core: Add feature gate to rfold example code

1 files changed, 2 insertions, 0 deletions

diff --git a/src/libcore/iter/traits.rs b/src/libcore/iter/traits.rs
index 85df8a669d1..bf74ed826bf 100644
--- a/src/libcore/iter/traits.rs
+++ b/src/libcore/iter/traits.rs
@@ -426,6 +426,7 @@ pub trait DoubleEndedIterator: Iterator {
     /// Basic usage:
     ///
     /// ```
+    /// #![feature(iter_rfold)]
     /// let a = [1, 2, 3];
     ///
     /// // the sum of all of the elements of a
@@ -439,6 +440,7 @@ pub trait DoubleEndedIterator: Iterator {
     /// and continuing with each element from the back until the front:
     ///
     /// ```
+    /// #![feature(iter_rfold)]
     /// let numbers = [1, 2, 3, 4, 5];
     ///
     /// let zero = "0".to_string();