Index: src/ResolvExpr/ConversionCost.h
===================================================================
--- src/ResolvExpr/ConversionCost.h	(revision 721cd19ff0bf583b48c8ce89d21b2892d6bb485f)
+++ src/ResolvExpr/ConversionCost.h	(revision 92f8e186429e9bdf92b7aeb6a8defdbbf5ec2dfd)
@@ -19,4 +19,6 @@
 
 #include "Cost.h"             // for Cost
+
+#include "Common/PassVisitor.h"
 #include "SynTree/Visitor.h"  // for Visitor
 #include "SynTree/SynTree.h"  // for Visitor Nodes
@@ -30,5 +32,5 @@
 
 	typedef std::function<Cost(Type *, Type *, const SymTab::Indexer &, const TypeEnvironment &)> CostFunction;
-	class ConversionCost : public Visitor {
+	struct ConversionCost : public WithShortCircuiting {
 	  public:
 		ConversionCost( Type *dest, const SymTab::Indexer &indexer, const TypeEnvironment &env, CostFunction );
@@ -36,19 +38,21 @@
 		Cost get_cost() const { return cost; }
 
-		virtual void visit(VoidType *voidType);
-		virtual void visit(BasicType *basicType);
-		virtual void visit(PointerType *pointerType);
-		virtual void visit(ArrayType *arrayType);
-		virtual void visit(ReferenceType *refType);
-		virtual void visit(FunctionType *functionType);
-		virtual void visit(StructInstType *aggregateUseType);
-		virtual void visit(UnionInstType *aggregateUseType);
-		virtual void visit(EnumInstType *aggregateUseType);
-		virtual void visit(TraitInstType *aggregateUseType);
-		virtual void visit(TypeInstType *aggregateUseType);
-		virtual void visit(TupleType *tupleType);
-		virtual void visit(VarArgsType *varArgsType);
-		virtual void visit(ZeroType *zeroType);
-		virtual void visit(OneType *oneType);
+		void previsit( BaseSyntaxNode * ) { visit_children = false; }
+
+		void postvisit( VoidType * voidType );
+		void postvisit( BasicType * basicType );
+		void postvisit( PointerType * pointerType );
+		void postvisit( ArrayType * arrayType );
+		void postvisit( ReferenceType * refType );
+		void postvisit( FunctionType * functionType );
+		void postvisit( StructInstType * aggregateUseType );
+		void postvisit( UnionInstType * aggregateUseType );
+		void postvisit( EnumInstType * aggregateUseType );
+		void postvisit( TraitInstType * aggregateUseType );
+		void postvisit( TypeInstType * aggregateUseType );
+		void postvisit( TupleType * tupleType );
+		void postvisit( VarArgsType * varArgsType );
+		void postvisit( ZeroType * zeroType );
+		void postvisit( OneType * oneType );
 	  protected:
 		Type *dest;