# File lib/active_support/multibyte/chars.rb, line 211
      def rindex(needle, offset=nil)
        offset ||= length
        wrapped_offset = self.first(offset).wrapped_string.length
        index = @wrapped_string.rindex(needle, wrapped_offset)
        index ? (self.class.u_unpack(@wrapped_string.slice(0...index)).size) : nil
      end