From 393434c29eee2aa939dddfb8db0a4d692bcb96c0 Mon Sep 17 00:00:00 2001
From: Alex Saveau <saveau.alexandre@gmail.com>
Date: Sat, 15 Oct 2022 15:57:19 -0700
Subject: [PATCH] Add MaybeUninit array transpose impls

Signed-off-by: Alex Saveau <saveau.alexandre@gmail.com>
---
 library/core/src/mem/maybe_uninit.rs | 37 ++++++++++++++++++++++++++++
 1 file changed, 37 insertions(+)

diff --git a/library/core/src/mem/maybe_uninit.rs b/library/core/src/mem/maybe_uninit.rs
index e2ae39fbab3..2ae96367628 100644
--- a/library/core/src/mem/maybe_uninit.rs
+++ b/library/core/src/mem/maybe_uninit.rs
@@ -1284,3 +1284,40 @@ pub fn slice_as_bytes_mut(this: &mut [MaybeUninit<T>]) -> &mut [MaybeUninit<u8>]
         }
     }
 }
+
+impl<T, const N: usize> MaybeUninit<[T; N]> {
+    /// Transposes a `MaybeUninit<[T; N]>` into a `[MaybeUninit<T>; N]`.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// #![feature(maybe_uninit_uninit_array_transpose)]
+    /// # use std::mem::MaybeUninit;
+    ///
+    /// let data: [MaybeUninit<u8>; 1000] = MaybeUninit::uninit().transpose();
+    /// ```
+    #[unstable(feature = "maybe_uninit_uninit_array_transpose", issue = "96097")]
+    pub fn transpose(self) -> [MaybeUninit<T>; N] {
+        // SAFETY: T and MaybeUninit<T> have the same layout
+        unsafe { super::transmute_copy(&ManuallyDrop::new(self)) }
+    }
+}
+
+impl<T, const N: usize> [MaybeUninit<T>; N] {
+    /// Transposes a `[MaybeUninit<T>; N]` into a `MaybeUninit<[T; N]>`.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// #![feature(maybe_uninit_uninit_array_transpose)]
+    /// # use std::mem::MaybeUninit;
+    ///
+    /// let data = [MaybeUninit::<u8>::uninit(); 1000];
+    /// let data: MaybeUninit<[u8; 1000]> = data.transpose();
+    /// ```
+    #[unstable(feature = "maybe_uninit_uninit_array_transpose", issue = "96097")]
+    pub fn transpose(self) -> MaybeUninit<[T; N]> {
+        // SAFETY: T and MaybeUninit<T> have the same layout
+        unsafe { super::transmute_copy(&ManuallyDrop::new(self)) }
+    }
+}