diff options
| -rw-r--r-- | src/libcore/iter/traits.rs | 5 |
1 files changed, 4 insertions, 1 deletions
diff --git a/src/libcore/iter/traits.rs b/src/libcore/iter/traits.rs index 25406696620..1e127148300 100644 --- a/src/libcore/iter/traits.rs +++ b/src/libcore/iter/traits.rs @@ -260,7 +260,10 @@ impl<I: Iterator> IntoIterator for I { /// /// Iterators produce a series of values, and collections can also be thought /// of as a series of values. The `Extend` trait bridges this gap, allowing you -/// to extend a collection by including the contents of that iterator. +/// to extend a collection by including the contents of that iterator. When +/// extending a collection with an already existing key, that entry is updated +/// or, in the case of collections that permit multiple entries with equal +/// keys, that entry is inserted. /// /// # Examples /// |