// run-pass fn main() { let x = X(15); let y = x.foo(); println!("{:?}",y); } trait Foo where for<'a> &'a Self: Bar { fn foo<'a>(&'a self) -> <&'a Self as Bar>::Output; } trait Bar { type Output; } struct X(i32); impl<'a> Bar for &'a X { type Output = &'a i32; } impl Foo for X { fn foo<'a>(&'a self) -> <&'a Self as Bar>::Output { &self.0 } }