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//@ check-pass
pub trait FirstTrait {
type Item;
type Extra: Extra<(), Error = Self::Item>;
}
trait SecondTrait {
type Item2;
}
trait ThirdTrait: SecondTrait {
type Item3;
}
trait FourthTrait {
type Item4;
}
impl<First> SecondTrait for First
where
First: FirstTrait,
{
type Item2 = First::Extra;
}
impl<Second, T> ThirdTrait for Second
where
Second: SecondTrait<Item2 = T>,
{
type Item3 = T;
}
impl<S, Third: ?Sized> FourthTrait for Third
where
Third: ThirdTrait<Item3 = S>,
{
type Item4 = S;
}
pub trait Extra<Request> {
type Error;
}
struct ImplShoulExist<D, Req> {
_gen: (D, Req),
}
impl<D, Req> ImplShoulExist<D, Req>
where
D: FourthTrait,
D::Item4: Extra<Req>,
<D::Item4 as Extra<Req>>::Error: Into<()>,
{
fn access_fn(_: D) {
todo!()
}
}
impl<D, Req> Extra<Req> for ImplShoulExist<D, Req> {
type Error = ();
}
pub fn broken<MS>(ms: MS)
where
MS: FirstTrait,
MS::Item: Into<()>,
{
// Error: Apparently Balance::new doesn't exist during MIR validation
ImplShoulExist::<MS, ()>::access_fn(ms);
}
fn main() {}
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