extern crate indexing; use indexing::scope; fn main() { let arr1 = [1, 2, 3, 4, 5]; // The .first() ptr is not dereferenceable when we don't have a length proof let _a = scope(&arr1[..], |arr| { let r = arr.pointer_range(); println!("{}", &arr[r.first()]); //~ ERROR cannot be indexed by }); }