Add some sanity checking of defun arglist

* lisp/emacs-lisp/byte-run.el (defun):
Check for malformed argument lists.  (Bug#15715)

1 files changed, 4 insertions, 0 deletions

diff --git a/lisp/emacs-lisp/byte-run.el b/lisp/emacs-lisp/byte-run.el
index 818c2683463..69b4f41fef6 100644
--- a/lisp/emacs-lisp/byte-run.el
+++ b/lisp/emacs-lisp/byte-run.el
@@ -240,6 +240,10 @@ The return value is undefined.
   ;; from
   ;;    (defun foo (arg) (toto)).
   (declare (doc-string 3) (indent 2))
+  (if (null
+       (and (listp arglist)
+            (null (delq t (mapcar #'symbolp arglist)))))
+      (error "Malformed arglist: %s" arglist))
   (let ((decls (cond
                 ((eq (car-safe docstring) 'declare)
                  (prog1 (cdr docstring) (setq docstring nil)))