Rollup merge of #89086 - WaffleLapkin:stabilize_iter_map_while, r=kennytm

Stabilize `Iterator::map_while`

Per the FCP: https://github.com/rust-lang/rust/issues/68537#issuecomment-922385035

This PR stabilizes `Iterator::map_while` and `iter::MapWhile` in Rust 1.57.

compiler/rustc_data_structures/src/lib.rs

@@ -18,7 +18,6 @@
 #![feature(extend_one)]
 #![feature(hash_raw_entry)]
 #![feature(in_band_lifetimes)]
-#![feature(iter_map_while)]
 #![feature(maybe_uninit_uninit_array)]
 #![feature(min_specialization)]
 #![feature(never_type)]

library/alloc/tests/lib.rs

@@ -18,7 +18,6 @@
 #![feature(binary_heap_retain)]
 #![feature(binary_heap_as_slice)]
 #![feature(inplace_iteration)]
-#![feature(iter_map_while)]
 #![feature(slice_group_by)]
 #![feature(slice_partition_dedup)]
 #![feature(vec_spare_capacity)]

library/core/src/iter/adapters/map_while.rs

@@ -10,7 +10,7 @@ use crate::ops::{ControlFlow, Try};
 /// [`map_while`]: Iterator::map_while
 /// [`Iterator`]: trait.Iterator.html
 #[must_use = "iterators are lazy and do nothing unless consumed"]
-#[unstable(feature = "iter_map_while", reason = "recently added", issue = "68537")]
+#[stable(feature = "iter_map_while", since = "1.57.0")]
 #[derive(Clone)]
 pub struct MapWhile<I, P> {
     iter: I,
@@ -23,14 +23,14 @@ impl<I, P> MapWhile<I, P> {
     }
 }
 
-#[unstable(feature = "iter_map_while", reason = "recently added", issue = "68537")]
+#[stable(feature = "iter_map_while", since = "1.57.0")]
 impl<I: fmt::Debug, P> fmt::Debug for MapWhile<I, P> {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         f.debug_struct("MapWhile").field("iter", &self.iter).finish()
     }
 }
 
-#[unstable(feature = "iter_map_while", reason = "recently added", issue = "68537")]
+#[stable(feature = "iter_map_while", since = "1.57.0")]
 impl<B, I: Iterator, P> Iterator for MapWhile<I, P>
 where
     P: FnMut(I::Item) -> Option<B>,

library/core/src/iter/adapters/mod.rs

@@ -45,7 +45,7 @@ pub use self::copied::Copied;
 #[stable(feature = "iter_intersperse", since = "1.56.0")]
 pub use self::intersperse::{Intersperse, IntersperseWith};
 
-#[unstable(feature = "iter_map_while", reason = "recently added", issue = "68537")]
+#[stable(feature = "iter_map_while", since = "1.57.0")]
 pub use self::map_while::MapWhile;
 
 #[unstable(feature = "trusted_random_access", issue = "none")]

library/core/src/iter/mod.rs

@@ -399,7 +399,7 @@ pub use self::adapters::Cloned;
 pub use self::adapters::Copied;
 #[stable(feature = "iterator_flatten", since = "1.29.0")]
 pub use self::adapters::Flatten;
-#[unstable(feature = "iter_map_while", reason = "recently added", issue = "68537")]
+#[stable(feature = "iter_map_while", since = "1.57.0")]
 pub use self::adapters::MapWhile;
 #[unstable(feature = "inplace_iteration", issue = "none")]
 pub use self::adapters::SourceIter;

library/core/src/iter/traits/iterator.rs

@@ -1116,7 +1116,6 @@ pub trait Iterator {
     /// Basic usage:
     ///
     /// ```
-    /// #![feature(iter_map_while)]
     /// let a = [-1i32, 4, 0, 1];
     ///
     /// let mut iter = a.iter().map_while(|x| 16i32.checked_div(*x));
@@ -1147,7 +1146,6 @@ pub trait Iterator {
     /// Stopping after an initial [`None`]:
     ///
     /// ```
-    /// #![feature(iter_map_while)]
     /// use std::convert::TryFrom;
     ///
     /// let a = [0, 1, 2, -3, 4, 5, -6];
@@ -1165,7 +1163,6 @@ pub trait Iterator {
     /// removed:
     ///
     /// ```
-    /// #![feature(iter_map_while)]
     /// use std::convert::TryFrom;
     ///
     /// let a = [1, 2, -3, 4];
@@ -1191,7 +1188,7 @@ pub trait Iterator {
     ///
     /// [`fuse`]: Iterator::fuse
     #[inline]
-    #[unstable(feature = "iter_map_while", reason = "recently added", issue = "68537")]
+    #[stable(feature = "iter_map_while", since = "1.57.0")]
     fn map_while<B, P>(self, predicate: P) -> MapWhile<Self, P>
     where
         Self: Sized,

library/core/tests/lib.rs

@@ -50,7 +50,6 @@
 #![feature(iter_partition_in_place)]
 #![feature(iter_is_partitioned)]
 #![feature(iter_order_by)]
-#![feature(iter_map_while)]
 #![feature(const_mut_refs)]
 #![feature(const_pin)]
 #![feature(const_slice_from_raw_parts)]