25 lines
561 B
Rust
25 lines
561 B
Rust
|
// The WF requirements of the *unnormalized* form of type annotations
|
||
|
|
// can guide inference.
|
||
|
|
// check-pass
|
||
|
|
|
||
|
|
pub trait EqualTo {
|
||
|
|
type Ty;
|
||
|
|
}
|
||
|
|
impl<X> EqualTo for X {
|
||
|
|
type Ty = X;
|
||
|
|
}
|
||
|
|
|
||
|
|
trait MyTrait<U: EqualTo<Ty = Self>> {
|
||
|
|
type Out;
|
||
|
|
}
|
||
|
|
impl<T, U: EqualTo<Ty = T>> MyTrait<U> for T {
|
||
|
|
type Out = ();
|
||
|
|
}
|
||
|
|
|
||
|
|
fn main() {
|
||
|
|
let _: <_ as MyTrait<u8>>::Out;
|
||
|
|
// We shoud be able to infer a value for the inference variable above.
|
||
|
|
// The WF of the unnormalized projection requires `u8: EqualTo<Ty = _>`,
|
||
|
|
// which is sufficient to guide inference.
|
||
|
|
}
|