knah/Il2CppAssemblyUnhollower

TypeLoadException when using classes which inherit from generic types with explicit UnityEngine-namespace struct arguments.

sinai-dev opened this issue · 1 comments

sinai-dev commented

Hey knah, so I found an issue with generic types which I don't think is covered by your known issues.

Consider the following class, assuming it existed in the original game.

public class Test : UnityEvent<Vector2>

This will throw a TypeLoadException if you attempt to access it in any way.

The issue is the explicit generic argument, and the fact that argument type is in the UnityEngine dll. If I used or any System or custom type as the argument it would work fine.

I thought perhaps it was the known blittable struct delegate issue, but this was proven to be unrelated. This does not cause a TypeLoadException:

public struct NonBlittableStruct
{
    public string s;
}
public class Test : UnityEvent<NonBlittableStruct>

Nor does this:

public class Test2<T> : UnityEvent<T>

public Test2<Vector2> test;

The same issue affects InputSystem as well, such as Mouse.current.position, as the value is a Vector2Control : InputControl<Vector2>.

Let me know if I can provide any more details!

And again, these are types which exist in the actual game, not new generic types created in a mod. Have not tested if the same issue affects custom mod classes.

sinai-dev commented

Got some more details for you.

So I noticed when I did this:
eg2

I get this different error:

[17:25:13.694] [UnityExplorer] [Error] System.TypeLoadException: 
Could not load type of field 'UnityExplorer.ExplorerCore:v2Event' (0) due to: 
Expected reference type but got type kind 17 assembly:Assembly-CSharp type:<unknown type> member:(null) signature:<none>

  at MelonLoader.MelonHandler.OnApplicationStart () [0x0015d] in <0b18a86417cb47c8b3fed3a346dfca50>:0

So to make sure, I did a quick test. Only the UnityEngine struct types are affected (and only the explicit inheritance ones):

eg

Now that I think about it, it really does sound like this known issue:

  • Using generics with value types may lead to exceptions or crashes because of missing method bodies. If a specific value-typed generic signature was not used in original game code, it can't be used externally either.

Except this generic signature should exist in the original game, right?

eg3