{ lib, extendModules, ... }:

let
  inherit (lib) mkOption mkOverride types;
in
{
  imports = [

    {
      options.sub = mkOption {
        default = { };
        type = types.submodule (
          { config, extendModules, ... }:
          {
            options.value = mkOption { type = types.int; };

            options.specialisation = mkOption {
              default = { };
              inherit (extendModules { modules = [ { specialisation = mkOverride 0 { }; } ]; }) type;
            };
          }
        );
      };
    }

    { config.sub.value = 1; }

  ];
}