From f0483f76e6feb256abffb060029f57e09c6d4dc0 Mon Sep 17 00:00:00 2001
From: Shotaro Yamada <sinkuu@sinkuu.xyz>
Date: Mon, 17 Dec 2018 09:35:28 +0900
Subject: [PATCH] Remove `<Cycle as Iterator>::try_fold` override

It was a incorrect optimization.
---
 src/libcore/iter/mod.rs   | 13 -------------
 src/libcore/tests/iter.rs |  2 ++
 2 files changed, 2 insertions(+), 13 deletions(-)

diff --git a/src/libcore/iter/mod.rs b/src/libcore/iter/mod.rs
index 7b273f7862a..aa23d49672a 100644
--- a/src/libcore/iter/mod.rs
+++ b/src/libcore/iter/mod.rs
@@ -649,19 +649,6 @@ fn size_hint(&self) -> (usize, Option<usize>) {
             _ => (usize::MAX, None)
         }
     }
-
-    #[inline]
-    fn try_fold<Acc, F, R>(&mut self, init: Acc, mut f: F) -> R where
-        Self: Sized, F: FnMut(Acc, Self::Item) -> R, R: Try<Ok=Acc>
-    {
-        let mut accum = init;
-        while let Some(x) = self.iter.next() {
-            accum = f(accum, x)?;
-            accum = self.iter.try_fold(accum, &mut f)?;
-            self.iter = self.orig.clone();
-        }
-        Try::from_ok(accum)
-    }
 }
 
 #[stable(feature = "fused", since = "1.26.0")]
diff --git a/src/libcore/tests/iter.rs b/src/libcore/tests/iter.rs
index 4efa0136314..00b4aa4fa2d 100644
--- a/src/libcore/tests/iter.rs
+++ b/src/libcore/tests/iter.rs
@@ -1003,6 +1003,8 @@ fn test_cycle() {
     assert_eq!(it.next(), None);
 
     assert_eq!(empty::<i32>().cycle().fold(0, |acc, x| acc + x), 0);
+
+    assert_eq!(once(1).cycle().skip(1).take(4).fold(0, |acc, x| acc + x), 4);
 }
 
 #[test]