Is a slice writable through an immutable binding?

Decided

D-0022, settled by the language’s author: part of spec §18. Older text cites it as 18.22.

Neither — writability moves into the type. []T is a read-only view and []mut T a writable one, standing to each other as &T and &mut T do. Following the binding was rejected because a slice is a view, so the binding says nothing about the elements (§5.3)