// check-pass #![feature(specialization)] //~^ WARN the feature `specialization` is incomplete fn main() {} pub trait Alpha<T> { } pub trait Beta { type Event; } pub trait Delta { type Handle; fn process(&self); } pub struct Parent<A, T>(A, T); impl<A, T> Delta for Parent<A, T> where A: Alpha<T::Handle>, T: Delta, T::Handle: Beta<Event = <Handle as Beta>::Event> { type Handle = Handle; default fn process(&self) { unimplemented!() } } impl<A, T> Delta for Parent<A, T> where A: Alpha<T::Handle> + Alpha<Handle>, T: Delta, T::Handle: Beta<Event = <Handle as Beta>::Event> { fn process(&self) { unimplemented!() } } pub struct Handle; impl Beta for Handle { type Event = (); }