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
28
29
30
31
32
33
34
35
36
|
//@ check-pass
//@ compile-flags: -Znext-solver
#![feature(rustc_attrs, marker_trait_attr)]
#[rustc_coinductive]
trait Trait {}
impl<T, U> Trait for (T, U)
where
(U, T): Trait,
(T, U): Inductive,
(): ConstrainToU32<T>,
{}
trait ConstrainToU32<T> {}
impl ConstrainToU32<u32> for () {}
// We only prefer the candidate without an inductive cycle
// once the inductive cycle has the same constraints as the
// other goal.
#[marker]
trait Inductive {}
impl<T, U> Inductive for (T, U)
where
(T, U): Trait,
{}
impl Inductive for (u32, u32) {}
fn impls_trait<T, U>()
where
(T, U): Trait,
{}
fn main() {
impls_trait::<_, _>();
}
|
