From 87941b079ab29a3831c659bf467d7fb87d347c36 Mon Sep 17 00:00:00 2001
From: Thayne McCombs <astrothayne@gmail.com>
Date: Tue, 29 May 2018 23:30:16 -0600
Subject: [PATCH] Stabilize iterator_repeat_with

Fixes #48169
---
 src/libcore/iter/mod.rs     |  2 +-
 src/libcore/iter/sources.rs | 26 +++++++-------------------
 src/libcore/lib.rs          |  1 -
 src/libcore/tests/iter.rs   | 12 ------------
 src/libcore/tests/lib.rs    |  1 -
 5 files changed, 8 insertions(+), 34 deletions(-)

diff --git a/src/libcore/iter/mod.rs b/src/libcore/iter/mod.rs
index 1e8476d3880..f313f0d9147 100644
--- a/src/libcore/iter/mod.rs
+++ b/src/libcore/iter/mod.rs
@@ -333,7 +333,7 @@ pub use self::range::Step;
 
 #[stable(feature = "rust1", since = "1.0.0")]
 pub use self::sources::{Repeat, repeat};
-#[unstable(feature = "iterator_repeat_with", issue = "48169")]
+#[stable(feature = "iterator_repeat_with", since = "1.28.0")]
 pub use self::sources::{RepeatWith, repeat_with};
 #[stable(feature = "iter_empty", since = "1.2.0")]
 pub use self::sources::{Empty, empty};
diff --git a/src/libcore/iter/sources.rs b/src/libcore/iter/sources.rs
index 0fc1a3aa8ac..d500cc99fa1 100644
--- a/src/libcore/iter/sources.rs
+++ b/src/libcore/iter/sources.rs
@@ -113,12 +113,12 @@ pub fn repeat<T: Clone>(elt: T) -> Repeat<T> {
 ///
 /// [`repeat_with`]: fn.repeat_with.html
 #[derive(Copy, Clone, Debug)]
-#[unstable(feature = "iterator_repeat_with", issue = "48169")]
+#[stable(feature = "iterator_repeat_with", since = "1.28.0")]
 pub struct RepeatWith<F> {
     repeater: F
 }
 
-#[unstable(feature = "iterator_repeat_with", issue = "48169")]
+#[stable(feature = "iterator_repeat_with", since = "1.28.0")]
 impl<A, F: FnMut() -> A> Iterator for RepeatWith<F> {
     type Item = A;
 
@@ -129,13 +129,7 @@ impl<A, F: FnMut() -> A> Iterator for RepeatWith<F> {
     fn size_hint(&self) -> (usize, Option<usize>) { (usize::MAX, None) }
 }
 
-#[unstable(feature = "iterator_repeat_with", issue = "48169")]
-impl<A, F: FnMut() -> A> DoubleEndedIterator for RepeatWith<F> {
-    #[inline]
-    fn next_back(&mut self) -> Option<A> { self.next() }
-}
-
-#[unstable(feature = "iterator_repeat_with", issue = "48169")]
+#[stable(feature = "iterator_repeat_with", since = "1.28.0")]
 impl<A, F: FnMut() -> A> FusedIterator for RepeatWith<F> {}
 
 #[unstable(feature = "trusted_len", issue = "37572")]
@@ -158,19 +152,15 @@ unsafe impl<A, F: FnMut() -> A> TrustedLen for RepeatWith<F> {}
 ///
 /// [`repeat`]: fn.repeat.html
 ///
-/// An iterator produced by `repeat_with()` is a `DoubleEndedIterator`.
-/// It is important to note that reversing `repeat_with(f)` will produce
-/// the exact same sequence as the non-reversed iterator. In other words,
-/// `repeat_with(f).rev().collect::<Vec<_>>()` is equivalent to
-/// `repeat_with(f).collect::<Vec<_>>()`.
+/// An iterator produced by `repeat_with()` is not a `DoubleEndedIterator`.
+/// If you need `repeat_with()` to return a `DoubleEndedIterator`,
+/// please open a GitHub issue explaining your use case.
 ///
 /// # Examples
 ///
 /// Basic usage:
 ///
 /// ```
-/// #![feature(iterator_repeat_with)]
-///
 /// use std::iter;
 ///
 /// // let's assume we have some value of a type that is not `Clone`
@@ -191,8 +181,6 @@ unsafe impl<A, F: FnMut() -> A> TrustedLen for RepeatWith<F> {}
 /// Using mutation and going finite:
 ///
 /// ```rust
-/// #![feature(iterator_repeat_with)]
-///
 /// use std::iter;
 ///
 /// // From the zeroth to the third power of two:
@@ -209,7 +197,7 @@ unsafe impl<A, F: FnMut() -> A> TrustedLen for RepeatWith<F> {}
 /// assert_eq!(None, pow2.next());
 /// ```
 #[inline]
-#[unstable(feature = "iterator_repeat_with", issue = "48169")]
+#[stable(feature = "iterator_repeat_with", since = "1.28.0")]
 pub fn repeat_with<A, F: FnMut() -> A>(repeater: F) -> RepeatWith<F> {
     RepeatWith { repeater }
 }
diff --git a/src/libcore/lib.rs b/src/libcore/lib.rs
index 32cf31231c3..ce86f469695 100644
--- a/src/libcore/lib.rs
+++ b/src/libcore/lib.rs
@@ -89,7 +89,6 @@
 #![feature(fundamental)]
 #![feature(intrinsics)]
 #![feature(iterator_flatten)]
-#![feature(iterator_repeat_with)]
 #![feature(lang_items)]
 #![feature(link_llvm_intrinsics)]
 #![feature(never_type)]
diff --git a/src/libcore/tests/iter.rs b/src/libcore/tests/iter.rs
index 2abac0cf1d5..9b8d7031f8e 100644
--- a/src/libcore/tests/iter.rs
+++ b/src/libcore/tests/iter.rs
@@ -1722,18 +1722,6 @@ fn test_repeat_with() {
     assert_eq!(repeat_with(|| NotClone(42)).size_hint(), (usize::MAX, None));
 }
 
-#[test]
-fn test_repeat_with_rev() {
-    let mut curr = 1;
-    let mut pow2 = repeat_with(|| { let tmp = curr; curr *= 2; tmp })
-                    .rev().take(4);
-    assert_eq!(pow2.next(), Some(1));
-    assert_eq!(pow2.next(), Some(2));
-    assert_eq!(pow2.next(), Some(4));
-    assert_eq!(pow2.next(), Some(8));
-    assert_eq!(pow2.next(), None);
-}
-
 #[test]
 fn test_repeat_with_take() {
     let mut it = repeat_with(|| 42).take(3);
diff --git a/src/libcore/tests/lib.rs b/src/libcore/tests/lib.rs
index 13189d532ab..b17c240f0eb 100644
--- a/src/libcore/tests/lib.rs
+++ b/src/libcore/tests/lib.rs
@@ -25,7 +25,6 @@
 #![feature(hashmap_internals)]
 #![feature(iterator_step_by)]
 #![feature(iterator_flatten)]
-#![feature(iterator_repeat_with)]
 #![feature(pattern)]
 #![feature(range_is_empty)]
 #![feature(raw)]