fn example2(x: &i32, f: impl FnOnce(&i32)) -> i32 {
  let val = *x / 3;
  f(x);
  return *x / 3; // We want to optimize this to return `val`.
}

fn main() {
  let mut local = 6;
  let x = &local;
  let result = example2(x, |inner_x| {
    let raw_pointer = inner_x as *const i32 as *mut i32;
    unsafe { *raw_pointer = 15; }
  });
  println!("{}", result); // Prints "5" (aka 15/3).
}