lib.maintainers: Enforce unique github[Id], email, matrix

  missingGithubIds = lib.concatLists (lib.mapAttrsToList checkMaintainer lib.maintainers);

  uniqueFields = [

    "github"

    "githubId"

    "email"

    "matrix"

  ];

  nonUniqueFields = lib.filterAttrs (field: nonUnique: nonUnique != { }) (

    lib.genAttrs uniqueFields (

      field:

      lib.pipe lib.maintainers [

        (lib.mapAttrsToList (handle: m: m // { inherit handle; }))

        (lib.groupBy (m: toString (m.${field} or null)))

        (lib.filterAttrs (v: ms: v != "" && lib.length ms > 1))

        (lib.mapAttrs (v: ms: map (m: m.handle) ms))

      ]

    )

  );

  uniquenessError =

    value:

    if nonUniqueFields == { } then

      value

    else

      throw "lib.maintainers has non-unique fields: ${lib.generators.toPretty { } nonUniqueFields}";

  success = pkgs.runCommand "checked-maintainers-success" { } "mkdir $out";

  failure =

        exit 1

      '';

in

if missingGithubIds == [ ] then success else failure

uniquenessError (if missingGithubIds == [ ] then success else failure)