Auto merge of #91799 - matthiaskrgr:rollup-b38xx6i, r=matthiaskrgr

Rollup of 6 pull requests

Successful merges:

 - #83174 (Suggest using a temporary variable to fix borrowck errors)
 - #89734 (Point at capture points for non-`'static` reference crossing a `yield` point)
 - #90270 (Make `Borrow` and `BorrowMut` impls `const`)
 - #90741 (Const `Option::cloned`)
 - #91548 (Add spin_loop hint for RISC-V architecture)
 - #91721 (Minor improvements to `future::join!`'s implementation)

Failed merges:

r? `@ghost`
`@rustbot` modify labels: rollup

1 files changed, 4 insertions, 2 deletions

diff --git a/library/core/src/array/mod.rs b/library/core/src/array/mod.rs
index 5e295ffbff7..0e33e95271e 100644
--- a/library/core/src/array/mod.rs
+++ b/library/core/src/array/mod.rs
@@ -162,14 +162,16 @@ impl<T, const N: usize> AsMut<[T]> for [T; N] {
 }
 
 #[stable(feature = "array_borrow", since = "1.4.0")]
-impl<T, const N: usize> Borrow<[T]> for [T; N] {
+#[rustc_const_unstable(feature = "const_borrow", issue = "91522")]
+impl<T, const N: usize> const Borrow<[T]> for [T; N] {
     fn borrow(&self) -> &[T] {
         self
     }
 }
 
 #[stable(feature = "array_borrow", since = "1.4.0")]
-impl<T, const N: usize> BorrowMut<[T]> for [T; N] {
+#[rustc_const_unstable(feature = "const_borrow", issue = "91522")]
+impl<T, const N: usize> const BorrowMut<[T]> for [T; N] {
     fn borrow_mut(&mut self) -> &mut [T] {
         self
     }