keymap problem with modes derived from sh-mode

[Andreas Voegele]

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In GNU Emacs 21.1.1 (i586-pc-linux-gnu, X toolkit)
 of 2001-10-23 on columbus.localdomain
configured using `configure  --host=i586-pc-linux-gnu --prefix=/usr 
--libexecdir=/usr/lib --mandir=/usr/share/man --infodir=/usr/share/info 
--with-x --with-xpm --with-jpeg --with-tiff --with-gif --with-png'
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: nil
  locale-coding-system: nil
  default-enable-multibyte-characters: t

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

I use a major mode derived from sh-mode.  Under GNU Emacs 21, I get
the message "This buffer is not in Shell-script mode" when I try to
intend a line with the TAB key.

The function sh-must-be-shell-mode uses the expression
(eq major-mode 'sh-mode) to check the mode. Since the derived mode
is called ebuild-script-mode the check fails.

I think that sh-must-be-shell-mode should use the expression

(derived-mode-p 'sh-mode)

instead of

(eq major-mode 'sh-mode).

I've written an advice for sh-must-be-shell-mode but IMHO the next
Emacs revision should include a fix.

Here's the code that I use:

(define-derived-mode ebuild-script-mode
  sh-mode "Ebuild-script" nil
  (setq tab-width 4))

(setq auto-mode-alist
      (append
       '(("\\.ebuild$" . ebuild-script-mode))
       auto-mode-alist))

(defadvice sh-must-be-shell-mode
  (around sh-must-be-shell-mode-around activate)
  "Accept modes derived from sh-mode."
  (unless (derived-mode-p 'sh-mode)
    ad-do-it))


Recent input:
<help-echo> C-y C-x C-e <escape> x e b u i l d - s 
c r i p t - m o d e <return> <tab> <help-echo> <help-echo> 
<help-echo> <help-echo> <help-echo> <menu-bar> <help-menu> 
<report-emacs-bug>

Recent messages:
Loading easy-mmode...done
Loading sh-script...done
Setting up indent for shell type sh
Loading regexp-opt...done
Loading mule-util...done
setting up indent stuff
Indentation variable are now local.
Indentation setup for shell type sh
sh-must-be-shell-mode: This buffer is not in Shell-script mode
Loading emacsbug...done