Fix a warning about virtual destructors and virtual functions.

diff --git a/include/deal.II/grid/reference_cell.h b/include/deal.II/grid/reference_cell.h
index 8832704e63af3542c8453213ed2afef34baea433..d4bcccb6d04b393d357a6a667d3084499d2c8ee1 100644 (file)
--- a/include/deal.II/grid/reference_cell.h
+++ b/include/deal.II/grid/reference_cell.h
@@ -89,6 +89,11 @@ namespace ReferenceCell
        */
       struct Base
       {
+        /**
+         * Destructor.
+         */
+        virtual ~Base() = default;
+
         /**
          * Number of vertices.
          */