Importer create ClassSig rather than GenericInstSig for generic type

I don’t know if it’s a .NET runtime bug or dnlib bug. .NET runtime indicate different IsGenericTypeDefinition for the same type Task<> dnlib create ClassSig since IsGenericType and IsGenericTypeDefinition are both True;

			if (a.IsGenericType && !a.IsGenericTypeDefinition)
				return ElementType.GenericInst;

using System;
using System.Reflection;
using System.Threading.Tasks;
using dnlib.DotNet;

class Program {
	static void Main() {
		var methodInfo1 = typeof(Task<string>).GetMethod("ContinueWith", new Type[] { typeof(Action<Task<string>>) });
		Show(methodInfo1); // True

		var methodInfo2 = typeof(Demo2<string>).GetMethod("Test");
		Show(methodInfo2); // False

		var moule = ModuleDefMD.Load(typeof(Program).Module);
		var method1 = moule.Import(methodInfo1); // System.Threading.Tasks.Task System.Threading.Tasks.Task`1<System.String>::ContinueWith(System.Action`1<System.Threading.Tasks.Task`1>)
		Show(method1); // Class
		var method2 = moule.Import(methodInfo2); // System.Void Demo2`1<System.String>::Test(System.Action`1<System.Threading.Tasks.Task`1<System.String>>)
		Show(method2); // GenericInst
		Console.ReadKey();
	}

	static void Show(MethodInfo method) {
		var origMethod = method.Module.ResolveMethod(method.MetadataToken);
		var type = origMethod.GetParameters()[0].ParameterType.GenericTypeArguments[0];
		Console.WriteLine(type.IsGenericTypeDefinition);
	}

	static void Show(IMethod method) {
		var typeSig = (method.MethodSig.Params[0] as GenericInstSig).GenericArguments[0];
		Console.WriteLine(typeSig.ElementType);
	}
}

class Demo2<T> {
	public void Test(Action<Task<T>> arg) { }
}

[wwh1004]

In old commit https://github.com/0xd4d/dnlib/commit/4ebebc1cd335676158688cc2e786de16b152f173#diff-3bc1d65c9144274297f0e9a1b2e194898aa3aa9e441d2956ab303ab4522dc554L488 code is

var fieldSig = new FieldSig(ImportAsTypeSig(origField.FieldType));

So I use “origField” instead of “fieldInfo”. But after running more tests I find “fieldInfo” is true.
Also I find more problems about generic like nested case of “MustTreatTypeAsGenericInstType”, wrong result of “FieldComparer.Equals”, inconsistent result of GetHashCode(SRM.FieldInfo) and GetHashCode(DNN.IField), ContainsGenericParameter for generic MemberRef always return true.
I will fix them these days.

[wtfsck]

PRs welcome. I don’t have time.