Auto merge of #50234 - cramertj:extend, r=alexcrichton

Add implementation of Extend for ()

This is useful in some generic code which wants to collect iterators of items into a result.

1 files changed, 7 insertions, 0 deletions

diff --git a/src/libcore/iter/traits.rs b/src/libcore/iter/traits.rs
index 173dfc36f04..1551429557f 100644
--- a/src/libcore/iter/traits.rs
+++ b/src/libcore/iter/traits.rs
@@ -352,6 +352,13 @@ pub trait Extend<A> {
     fn extend<T: IntoIterator<Item=A>>(&mut self, iter: T);
 }
 
+#[stable(feature = "extend_for_unit", since = "1.28.0")]
+impl Extend<()> for () {
+    fn extend<T: IntoIterator<Item = ()>>(&mut self, iter: T) {
+        iter.into_iter().for_each(drop)
+    }
+}
+
 /// An iterator able to yield elements from both ends.
 ///
 /// Something that implements `DoubleEndedIterator` has one extra capability