#![allow(dead_code, deprecated, unused_variables, unused_mut)]
use std::borrow::BorrowMut;
fn check<T: BorrowMut<[i32]>>(mut v: T) {
    assert_eq!(& mut [1, 2, 3], v.borrow_mut());
}
fn main() {
    let v = vec![1, 2, 3];
    check(v);
}