Question

I wanted to use protocolbuf .net version without attributes, with RuntimeTypeModel created via specific code. It worked pretty good till I hit the case, which was extracted in the case below. The referenced protobuf-net library’s version is 2.0.0.447. What’s wrong with this model’s creation? Any clues?

public class ProtoBufFailingTest
{
    public abstract class Message
    {
    }

    public class SomeMessage : Message
    {
        public readonly Descriptor Desc;

        public SomeMessage(Descriptor desc)
        {
            Desc = desc;
        }
    }

    public struct Descriptor
    {
        public readonly Event EventData;

        public Descriptor(Event eventData)
        {
            EventData = eventData;
        }
    }

    public abstract class Event
    {
    }

    public class SomeEvent : Event
    {
        public int SomeField;
    }

    [Test]
    public void FailingTest( )
    {
        var model = TypeModel.Create();

        // message hierarchy
        {
            var messages = model.Add(typeof(Message), true);
            messages.AddSubType(1, typeof(SomeMessage));
            model[typeof(SomeMessage)].UseConstructor = false;
        }

        // events hierarchy
        {
            var events = model.Add(typeof (Event), true);
            events.AddSubType(1, typeof (SomeEvent));
            model[typeof (SomeEvent)].UseConstructor = false;
        }

        // descriptor
        var eventDescriptorModel = model.Add(typeof(Descriptor), true);
        eventDescriptorModel.UseConstructor = false;

        var typeModel = model.Compile();

        const PrefixStyle prefixStyle = PrefixStyle.Base128;
        const int testValue = 5;
        using (var ms = new MemoryStream())
        {

            typeModel.SerializeWithLengthPrefix(ms, new SomeMessage(new Descriptor(new SomeEvent { SomeField = testValue })), null, prefixStyle, 0);

            ms.Seek(0, SeekOrigin.Begin);

            // fails here
            var message = (SomeMessage)typeModel.DeserializeWithLengthPrefix(ms, null, typeof(Message), prefixStyle, 0);

            Assert.AreEqual(testValue, ((SomeEvent)message.Desc.EventData).SomeField);
        }
    }
}

Answer 1

Very simply; the library has (had) a bug, emitting

initobj {type}
stloc.0

when obviously (cough) for a value-type Descriptor it should have been emitting

ldloca.s 0
initobj {type}

I’ll get this deployed as soon as I’ve checked I haven’t destabilised anything.