From b6ea93e46410cccf8d115e57283d1df5968dd0f2 Mon Sep 17 00:00:00 2001
From: kennytm <kennytm@gmail.com>
Date: Sat, 23 Jun 2018 01:42:29 +0800
Subject: [PATCH] Upgrade implementation of StepBy<RangeInclusive<_>>.

---
 src/libcore/iter/mod.rs | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/src/libcore/iter/mod.rs b/src/libcore/iter/mod.rs
index 86b297557dd..32134783516 100644
--- a/src/libcore/iter/mod.rs
+++ b/src/libcore/iter/mod.rs
@@ -787,17 +787,19 @@ impl<T> StepBySpecIterator for StepBy<ops::RangeInclusive<T>>
     #[inline]
     fn spec_next(&mut self) -> Option<Self::Item> {
         self.first_take = false;
-        if !(self.iter.start <= self.iter.end) {
+        if self.iter.is_empty() {
+            self.iter.is_iterating = Some(false);
             return None;
         }
         // add 1 to self.step to get original step size back
         // it was decremented for the general case on construction
         if let Some(n) = self.iter.start.add_usize(self.step+1) {
+            self.iter.is_iterating = Some(n <= self.iter.end);
             let next = mem::replace(&mut self.iter.start, n);
             Some(next)
         } else {
-            let last = self.iter.start.replace_one();
-            self.iter.end.replace_zero();
+            let last = self.iter.start.clone();
+            self.iter.is_iterating = Some(false);
             Some(last)
         }
     }
-- 
2.44.0