--- a/src/hotspot/share/gc/shared/generation.hpp	Thu Apr 26 12:54:53 2018 +0200
+++ b/src/hotspot/share/gc/shared/generation.hpp	Thu May 03 14:09:00 2018 +0200
@@ -100,6 +100,7 @@
   VirtualSpace _virtual_space;
 
   // ("Weak") Reference processing support
+  SpanSubjectToDiscoveryClosure _span_based_discoverer;
   ReferenceProcessor* _ref_processor;
 
   // Performance Counters