    # File lib/yard/rubygems/backports/source_index.rb, line 315
      def outdated
        outdateds = []

        latest_specs.each do |local|
          dependency = Gem::Dependency.new local.name, ">= #{local.version}"

          fetcher = Gem::SpecFetcher.fetcher
          remotes = fetcher.find_matching dependency
          remotes = remotes.map { |(_, version, _), _| version }

          latest = remotes.sort.last

          outdateds << local.name if latest and local.version < latest
        end

        outdateds
      end