Don't try to use private members..

dune/subgrid/subgrid/subgridintersection.hh

@@ -88,7 +88,7 @@ class SubGridLeafIntersection :
 
     // The type of the actual local geometry implementation
     typedef SubGridLocalGeometry<dim-1, dimworld, GridImp> LocalGeometryImpl;
-    using ctype = Base::ctype;
+    using ctype = typename GridImp::ctype;
 
     using Base::insideIntersect_;