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-rw-r--r--lisp/emacs-lisp/cl-macs.el15
1 files changed, 15 insertions, 0 deletions
diff --git a/lisp/emacs-lisp/cl-macs.el b/lisp/emacs-lisp/cl-macs.el
index 946d2c09a92..5d330f32d66 100644
--- a/lisp/emacs-lisp/cl-macs.el
+++ b/lisp/emacs-lisp/cl-macs.el
@@ -788,6 +788,21 @@ compared by `eql'.
((eq (car c) 'cl--ecase-error-flag)
`(error "cl-ecase failed: %s, %s"
,temp ',(reverse head-list)))
+ ((null (car c))
+ (macroexp-warn-and-return
+ "Case nil will never match"
+ nil 'suspicious))
+ ((and (consp (car c)) (not (cddar c))
+ (memq (caar c) '(quote function)))
+ (macroexp-warn-and-return
+ (format-message
+ (concat "Case %s will match `%s'. If "
+ "that's intended, write %s "
+ "instead. Otherwise, don't "
+ "quote `%s'.")
+ (car c) (caar c) (list (cadar c) (caar c))
+ (cadar c))
+ `(cl-member ,temp ',(car c)) 'suspicious))
((listp (car c))
(setq head-list (append (car c) head-list))
`(cl-member ,temp ',(car c)))