Steven Sheldon

Convert a slice of Ids to references at zero-cost

1

There used to be an `IdSlice` trait for doing this, but it was removed in SSheldon/rust-objc@4118e96. This isn't possible until rust-lang/rust#5016 is completed, because until then an `Id` is a...

Since `Id`s will never be null, the representation of `Option` can take advantage of this to be the same size as an `Id`. Doing this requires the `NonZero` struct, which...