bug#24992: 25.1; Using mouse, can put empty keyboard macro in macro ring

[Gemini Lasswell]

The commentary in lisp/kmacro.el says "Note: an empty macro is never
added to the macro ring.", but here is a way to add an empty macro to
the ring using kmacro-end-call-mouse, which is by default bound to
S-mouse-3. I am not aware of any serious side effects of there being an
empty macro in the ring.

To reproduce, with emacs -Q and the mouse pointer positioned over your
Emacs window:

C-x ( aaa S-mouse-3
C-x ( S-mouse-3
C-x ( bbb S-mouse-3
C-x C-k C-n C-n C-n

This defines three macros, one which inserts "aaa", an empty one, and one
which inserts "bbb". Then the repeated C-n's of the last step cycle
through the macros in the ring and display them in the echo area.

I'm attaching a patch which makes kmacro-end-call-mouse do the same
thing that kmacro-end-and-call-macro does in this case, which is to end
the definition of the empty macro, pop the empty macro off the ring, and
then run the macro which becomes current.

0001-Don-t-add-empty-keyboard-macro-to-macro-ring.patch
Description: Text document

 GNU Emacs 25.1.1 (x86_64-apple-darwin15.6.0, NS appkit-1404.47 Version 10.11.6 
(Build 15G1004))
 of 2016-10-09 built on rainbow.local
Windowing system distributor 'Apple', version 10.3.1404
Configured using:
 'configure --disable-dependency-tracking --disable-silent-rules
 --enable-locallisppath=/usr/local/share/emacs/site-lisp
 --infodir=/usr/local/Cellar/emacs/25.1/share/info/emacs
 --prefix=/usr/local/Cellar/emacs/25.1 --without-x --with-xml2
 --without-dbus --with-gnutls --with-imagemagick --with-rsvg --with-ns
 --disable-ns-self-contained'

Configured features:
JPEG RSVG IMAGEMAGICK NOTIFY ACL GNUTLS LIBXML2 ZLIB TOOLKIT_SCROLL_BARS
NS

Important settings:
  value of $LANG: en_US.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

Recent messages:
Defining kbd macro...
Keyboard macro defined
Defining kbd macro...
Keyboard macro defined
Macro: aaa
Macro:
Macro: bbb
Macro: aaa
Macro:
Macro: bbb

Load-path shadows:
None found.

Features:
(shadow sort mail-extr emacsbug message dired format-spec rfc822 mml
mml-sec password-cache epg epg-config gnus-util 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 cl-seq
cl-extra help-mode easymenu edmacro cl-loaddefs pcase cl-lib kmacro
time-date mule-util tooltip eldoc electric uniquify ediff-hook vc-hooks
lisp-float-type mwheel 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 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 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 kqueue cocoa ns
multi-tty make-network-process emacs)

Memory information:
((conses 16 197854 6343)
 (symbols 48 19937 0)
 (miscs 40 49 173)
 (strings 32 15610 5377)
 (string-bytes 1 449702)
 (vectors 16 33190)
 (vector-slots 8 656305 5396)
 (floats 8 159 206)
 (intervals 56 215 0)
 (buffers 976 17))