X-Git-Url: https://code.delx.au/gnu-emacs/blobdiff_plain/7e09ef09a479731d01b1ca46e94ddadd73ac98e3..dacde7ee5d37a1fe685a489c65678a8f2c2535ce:/lisp/files-x.el

diff --git a/lisp/files-x.el b/lisp/files-x.el
index 248c307330..f0102fd83a 100644
--- a/lisp/files-x.el
+++ b/lisp/files-x.el
@@ -1,6 +1,6 @@
 ;;; files-x.el --- extended file handling commands
 
-;; Copyright (C) 2009-2015 Free Software Foundation, Inc.
+;; Copyright (C) 2009-2016 Free Software Foundation, Inc.
 
 ;; Author: Juri Linkov <juri@jurta.org>
 ;; Maintainer: emacs-devel@gnu.org
@@ -247,7 +247,14 @@ then this function adds the first line containing the string
 `Local Variables:' and the last line containing the string `End:'."
   (interactive
    (let ((variable (read-file-local-variable "Add file-local variable")))
+     ;; Error before reading value.
+     (if (equal variable 'lexical-binding)
+	 (user-error "The `%s' variable must be set at the start of the file"
+		     variable))
      (list variable (read-file-local-variable-value variable) t)))
+  (if (equal variable 'lexical-binding)
+      (user-error "The `%s' variable must be set at the start of the file"
+                  variable))
   (modify-file-local-variable variable value 'add-or-replace interactive))
 
 ;;;###autoload