// check-pass #![feature(type_alias_impl_trait)] pub trait Trait { type A; fn f() -> Self::A; } pub trait Tr2<'a, 'b> {} pub struct A<T>(T); pub trait Tr { type B; } impl<'a, 'b, T: Tr<B = dyn Tr2<'a, 'b>>> Trait for A<T> { type A = impl core::fmt::Debug; fn f() -> Self::A {} } fn main() {}