Deserializing int& type with protobuf-net

Question

I am trying to upgrade dependencies of a legacy code base to use protobuf-net 2.3.7 instead of protobuf-net 1.0

The following code used to work with version 1 and prints 2147483647

var stream = new MemoryStream();
Serializer.NonGeneric.SerializeWithLengthPrefix(stream, int.MaxValue, PrefixStyle.Base128, 1);
stream.Position = 0;

Serializer.NonGeneric.TryDeserializeWithLengthPrefix(stream, PrefixStyle.Base128, _ => typeof(int).MakeByRefType(), out var lastItem);
Console.WriteLine(lastItem);

But the same code doesn't work with protobuf-net 2.3.7 and throws:

Unhandled Exception: System.InvalidOperationException: Type is not expected, and no contract can be inferred: System.Int32& at ProtoBuf.Meta.TypeModel.ThrowUnexpectedType(Type type) at ProtoBuf.Meta.TypeModel.TryDeserializeAuxiliaryType(ProtoReader reader, DataFormat format, Int32 tag, Type type, Object& value, Boolean skipOtherFields, Boolean asListItem, Boolean autoCreate, Boolean insideList, Object parentListOrType) at ProtoBuf.Meta.TypeModel.DeserializeWithLengthPrefix(Stream source, Object value, Type type, PrefixStyle style, Int32 expectedField, TypeResolver resolver, Int64& bytesRead, Boolean& haveObject, SerializationContext context) at ProtoBuf.Serializer.NonGeneric.TryDeserializeWithLengthPrefix(Stream source, PrefixStyle style, TypeResolver resolver, Object& value)

Although the exception makes sense I am trying to find a way to make the code to work with the new version of the library without doing a massive refactoring.

Any suggestions?

EDIT:

MemoryStream contains 8 bytes after serialization: new byte[] {10,6,8,255,255,255,255,7}

base64: CgYI/////wc=

Wow, that's an edge case! Do you happen to know what bytes that used to serialize as? I.e. the hex or base-64 of the output? — Marc Gravell♦
@MarcGravell I have added the stream output to the question now. — idursun

Marc Gravell Marc Gravell · Accepted Answer · 2018-04-27T21:28:24

That has never been a specifically designed scenario, and frankly I'm amazed that it ever worked, even in 1.something, but: this seems to work:

Serializer.NonGeneric.TryDeserializeWithLengthPrefix(stream, PrefixStyle.Base128, _ => typeof(int), out var lastItem);
 Console.WriteLine(lastItem); // lastItem is a boxed int

Is there a specific reason you want a wrapped pointer?

Deserializing int& type with protobuf-net

1 Answers