bug#21452: 24.5; conf-mode has no parent

[Kurt Hackenberg]

The major mode conf-mode has no parent mode, and does not inherit
anything, because it's not defined with define-derived-mode, just with
defun.

The source file conf-mode.el is in lisp/textmodes, but that seems
wrong.  Conf-mode's children edit files that contain software
configuration, not human language.  Probably conf-mode should be
derived from prog-mode.

Because of the lack of inheritance, my init file contains this
workaround:

;; show trailing whitespace (GNU 21)
;;for programming language modes and text modes, but not special modes
;;(dired, shell, etc.)
;;The minor mode whitespace-mode can do this now, but I haven't converted.
(if (not (featurep 'xemacs))
  (let ((tmp '(lambda () (setq show-trailing-whitespace t))))
    ;;use major mode inheritance to do this for these and their descendants
    (add-hook 'prog-mode-hook tmp)
    (add-hook 'text-mode-hook tmp)
    ;;bug: conf-mode is not derived from any other mode, doesn't inherit
    (add-hook 'conf-mode-hook tmp)))





In GNU Emacs 24.5.1 (amd64-portbld-freebsd10.1, GTK+ Version 2.24.27)
 of 2015-05-23 on 101amd64-default-job-03
Windowing system distributor `The X.Org Foundation', version
 11.0.11407000
Configured using:
 `configure --localstatedir=/var --disable-acl --with-dbus
 --without-file-notification --with-gconf --with-gif --with-gnutls
 --with-gsettings --with-jpeg --with-m17n-flt --with-imagemagick
 --with-libotf --with-png --with-toolkit-scroll-bars --with-rsvg
 --with-tiff --with-x --with-xft --with-xim --with-xml2 --with-xpm
 --with-x-toolkit=gtk2 --with-sound=oss --x-libraries=/usr/local/lib
 --x-includes=/usr/local/include --prefix=/usr/local
 --mandir=/usr/local/man --infodir=/usr/local/share/emacs/info/
 --build=amd64-portbld-freebsd10.1 'CFLAGS=-O2 -pipe -fstack-protector
 -fno-strict-aliasing' CPPFLAGS=-I/usr/local/include 'LDFLAGS=
 -L/usr/local/lib -Wl,-rpath=/usr/lib:/usr/local/lib
 -fstack-protector''

Important settings:
   locale-coding-system: nil

Major mode: Lisp Interaction

Minor modes in effect:
  tooltip-mode: t
  electric-indent-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-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t
  line-number-mode: t
  transient-mark-mode: t

Recent messages:
For information about GNU Emacs and the GNU system, type C-h C-a.

Load-path shadows:
None found.

Features:
(shadow sort gnus-util mail-extr emacsbug message format-spec rfc822
mml
easymenu mml-sec mm-decode mm-bodies mm-encode mail-parse rfc2231
mailabbrev gmm-utils mailheader sendmail rfc2047 rfc2045 ietf-drums
mm-util help-fns mail-prsvr mail-utils time-date tooltip electric
uniquify ediff-hook vc-hooks lisp-float-type mwheel x-win x-dnd
tool-bar
dnd fontset image regexp-opt fringe tabulated-list newcomment
lisp-mode
prog-mode register page menu-bar rfn-eshadow timer select scroll-bar
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
minibuffer nadvice loaddefs button faces cus-face macroexp files
text-properties overlay sha1 md5 base64 format env code-pages mule
custom widget hashtable-print-readable backquote make-network-process
dbusbind dynamic-setting system-font-setting font-render-setting
move-toolbar gtk x-toolkit x multi-tty emacs)

Memory information:
((conses 16 70974 6840)
 (symbols 48 17553 0)
 (miscs 40 35 128)
 (strings 32 9003 4327)
 (string-bytes 1 247987)
 (vectors 16 8908)
 (vector-slots 8 383144 18301)
 (floats 8 63 154)
 (intervals 56 200 146)
 (buffers 960 11))