#![allow(dead_code, deprecated, unused_variables, unused_mut)]
fn main() {
    let s: &str = "123";
    unsafe {
        let end: *const u8 = s.as_ptr().add(3);
        assert_eq!('3', * end.sub(1) as char);
        assert_eq!('2', * end.sub(2) as char);
    }
}