src/test/ui/variance/variance-covariant-arg-trait-match.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> {
    fn get(&self) -> T;
}

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

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

fn impls_get<G,T>() where G : Get<T> { }

fn main() { }