bug#19812: 24.4; suggest `shell-mode' not interactive

[Kevin Ryde]

Severity: wishlist

The `shell-mode' function is interactive, but I think perhaps it should
not be since it is not designed for use as M-x shell-mode in an
arbitrary buffer, but only after the `shell' function makes various
setups.

I struck this when a brain fade confused me between shell-command,
shell-mode and shell and I did M-x shell-mode in a file buffer and
nearly made a big mess.  The problem is only seen when shell.el has been
loaded (for any reason) since shell-mode is not autoloaded.

Similar could apply to other special modes, maybe even to most modes
derived from `special-mode'.


In GNU Emacs 24.4.1 (i586-pc-linux-gnu, X toolkit, Xaw3d scroll bars)
 of 2014-12-20 on brahms, modified by Debian
Windowing system distributor `The X.Org Foundation', version 11.0.11602901
Configured using:
 `configure --build i586-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/emacs24:/etc/emacs:/usr/local/share/emacs/24.4/site-lisp:/usr/local/share/emacs/site-lisp:/usr/share/emacs/24.4/site-lisp:/usr/share/emacs/site-lisp
 --build i586-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/emacs24:/etc/emacs:/usr/local/share/emacs/24.4/site-lisp:/usr/local/share/emacs/site-lisp:/usr/share/emacs/24.4/site-lisp:/usr/share/emacs/site-lisp
 --with-x=yes --with-x-toolkit=lucid --with-toolkit-scroll-bars
 --without-gconf --without-gsettings 'CFLAGS=-g -O2
 -fstack-protector-strong -Wformat -Werror=format-security -Wall'
 CPPFLAGS=-D_FORTIFY_SOURCE=2 LDFLAGS=-Wl,-z,relro'