--- a/src/hotspot/share/gc/shared/cardTableBarrierSet.hpp	Wed Mar 13 12:30:20 2019 -0700
+++ b/src/hotspot/share/gc/shared/cardTableBarrierSet.hpp	Wed Mar 13 21:01:56 2019 +0100
@@ -25,11 +25,10 @@
 #ifndef SHARE_GC_SHARED_CARDTABLEBARRIERSET_HPP
 #define SHARE_GC_SHARED_CARDTABLEBARRIERSET_HPP
 
+#include "gc/shared/cardTable.hpp"
 #include "gc/shared/modRefBarrierSet.hpp"
 #include "utilities/align.hpp"
 
-class CardTable;
-
 // This kind of "BarrierSet" allows a "CollectedHeap" to detect and
 // enumerate ref fields that have been modified (since the last
 // enumeration.)
@@ -45,8 +44,11 @@
 class CardTableBarrierSet: public ModRefBarrierSet {
   // Some classes get to look at some private stuff.
   friend class VMStructs;
- protected:
+
+public:
 
+  typedef CardTable::CardValue CardValue;
+protected:
   // Used in support of ReduceInitialCardMarks; only consulted if COMPILER2
   // or INCLUDE_JVMCI is being used
   bool       _defer_initial_card_mark;