using System.Data;
using System.Reflection.Metadata;
using System.Runtime.CompilerServices;
[assembly: MetadataUpdateHandlerAttribute(typeof(Handler))]

class Handler
{
    static void ClearCache(Type[]? updatedTypes)
    {
        
    }

    static void UpdateApplication(Type[]? updatedTypes)
    {
        if (updatedTypes != null)
        {
            Console.WriteLine("Update: " + String.Join(",", updatedTypes.Select(t => t.Name)));

            var newType = updatedTypes.FirstOrDefault(t => t.Name.StartsWith("C#"));
            if (newType != null)
            {
                C.Instance = (I)Activator.CreateInstance(newType)!;
            }
        }
    }
}

interface I
{
    Task F();
}

[CreateNewOnMetadataUpdate]
class C : I
{
    public static I Instance = new C();

    public static void Main()
    {
        while (true)
        {
            Instance.F();
            Thread.Sleep(1000);
        }
    }

    public void F()
    {
        Console.WriteLine('.');
        G(() => { });  // exception
    }

    public void G(Action f) => f();
}