Rollup merge of #85930 - mominul:array_into_iter, r=m-ou-se

Update standard library for IntoIterator implementation of arrays

This PR partially resolves issue #84513 of updating the standard library part.

I haven't found any remaining doctest examples which are using iterators over e.g. &i32 instead of just i32 in the standard library. Can anyone point me to them if there's remaining any?

Thanks!

r? ```@m-ou-se```

11 files changed, 55 insertions, 64 deletions

diff --git a/library/alloc/benches/vec.rs b/library/alloc/benches/vec.rs
index c9bdcaa78f3..91eec10d575 100644
--- a/library/alloc/benches/vec.rs
+++ b/library/alloc/benches/vec.rs
@@ -551,19 +551,13 @@ const LEN: usize = 16384;
 #[bench]
 fn bench_chain_collect(b: &mut Bencher) {
     let data = black_box([0; LEN]);
-    b.iter(|| data.iter().cloned().chain([1].iter().cloned()).collect::<Vec<_>>());
+    b.iter(|| data.iter().cloned().chain([1]).collect::<Vec<_>>());
 }
 
 #[bench]
 fn bench_chain_chain_collect(b: &mut Bencher) {
     let data = black_box([0; LEN]);
-    b.iter(|| {
-        data.iter()
-            .cloned()
-            .chain([1].iter().cloned())
-            .chain([2].iter().cloned())
-            .collect::<Vec<_>>()
-    });
+    b.iter(|| data.iter().cloned().chain([1]).chain([2]).collect::<Vec<_>>());
 }
 
 #[bench]
diff --git a/library/alloc/src/collections/vec_deque/pair_slices.rs b/library/alloc/src/collections/vec_deque/pair_slices.rs
index 812765d0b0d..7b87090fb07 100644
--- a/library/alloc/src/collections/vec_deque/pair_slices.rs
+++ b/library/alloc/src/collections/vec_deque/pair_slices.rs
@@ -1,4 +1,3 @@
-use core::array;
 use core::cmp::{self};
 use core::mem::replace;
 
@@ -37,7 +36,7 @@ impl<'a, 'b, T> PairSlices<'a, 'b, T> {
     }
 
     pub fn remainder(self) -> impl Iterator<Item = &'b [T]> {
-        array::IntoIter::new([self.b0, self.b1])
+        IntoIterator::into_iter([self.b0, self.b1])
     }
 }
 
diff --git a/library/alloc/src/vec/mod.rs b/library/alloc/src/vec/mod.rs
index 105c60e7bf0..4a1d564e2ab 100644
--- a/library/alloc/src/vec/mod.rs
+++ b/library/alloc/src/vec/mod.rs
@@ -921,7 +921,7 @@ impl<T, A: Allocator> Vec<T, A> {
     ///
     /// ```
     /// let mut vec = Vec::with_capacity(10);
-    /// vec.extend([1, 2, 3].iter().cloned());
+    /// vec.extend([1, 2, 3]);
     /// assert_eq!(vec.capacity(), 10);
     /// vec.shrink_to_fit();
     /// assert!(vec.capacity() >= 3);
@@ -950,7 +950,7 @@ impl<T, A: Allocator> Vec<T, A> {
     /// ```
     /// #![feature(shrink_to)]
     /// let mut vec = Vec::with_capacity(10);
-    /// vec.extend([1, 2, 3].iter().cloned());
+    /// vec.extend([1, 2, 3]);
     /// assert_eq!(vec.capacity(), 10);
     /// vec.shrink_to(4);
     /// assert!(vec.capacity() >= 4);
@@ -984,7 +984,7 @@ impl<T, A: Allocator> Vec<T, A> {
     ///
     /// ```
     /// let mut vec = Vec::with_capacity(10);
-    /// vec.extend([1, 2, 3].iter().cloned());
+    /// vec.extend([1, 2, 3]);
     ///
     /// assert_eq!(vec.capacity(), 10);
     /// let slice = vec.into_boxed_slice();
@@ -2586,7 +2586,7 @@ impl<T, A: Allocator> Vec<T, A> {
     /// ```
     /// let mut v = vec![1, 2, 3];
     /// let new = [7, 8];
-    /// let u: Vec<_> = v.splice(..2, new.iter().cloned()).collect();
+    /// let u: Vec<_> = v.splice(..2, new).collect();
     /// assert_eq!(v, &[7, 8, 3]);
     /// assert_eq!(u, &[1, 2]);
     /// ```
diff --git a/library/alloc/src/vec/splice.rs b/library/alloc/src/vec/splice.rs
index 0a27b5b62ec..bad765c7f51 100644
--- a/library/alloc/src/vec/splice.rs
+++ b/library/alloc/src/vec/splice.rs
@@ -14,7 +14,7 @@ use super::{Drain, Vec};
 /// ```
 /// let mut v = vec![0, 1, 2];
 /// let new = [7, 8];
-/// let iter: std::vec::Splice<_> = v.splice(1.., new.iter().cloned());
+/// let iter: std::vec::Splice<_> = v.splice(1.., new);
 /// ```
 #[derive(Debug)]
 #[stable(feature = "vec_splice", since = "1.21.0")]
diff --git a/library/alloc/tests/vec.rs b/library/alloc/tests/vec.rs
index 36c81b49709..c203cdafecb 100644
--- a/library/alloc/tests/vec.rs
+++ b/library/alloc/tests/vec.rs
@@ -793,7 +793,7 @@ fn test_drain_leak() {
 fn test_splice() {
     let mut v = vec![1, 2, 3, 4, 5];
     let a = [10, 11, 12];
-    v.splice(2..4, a.iter().cloned());
+    v.splice(2..4, a);
     assert_eq!(v, &[1, 2, 10, 11, 12, 5]);
     v.splice(1..3, Some(20));
     assert_eq!(v, &[1, 20, 11, 12, 5]);
@@ -803,7 +803,7 @@ fn test_splice() {
 fn test_splice_inclusive_range() {
     let mut v = vec![1, 2, 3, 4, 5];
     let a = [10, 11, 12];
-    let t1: Vec<_> = v.splice(2..=3, a.iter().cloned()).collect();
+    let t1: Vec<_> = v.splice(2..=3, a).collect();
     assert_eq!(v, &[1, 2, 10, 11, 12, 5]);
     assert_eq!(t1, &[3, 4]);
     let t2: Vec<_> = v.splice(1..=2, Some(20)).collect();
@@ -816,7 +816,7 @@ fn test_splice_inclusive_range() {
 fn test_splice_out_of_bounds() {
     let mut v = vec![1, 2, 3, 4, 5];
     let a = [10, 11, 12];
-    v.splice(5..6, a.iter().cloned());
+    v.splice(5..6, a);
 }
 
 #[test]
@@ -824,7 +824,7 @@ fn test_splice_out_of_bounds() {
 fn test_splice_inclusive_out_of_bounds() {
     let mut v = vec![1, 2, 3, 4, 5];
     let a = [10, 11, 12];
-    v.splice(5..=5, a.iter().cloned());
+    v.splice(5..=5, a);
 }
 
 #[test]
@@ -848,7 +848,7 @@ fn test_splice_unbounded() {
 fn test_splice_forget() {
     let mut v = vec![1, 2, 3, 4, 5];
     let a = [10, 11, 12];
-    std::mem::forget(v.splice(2..4, a.iter().cloned()));
+    std::mem::forget(v.splice(2..4, a));
     assert_eq!(v, &[1, 2]);
 }
 
diff --git a/library/core/src/array/mod.rs b/library/core/src/array/mod.rs
index e25d006d213..37af3557fdd 100644
--- a/library/core/src/array/mod.rs
+++ b/library/core/src/array/mod.rs
@@ -416,7 +416,7 @@ impl<T, const N: usize> [T; N] {
     {
         // SAFETY: we know for certain that this iterator will yield exactly `N`
         // items.
-        unsafe { collect_into_array_unchecked(&mut IntoIter::new(self).map(f)) }
+        unsafe { collect_into_array_unchecked(&mut IntoIterator::into_iter(self).map(f)) }
     }
 
     /// 'Zips up' two arrays into a single array of pairs.
@@ -437,7 +437,7 @@ impl<T, const N: usize> [T; N] {
     /// ```
     #[unstable(feature = "array_zip", issue = "80094")]
     pub fn zip<U>(self, rhs: [U; N]) -> [(T, U); N] {
-        let mut iter = IntoIter::new(self).zip(IntoIter::new(rhs));
+        let mut iter = IntoIterator::into_iter(self).zip(rhs);
 
         // SAFETY: we know for certain that this iterator will yield exactly `N`
         // items.
diff --git a/library/core/src/char/methods.rs b/library/core/src/char/methods.rs
index dcab2cd2d9d..2da3d6a72fb 100644
--- a/library/core/src/char/methods.rs
+++ b/library/core/src/char/methods.rs
@@ -58,7 +58,7 @@ impl char {
     /// ];
     ///
     /// assert_eq!(
-    ///     decode_utf16(v.iter().cloned())
+    ///     decode_utf16(v)
     ///         .map(|r| r.map_err(|e| e.unpaired_surrogate()))
     ///         .collect::<Vec<_>>(),
     ///     vec![
@@ -82,7 +82,7 @@ impl char {
     /// ];
     ///
     /// assert_eq!(
-    ///     decode_utf16(v.iter().cloned())
+    ///     decode_utf16(v)
     ///        .map(|r| r.unwrap_or(REPLACEMENT_CHARACTER))
     ///        .collect::<String>(),
     ///     "𝄞mus�ic�"
diff --git a/library/core/tests/array.rs b/library/core/tests/array.rs
index ce7480ce2ee..0ae625bdb68 100644
--- a/library/core/tests/array.rs
+++ b/library/core/tests/array.rs
@@ -1,4 +1,4 @@
-use core::array::{self, IntoIter};
+use core::array;
 use core::convert::TryFrom;
 
 #[test]
@@ -41,14 +41,14 @@ fn array_try_from() {
 #[test]
 fn iterator_collect() {
     let arr = [0, 1, 2, 5, 9];
-    let v: Vec<_> = IntoIter::new(arr.clone()).collect();
+    let v: Vec<_> = IntoIterator::into_iter(arr.clone()).collect();
     assert_eq!(&arr[..], &v[..]);
 }
 
 #[test]
 fn iterator_rev_collect() {
     let arr = [0, 1, 2, 5, 9];
-    let v: Vec<_> = IntoIter::new(arr.clone()).rev().collect();
+    let v: Vec<_> = IntoIterator::into_iter(arr.clone()).rev().collect();
     assert_eq!(&v[..], &[9, 5, 2, 1, 0]);
 }
 
@@ -56,11 +56,11 @@ fn iterator_rev_collect() {
 fn iterator_nth() {
     let v = [0, 1, 2, 3, 4];
     for i in 0..v.len() {
-        assert_eq!(IntoIter::new(v.clone()).nth(i).unwrap(), v[i]);
+        assert_eq!(IntoIterator::into_iter(v.clone()).nth(i).unwrap(), v[i]);
     }
-    assert_eq!(IntoIter::new(v.clone()).nth(v.len()), None);
+    assert_eq!(IntoIterator::into_iter(v.clone()).nth(v.len()), None);
 
-    let mut iter = IntoIter::new(v);
+    let mut iter = IntoIterator::into_iter(v);
     assert_eq!(iter.nth(2).unwrap(), v[2]);
     assert_eq!(iter.nth(1).unwrap(), v[4]);
 }
@@ -68,17 +68,17 @@ fn iterator_nth() {
 #[test]
 fn iterator_last() {
     let v = [0, 1, 2, 3, 4];
-    assert_eq!(IntoIter::new(v).last().unwrap(), 4);
-    assert_eq!(IntoIter::new([0]).last().unwrap(), 0);
+    assert_eq!(IntoIterator::into_iter(v).last().unwrap(), 4);
+    assert_eq!(IntoIterator::into_iter([0]).last().unwrap(), 0);
 
-    let mut it = IntoIter::new([0, 9, 2, 4]);
+    let mut it = IntoIterator::into_iter([0, 9, 2, 4]);
     assert_eq!(it.next_back(), Some(4));
     assert_eq!(it.last(), Some(2));
 }
 
 #[test]
 fn iterator_clone() {
-    let mut it = IntoIter::new([0, 2, 4, 6, 8]);
+    let mut it = IntoIterator::into_iter([0, 2, 4, 6, 8]);
     assert_eq!(it.next(), Some(0));
     assert_eq!(it.next_back(), Some(8));
     let mut clone = it.clone();
@@ -92,7 +92,7 @@ fn iterator_clone() {
 
 #[test]
 fn iterator_fused() {
-    let mut it = IntoIter::new([0, 9, 2]);
+    let mut it = IntoIterator::into_iter([0, 9, 2]);
     assert_eq!(it.next(), Some(0));
     assert_eq!(it.next(), Some(9));
     assert_eq!(it.next(), Some(2));
@@ -105,7 +105,7 @@ fn iterator_fused() {
 
 #[test]
 fn iterator_len() {
-    let mut it = IntoIter::new([0, 1, 2, 5, 9]);
+    let mut it = IntoIterator::into_iter([0, 1, 2, 5, 9]);
     assert_eq!(it.size_hint(), (5, Some(5)));
     assert_eq!(it.len(), 5);
     assert_eq!(it.is_empty(), false);
@@ -121,7 +121,7 @@ fn iterator_len() {
     assert_eq!(it.is_empty(), false);
 
     // Empty
-    let it = IntoIter::new([] as [String; 0]);
+    let it = IntoIterator::into_iter([] as [String; 0]);
     assert_eq!(it.size_hint(), (0, Some(0)));
     assert_eq!(it.len(), 0);
     assert_eq!(it.is_empty(), true);
@@ -130,9 +130,9 @@ fn iterator_len() {
 #[test]
 fn iterator_count() {
     let v = [0, 1, 2, 3, 4];
-    assert_eq!(IntoIter::new(v.clone()).count(), 5);
+    assert_eq!(IntoIterator::into_iter(v.clone()).count(), 5);
 
-    let mut iter2 = IntoIter::new(v);
+    let mut iter2 = IntoIterator::into_iter(v);
     iter2.next();
     iter2.next();
     assert_eq!(iter2.count(), 3);
@@ -140,13 +140,13 @@ fn iterator_count() {
 
 #[test]
 fn iterator_flat_map() {
-    assert!((0..5).flat_map(|i| IntoIter::new([2 * i, 2 * i + 1])).eq(0..10));
+    assert!((0..5).flat_map(|i| IntoIterator::into_iter([2 * i, 2 * i + 1])).eq(0..10));
 }
 
 #[test]
 fn iterator_debug() {
     let arr = [0, 1, 2, 5, 9];
-    assert_eq!(format!("{:?}", IntoIter::new(arr)), "IntoIter([0, 1, 2, 5, 9])",);
+    assert_eq!(format!("{:?}", IntoIterator::into_iter(arr)), "IntoIter([0, 1, 2, 5, 9])",);
 }
 
 #[test]
@@ -176,14 +176,14 @@ fn iterator_drops() {
     // Simple: drop new iterator.
     let i = Cell::new(0);
     {
-        IntoIter::new(five(&i));
+        IntoIterator::into_iter(five(&i));
     }
     assert_eq!(i.get(), 5);
 
     // Call `next()` once.
     let i = Cell::new(0);
     {
-        let mut iter = IntoIter::new(five(&i));
+        let mut iter = IntoIterator::into_iter(five(&i));
         let _x = iter.next();
         assert_eq!(i.get(), 0);
         assert_eq!(iter.count(), 4);
@@ -194,7 +194,7 @@ fn iterator_drops() {
     // Check `clone` and calling `next`/`next_back`.
     let i = Cell::new(0);
     {
-        let mut iter = IntoIter::new(five(&i));
+        let mut iter = IntoIterator::into_iter(five(&i));
         iter.next();
         assert_eq!(i.get(), 1);
         iter.next_back();
@@ -217,7 +217,7 @@ fn iterator_drops() {
     // Check via `nth`.
     let i = Cell::new(0);
     {
-        let mut iter = IntoIter::new(five(&i));
+        let mut iter = IntoIterator::into_iter(five(&i));
         let _x = iter.nth(2);
         assert_eq!(i.get(), 2);
         let _y = iter.last();
@@ -227,13 +227,13 @@ fn iterator_drops() {
 
     // Check every element.
     let i = Cell::new(0);
-    for (index, _x) in IntoIter::new(five(&i)).enumerate() {
+    for (index, _x) in IntoIterator::into_iter(five(&i)).enumerate() {
         assert_eq!(i.get(), index);
     }
     assert_eq!(i.get(), 5);
 
     let i = Cell::new(0);
-    for (index, _x) in IntoIter::new(five(&i)).rev().enumerate() {
+    for (index, _x) in IntoIterator::into_iter(five(&i)).rev().enumerate() {
         assert_eq!(i.get(), index);
     }
     assert_eq!(i.get(), 5);
diff --git a/library/core/tests/iter/adapters/zip.rs b/library/core/tests/iter/adapters/zip.rs
index 000c15f72c8..797bfd957f9 100644
--- a/library/core/tests/iter/adapters/zip.rs
+++ b/library/core/tests/iter/adapters/zip.rs
@@ -236,9 +236,7 @@ fn test_zip_trusted_random_access_composition() {
 fn test_double_ended_zip() {
     let xs = [1, 2, 3, 4, 5, 6];
     let ys = [1, 2, 3, 7];
-    let a = xs.iter().cloned();
-    let b = ys.iter().cloned();
-    let mut it = a.zip(b);
+    let mut it = xs.iter().cloned().zip(ys);
     assert_eq!(it.next(), Some((1, 1)));
     assert_eq!(it.next(), Some((2, 2)));
     assert_eq!(it.next_back(), Some((4, 7)));
diff --git a/src/test/ui/const-generics/array-impls/into-iter-impls-length-32.rs b/src/test/ui/const-generics/array-impls/into-iter-impls-length-32.rs
index 6ba1b2813a1..457e5ae6049 100644
--- a/src/test/ui/const-generics/array-impls/into-iter-impls-length-32.rs
+++ b/src/test/ui/const-generics/array-impls/into-iter-impls-length-32.rs
@@ -9,31 +9,31 @@ use std::{
 };
 
 pub fn yes_iterator() -> impl Iterator<Item = i32> {
-    IntoIter::new([0i32; 32])
+    IntoIterator::into_iter([0i32; 32])
 }
 
 pub fn yes_double_ended_iterator() -> impl DoubleEndedIterator {
-    IntoIter::new([0i32; 32])
+    IntoIterator::into_iter([0i32; 32])
 }
 
 pub fn yes_exact_size_iterator() -> impl ExactSizeIterator {
-    IntoIter::new([0i32; 32])
+    IntoIterator::into_iter([0i32; 32])
 }
 
 pub fn yes_fused_iterator() -> impl FusedIterator {
-    IntoIter::new([0i32; 32])
+    IntoIterator::into_iter([0i32; 32])
 }
 
 pub fn yes_trusted_len() -> impl TrustedLen {
-    IntoIter::new([0i32; 32])
+    IntoIterator::into_iter([0i32; 32])
 }
 
 pub fn yes_clone() -> impl Clone {
-    IntoIter::new([0i32; 32])
+    IntoIterator::into_iter([0i32; 32])
 }
 
 pub fn yes_debug() -> impl Debug {
-    IntoIter::new([0i32; 32])
+    IntoIterator::into_iter([0i32; 32])
 }
 
 
diff --git a/src/test/ui/const-generics/array-impls/into-iter-impls-length-33.rs b/src/test/ui/const-generics/array-impls/into-iter-impls-length-33.rs
index deafde2912b..4f343f3f97e 100644
--- a/src/test/ui/const-generics/array-impls/into-iter-impls-length-33.rs
+++ b/src/test/ui/const-generics/array-impls/into-iter-impls-length-33.rs
@@ -9,31 +9,31 @@ use std::{
 };
 
 pub fn yes_iterator() -> impl Iterator<Item = i32> {
-    IntoIter::new([0i32; 33])
+    IntoIterator::into_iter([0i32; 33])
 }
 
 pub fn yes_double_ended_iterator() -> impl DoubleEndedIterator {
-    IntoIter::new([0i32; 33])
+    IntoIterator::into_iter([0i32; 33])
 }
 
 pub fn yes_exact_size_iterator() -> impl ExactSizeIterator {
-    IntoIter::new([0i32; 33])
+    IntoIterator::into_iter([0i32; 33])
 }
 
 pub fn yes_fused_iterator() -> impl FusedIterator {
-    IntoIter::new([0i32; 33])
+    IntoIterator::into_iter([0i32; 33])
 }
 
 pub fn yes_trusted_len() -> impl TrustedLen {
-    IntoIter::new([0i32; 33])
+    IntoIterator::into_iter([0i32; 33])
 }
 
 pub fn yes_clone() -> impl Clone {
-    IntoIter::new([0i32; 33])
+    IntoIterator::into_iter([0i32; 33])
 }
 
 pub fn yes_debug() -> impl Debug {
-    IntoIter::new([0i32; 33])
+    IntoIterator::into_iter([0i32; 33])
 }