bug#24706: 26.0.50; Minor mode functions should do strict argument type checking

[Philipp Stephani]

After defining a minor mode with

(define-minor-mode foo-mode nil)

its docstring will be

"Toggle Foo mode on or off.
With a prefix argument ARG, enable Foo mode if ARG is
positive, and disable it otherwise.  If called from Lisp, enable
the mode if ARG is omitted or nil, and toggle it if ARG is ‘toggle’."

This appears to indicate that

(foo-mode 'banana)

should disable foo-mode, but it enables it.  I think minor modes should
simply not allow anything but integers and 'toggle for ARG, avoiding
this confusion.


In GNU Emacs 26.0.50.3 (x86_64-apple-darwin16.0.0, NS appkit-1504.00 Version 
10.12 (Build 16A323))
 of 2016-10-16 built on p
Repository revision: cf566b46a6cf85c6d54d0b0db80e32ed6ae8d1ca
Windowing system distributor 'Apple', version 10.3.1504
Recent messages:
For information about GNU Emacs and the GNU system, type C-h C-a.
Making completion list...

Configured using:
 'configure --with-modules --enable-checking
 --enable-check-lisp-object-type --without-xml2'

Configured features:
RSVG IMAGEMAGICK DBUS NOTIFY ACL GNUTLS ZLIB TOOLKIT_SCROLL_BARS NS
MODULES

Important settings:
  value of $LANG: de_DE.UTF-8
  locale-coding-system: utf-8-unix

Major mode: Lisp Interaction

Minor modes in effect:
  tooltip-mode: t
  global-eldoc-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

Load-path shadows:
None found.

Features:
(shadow sort mail-extr emacsbug message subr-x puny seq byte-opt gv
bytecomp byte-compile cl-extra help-mode cconv cl-loaddefs pcase cl-lib
dired dired-loaddefs format-spec rfc822 mml easymenu mml-sec
password-cache epa derived epg epg-config gnus-util rmail rmail-loaddefs
mm-decode mm-bodies mm-encode mail-parse rfc2231 mailabbrev gmm-utils
mailheader sendmail rfc2047 rfc2045 ietf-drums mm-util mail-prsvr
mail-utils time-date mule-util tooltip eldoc electric uniquify
ediff-hook vc-hooks lisp-float-type mwheel term/ns-win ns-win
ucs-normalize term/common-win tool-bar dnd fontset image regexp-opt
fringe tabulated-list newcomment elisp-mode lisp-mode prog-mode register
page menu-bar rfn-eshadow timer select scroll-bar mouse jit-lock
font-lock syntax facemenu font-core term/tty-colors frame cl-generic
cham georgian utf-8-lang misc-lang vietnamese tibetan thai tai-viet lao
korean japanese eucjp-ms cp51932 hebrew greek romanian slovak czech
european ethiopic indian cyrillic chinese charscript case-table epa-hook
jka-cmpr-hook help simple abbrev obarray minibuffer cl-preloaded 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 dbusbind kqueue cocoa ns multi-tty
make-network-process emacs)

Memory information:
((conses 16 206734 11456)
 (symbols 48 20333 0)
 (miscs 40 50 157)
 (strings 32 18351 5209)
 (string-bytes 1 593891)
 (vectors 16 35291)
 (vector-slots 8 676180 5448)
 (floats 8 183 64)
 (intervals 56 219 0)
 (buffers 976 12))