(regexp-opt-group): Use substring-no-properties for correct handling

of unibyte strings.

diff --git a/lisp/emacs-lisp/regexp-opt.el b/lisp/emacs-lisp/regexp-opt.el
index 18bd094e4d4ecb80c6a5aea2754c605dfeae7384..51ed53e71fc27717af706269340298b72d1a4a56 100644 (file)
--- a/lisp/emacs-lisp/regexp-opt.el
+++ b/lisp/emacs-lisp/regexp-opt.el
@@ -226,7 +226,7 @@ This means the number of non-shy regexp grouping constructs
 
              ;; Otherwise, divide the list into those that start with a
              ;; particular letter and those that do not, and recurse on them.
-             (let* ((char (char-to-string (string-to-char (car strings))))
+             (let* ((char (substring-no-properties (car strings) 0 1))
                     (half1 (all-completions char strings))
                     (half2 (nthcdr (length half1) strings)))
                (concat open-group