missing_name

# File activesupport/lib/active_support/core_ext/name_error.rb, line 12
  def missing_name
    # Since ruby v2.3.0 `did_you_mean` gem is loaded by default.
    # It extends NameError#message with spell corrections which are SLOW.
    # We should use original_message message instead.
    message = respond_to?(:original_message) ? original_message : self.message
    return unless message.start_with?("uninitialized constant ")

    receiver = begin
      self.receiver
    rescue ArgumentError
      nil
    end

    if receiver == Object
      name.to_s
    elsif receiver
      "#{real_mod_name(receiver)}::#{self.name}"
    else
      if match = message.match(/((::)?([A-Z]\w*)(::[A-Z]\w*)*)$/)
        match[1]
      end
    end
  end