trait Base {
    type Item;
    type Item2;
}

trait Service {
    type R;
    type E;
    type C: Base<Item = Self::R, Item2 = Self::E>;
}

fn create() -> impl Service {
    struct BaseImpl {}
    impl Base for BaseImpl {
        type Item = u64;
        type Item2 = String;
    }

    struct ServiceImpl {}
    impl Service for ServiceImpl {
        type R = u64;
        type E = String;
        type C = BaseImpl;
    }

    ServiceImpl {}
}

fn create_config() -> impl Service {
    let mut srv = create();
    srv
}

struct S1<T: Service> {
    service: T,
}

impl<S: Service> S1<S> {
    fn new() -> Self {
        S1{
            service: create_config()
        }
    }
}

struct S2<T: Service> {
    s1: S1<T>,
}

fn create_s2<S: Service>(s1: S1<S>) -> S2<S>{
    S2{s1}
}

fn main() {
    let s1 = S1::new();
    let s2 = create_s2(s1);
}