Why are nested associated type paths considered ambiguous?
fn flatten<I>(iter: I) -> Option<I::Item::Item>
where
I: Iterator,
I::Item: IntoIterator,
{
None
}
error[E0223]: ambiguous associated type
--> src/lib.rs:1:34
|
1 | fn flatten<I>(iter: I) -> Option<I::Item::Item>
| ^^^^^^^^^^^^^ help: use fully-qualified syntax: `<<I as Iterator>::Item as Trait>::Item`
Shouldn't the compiler be able to resolve the path without fully-qualified syntax? There is only one type I could be referring to, so I don't see why it is ambiguous. Is this a limitation of the compiler or is it intended behavior?