nixpkgs/lib/tests/modules/declare-submoduleWith-shorthand.nix

{ lib, ... }: let
  sub.options.config = lib.mkOption {
    type = lib.types.bool;
    default = false;
  };
in {
  options.submodule = lib.mkOption {
    type = lib.types.submoduleWith {
      modules = [ sub ];
      shorthandOnlyDefinesConfig = true;
    };
    default = {};
  };
}