impl<I: DoubleEndedIterator, U, F> DoubleEndedIterator for FlatMap<I, U, F>
where
F: FnMut(I::Item) -> U,
- U: IntoIterator,
- U::IntoIter: DoubleEndedIterator,
+ U: IntoIterator<IntoIter: DoubleEndedIterator>,
{
#[inline]
fn next_back(&mut self) -> Option<U::Item> { self.inner.next_back() }
/// [`Iterator`]: trait.Iterator.html
#[must_use = "iterators are lazy and do nothing unless consumed"]
#[stable(feature = "iterator_flatten", since = "1.29.0")]
-pub struct Flatten<I: Iterator>
-where
- I::Item: IntoIterator,
-{
+pub struct Flatten<I: Iterator<Item: IntoIterator>> {
inner: FlattenCompat<I, <I::Item as IntoIterator>::IntoIter>,
}