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// build-pass
#![allow(incomplete_features)]
#![feature(generic_const_exprs)]
use std::marker::PhantomData;
fn main() {
let x = FooImpl::<BarImpl<1>> { phantom: PhantomData };
let _ = x.foo::<BarImpl<1>>();
}
trait Foo<T>
where
T: Bar,
{
fn foo<U>(&self)
where
T: Operation<U>,
<T as Operation<U>>::Output: Bar;
}
struct FooImpl<T>
where
T: Bar,
{
phantom: PhantomData<T>,
}
impl<T> Foo<T> for FooImpl<T>
where
T: Bar,
{
fn foo<U>(&self)
where
T: Operation<U>,
<T as Operation<U>>::Output: Bar,
{
<<T as Operation<U>>::Output as Bar>::error_occurs_here();
}
}
trait Bar {
fn error_occurs_here();
}
struct BarImpl<const N: usize>;
impl<const N: usize> Bar for BarImpl<N> {
fn error_occurs_here() {}
}
trait Operation<Rhs> {
type Output;
}
//// Part-A: This causes error.
impl<const M: usize, const N: usize> Operation<BarImpl<M>> for BarImpl<N>
where
BarImpl<{ N + M }>: Sized,
{
type Output = BarImpl<{ N + M }>;
}
//// Part-B: This doesn't cause error.
// impl<const M: usize, const N: usize> Operation<BarImpl<M>> for BarImpl<N> {
// type Output = BarImpl<M>;
// }
//// Part-C: This also doesn't cause error.
// impl<const M: usize, const N: usize> Operation<BarImpl<M>> for BarImpl<N> {
// type Output = BarImpl<{ M }>;
// }
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