Add obarray-clear and use it

* lisp/obarray.el (obarray-clear): New.
* lisp/abbrev.el (clear-abbrev-table):
* lisp/vc/vc.el (vc-clear-context): Use it instead of assuming the
obarray is a vector that can be 0-filled.
* test/lisp/obarray-tests.el (obarray-clear): New test.

1 files changed, 5 insertions, 0 deletions

diff --git a/lisp/obarray.el b/lisp/obarray.el
index a26992df8e2..e1ebb2ade51 100644
--- a/lisp/obarray.el
+++ b/lisp/obarray.el
@@ -66,5 +66,10 @@ Return t on success, nil otherwise."
   "Call function FN on every symbol in obarray OB and return nil."
   (mapatoms fn ob))
 
+(defun obarray-clear (ob)
+  "Remove all symbols from obarray OB."
+  ;; FIXME: This doesn't change the symbols to uninterned status.
+  (fillarray ob 0))
+
 (provide 'obarray)
 ;;; obarray.el ends here