I have owned and borrowed versions of a struct: the owned one has a Vec field, the borrowed one has a slice field. It looks like Foo<'a> and OwnedFoo. Is there a way to impl Deref here? (The problem is that there is no 'a in Deref).

My gut feeling is "No because OwnedFoo is not a smart pointer to a Foo" I'd probably lean toward an `impl AsRef<[_]> for OwnedFoo` or else a `pub fn borrow(&self) -> Foo<'_>` Deref requires that the implementing type "contain" the target.