# File lib/rubygems.rb, line 351
    def required_location(gemname, libfile, *version_constraints)
      version_constraints = [">0"] if version_constraints.empty?
      matches = Gem.source_index.find_name(gemname, version_constraints)
      return nil if matches.empty?
      spec = matches.last
      spec.require_paths.each do |path|
        result = File.join(spec.full_gem_path, path, libfile)
        return result if File.exists?(result)
      end
      nil
    end