--- a/src/hotspot/share/gc/shared/cardTableRS.hpp	Mon Nov 20 12:04:13 2017 +0100
+++ b/src/hotspot/share/gc/shared/cardTableRS.hpp	Mon Nov 20 13:07:44 2017 +0100
@@ -28,6 +28,7 @@
 #include "gc/shared/cardTableModRefBSForCTRS.hpp"
 #include "memory/memRegion.hpp"
 
+class Generation;
 class Space;
 class OopsInGenClosure;