Exception GetSerializer<UnityEngine.Quaternion> (object)' while running with --aot-only.

[bnaka]

Title exception in Unity iOS build.

ExecutionEngineException: Attempting to JIT compile method 'MsgPack.Serialization.SerializationContext:GetSerializer<UnityEngine.Quaternion> (object)' while running with --aot-only.

When Serialize does UnityEngine.Quaternion, on used Serializers.RegisterOverride.

But I found a method to avoid an exception.
Exclude comment out in method JIT_compile_Exception_Avoid_Method from next simple code.
Why is this code necessary?

Simple code

using UnityEngine;
using System.IO;
using System.Collections.Generic;

public class QuaternionSerializer: MsgPack.Serialization.MessagePackSerializer<Quaternion>
{
    public QuaternionSerializer(MsgPack.Serialization.SerializationContext c)
        : base(c)
    {
    }

    protected override void PackToCore(MsgPack.Packer packer, Quaternion objectTree)
    {
        packer.PackArrayHeader(4);
        packer.Pack(objectTree.x);
        packer.Pack(objectTree.y);
        packer.Pack(objectTree.z);
        packer.Pack(objectTree.w);
    }

    protected override Quaternion UnpackFromCore(MsgPack.Unpacker unpacker)
    {
        if (!unpacker.IsArrayHeader)
        {
            throw MsgPack.Serialization.SerializationExceptions.NewIsNotArrayHeader();
        }

        var count = MsgPack.Serialization.UnpackHelpers.GetItemsCount(unpacker);
        if( count != 4 )
        {
            throw MsgPack.Serialization.SerializationExceptions.NewIsNotArrayHeader();
        }

        if (!unpacker.IsArrayHeader)
        {
            throw MsgPack.Serialization.SerializationExceptions.NewIsNotArrayHeader();
        }

        System.Single x, y, z, w;

        if (!unpacker.ReadSingle(out x))
        {
            throw MsgPack.Serialization.SerializationExceptions.NewMissingItem(0);
        }
        if (!unpacker.ReadSingle(out y))
        {
            throw MsgPack.Serialization.SerializationExceptions.NewMissingItem(1);
        }
        if (!unpacker.ReadSingle(out z))
        {
            throw MsgPack.Serialization.SerializationExceptions.NewMissingItem(2);
        }
        if (!unpacker.ReadSingle(out w))
        {
            throw MsgPack.Serialization.SerializationExceptions.NewMissingItem(2);
        }
        return new Quaternion(x, y, z, w);

    }
}

public class TestMain : MonoBehaviour
{
    public class QTest
    {
        public Quaternion q;
    }

    void Start()
    {
        var context = MsgPack.Serialization.SerializationContext.Default;
        context.Serializers.RegisterOverride(new QuaternionSerializer(context));

        var stream = new MemoryStream(); 

        var q = new QTest();
        var serializer = context.GetSerializer<QTest>();
        serializer.Pack(stream, q);

        stream.Position = 0;
        serializer.Unpack(stream);
    }

    // Avoiding => ExecutionEngineException: Attempting to JIT compile method 'MsgPack.Serialization.SerializationContext:GetSerializer<UnityEngine.Quaternion> (object)' while running with --aot-only.'
    public void JIT_compile_Exception_Avoid_Method()
    {
        //var context = MsgPack.Serialization.SerializationContext.Default;
        //context.GetSerializer<Quaternion>();
    }
}

Environment.
Unity: 5.2.1p4
Xcode: 7.0.1
iOS: 9.0.2
msgpack-cli: 0.6.4 unity3d/MsgPack.dll

Unity iOS Player Settings.
Scripting Backend: Mono2x
Api Compatibility Level: .Net 2.0 Subset
Stripping Level: Disabled

---

iOSビルドでタイトルにあるExceptionが発生します。
Serializers.RegisterOverrideを使い、UnityEngine.Quaternionをシリアライズする際に起こります。
ただ、Exceptionを回避する方法を見つけました。
次のSimple code中のJIT_compile_Exception_Avoid_Method関数のコメントアウト部分を外すことです。
なぜこのコードが必要なのでしょうか？

[yfakariya]

Thank you for reporting! It looks limitation of Unity AOT. Your workaround should work fine. I found that there was same issue for KeyValuePair<int, string> (see https://github.com/msgpack/msgpack-cli/blob/master/test/NUnitLiteRunner/Program.cs#L54, and there are no counterparts for Xamarin iOS tests), but I did not recognize for other complex value types.

[yfakariya]

It should be solved with PrepareType<T>.

[bnaka]

Thank you so much!