From 1ed32c51fb2fc571c67b1303721ea772a9c468d6 Mon Sep 17 00:00:00 2001
From: Trevor Gross <tmgross@umich.edu>
Date: Mon, 14 Oct 2024 18:32:54 -0400
Subject: [PATCH] Stabilize `const_maybe_uninit_write`

Mark the following API const stable:

    impl<T> MaybeUninit<T> {
        pub const fn write(&mut self, val: T) -> &mut T;
    }

This depends on `const_mut_refs` and `const_maybe_uninit_assume_init`,
both of which have recently been stabilized.

Tracking issue: <https://github.com/rust-lang/rust/issues/63567>
---
 library/alloc/src/lib.rs             | 1 -
 library/core/src/mem/maybe_uninit.rs | 5 +++--
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/library/alloc/src/lib.rs b/library/alloc/src/lib.rs
index 50bf385d671e3..043c00d79edca 100644
--- a/library/alloc/src/lib.rs
+++ b/library/alloc/src/lib.rs
@@ -110,7 +110,6 @@
 #![feature(const_box)]
 #![feature(const_eval_select)]
 #![feature(const_heap)]
-#![feature(const_maybe_uninit_write)]
 #![feature(const_pin)]
 #![feature(const_size_of_val)]
 #![feature(const_vec_string_slice)]
diff --git a/library/core/src/mem/maybe_uninit.rs b/library/core/src/mem/maybe_uninit.rs
index f992785c43bb7..b3398ca59e185 100644
--- a/library/core/src/mem/maybe_uninit.rs
+++ b/library/core/src/mem/maybe_uninit.rs
@@ -485,9 +485,10 @@ impl<T> MaybeUninit<T> {
     ///     }
     /// }
     /// ```
-    #[stable(feature = "maybe_uninit_write", since = "1.55.0")]
-    #[rustc_const_unstable(feature = "const_maybe_uninit_write", issue = "63567")]
     #[inline(always)]
+    #[stable(feature = "maybe_uninit_write", since = "1.55.0")]
+    #[cfg_attr(bootstrap, rustc_allow_const_fn_unstable(const_mut_refs))]
+    #[rustc_const_stable(feature = "const_maybe_uninit_write", since = "CURRENT_RUSTC_VERSION")]
     pub const fn write(&mut self, val: T) -> &mut T {
         *self = MaybeUninit::new(val);
         // SAFETY: We just initialized this value.