wtf.rb

class Wtf
  def method_missing(name, *args)
    :lol
  end

  def respond_to?(name)
    :nope
  end

  def respond_to_missing?(name)
    :kek
  end
end

puts "method_missing owner: #{Wtf.instance_method(:method_missing).owner}"
puts "respond_to? owner: #{Wtf.instance_method(:respond_to?).owner}"
puts "respond_to_missing? owner: #{Wtf.instance_method(:respond_to_missing?).owner}"

puts "instance_methods: #{Wtf.instance_methods.select { |m|
  Wtf.instance_method(m).owner == Wtf
}}"

respond_to_missing? is always set to private - found the spec for that.

TIL there are 4 names that will always be private:

https://github.com/ruby/ruby/blob/eaeb0a008ba13ba0e531f3ccf589c44351cddbfe/vm_method.c#L776-L787