tests/ui/variance/variance-covariant-arg-object.rs


1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27

#![allow(dead_code)]

// Test that even when `T` is only used in covariant position, it
// is treated as invariant.

trait Get<T> : 'static {
    fn get(&self) -> T;
}

fn get_min_from_max<'min, 'max>(v: Box<dyn Get<&'max i32>>)
                                -> Box<dyn Get<&'min i32>>
    where 'max : 'min
{
    // Previously OK, now an error as traits are invariant.
    v
    //~^ ERROR lifetime may not live long enough
}

fn get_max_from_min<'min, 'max>(v: Box<dyn Get<&'min i32>>)
                                -> Box<dyn Get<&'max i32>>
    where 'max : 'min
{
    v
    //~^ ERROR lifetime may not live long enough
}

fn main() { }