* mule-cmds.el (encoded-string-description): Require unibyte string as input

diff --git a/lisp/international/mule-cmds.el b/lisp/international/mule-cmds.el
index ecdab5e931d8481a3b85c63f07eb95121c6cb4eb..47b07479c3c35d00234a932fd7b630b320d959cf 100644 (file)
--- a/lisp/international/mule-cmds.el
+++ b/lisp/international/mule-cmds.el
@@ -2898,8 +2898,9 @@ If there's no description string for VALUE, return nil."
     (?\x9b . "CSI")))
 
 (defun encoded-string-description (str coding-system)
-  "Return a pretty description of STR that is encoded by CODING-SYSTEM."
-  (setq str (string-as-unibyte str))
+  "Return a pretty description of STR that is encoded by CODING-SYSTEM.
+STR should be a unibyte string."
+  (cl-assert (not (multibyte-string-p str)))
   (mapconcat
    (if (and coding-system (eq (coding-system-type coding-system) 'iso-2022))
        ;; Try to get a pretty description for ISO 2022 escape sequences.