Index: src/Virtual/Tables.cpp
===================================================================
--- src/Virtual/Tables.cpp	(revision 9c447e225244a18c96cc4536ae39da1e56abe7b3)
+++ src/Virtual/Tables.cpp	(revision 3e135c895c889427f3db85749ee5eab83dd48070)
@@ -122,6 +122,4 @@
 			) );
 		}
-		//ast::Expr * expr = buildInitExpr(...);
-		//inits.push_back( new ast::SingleInit( location, expr ) )
 	}
 
@@ -162,4 +160,14 @@
 	assert( vtableType );
 	assert( exceptType );
+
+	// If this is called after Fix Return Statements (currently it is in
+	// Implement Concurrent Keywords) then this must be marked as unused
+	// to avoid warnings.
+	ast::ObjectDecl * frontRet = new ast::ObjectDecl( location,
+		"_retvalue",
+		new ast::ReferenceType( vtableType )
+	);
+	frontRet->attributes.emplace_back( new ast::Attribute( "unused" ) );
+
 	return new ast::FunctionDecl(
 		location,
@@ -170,9 +178,5 @@
 			new ast::PointerType( exceptType )
 		) },
-		{ new ast::ObjectDecl(
-			location,
-			"_retvalue",
-			new ast::ReferenceType( vtableType )
-		) },
+		{ frontRet },
 		nullptr,
 		ast::Storage::Classes(),