(define-mail-alias): Avoid error if DEFINITION is "".

1 files changed, 4 insertions, 3 deletions

diff --git a/lisp/mail/mailalias.el b/lisp/mail/mailalias.el
index 25d52cfae23..6addb3c5a90 100644
--- a/lisp/mail/mailalias.el
+++ b/lisp/mail/mailalias.el
@@ -178,7 +178,8 @@ An address can contain spaces if it is quoted with double-quotes."
   (if (string-match "[ \t\n,]+\\'" definition)
       (setq definition (substring definition 0 (match-beginning 0))))
   (let ((result '())
-        (start 0)
+        ;; If DEFINITION is null string, avoid looping even once.
+        (start (and (not (equal definition "")) 0))
         (L (length definition))
         end tem)
     (while start
@@ -189,8 +190,8 @@ An address can contain spaces if it is quoted with double-quotes."
           (if (eq ?\" (aref definition start))
               (setq start (1+ start)
                     end (string-match "\"[ \t,]*" definition start))
-              (setq end (string-match "[ \t,]+" definition start)))
-          (setq end (string-match "[ \t\n,]*,[ \t\n,]*" definition start)))
+            (setq end (string-match "[ \t,]+" definition start)))
+        (setq end (string-match "[ \t\n,]*,[ \t\n,]*" definition start)))
       (setq result (cons (substring definition start end) result))
       (setq start (and end
                        (/= (match-end 0) L)