nixos/mandoc: fix invalid manpath directory and add cachePath option

        '';

      };

      cachePath = lib.mkOption {

        type = with lib.types; listOf str;

        default = cfg.manPath;

        defaultText = lib.literalExpression "config.documentation.man.mandoc.manPath";

        example = lib.literalExpression "[ \"share/man\" \"share/man/fr\" ]";

        description = ''

          Change the paths where mandoc {manpage}`makewhatis(8)`generates the

          manual page index caches. {option}`documentation.man.generateCaches`

          should be enabled to allow cache generation. This list should only

          include the paths to manpages installed in the system configuration,

          i. e. /run/current-system/sw/share/man. {manpage}`makewhatis(8)`

          creates a database in each directory using the files

          `mansection/[arch/]title.section` and `catsection/[arch/]title.0`

          in it. If a directory contains no manual pages, no database is

          created in that directory.

          This option only needs to be set manually if extra paths should be

          indexed or {option}`documentation.man.manPath` contains paths that

          can't be indexed.

        '';

      };

      package = lib.mkOption {

        type = lib.types.package;

        default = pkgs.mandoc;

      # TODO(@sternenseemman): fix symlinked directories not getting indexed,

      # see: https://inbox.vuxu.org/mandoc-tech/20210906171231.GF83680@athene.usta.de/T/#e85f773c1781e3fef85562b2794f9cad7b2909a3c

      extraSetup = lib.mkIf config.documentation.man.generateCaches ''

        for man_path in ${

          lib.concatMapStringsSep " " (path:

            "$out/" + lib.escapeShellArg path

            ) cfg.manPath} ${lib.concatMapStringsSep " " (path:

            lib.escapeShellArg path) cfg.settings.manpath

          }

        for man_path in ${lib.concatMapStringsSep " " (path: "$out/" + lib.escapeShellArg path) cfg.cachePath}

        do

          [[ -d "$man_path" ]] && ${makewhatis} -T utf8 $man_path

        done