1 #![feature(type_alias_impl_trait)] 2 #![feature(generic_associated_types)] 3 4 // See https://github.com/rust-lang/rust/issues/87258#issuecomment-883293367 5 6 trait Trait1 {} 7 8 struct Struct<'b>(&'b ()); 9 10 impl<'d> Trait1 for Struct<'d> {} 11 12 pub trait Trait2 { 13 type FooFuture<'a>: Trait1; foo<'a>() -> Self::FooFuture<'a>14 fn foo<'a>() -> Self::FooFuture<'a>; 15 } 16 17 impl<'c, S: Trait2> Trait2 for &'c mut S { 18 type FooFuture<'a> = impl Trait1; 19 fn foo<'a>() -> Self::FooFuture<'a> { //~ ERROR 20 Struct(unimplemented!()) 21 } 22 } 23 main()24fn main() {} 25