Rollup merge of #47463 - bluss:fused-iterator, r=alexcrichton

Stabilize FusedIterator

FusedIterator is a marker trait that promises that the implementing
iterator continues to return `None` from `.next()` once it has returned
`None` once (and/or `.next_back()`, if implemented).

The effects of FusedIterator are already widely available through
`.fuse()`, but with stable `FusedIterator`, stable Rust users can
implement this trait for their iterators when appropriate.

Closes #35602

src/libstd/ascii.rs

@@ -590,7 +590,7 @@ impl DoubleEndedIterator for EscapeDefault {
 }
 #[stable(feature = "rust1", since = "1.0.0")]
 impl ExactSizeIterator for EscapeDefault {}
-#[unstable(feature = "fused", issue = "35602")]
+#[stable(feature = "fused", since = "1.26.0")]
 impl FusedIterator for EscapeDefault {}
 
 #[stable(feature = "std_debug", since = "1.16.0")]

src/libstd/collections/hash/map.rs

@@ -1750,7 +1750,7 @@ impl<'a, K, V> ExactSizeIterator for Iter<'a, K, V> {
     }
 }
 
-#[unstable(feature = "fused", issue = "35602")]
+#[stable(feature = "fused", since = "1.26.0")]
 impl<'a, K, V> FusedIterator for Iter<'a, K, V> {}
 
 #[stable(feature = "rust1", since = "1.0.0")]
@@ -1773,7 +1773,7 @@ impl<'a, K, V> ExactSizeIterator for IterMut<'a, K, V> {
         self.inner.len()
     }
 }
-#[unstable(feature = "fused", issue = "35602")]
+#[stable(feature = "fused", since = "1.26.0")]
 impl<'a, K, V> FusedIterator for IterMut<'a, K, V> {}
 
 #[stable(feature = "std_debug", since = "1.16.0")]
@@ -1808,7 +1808,7 @@ impl<K, V> ExactSizeIterator for IntoIter<K, V> {
         self.inner.len()
     }
 }
-#[unstable(feature = "fused", issue = "35602")]
+#[stable(feature = "fused", since = "1.26.0")]
 impl<K, V> FusedIterator for IntoIter<K, V> {}
 
 #[stable(feature = "std_debug", since = "1.16.0")]
@@ -1840,7 +1840,7 @@ impl<'a, K, V> ExactSizeIterator for Keys<'a, K, V> {
         self.inner.len()
     }
 }
-#[unstable(feature = "fused", issue = "35602")]
+#[stable(feature = "fused", since = "1.26.0")]
 impl<'a, K, V> FusedIterator for Keys<'a, K, V> {}
 
 #[stable(feature = "rust1", since = "1.0.0")]
@@ -1863,7 +1863,7 @@ impl<'a, K, V> ExactSizeIterator for Values<'a, K, V> {
         self.inner.len()
     }
 }
-#[unstable(feature = "fused", issue = "35602")]
+#[stable(feature = "fused", since = "1.26.0")]
 impl<'a, K, V> FusedIterator for Values<'a, K, V> {}
 
 #[stable(feature = "map_values_mut", since = "1.10.0")]
@@ -1886,7 +1886,7 @@ impl<'a, K, V> ExactSizeIterator for ValuesMut<'a, K, V> {
         self.inner.len()
     }
 }
-#[unstable(feature = "fused", issue = "35602")]
+#[stable(feature = "fused", since = "1.26.0")]
 impl<'a, K, V> FusedIterator for ValuesMut<'a, K, V> {}
 
 #[stable(feature = "std_debug", since = "1.16.0")]
@@ -1921,7 +1921,7 @@ impl<'a, K, V> ExactSizeIterator for Drain<'a, K, V> {
         self.inner.len()
     }
 }
-#[unstable(feature = "fused", issue = "35602")]
+#[stable(feature = "fused", since = "1.26.0")]
 impl<'a, K, V> FusedIterator for Drain<'a, K, V> {}
 
 #[stable(feature = "std_debug", since = "1.16.0")]

src/libstd/collections/hash/set.rs

@@ -1097,7 +1097,7 @@ impl<'a, K> ExactSizeIterator for Iter<'a, K> {
         self.iter.len()
     }
 }
-#[unstable(feature = "fused", issue = "35602")]
+#[stable(feature = "fused", since = "1.26.0")]
 impl<'a, K> FusedIterator for Iter<'a, K> {}
 
 #[stable(feature = "std_debug", since = "1.16.0")]
@@ -1124,7 +1124,7 @@ impl<K> ExactSizeIterator for IntoIter<K> {
         self.iter.len()
     }
 }
-#[unstable(feature = "fused", issue = "35602")]
+#[stable(feature = "fused", since = "1.26.0")]
 impl<K> FusedIterator for IntoIter<K> {}
 
 #[stable(feature = "std_debug", since = "1.16.0")]
@@ -1155,7 +1155,7 @@ impl<'a, K> ExactSizeIterator for Drain<'a, K> {
         self.iter.len()
     }
 }
-#[unstable(feature = "fused", issue = "35602")]
+#[stable(feature = "fused", since = "1.26.0")]
 impl<'a, K> FusedIterator for Drain<'a, K> {}
 
 #[stable(feature = "std_debug", since = "1.16.0")]
@@ -1208,7 +1208,7 @@ impl<'a, T, S> fmt::Debug for Intersection<'a, T, S>
     }
 }
 
-#[unstable(feature = "fused", issue = "35602")]
+#[stable(feature = "fused", since = "1.26.0")]
 impl<'a, T, S> FusedIterator for Intersection<'a, T, S>
     where T: Eq + Hash,
           S: BuildHasher
@@ -1244,7 +1244,7 @@ impl<'a, T, S> Iterator for Difference<'a, T, S>
     }
 }
 
-#[unstable(feature = "fused", issue = "35602")]
+#[stable(feature = "fused", since = "1.26.0")]
 impl<'a, T, S> FusedIterator for Difference<'a, T, S>
     where T: Eq + Hash,
           S: BuildHasher
@@ -1283,7 +1283,7 @@ impl<'a, T, S> Iterator for SymmetricDifference<'a, T, S>
     }
 }
 
-#[unstable(feature = "fused", issue = "35602")]
+#[stable(feature = "fused", since = "1.26.0")]
 impl<'a, T, S> FusedIterator for SymmetricDifference<'a, T, S>
     where T: Eq + Hash,
           S: BuildHasher
@@ -1307,7 +1307,7 @@ impl<'a, T, S> Clone for Union<'a, T, S> {
     }
 }
 
-#[unstable(feature = "fused", issue = "35602")]
+#[stable(feature = "fused", since = "1.26.0")]
 impl<'a, T, S> FusedIterator for Union<'a, T, S>
     where T: Eq + Hash,
           S: BuildHasher

src/libstd/lib.rs

@@ -266,7 +266,6 @@
 #![feature(float_from_str_radix)]
 #![feature(fn_traits)]
 #![feature(fnbox)]
-#![feature(fused)]
 #![feature(generic_param_attrs)]
 #![feature(hashmap_hasher)]
 #![feature(heap_api)]

src/libstd/path.rs

@@ -905,7 +905,7 @@ impl<'a> DoubleEndedIterator for Iter<'a> {
     }
 }
 
-#[unstable(feature = "fused", issue = "35602")]
+#[stable(feature = "fused", since = "1.26.0")]
 impl<'a> FusedIterator for Iter<'a> {}
 
 #[stable(feature = "rust1", since = "1.0.0")]
@@ -1008,7 +1008,7 @@ impl<'a> DoubleEndedIterator for Components<'a> {
     }
 }
 
-#[unstable(feature = "fused", issue = "35602")]
+#[stable(feature = "fused", since = "1.26.0")]
 impl<'a> FusedIterator for Components<'a> {}
 
 #[stable(feature = "rust1", since = "1.0.0")]
@@ -1076,7 +1076,7 @@ impl<'a> Iterator for Ancestors<'a> {
     }
 }
 
-#[unstable(feature = "fused", issue = "35602")]
+#[unstable(feature = "path_ancestors", issue = "48581")]
 impl<'a> FusedIterator for Ancestors<'a> {}
 
 ////////////////////////////////////////////////////////////////////////////////