|  | //@ run-crash | 
|  | //@ compile-flags: -Copt-level=3 -Cdebug-assertions=no -Zub-checks=yes | 
|  | //@ error-pattern: unsafe precondition(s) violated: str::get_unchecked_mut requires | 
|  | //@ revisions: range range_to range_from backwards_range | 
|  |  | 
|  | fn main() { | 
|  | unsafe { | 
|  | let mut s: String = "💅".chars().collect(); | 
|  | let mut s: &mut str = &mut s; | 
|  | #[cfg(range)] | 
|  | s.get_unchecked_mut(4..5); | 
|  | #[cfg(range_to)] | 
|  | s.get_unchecked_mut(..5); | 
|  | #[cfg(range_from)] | 
|  | s.get_unchecked_mut(5..); | 
|  | #[cfg(backwards_range)] | 
|  | s.get_unchecked_mut(1..0); | 
|  | } | 
|  | } |