Subclassing nil in Ruby 2.7.2 (the old version broke)

subclassing_nil.rb

RUBY_VERSION # => "2.7.2"
require 'fiddle'

User = Struct.new :name

class NullUser < NilClass
  # We have no way to allocate a new NullUser... BUT! We can hack around this
  # by making a new object and setting its class pointer to point at NullUser
  def self.new(*)
    instance     = Object.new
    instance_ptr = Fiddle::Pointer.new Fiddle.dlwrap instance
    klass_ptr    = Fiddle::Pointer.new Fiddle.dlwrap self
    instance.class # => Object
    instance_ptr[8, 8] = klass_ptr.ref[0, 8] # set the new object's class 
    instance.class # => NullUser
    instance
  end

  def name
    ''
  end
end

user = User.new 'Samantha'
user.name # => "Samantha"
user.to_h # => {:name=>"Samantha"}
user.nil? # => false
user      # => #<struct User name="Samantha">

user = NullUser.new
user.name # => ""
user.to_h # => {}
user.nil? # => true
user      # => nil

# Just to prove the point:
def nil.omg?
  :wtf
end
user.omg? # => :wtf

# One reason this works is b/c of this possible bug
# if they ever fix this, we'll have to do more work to hack around it.
nil.singleton_class.singleton_class? # => false