Question

I’m attempting to use the precompile.exe tool to generate a serialization assembly that can be used in a Windows Phone 7 program. The data model I have uses inheritance – and runs just fine as a .NET 4.0 program (serialization works). However, when attempting to generate a serialization assembly, I get the error:

Adding Program.Serialization.MessagePeer...
A type can only participate in one inheritance hierarchy
at ProtoBuf.Meta.MetaType.SetBaseType(MetaType baseType) in c:\Dev\protobuf-net\protobuf-net\Meta\MetaType.cs:line 138
at ProtoBuf.Meta.MetaType.AddSubType(Int32 fieldNumber, Type derivedType, DataFormat dataFormat) in c:\Dev\protobuf-net\protobuf-net\Meta\MetaType.cs:line 125
at ProtoBuf.Meta.MetaType.ApplyDefaultBehaviour() in c:\Dev\protobuf-net\protobuf-net\Meta\MetaType.cs:line 553
at ProtoBuf.Meta.RuntimeTypeModel.Add(Type type, Boolean applyDefaultBehaviour) in C:\Dev\protobuf-net\protobuf-net\Meta\RuntimeTypeModel.cs:line 494
at ProtoBuf.Precompile.PreCompileContext.Execute() in c:\Dev\protobuf-net\precompile\Program.cs:line 340
at ProtoBuf.Precompile.Program.Main(String[] args) in c:\Dev\protobuf-net\precompile\Program.cs:line 33

I’ve been able to repro the issue with a simpler data model:

[ProtoContract]
[ProtoInclude(2, typeof(Bar))]
public abstract class Foo
{
    [ProtoMember(1)]
    public int Value { get; set; }
}

[ProtoContract]
public class Bar : Foo
{
    [ProtoMember(2)]
    public string Name { get; set; }
}

I have tried using both r284 ad 2485 builds of protobuf from http://code.google.com/p/protobuf-net/.

The command line to precompile.exe is straightforward as well:

D:\Projects\Program\Precompile>precompile
   "..\SerializerGen\bin\Debug\SerializerGen.dll"
   -o:MySerialization.dll
   -t:MyProgram.Serialization.PeerMessageSerializer

Is this a known problem in protobuf-net, or am I doing something wrong?

Answer 1

Hmmm; there was a little difference in how System.Reflection and IKVM.Reflection were reporting inherited attributes, i.e. the precompiler (which uses IKVM.Reflection) was seeing the inherited ProtoIncludeAttribute, plus 2 (instead of 1) ProtoContractAttributes.

This is fixed in r571