable-multibyte-characters: t

Major mode: Lisp Interaction

Minor modes in effect:
  tooltip-mode: t
  mouse-wheel-mode: t
  tool-bar-mode: t
  menu-bar-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  font-lock-mode: t
  blink-cursor-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t
  line-number-mode: t
  transient-mark-mode: t

Recent input:
<help-echo> <help-echo> <help-echo> <help-echo> C-h 
H <up> <down> M-x r e p o r t - e m a <tab> <retur
n>

Recent messages:
For information about GNU Emacs and the GNU system, type C-h C-a.
byte-code: Attempt to set a constant symbol: enable-multibyte-characters

Load-path shadows:
None found.

Features:
(shadow sort gnus-util mail-extr message rfc822 mml easymenu mml-sec
mm-decode mm-bodies mm-encode mail-parse rfc2231 rfc2047 rfc2045
ietf-drums mm-util mail-prsvr mailabbrev mail-utils gmm-utils mailheader
emacsbug tooltip ediff-hook vc-hooks lisp-float-type mwheel dos-w32
disp-table ls-lisp w32-win w32-vars tool-bar dnd fontset image fringe
lisp-mode register page menu-bar rfn-eshadow timer select scroll-bar
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 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 multi-tty emacs)

bug#5981: 24.0.50; Attempt to set a constant symbol: enable-multibyte-characters

[Stefan Monnier]

> With today's trunk, trying to display the HELLO file, like this:

>   emacs -Q
>   C-h H

> Causes Emacs to signal an error:

>    Attempt to set a constant symbol: enable-multibyte-characters

Fixed.
The problem was that view-hello-file did
(setq-default 'enable-multibyte-characters) so as to "DTRT" in
a unibyte session.  The previous code had a bug which made it allow this
even though enable-multibyte-characters is read-only.  I've fixed this
bug in the new variable code, which is why you now saw this error.

Since unibyte sessions are deprecated, I just removed the code (the
alternative would have been to revert to using
default-enable-multibyte-characters, since this variable has the curious
property of being real-only except when accessed via its
default-enable-multibyte-characters alias: another good reason to
dislike it).


        Stefan

bug#5981: 24.0.50; Attempt to set a constant symbol: enable-multibyte-characters

[ShiroiKuma]

This bug persists for me with the current trunk in Gnus.
When trying to `S o m' forward a mail, it reports:
Attempt to set a constant symbol: enable-multibyte-characters

For Gnus in this way it was introduced with revision 99947. Revision
99946 doesn't elicit this behavior when forwarding an email.
-- 
ShiroiKuma

bug#5981: 24.0.50; Attempt to set a constant symbol: enable-multibyte-characters

[JJ]

This bug persists for me with the current 100012 bzr Emacs
trunk. Problems arise in Gnus.
When trying to `S o m' forward a mail, it reports:
Attempt to set a constant symbol: enable-multibyte-characters

For Gnus in this way it was introduced with Emacs revision 99947. Revision
99946 doesn't elicit this behavior when forwarding an email.
-- 
JJ

bug#5981: 24.0.50; Attempt to set a constant symbol: enable-multibyte-characters

[JJ]

This bug persists for me with the current 100012 bzr Emacs
trunk. Problems arise in Gnus.
When trying to `S o m' forward a mail, it reports:
Attempt to set a constant symbol: enable-multibyte-characters

For Gnus in this way it was introduced with Emacs revision 99947. Revision
99946 doesn't elicit this behavior when forwarding an email.
-- 
JJ

bug#5981: 24.0.50; Attempt to set a constant symbol: enable-multibyte-characters

[JJ]

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>This bug persists for me with the current 100012 bzr Emacs
>trunk. Problems arise in Gnus.
>When trying to `S o m' forward a mail, it reports:
>Attempt to set a constant symbol: enable-multibyte-characters

Here is a patch to fix this error on the latest GNU Emacs bzr trunk:


[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
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--- trunk/lisp/gnus/mm-util.el	2010-04-24 18:49:21.189375459 +0200
+++ trunk-patched/lisp/gnus/mm-util.el	2010-04-24 18:50:30.610376339 +0200
@@ -1248,13 +1248,15 @@
 	 (let ((,multibyte enable-multibyte-characters)
 	       (,buffer (current-buffer)))
 	   (unwind-protect
-	       (letf (((default-value 'enable-multibyte-characters) nil))
+	       (letf ()
 		 (set-buffer-multibyte nil)
 		 ,@forms)
 	     (set-buffer ,buffer)
 	     (set-buffer-multibyte ,multibyte)))
-       (letf (((default-value 'enable-multibyte-characters) nil))
-	 ,@forms))))
+       (letf ()
+	 (set-buffer-multibyte nil)
+	 ,@forms
+	 (set-buffer-multibyte ,multibyte)))))
 (put 'mm-with-unibyte-current-buffer 'lisp-indent-function 0)
 (put 'mm-with-unibyte-current-buffer 'edebug-form-spec '(body))
 

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-- 
JJ