# File lib/rubygems/doc_manager.rb, line 60
    def load_rdoc
      if File.exist?(@doc_dir) && !File.writable?(@doc_dir) then
        raise Gem::FilePermissionError.new(@doc_dir)
      end

      FileUtils.mkdir_p @doc_dir unless File.exist?(@doc_dir)

      begin
        gem 'rdoc'
      rescue Gem::LoadError
        # use built-in RDoc
      end

      begin
        require 'rdoc/rdoc'
      rescue LoadError => e
        raise Gem::DocumentError,
          "ERROR: RDoc documentation generator not installed!"
      end
    end