Then I misunderstood you, but now you have driven a fence between types that can be converted to iterators and types that implement IntoIterator. The purpose of

Then I misunderstood you, but now you have driven a fence between types that can be converted to iterators and types that implement IntoIterator. The purpose of IntoIterator is to describe a type that can be converted into an iterator; deliberately not implementing it for types that can, just so that there's no confusion for someone calling into_iter on a reference, does not seem like a net positive. I doubt anyone would have ever complained about references implementing IntoIterator if arrays had just implemented it from the start. Like I said, the only problem that's been brought up doesn't need a solution other than the one that's already been implemented.