// run-pass pub fn main() { let mut a: Vec<Box<_>> = vec![Box::new(10)]; let b = a.clone(); assert_eq!(*a[0], 10); assert_eq!(*b[0], 10); // This should only modify the value in a, not b *a[0] = 20; assert_eq!(*a[0], 20); assert_eq!(*b[0], 10); }