//@ run-rustfix use std::ops::Index; struct X; impl Index for X { type Output = (); fn index(&self, _: i32) -> &() { &() } } fn main() { let x = vec![1, 2, 3]; x[x.len() -1]; //~ ERROR negative integers cannot be used to index on a let x = [1, 2, 3]; x[x.len() -1]; //~ ERROR negative integers cannot be used to index on a let x = &[1, 2, 3]; x[x.len() -1]; //~ ERROR negative integers cannot be used to index on a let _ = x; X[-1]; }