序列化期间的 TypeLoadException

Question

当我尝试在 .NET Core 项目（面向 2.2）中的表达式树上打开 my custom visualizer 时，出现以下异常：

自定义可视化组件在正在调试的进程中引发了“System.TypeLoadException”类型的未处理异常。

无法从程序集“mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089”加载类型“System.Runtime.CompilerServices.IsReadOnlyAttribute”。

以下代码（来自问题末尾的堆栈跟踪）似乎有同样的问题：

// 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

当代码在 .NET Core 项目中运行，但使用来自引用的 .NET Framework 程序集（针对 4.7.2）的类 (VisualizerData) 时；该程序集具有对 WPF 程序集的引用。

如何调试此问题？可能是什么原因造成的？

请注意，这里没有进行任何反序列化；这都是在启动序列化时完成的。

Source code for VisualizerDataObjectSource.TransferData(Object target, Stream incomingData, Stream outgoingData) in VisualizerDataObjectSource.cs:line 9

---

堆栈跟踪：

   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)

Answer 1

如您所见，以下消息指的是 NET Framework 4.0 元素：

无法从程序集“mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089”加载类型“System.Runtime.CompilerServices.IsReadOnlyAttribute”。

您可以使用的最大 NetFramework 目标由该元素定义。

Answer 2

似乎序列化在引用的 .NET Framework 程序集中定义的值类型是问题的根源。

使用以下方法：

static (bool success, string failPath, string errorMessage) CanSerialize(object o, string path = "") {
    var formatter = new BinaryFormatter();
    using (var stream = File.Create(Path.GetTempFileName())) {
        return CanSerialize(o, path, formatter, stream);
    }
}

static (bool success, string failPath, string errorMessage) CanSerialize(object o, string path, BinaryFormatter formatter, Stream stream) {
    if (o == null) { return (false, path, "Null object"); }

    string msg;
    var t = o.GetType();
    if (t.IsPrimitive || t == typeof(string)) { return (true, path, null); }
    try {
        formatter.Serialize(stream, o);
        return (true, path, null);
    } catch (Exception ex) {
        msg = ex.Message;
    }

    List<(string, object)> values;
    if (t.IsArray) {
        values = (o as IEnumerable).ToObjectList()
            .Select((x, index) => ($"[{index}]", x))
            .Where(x => x.Item2 != null)
            .ToList();
    } else {
        values = t.GetFields(BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Instance)
            .Where(fld => !fld.IsStatic)
            .Select(fld => ($".{fld.Name}", fld.GetValue(o)))
            .Where(x => x.Item2 != null)
            .ToList();
    }

    foreach (var (name, value) in values) {
        var ret = CanSerialize(value, path + name, formatter, stream);
        if (!ret.success) { return ret; }
    }
    return (false, path, msg);
}

以下struct 定义：

[Serializable]
public struct EndNodeData {
    public string Closure { get; set; }
    public string Name { get; set; }
    public string Type { get; set; }
    public string Value { get; set; }
}

以下代码：

var endnodeData = new EndNodeData {
    Closure = null,
    Name = null,
    Type = "int",
    Value = "5"
};
Console.WriteLine(CanSerialize(endnodeData));

打印出来：

（假，无法从程序集“mscorlib”加载类型“System.Runtime.CompilerServices.IsReadOnlyAttribute”，Version=4.0.0.0，Culture=neutral，PublicKeyToken=b77a5c561934e089。）

问题似乎出在这种特定类型或一般的值类型上。