(regexp-opt-group): Avoid infinite

recursion on bogus input.

1 files changed, 3 insertions, 1 deletions

diff --git a/lisp/emacs-lisp/regexp-opt.el b/lisp/emacs-lisp/regexp-opt.el
index 589f1b70ac4..6627c20a7bf 100644
--- a/lisp/emacs-lisp/regexp-opt.el
+++ b/lisp/emacs-lisp/regexp-opt.el
@@ -141,7 +141,9 @@ in REGEXP."
          (open-charset (if lax "" open-group))
          (close-charset (if lax "" close-group)))
     (cond
-     ;;
+     ;; Protect against user-stupidity... could call error here
+     ((null strings)
+      nil)
      ;; If there is only one string, just return it.
      ((= (length strings) 1)
       (if (= (length (car strings)) 1)