* lisp/emacs-lisp/cl-generic.el: Clarify we can't define commands

(cl--generic-lambda): Warn about the presence of interactive specs.

1 files changed, 3 insertions, 0 deletions

diff --git a/lisp/emacs-lisp/cl-generic.el b/lisp/emacs-lisp/cl-generic.el
index 173173305b4..c7f0c48f85c 100644
--- a/lisp/emacs-lisp/cl-generic.el
+++ b/lisp/emacs-lisp/cl-generic.el
@@ -345,6 +345,9 @@ the specializer used will be the one returned by BODY."
                                    . ,(lambda () spec-args))
                                  macroexpand-all-environment)))
       (require 'cl-lib)        ;Needed to expand `cl-flet' and `cl-function'.
+      (when (interactive-form (cadr fun))
+        (message "Interactive forms unsupported in generic functions: %S"
+                 (interactive-form (cadr fun))))
       ;; First macroexpand away the cl-function stuff (e.g. &key and
       ;; destructuring args, `declare' and whatnot).
       (pcase (macroexpand fun macroenv)