use std::marker::PhantomData;

struct Bar<S> {
    phantom: PhantomData<S>,
}

impl<S> Bar<S>
where
    S: Foo,
{
    fn new() -> Self {
        Bar {phantom: PhantomData}
    }

    fn foo_method(&self) {
        S::new().do_stuff();
    }
}

trait Foo {
    fn new() -> Self;
    fn do_stuff(&self);
}

struct FooA<'a> {
    _data: &'a str,
}

impl<'a> Foo for FooA<'a> {
    fn new() -> FooA<'a> {
        FooA {
            _data: "",
        }
    }

    fn do_stuff(&self) {}
}

fn main() {
    Bar::<FooA>::new().foo_method();
}