anchor.diff:      vm.ProgramInfoNode? typedefNode = infoNodesByName[newTypedef.name];
       assert(typedefNode == null,
           "encountered constant with duplicated name: $newTypedef.name");
  -    outputInfo.add(newTypedef);
     }
   
     void makeClassType(ClassTypeInfo classTypeInfo) {
  
positive.code:     outputUnits[info.filename] = newUnit;
      outputUnits[info.filename]!.root.size = info.size;
      return outputUnits[info.filename]!.root;
    }
  
    @override
  
negative.code:       assert(classNode == null,
            "encountered class with duplicated name: $newClass.name");
        infoNodesByName[newClass.name] = newClass;
      }
    }
  
  