인프런 커뮤니티 질문&답변

아래처럼 itemBuilder를 넣어봤는데요,

 Widget build(BuildContext context) {
    return PaginationListView(
        provider: restaurantNotifierProvider, itemBuilder: itemBuilder<RestaurantModel>);
  }

  Widget itemBuilder<T extends IModelWithId>(BuildContext context, int index, T t) {
    t as RestaurantModel;
    return GestureDetector(
      onTap: () {
        Navigator.of(context).push(
          MaterialPageRoute(
            builder: (_) {
              return RestaurantDetailScreen(
                id: t.id,
              );
            },
          ),
        );
      },
      child: RestaurantCard.fromModel(
        restaurantModel: t,
      ),
    );
  }
}

아래와 같은 에러가 나옵니다

type '(BuildContext, int, RestaurantModel) => Widget' is not a subtype of type '(BuildContext, int, IModelWithId) => Widget'

근데, RestaurantModel implements IModelWithId라고 해주었으니 상속관계가 있는데 왜 subtype이 아니라는걸까요?