From d21b7d2735efd07cf7695486f65dc6690bd64311 Mon Sep 17 00:00:00 2001
From: Emil Hofstetter <emil.k.hofstetter@gmail.com>
Date: Sun, 12 Feb 2023 23:33:02 -0500
Subject: [PATCH 1/2] add try_from_iter

---
 library/core/src/array/mod.rs | 29 +++++++++++++++++++++++++++++
 library/core/tests/array.rs   | 12 ++++++++++++
 library/core/tests/lib.rs     |  1 +
 3 files changed, 42 insertions(+)

diff --git a/library/core/src/array/mod.rs b/library/core/src/array/mod.rs
index 5decd7d5a65bb..1d86cabd76aba 100644
--- a/library/core/src/array/mod.rs
+++ b/library/core/src/array/mod.rs
@@ -959,3 +959,32 @@ where
     let mut map = iter.map(NeverShortCircuit);
     try_collect_into_array(&mut map).map(|NeverShortCircuit(arr)| arr)
 }
+
+/// Tries to create an array `[T; N]` from the items of `iter`. If and only if `iter` holds
+/// `>= N` items it returns `OK([T; N])`. Otherwise, `Err(IntoIter<T; N>)` is returned.
+///
+/// # Arguments
+///
+/// * `iter`: Type that implements `IntoIterator` where `Items = T`.
+///
+/// # Example
+///
+/// ```rust
+/// #![feature(try_from_iter)]
+/// let vec = vec![0, 1, 2, 3];
+/// let array = core::array::try_from_iter::<_, 4>(vec);
+/// assert!(array.is_ok());
+/// assert_eq!(array.unwrap(), [0, 1, 2, 3]);
+///
+/// let vec = vec![0, 1, 2];
+/// let array = core::array::try_from_iter::<_, 4>(vec);
+/// assert!(array.is_err());
+/// ```
+#[unstable(feature = "try_from_iter", issue = "none")]
+#[inline]
+pub fn try_from_iter<I, const N: usize>(iter: I) -> Result<[I::Item; N], IntoIter<I::Item, N>>
+where
+    I: IntoIterator,
+{
+    iter.into_iter().next_chunk()
+}
diff --git a/library/core/tests/array.rs b/library/core/tests/array.rs
index f268fe3ae7ba8..580f5b4e8839b 100644
--- a/library/core/tests/array.rs
+++ b/library/core/tests/array.rs
@@ -700,3 +700,15 @@ fn array_into_iter_rfold() {
     let s = it.rfold(10, |a, b| 10 * a + b);
     assert_eq!(s, 10432);
 }
+
+#[test]
+fn array_try_fill_from() {
+    let vec = vec![0, 1, 2, 3];
+    let array = core::array::try_from_iter::<_, 4>(vec);
+    assert!(array.is_ok());
+    assert_eq!(array.unwrap(), [0, 1, 2, 3]);
+
+    let vec = vec![0, 1, 2];
+    let array = core::array::try_from_iter::<_, 4>(vec);
+    assert!(array.is_err());
+}
diff --git a/library/core/tests/lib.rs b/library/core/tests/lib.rs
index 42a26ae1675c1..17e57abed0c87 100644
--- a/library/core/tests/lib.rs
+++ b/library/core/tests/lib.rs
@@ -108,6 +108,7 @@
 #![feature(utf8_chunks)]
 #![feature(is_ascii_octdigit)]
 #![feature(get_many_mut)]
+#![feature(try_from_iter)]
 #![deny(unsafe_op_in_unsafe_fn)]
 #![deny(fuzzy_provenance_casts)]
 

From 7f856a332004fa0cfcf56b819b429442fcef7fc0 Mon Sep 17 00:00:00 2001
From: emilHof <95590295+emilHof@users.noreply.github.com>
Date: Mon, 13 Feb 2023 11:15:56 -0500
Subject: [PATCH 2/2] Add new line to EOF

---
 library/core/tests/array.rs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/library/core/tests/array.rs b/library/core/tests/array.rs
index d22d63ee3aea7..ea32e0f967f7f 100644
--- a/library/core/tests/array.rs
+++ b/library/core/tests/array.rs
@@ -736,4 +736,4 @@ fn array_map_drops_unmapped_elements_on_panic() {
         assert!(success.is_err());
         assert_eq!(counter.load(Ordering::SeqCst), MAX);
     }
-}
\ No newline at end of file
+}