Use a canonical name for extend_reserve(additional)

Co-authored-by: David Tolnay <dtolnay@gmail.com>

diff --git a/src/libcore/iter/traits/collect.rs b/src/libcore/iter/traits/collect.rs
index da859db545d7ec5f74ec73a043fc15a2c1efeb74..4a90aca148547b81b6003989dfbdcd6c7cb1e361 100644 (file)
--- a/src/libcore/iter/traits/collect.rs
+++ b/src/libcore/iter/traits/collect.rs
@@ -352,7 +352,9 @@ fn extend_one(&mut self, item: A) {
     ///
     /// The default implementation does nothing.
     #[unstable(feature = "extend_one", issue = "none")]
-    fn extend_reserve(&mut self, _additional: usize) {}
+    fn extend_reserve(&mut self, additional: usize) {
+        let _ = additional;
+    }
 }
 
 #[stable(feature = "extend_for_unit", since = "1.28.0")]