--- old/src/hotspot/share/gc/z/zBarrierSet.hpp	2020-05-29 12:04:26.000000000 +0200
+++ new/src/hotspot/share/gc/z/zBarrierSet.hpp	2020-05-29 12:04:26.000000000 +0200
@@ -40,7 +40,7 @@
   virtual void on_thread_attach(Thread* thread);
   virtual void on_thread_detach(Thread* thread);
 
-  virtual void print_on(outputStream* st) const {}
+  virtual void print_on(outputStream* st) const;
 
   template <DecoratorSet decorators, typename BarrierSetT = ZBarrierSet>
   class AccessBarrier : public BarrierSet::AccessBarrier<decorators, BarrierSetT> {