Serialization error in .NET Core projects

[zspitz]

ATM, using the visualizer against a .NET Core project fails, with the following stack trace:

An unhandled exception of type 'System.TypeLoadException' was thrown by the custom visualizer component in the process being debugged.

Could not load type 'System.Runtime.CompilerServices.IsReadOnlyAttribute' from assembly 'mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089'.

wtih the following stack trace:

 at System.ModuleHandle.ResolveType(RuntimeModule module, Int32 typeToken, IntPtr* typeInstArgs, Int32 typeInstCount, IntPtr* methodInstArgs, Int32 methodInstCount, ObjectHandleOnStack type)
   at System.ModuleHandle.ResolveTypeHandleInternal(RuntimeModule module, Int32 typeToken, RuntimeTypeHandle[] typeInstantiationContext, RuntimeTypeHandle[] methodInstantiationContext)
   at System.Reflection.RuntimeModule.ResolveType(Int32 metadataToken, Type[] genericTypeArguments, Type[] genericMethodArguments)
   at System.Reflection.CustomAttribute.FilterCustomAttributeRecord(CustomAttributeRecord caRecord, MetadataImport scope, Assembly& lastAptcaOkAssembly, RuntimeModule decoratedModule, MetadataToken decoratedToken, RuntimeType attributeFilterType, Boolean mustBeInheritable, Object[] attributes, IList derivedAttributes, RuntimeType& attributeType, IRuntimeMethodInfo& ctor, Boolean& ctorHasParameters, Boolean& isVarArg)
   at System.Reflection.CustomAttribute.IsCustomAttributeDefined(RuntimeModule decoratedModule, Int32 decoratedMetadataToken, RuntimeType attributeFilterType, Int32 attributeCtorToken, Boolean mustBeInheritable)
   at System.Reflection.CustomAttribute.IsDefined(RuntimeMethodInfo method, RuntimeType caType, Boolean inherit)
   at System.Runtime.Serialization.SerializationEvents.GetMethodsWithAttribute(Type attribute, Type t)
   at System.Runtime.Serialization.SerializationEvents..ctor(Type t)
   at System.Runtime.Serialization.SerializationEventsCache.<>c.<GetSerializationEventsForType>b__1_0(Type type)
   at System.Collections.Concurrent.ConcurrentDictionary`2.GetOrAdd(TKey key, Func`2 valueFactory)
   at System.Runtime.Serialization.SerializationEventsCache.GetSerializationEventsForType(Type t)
   at System.Runtime.Serialization.SerializationObjectManager.RegisterObject(Object obj)
   at System.Runtime.Serialization.Formatters.Binary.WriteObjectInfo.InitSerialize(Object obj, ISurrogateSelector surrogateSelector, StreamingContext context, SerObjectInfoInit serObjectInfoInit, IFormatterConverter converter, ObjectWriter objectWriter, SerializationBinder binder)
   at System.Runtime.Serialization.Formatters.Binary.ObjectWriter.Write(WriteObjectInfo objectInfo, NameInfo memberNameInfo, NameInfo typeNameInfo)
   at System.Runtime.Serialization.Formatters.Binary.ObjectWriter.WriteArrayMember(WriteObjectInfo objectInfo, NameInfo arrayElemTypeNameInfo, Object data)
   at System.Runtime.Serialization.Formatters.Binary.ObjectWriter.WriteArray(WriteObjectInfo objectInfo, NameInfo memberNameInfo, WriteObjectInfo memberObjectInfo)
   at System.Runtime.Serialization.Formatters.Binary.ObjectWriter.Write(WriteObjectInfo objectInfo, NameInfo memberNameInfo, NameInfo typeNameInfo)
   at System.Runtime.Serialization.Formatters.Binary.ObjectWriter.Serialize(Object graph, BinaryFormatterWriter serWriter, Boolean fCheck)
   at System.Runtime.Serialization.Formatters.Binary.BinaryFormatter.Serialize(Stream serializationStream, Object graph, Boolean check)
   at ExpressionTreeVisualizer.VisualizerDataObjectSource.TransferData(Object target, Stream incomingData, Stream outgoingData) in C:\Users\Spitz\source\repos\zspitz\ExpressionToString\Visualizer.Shared\VisualizerDataObjectSource.cs:line 9
   at Microsoft.VisualStudio.DebuggerVisualizers.DebuggeeSide.Impl.ClrCustomVisualizerDebuggeeHost.TransferData(Object visualizedObject, Byte[] uiSideData)

I've managed to isolate the problem outside of the context of the visualizer:

// using System;
// using System.IO;
// using System.Runtime.Serialization.Formatters.Binary;
var stream = File.Create(Path.GetTempFileName());
var formatter = new BinaryFormatter();
var data = new VisualizerData(expr); // serialized class with information about a given expression tree
formatter.Serialize(stream, data); // fails with the same exception

but only if there is a reference to the visualizer DLL project, and VisualizerData comes from there.

If I copy VisualizerData.cs to the .NET Core project and use that, without a reference to the visualizer DLL, the serialization works fine.

A possible workaround might be to move VisualizerData to the Shared project, as it doesn't have any dependencies on the visualizer DLL.

[zspitz]

See dotnet/core#2981 (comment).

When we upgrade to .NET Core 3, probably with the next version of .NET Standard, we can go back to auto-implemented properties.

[zspitz]

But since .NET Framework will never be adapted to match a later version of .NET Standard (>2), as long as Visual Studio runs on ,NET Framework, we'll never be able to use auto-implemented properties.