// core::iter
impl<I: ~const Iterator + ?Sized> const Iterator for &mut I;
impl<I: Iterator> const IntoIterator for I;
impl<B, I: ~const Iterator, F> const Iterator for Map<I, F>
where
    F: ~const FnMut(I::Item) -> B + ~const Drop;

// core::option
impl<T> Option<T> {
    pub const fn iter_mut(&mut self) -> IterMut<'_, T>;
}

impl<T> const IntoIterator for Option<T>;
impl<'a, T> const IntoIterator for &'a Option<T>;
impl<'a, T> const IntoIterator for &'a mut Option<T>;
impl<'a, A> const Iterator for Iter<'a, A>;
impl<'a, A> const Iterator for IterMut<'a, A>;
impl<A> const Iterator for IntoIter<A>;