#![feature(existential_type)]
#![feature(impl_trait_in_bindings)]

existential type T: Tr;

trait Tr {}

struct S<M> {
  m : M
}

impl<M> S<M> {
    fn new(m: M) -> Self {
        S { m }
    }
}

impl<M> Tr for S<M> {}

pub fn new<F, M>(f: F) -> T
where F: FnOnce() -> S<M>
{
    f()
}

pub fn new2<M>(m: M) -> impl Tr {
    S::new(m)
}

fn main() {
    println!("Hello, world!");
}