From 95d27959076836a70f28eb4fef217f93dd040e2d Mon Sep 17 00:00:00 2001
From: Simon Sapin <simon.sapin@exyr.org>
Date: Tue, 19 Feb 2019 13:58:55 +0100
Subject: [PATCH 1/2] Stabilize iter::successors

FCP: https://github.com/rust-lang/rust/issues/58045#issuecomment-464674773
---
 src/libcore/iter/mod.rs     |  4 +++-
 src/libcore/iter/sources.rs | 11 +++++------
 2 files changed, 8 insertions(+), 7 deletions(-)

diff --git a/src/libcore/iter/mod.rs b/src/libcore/iter/mod.rs
index 4e1dc108cc9bd..204c36a757169 100644
--- a/src/libcore/iter/mod.rs
+++ b/src/libcore/iter/mod.rs
@@ -327,7 +327,9 @@ pub use self::sources::{Once, once};
 #[unstable(feature = "iter_once_with", issue = "57581")]
 pub use self::sources::{OnceWith, once_with};
 #[unstable(feature = "iter_unfold", issue = "55977")]
-pub use self::sources::{FromFn, from_fn, Successors, successors};
+pub use self::sources::{FromFn, from_fn};
+#[stable(feature = "iter_successors", since = "1.34.0")]
+pub use self::sources::{Successors, successors};
 
 #[stable(feature = "rust1", since = "1.0.0")]
 pub use self::traits::{FromIterator, IntoIterator, DoubleEndedIterator, Extend};
diff --git a/src/libcore/iter/sources.rs b/src/libcore/iter/sources.rs
index 6f45f082d6a37..359cf24ec57d8 100644
--- a/src/libcore/iter/sources.rs
+++ b/src/libcore/iter/sources.rs
@@ -572,13 +572,12 @@ impl<F> fmt::Debug for FromFn<F> {
 /// and calls the given `FnMut(&T) -> Option<T>` closure to compute each item’s successor.
 ///
 /// ```
-/// #![feature(iter_unfold)]
 /// use std::iter::successors;
 ///
 /// let powers_of_10 = successors(Some(1_u16), |n| n.checked_mul(10));
 /// assert_eq!(powers_of_10.collect::<Vec<_>>(), &[1, 10, 100, 1_000, 10_000]);
 /// ```
-#[unstable(feature = "iter_unfold", issue = "55977")]
+#[stable(feature = "iter_successors", since = "1.34.0")]
 pub fn successors<T, F>(first: Option<T>, succ: F) -> Successors<T, F>
     where F: FnMut(&T) -> Option<T>
 {
@@ -598,13 +597,13 @@ pub fn successors<T, F>(first: Option<T>, succ: F) -> Successors<T, F>
 ///
 /// [`successors`]: fn.successors.html
 #[derive(Clone)]
-#[unstable(feature = "iter_unfold", issue = "55977")]
+#[stable(feature = "iter_successors", since = "1.34.0")]
 pub struct Successors<T, F> {
     next: Option<T>,
     succ: F,
 }
 
-#[unstable(feature = "iter_unfold", issue = "55977")]
+#[stable(feature = "iter_successors", since = "1.34.0")]
 impl<T, F> Iterator for Successors<T, F>
     where F: FnMut(&T) -> Option<T>
 {
@@ -628,12 +627,12 @@ impl<T, F> Iterator for Successors<T, F>
     }
 }
 
-#[unstable(feature = "iter_unfold", issue = "55977")]
+#[stable(feature = "iter_successors", since = "1.34.0")]
 impl<T, F> FusedIterator for Successors<T, F>
     where F: FnMut(&T) -> Option<T>
 {}
 
-#[unstable(feature = "iter_unfold", issue = "55977")]
+#[stable(feature = "iter_successors", since = "1.34.0")]
 impl<T: fmt::Debug, F> fmt::Debug for Successors<T, F> {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         f.debug_struct("Successors")

From 3906cb9187d92a39435086de113ab67b6dd9ba43 Mon Sep 17 00:00:00 2001
From: Simon Sapin <simon.sapin@exyr.org>
Date: Tue, 19 Feb 2019 14:10:07 +0100
Subject: [PATCH 2/2] Stabilize iter::from_fn

FCP: https://github.com/rust-lang/rust/issues/55977#issuecomment-463964234
---
 src/libcore/iter/mod.rs     | 2 +-
 src/libcore/iter/sources.rs | 9 ++++-----
 src/libcore/tests/lib.rs    | 1 -
 3 files changed, 5 insertions(+), 7 deletions(-)

diff --git a/src/libcore/iter/mod.rs b/src/libcore/iter/mod.rs
index 204c36a757169..5dcca7ee0ca01 100644
--- a/src/libcore/iter/mod.rs
+++ b/src/libcore/iter/mod.rs
@@ -326,7 +326,7 @@ pub use self::sources::{Empty, empty};
 pub use self::sources::{Once, once};
 #[unstable(feature = "iter_once_with", issue = "57581")]
 pub use self::sources::{OnceWith, once_with};
-#[unstable(feature = "iter_unfold", issue = "55977")]
+#[stable(feature = "iter_from_fn", since = "1.34.0")]
 pub use self::sources::{FromFn, from_fn};
 #[stable(feature = "iter_successors", since = "1.34.0")]
 pub use self::sources::{Successors, successors};
diff --git a/src/libcore/iter/sources.rs b/src/libcore/iter/sources.rs
index 359cf24ec57d8..74ff7f41d76fa 100644
--- a/src/libcore/iter/sources.rs
+++ b/src/libcore/iter/sources.rs
@@ -514,7 +514,6 @@ pub fn once_with<A, F: FnOnce() -> A>(gen: F) -> OnceWith<F> {
 /// [module-level documentation]: index.html
 ///
 /// ```
-/// #![feature(iter_unfold)]
 /// let mut count = 0;
 /// let counter = std::iter::from_fn(move || {
 ///     // Increment our count. This is why we started at zero.
@@ -530,7 +529,7 @@ pub fn once_with<A, F: FnOnce() -> A>(gen: F) -> OnceWith<F> {
 /// assert_eq!(counter.collect::<Vec<_>>(), &[1, 2, 3, 4, 5]);
 /// ```
 #[inline]
-#[unstable(feature = "iter_unfold", issue = "55977")]
+#[stable(feature = "iter_from_fn", since = "1.34.0")]
 pub fn from_fn<T, F>(f: F) -> FromFn<F>
     where F: FnMut() -> Option<T>
 {
@@ -544,10 +543,10 @@ pub fn from_fn<T, F>(f: F) -> FromFn<F>
 ///
 /// [`iter::from_fn`]: fn.from_fn.html
 #[derive(Clone)]
-#[unstable(feature = "iter_unfold", issue = "55977")]
+#[stable(feature = "iter_from_fn", since = "1.34.0")]
 pub struct FromFn<F>(F);
 
-#[unstable(feature = "iter_unfold", issue = "55977")]
+#[stable(feature = "iter_from_fn", since = "1.34.0")]
 impl<T, F> Iterator for FromFn<F>
     where F: FnMut() -> Option<T>
 {
@@ -559,7 +558,7 @@ impl<T, F> Iterator for FromFn<F>
     }
 }
 
-#[unstable(feature = "iter_unfold", issue = "55977")]
+#[stable(feature = "iter_from_fn", since = "1.34.0")]
 impl<F> fmt::Debug for FromFn<F> {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         f.debug_struct("FromFn").finish()
diff --git a/src/libcore/tests/lib.rs b/src/libcore/tests/lib.rs
index 3e8549f8ae366..4cd734bad90a4 100644
--- a/src/libcore/tests/lib.rs
+++ b/src/libcore/tests/lib.rs
@@ -14,7 +14,6 @@
 #![feature(iter_copied)]
 #![feature(iter_nth_back)]
 #![feature(iter_once_with)]
-#![feature(iter_unfold)]
 #![feature(pattern)]
 #![feature(range_is_empty)]
 #![feature(raw)]