null_challenge.cs

using System.Runtime.CompilerServices;

#pragma warning disable CS8604
#pragma warning disable CS8600

C local = null;

if (local != null && local.Prop)
{
    Console.WriteLine(local.ToString());
}

class C
{
    private int _h;

    public bool Prop
    {
        get
        {
            unsafe
            {
                fixed (int* iptr = &_h)
                {
                    var i = (nuint*) iptr;
                    // Kill the vtable
                    *(i - 1) = 0;
                    // Kill the object header too
                    *(i - 2) = 0;
                }
            }
            
            return true;
        }
    }

    public static bool operator !=(in C a, in C _)
    {
        Unsafe.AsRef(a) = new C();
        return true;
    }

    public static bool operator ==(C a, C b) => throw new NotImplementedException();
}