From 00d9db14f74c6b4d532547f7acf38b3538574958 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Martin=20Habov=C5=A1tiak?= <martin.habovstiak@gmail.com>
Date: Thu, 3 Oct 2019 10:09:04 +0200
Subject: [PATCH] Added doc about behavior of extend on HashMap

It was unclear what the implementation does when it encounters existing keys. This change makes it clear by documenting the trait impl.
---
 src/libstd/collections/hash/map.rs | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/libstd/collections/hash/map.rs b/src/libstd/collections/hash/map.rs
index ff50051ef5040..c9596dc05bbf5 100644
--- a/src/libstd/collections/hash/map.rs
+++ b/src/libstd/collections/hash/map.rs
@@ -2362,6 +2362,8 @@ where
     }
 }
 
+/// Inserts all new key-values from the iterator and replaces values with existing
+/// keys with new values returned from the iterator.
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<K, V, S> Extend<(K, V)> for HashMap<K, V, S>
 where