VecDeque::insert requires feature
collections, even though
VecDeque as a whole and most of its methods are marked as stable. Is there a reason for this, or is it just an oversight? The same is true of
shrink_to_fit as well.
Well, it’s definitely a bug that they require the “collections” feature… see https://github.com/rust-lang/rust/pull/28146 .
Some of the methods are newer features than the others. They simply need some time to stabilize.