Incomplete type inference: type annotations needed

[Veykril]

struct LocalClient(*const ());
trait AmbiguousIfSend<A> {
    fn some_item() {}
}
impl<T: ?Sized> AmbiguousIfSend<()> for T {}
impl<T: ?Sized + Send> AmbiguousIfSend<u8> for T {}
fn _assert_not_send() {
    <LocalClient as AmbiguousIfSend<_>>::some_item();
//                                  ^
// type annotations needed
// full type: fn some_item<LocalClient, {unknown}>()
// (rust-analyzer E0282)
}

[ChayimFriedman2]

That's because we don't implement auto traits correctly - we don't inspect the fields because it was deemed too expensive. As long as this does not change we cannot fix this.

[Veykril]

I forgot did we check the perf impact after we moved to the new trait solver? 🤔

[ChayimFriedman2]

I think yes, not sure.