LL | foo((), drop)
| ^^^^
| |
- | expected signature of `fn(<() as Trait<'a>>::Item) -> _`
+ | expected signature of `for<'a> fn(<() as Trait<'a>>::Item) -> _`
| found signature of `fn(()) -> _`
error[E0277]: the size for values of type `<() as Trait<'_>>::Item` cannot be known at compilation time