method_missing

# File activesupport/lib/active_support/whiny_nil.rb, line 45
    def method_missing(method, *args, &block)
      # Ruby 1.9.2: disallow explicit coercion via method_missing.
      if method == :to_ary || method == :to_str
        raise NoMethodError, "undefined method `#{method}' for nil:NilClass"
      elsif klass = METHOD_CLASS_MAP[method]
        raise_nil_warning_for klass, method, caller
      else
        super
      end
    end