IntoIterator::IntoIter docs show incomplete trait bounds

[chris-morgan]

Refer to the std::iter::IntoIterator docs (and the problem is also visible on nightly).

It shows in both the declaration code and under the “Associated Types” heading: _{(sans semicolon in the latter)}

type IntoIter: Iterator;

This is lacking a crucial part of the bound, the Item associated type. The source shows this:

type IntoIter: Iterator<Item = Self::Item>;

---

I’m confused about what’s going on here because my attempts at duplicating it are unsuccessful on both stable and nightly: when I compile the docs for just this code:

pub trait IntoIterator {
    type Item;
    type IntoIter: Iterator<Item = Self::Item>;
    fn into_iter(self) -> Self::IntoIter;
}

I see Iterator<Item = Self::Item> as expected, not Iterator as in the std docs. Hence my titling this bug about IntoIterator::IntoIter, rather than about associated types or whatnot, because I can’t reproduce it elsewhere.

[chris-morgan]

I just checked on old docs. Until 1.48.0, it looks like rustdoc translated that associated type bound to where <Self::IntoIter as Iterator>::Item == Self::Item in the declaration (or similar; back in 1.0.0 it was where Self::IntoIter::Item == Self::Item), but in 1.49 even that vanished.

No idea why it would be translating that associated type bound, especially since non-std docs aren’t doing it.

Haaaaaang on, core isn’t exhibiting this wonkiness either, core::iter::IntoIterator is correct (and never exhibited the translation into a where clause).

So I guess it’s something peculiar to std.

[veber-alex]

duplicate of #84579

[chris-morgan]

Ah hah, good find; thanks.