bug#51368: 29.0.50; `cl-case' should error on incorrect use

[Philipp Stephani <p.stephani2@gmail.com>]

This form demonstrates a few incorrect uses of `cl-case':

(cl-case a
  (nil 0)   ; doesn't match anything
  (t 1)     ; matches everything, but too early
  ('foo 2)) ; matches `quote' in addition to `foo'

It would be nice if `cl-case' would signal an error or at least warn
about these at macroexpansion time, since they are somewhat subtle and
easy to get wrong.


In GNU Emacs 29.0.50 (build 3, x86_64-pc-linux-gnu, GTK+ Version 3.24.30, cairo version 1.16.0)
 of 2021-10-24
Repository revision: aea4af5119fdf130f1df7190478a23c6777f92a2
Repository branch: master
Windowing system distributor 'The X.Org Foundation', version 11.0.12011000
System Description: Debian GNU/Linux rodete

Configured using:
 'configure --enable-gcc-warnings=warn-only
 --enable-gtk-deprecation-warnings --without-pop --with-mailutils
 --enable-checking=all --enable-check-lisp-object-type --with-modules
 'CFLAGS=-O0 -ggdb3''

Configured features:
CAIRO DBUS FREETYPE GIF GLIB GMP GNUTLS GSETTINGS HARFBUZZ JPEG JSON
LIBSELINUX LIBSYSTEMD LIBXML2 MODULES NOTIFY INOTIFY PDUMPER PNG SECCOMP
SOUND THREADS TIFF TOOLKIT_SCROLL_BARS X11 XDBE XIM XPM GTK3 ZLIB

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

Major mode: Lisp Interaction

Minor modes in effect:
  tooltip-mode: t
  global-eldoc-mode: t
  eldoc-mode: t
  show-paren-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
  indent-tabs-mode: t
  transient-mark-mode: t

Load-path shadows:
None found.

Features:
(shadow sort mail-extr emacsbug message rmc dired dired-loaddefs rfc822
mml mml-sec epa epg rfc6068 epg-config gnus-util rmail rmail-loaddefs
time-date mm-decode mm-bodies mm-encode mail-parse rfc2231 mailabbrev
gmm-utils mailheader sendmail rfc2047 rfc2045 ietf-drums mm-util
mail-prsvr mail-utils phst skeleton derived pcase ffap thingatpt url
url-proxy url-privacy url-expand url-methods url-history url-cookie
url-domsuf url-util url-parse auth-source cl-seq eieio eieio-core
cl-macs eieio-loaddefs password-cache json map url-vars mailcap rx
gnutls puny dbus xml seq gv subr-x byte-opt bytecomp byte-compile cconv
compile text-property-search comint ansi-color ring cl-loaddefs cl-lib
iso-transl tooltip eldoc paren electric uniquify ediff-hook vc-hooks
lisp-float-type elisp-mode mwheel term/x-win x-win term/common-win x-dnd
tool-bar dnd fontset image regexp-opt fringe tabulated-list replace
newcomment text-mode lisp-mode prog-mode register page tab-bar menu-bar
rfn-eshadow isearch easymenu timer select scroll-bar mouse jit-lock
font-lock syntax font-core term/tty-colors frame minibuffer 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 composite emoji-zwj charscript
charprop case-table epa-hook jka-cmpr-hook help simple abbrev obarray
cl-preloaded nadvice button loaddefs faces cus-face macroexp files
window text-properties overlay sha1 md5 base64 format env code-pages
mule custom widget hashtable-print-readable backquote threads dbusbind
inotify dynamic-setting system-font-setting font-render-setting cairo
move-toolbar gtk x-toolkit x multi-tty make-network-process emacs)

Memory information:
((conses 16 68529 4717)
 (symbols 48 8401 3)
 (strings 32 24306 1951)
 (string-bytes 1 786068)
 (vectors 16 15413)
 (vector-slots 8 204610 8730)
 (floats 8 26 36)
 (intervals 56 225 0)
 (buffers 992 11))

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