Rollup merge of rust-lang#80470 - SimonSapin:array-intoiter-type, r=m-ou-se

Stabilize by-value `[T; N]` iterator `core::array::IntoIter`

Tracking issue: rust-lang#65798

This is unblocked now that `min_const_generics` has been stabilized in rust-lang#79135.

This PR does *not* include the corresponding `IntoIterator` impl, which is rust-lang#65819. Instead, an iterator can be constructed through the `new` method.

`new` would become unnecessary when `IntoIterator` is implemented and might be deprecated then, although it will stay stable.

Author: jonas-schievink

alloc/src/lib.rs

@@ -78,7 +78,6 @@
 #![feature(allocator_api)]
 #![feature(array_chunks)]
 #![feature(array_methods)]
-#![feature(array_value_iter)]
 #![feature(array_windows)]
 #![feature(allow_internal_unstable)]
 #![feature(arbitrary_self_types)]

core/src/array/iter.rs

@@ -11,7 +11,7 @@ use crate::{
 /// A by-value [array] iterator.
 ///
 /// [array]: ../../std/primitive.array.html
-#[unstable(feature = "array_value_iter", issue = "65798")]
+#[stable(feature = "array_value_iter", since = "1.51.0")]
 pub struct IntoIter<T, const N: usize> {
     /// This is the array we are iterating over.
     ///
@@ -38,10 +38,21 @@ pub struct IntoIter<T, const N: usize> {
 impl<T, const N: usize> IntoIter<T, N> {
     /// Creates a new iterator over the given `array`.
     ///
-    /// *Note*: this method might never get stabilized and/or removed in the
-    /// future as there will likely be another, preferred way of obtaining this
-    /// iterator (either via `IntoIterator` for arrays or via another way).
-    #[unstable(feature = "array_value_iter", issue = "65798")]
+    /// *Note*: this method might be deprecated in the future,
+    /// after [`IntoIterator` is implemented for arrays][array-into-iter].
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use std::array;
+    ///
+    /// for value in array::IntoIter::new([1, 2, 3, 4, 5]) {
+    ///     // The type of `value` is a `i32` here, instead of `&i32`
+    ///     let _: i32 = value;
+    /// }
+    /// ```
+    /// [array-into-iter]: https://github.com/rust-lang/rust/pull/65819
+    #[stable(feature = "array_value_iter", since = "1.51.0")]
     pub fn new(array: [T; N]) -> Self {
         // SAFETY: The transmute here is actually safe. The docs of `MaybeUninit`
         // promise:
@@ -69,7 +80,7 @@ impl<T, const N: usize> IntoIter<T, N> {
 
     /// Returns an immutable slice of all elements that have not been yielded
     /// yet.
-    #[unstable(feature = "array_value_iter_slice", issue = "65798")]
+    #[stable(feature = "array_value_iter", since = "1.51.0")]
     pub fn as_slice(&self) -> &[T] {
         // SAFETY: We know that all elements within `alive` are properly initialized.
         unsafe {
@@ -79,7 +90,7 @@ impl<T, const N: usize> IntoIter<T, N> {
     }
 
     /// Returns a mutable slice of all elements that have not been yielded yet.
-    #[unstable(feature = "array_value_iter_slice", issue = "65798")]
+    #[stable(feature = "array_value_iter", since = "1.51.0")]
     pub fn as_mut_slice(&mut self) -> &mut [T] {
         // SAFETY: We know that all elements within `alive` are properly initialized.
         unsafe {

core/src/array/mod.rs

@@ -18,7 +18,7 @@ use crate::slice::{Iter, IterMut};
 
 mod iter;
 
-#[unstable(feature = "array_value_iter", issue = "65798")]
+#[stable(feature = "array_value_iter", since = "1.51.0")]
 pub use iter::IntoIter;
 
 /// Converts a reference to `T` into a reference to an array of length 1 (without copying).

core/tests/lib.rs

@@ -50,7 +50,6 @@
 #![feature(slice_internals)]
 #![feature(slice_partition_dedup)]
 #![feature(int_error_matching)]
-#![feature(array_value_iter)]
 #![feature(iter_advance_by)]
 #![feature(iter_partition_in_place)]
 #![feature(iter_intersperse)]