From 85796dd0bad3486f52e3ff9ecb0db6f52d3c460f Mon Sep 17 00:00:00 2001
From: Mazdak Farrokhzad <twingoow@gmail.com>
Date: Mon, 11 Jun 2018 23:10:51 +0200
Subject: [PATCH] stabilize Iterator::flatten in 1.29, fixes #48115.

---
 src/libcore/iter/iterator.rs |  8 +-------
 src/libcore/iter/mod.rs      | 12 ++++++------
 src/libcore/lib.rs           |  1 -
 src/libcore/tests/lib.rs     |  1 -
 4 files changed, 7 insertions(+), 15 deletions(-)

diff --git a/src/libcore/iter/iterator.rs b/src/libcore/iter/iterator.rs
index 1972b0099053e..102e46dc0f48a 100644
--- a/src/libcore/iter/iterator.rs
+++ b/src/libcore/iter/iterator.rs
@@ -1036,8 +1036,6 @@ pub trait Iterator {
     /// Basic usage:
     ///
     /// ```
-    /// #![feature(iterator_flatten)]
-    ///
     /// let data = vec![vec![1, 2, 3, 4], vec![5, 6]];
     /// let flattened = data.into_iter().flatten().collect::<Vec<u8>>();
     /// assert_eq!(flattened, &[1, 2, 3, 4, 5, 6]);
@@ -1046,8 +1044,6 @@ pub trait Iterator {
     /// Mapping and then flattening:
     ///
     /// ```
-    /// #![feature(iterator_flatten)]
-    ///
     /// let words = ["alpha", "beta", "gamma"];
     ///
     /// // chars() returns an iterator
@@ -1074,8 +1070,6 @@ pub trait Iterator {
     /// Flattening once only removes one level of nesting:
     ///
     /// ```
-    /// #![feature(iterator_flatten)]
-    ///
     /// let d3 = [[[1, 2], [3, 4]], [[5, 6], [7, 8]]];
     ///
     /// let d2 = d3.iter().flatten().collect::<Vec<_>>();
@@ -1093,7 +1087,7 @@ pub trait Iterator {
     ///
     /// [`flat_map()`]: #method.flat_map
     #[inline]
-    #[unstable(feature = "iterator_flatten", issue = "48213")]
+    #[stable(feature = "iterator_flatten", since = "1.29")]
     fn flatten(self) -> Flatten<Self>
     where Self: Sized, Self::Item: IntoIterator {
         Flatten { inner: flatten_compat(self) }
diff --git a/src/libcore/iter/mod.rs b/src/libcore/iter/mod.rs
index f152ee73b6996..9ab3b786e9218 100644
--- a/src/libcore/iter/mod.rs
+++ b/src/libcore/iter/mod.rs
@@ -2524,13 +2524,13 @@ impl<I, U, F> FusedIterator for FlatMap<I, U, F>
 /// [`flatten`]: trait.Iterator.html#method.flatten
 /// [`Iterator`]: trait.Iterator.html
 #[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
-#[unstable(feature = "iterator_flatten", issue = "48213")]
+#[stable(feature = "iterator_flatten", since = "1.29")]
 pub struct Flatten<I: Iterator>
 where I::Item: IntoIterator {
     inner: FlattenCompat<I, <I::Item as IntoIterator>::IntoIter>,
 }
 
-#[unstable(feature = "iterator_flatten", issue = "48213")]
+#[stable(feature = "iterator_flatten", since = "1.29")]
 impl<I, U> fmt::Debug for Flatten<I>
     where I: Iterator + fmt::Debug, U: Iterator + fmt::Debug,
           I::Item: IntoIterator<IntoIter = U, Item = U::Item>,
@@ -2540,7 +2540,7 @@ impl<I, U> fmt::Debug for Flatten<I>
     }
 }
 
-#[unstable(feature = "iterator_flatten", issue = "48213")]
+#[stable(feature = "iterator_flatten", since = "1.29")]
 impl<I, U> Clone for Flatten<I>
     where I: Iterator + Clone, U: Iterator + Clone,
           I::Item: IntoIterator<IntoIter = U, Item = U::Item>,
@@ -2548,7 +2548,7 @@ impl<I, U> Clone for Flatten<I>
     fn clone(&self) -> Self { Flatten { inner: self.inner.clone() } }
 }
 
-#[unstable(feature = "iterator_flatten", issue = "48213")]
+#[stable(feature = "iterator_flatten", since = "1.29")]
 impl<I, U> Iterator for Flatten<I>
     where I: Iterator, U: Iterator,
           I::Item: IntoIterator<IntoIter = U, Item = U::Item>
@@ -2576,7 +2576,7 @@ impl<I, U> Iterator for Flatten<I>
     }
 }
 
-#[unstable(feature = "iterator_flatten", issue = "48213")]
+#[stable(feature = "iterator_flatten", since = "1.29")]
 impl<I, U> DoubleEndedIterator for Flatten<I>
     where I: DoubleEndedIterator, U: DoubleEndedIterator,
           I::Item: IntoIterator<IntoIter = U, Item = U::Item>
@@ -2599,7 +2599,7 @@ impl<I, U> DoubleEndedIterator for Flatten<I>
     }
 }
 
-#[unstable(feature = "iterator_flatten", issue = "48213")]
+#[stable(feature = "iterator_flatten", since = "1.29")]
 impl<I, U> FusedIterator for Flatten<I>
     where I: FusedIterator, U: Iterator,
           I::Item: IntoIterator<IntoIter = U, Item = U::Item> {}
diff --git a/src/libcore/lib.rs b/src/libcore/lib.rs
index a2ee0033872d3..4edfb06944ba9 100644
--- a/src/libcore/lib.rs
+++ b/src/libcore/lib.rs
@@ -89,7 +89,6 @@
 #![feature(extern_types)]
 #![feature(fundamental)]
 #![feature(intrinsics)]
-#![feature(iterator_flatten)]
 #![feature(lang_items)]
 #![feature(link_llvm_intrinsics)]
 #![feature(never_type)]
diff --git a/src/libcore/tests/lib.rs b/src/libcore/tests/lib.rs
index 11765e3ef56ee..4c8f72010a2d2 100644
--- a/src/libcore/tests/lib.rs
+++ b/src/libcore/tests/lib.rs
@@ -23,7 +23,6 @@
 #![feature(flt2dec)]
 #![feature(fmt_internals)]
 #![feature(hashmap_internals)]
-#![feature(iterator_flatten)]
 #![feature(pattern)]
 #![feature(range_is_empty)]
 #![feature(raw)]