diff options
| -rw-r--r-- | library/alloc/src/collections/btree/map.rs | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/library/alloc/src/collections/btree/map.rs b/library/alloc/src/collections/btree/map.rs index ee0f525fb15..4ca93a4eb83 100644 --- a/library/alloc/src/collections/btree/map.rs +++ b/library/alloc/src/collections/btree/map.rs @@ -1748,6 +1748,10 @@ impl<'a, K: 'a, V: 'a> DrainFilterInner<'a, K, V> { /// Implementation of a typical `DrainFilter::size_hint` method. pub(super) fn size_hint(&self) -> (usize, Option<usize>) { + // In most of the btree iterators, `self.length` is the number of elements + // yet to be visited. Here, it includes elements that were visited and that + // the predicate decided not to drain. Making this upper bound more accurate + // requires maintaining an extra field and is not worth while. (0, Some(*self.length)) } } |