mailabbrev clobbers local-abbrev-table, syntax table

[Matt Armstrong]

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In GNU Emacs 21.1.1 (i386-debian-linux-gnu, X toolkit, Xaw3d scroll bars)
 of 2001-12-06 on raven, modified by Debian
configured using `configure  i386-debian-linux-gnu --prefix=/usr 
--sharedstatedir=/var/lib --libexecdir=/usr/lib --localstatedir=/var/lib 
--infodir=/usr/share/info --mandir=/usr/share/man --with-pop=yes --with-x=yes 
--with-x-toolkit=athena --without-gif'
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: C
  locale-coding-system: nil
  default-enable-multibyte-characters: t

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

This is a courtesy copy of a problem I found while looking into abbrev
issues for Gnus' message mode.  It is part of a thread that took place
on emacs-devel@gnu.org and ding@gnus.org.

Richard Stallman <rms@gnu.org> writes:

> Mailabbrevs is something different; those abbrevs use a special
> abbrev table.
>
> Message mode ought to use text-mode-abbrev-table for its ordinary
> abbrev table.  It should set local-abbrev-table to
> text-mode-abbrev-table.

I attempted to implement this change, but mailabbrev clobbers the
value of local-abbrev-table (and the message mode syntax table).

It turns out that mailabbrev does not restore the previous values of
the syntax-table and local-abbrev-table after it is done.  Instead, it
restores the mail-* versions of those variables.  Since there is no
mail-mode-abbrev-table variable, it *always* sets local-abbrev-table
to nil.  It also always sets the syntax table back to
mail-mode-syntax-table, which is not desirable for message mode.

The offending function is sendmail-pre-abbrev-expand-hook in
mailabbrev.el.

    (defun sendmail-pre-abbrev-expand-hook ()

    [...]

         (if (or (not mail-abbrevs-only)
                 (eq this-command 'expand-abbrev))
             (progn
               ;; We're not in a mail header where mail aliases should
               ;; be expanded, then use the normal mail-mode abbrev table
               ;; (if any) and the normal mail-mode syntax table.

               (setq local-abbrev-table (and (boundp 'mail-mode-abbrev-table)
                                             mail-mode-abbrev-table))
               (set-syntax-table mail-mode-syntax-table))

    [...]

Maybe sendmail-pre-abbrev-expand-hook needs to always restore
local-abbrev-table and the syntax table to whatever they were before
it was called?



Recent input:
a b l e ) . M-q C-n C-n C-n C-n C-n C-n C-p M-b M-b 
M-b M-d f o r M-q C-n C-n C-n C-n C-n C-n C-n C-n C-n 
C-n C-n C-n C-n C-n C-n C-n C-n C-n C-n C-n C-n C-n 
C-l M-q M-f M-f M-f M-f M-f M-f M-f <right> C-n C-a 
M-f M-f M-f <right> M-q M-f M-f M-f M-f M-f M-f M-f 
M-f M-f M-f M-f M-f M-f M-f M-f M-f M-f M-f M-f C-x 
C-s <switch-frame> C-x 1 M-x b u <tab> <backspace> 
<backspace> C-g <help-echo> <help-echo> <help-echo> 
<help-echo> <help-echo> <menu-bar> <help-menu> <re
port-emacs-bug>

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-- 
matt