File: variance-covariant-self-trait-match.rs

package info (click to toggle)
rustc 1.88.0%2Bdfsg1-1
  • links: PTS, VCS
  • area: main
  • in suites: forky, sid
  • size: 934,128 kB
  • sloc: xml: 158,127; python: 36,062; javascript: 19,855; sh: 19,700; cpp: 18,947; ansic: 12,993; asm: 4,792; makefile: 690; lisp: 29; perl: 29; ruby: 19; sql: 11
file content (27 lines) | stat: -rw-r--r-- 600 bytes parent folder | download | duplicates (20)
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 `Self` is only used in covariant position, it
// is treated as invariant.

trait Get {
    fn get() -> Self;
}

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

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

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

fn main() { }