bug#24255: 25.1; incorrect edebug spec for cl-defun

[Ben Liblit <liblit@acm.org>]

The edebug specification for cl-defun seems to be incorrect.  I believe
it does not properly cover cases where cl-defun is used for
destructuring along the lines of cl-destructuring-bind, such as in:

	(require 'cl-lib)
	(cl-defun sum ((x y)) (+ x y))

Notice that the argument list to sum is performing a destructuring
bind.  Thus, one would call this using something like "(sum '(1 2))".

To see the bug, proceed as follows:

(1) Start emacs using "emacs -Q".

(2) Place the two-line example given above in an Emacs Lisp buffer.

(3) Type "M-x eval-buffer".  Observe that there is no error.

(4) Type "M-x edebug-all-defs".

(5) Type "M-x eval-buffer" again.  Observe the following error:

	edebug-syntax-error: Invalid read syntax: "Failed matching",
	([&rest arg] [&optional ["&optional" cl-&optional-arg &rest
	cl-&optional-arg]] [&optional ["&rest" arg]] [&optional ["&key"
	[cl-&key-arg &rest cl-&key-arg] &optional "&allow-other-keys"]]
	[&optional ["&aux" &rest &or (symbolp &optional def-form)
	symbolp]])

Destructuring in cl-defun is certainly valid.  You can see this in the
documentation for cl-defun, which notes that "VAR maybe be replaced
recursively with an argument list for destructing".  The info
documentation for cl also states that "In Common Lisp, destructuring is
only allowed with 'defmacro'; this package allows it with 'cl-defun' and
other argument lists as well."

I am reporting this bug against Emacs 25.1 rc1.  However, I see the same
problem going at least as far back as Emacs 24.3.  You definitely do not
need to build the release candidate in order to reproduce this bug.



In GNU Emacs 25.1.1 (x86_64-unknown-linux-gnu, GTK+ Version 3.14.13)
  of 2016-08-16 built on localhost.localdomain
Windowing system distributor 'The X.Org Foundation', version 11.0.11702000
System Description:	Red Hat Enterprise Linux Server release 7.2 (Maipo)

Configured using:
  'configure --with-dbus --with-gif --with-jpeg --with-png --with-rsvg
  --with-tiff --with-xft --with-xpm --with-x-toolkit=gtk3 --with-gpm=no
  --with-xwidgets --prefix=/u/l/i/liblit/Downloads/emacs-25.1-rc1'

Configured features:
XPM JPEG TIFF GIF PNG RSVG IMAGEMAGICK SOUND DBUS GCONF GSETTINGS NOTIFY
LIBSELINUX GNUTLS LIBXML2 FREETYPE M17N_FLT LIBOTF XFT ZLIB
TOOLKIT_SCROLL_BARS GTK3 X11 XWIDGETS

Important settings:
   value of $LC_CTYPE: en_US.UTF-8
   value of $LC_MONETARY: en_US.utf8
   value of $LC_NUMERIC: en_US.utf8
   value of $LC_TIME: en_US.utf8
   value of $LANG: en_US.UTF-8
   value of $XMODIFIERS: @im=ibus
   locale-coding-system: utf-8-unix

Major mode: Emacs-Lisp

Minor modes in effect:
   diff-auto-refine-mode: t
   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:
For information about GNU Emacs and the GNU system, type C-h C-a.
Please type y, n, or !: y
Making completion list...
Edebugging all definitions is on.
edebug-syntax-error: Invalid read syntax: "Failed matching", ([&rest 
arg] [&optional ["&optional" cl-&optional-arg &rest cl-&optional-arg]] 
[&optional ["&rest" arg]] [&optional ["&key" [cl-&key-arg &rest 
cl-&key-arg] &optional "&allow-other-keys"]] [&optional ["&aux" &rest 
&or (symbolp &optional def-form) symbolp]])

Load-path shadows:
None found.

Features:
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mm-encode mail-parse rfc2231 mailabbrev gmm-utils mailheader sendmail
rfc2047 rfc2045 ietf-drums mm-util help-fns help-mode mail-prsvr
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term/common-win x-dnd tool-bar dnd fontset image regexp-opt fringe
tabulated-list newcomment elisp-mode lisp-mode prog-mode register page
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cus-face macroexp files text-properties overlay sha1 md5 base64 format
env code-pages mule custom widget hashtable-print-readable backquote
dbusbind inotify dynamic-setting system-font-setting font-render-setting
xwidget-internal move-toolbar gtk x-toolkit x multi-tty
make-network-process emacs)

Memory information:
((conses 16 95803 5203)
  (symbols 48 20828 0)
  (miscs 40 102 107)
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