Minor fix for define-derived-mode

* lisp/emacs-lisp/derived.el (define-derived-mode):
Do not let eg eval-defun reset the values of syntax or abbrev tables,
since they might have been defined externally.  (Bug#16160)

1 files changed, 6 insertions, 5 deletions

diff --git a/lisp/emacs-lisp/derived.el b/lisp/emacs-lisp/derived.el
index 0f7691af0f4..31170270f5c 100644
--- a/lisp/emacs-lisp/derived.el
+++ b/lisp/emacs-lisp/derived.el
@@ -217,16 +217,17 @@ No problems result if this variable is not bound.
        ,(if declare-syntax
             `(progn
                (unless (boundp ',syntax)
-                 (put ',syntax 'definition-name ',child))
-               (defvar ,syntax (make-syntax-table))
+                 (put ',syntax 'definition-name ',child)
+                 (defvar ,syntax (make-syntax-table)))
                (unless (get ',syntax 'variable-documentation)
                  (put ',syntax 'variable-documentation
                       (purecopy ,(format "Syntax table for `%s'." child))))))
        ,(if declare-abbrev
             `(progn
-               (put ',abbrev 'definition-name ',child)
-               (defvar ,abbrev
-                 (progn (define-abbrev-table ',abbrev nil) ,abbrev))
+               (unless (boundp ',abbrev)
+                 (put ',abbrev 'definition-name ',child)
+                 (defvar ,abbrev
+                   (progn (define-abbrev-table ',abbrev nil) ,abbrev)))
                (unless (get ',abbrev 'variable-documentation)
                  (put ',abbrev 'variable-documentation
                       (purecopy ,(format "Abbrev table for `%s'." child))))))