stabilize box_uninit_write

Author: slanterns

Diff for: library/alloc/src/boxed.rs

@@ -937,8 +937,6 @@ impl<T, A: Allocator> Box<mem::MaybeUninit<T>, A> {
     /// # Examples
     ///
     /// ```
-    /// #![feature(box_uninit_write)]
-    ///
     /// let big_box = Box::<[usize; 1024]>::new_uninit();
     ///
     /// let mut array = [0; 1024];
@@ -954,7 +952,7 @@ impl<T, A: Allocator> Box<mem::MaybeUninit<T>, A> {
     ///     assert_eq!(*x, i);
     /// }
     /// ```
-    #[unstable(feature = "box_uninit_write", issue = "129397")]
+    #[unstable(feature = "box_uninit_write", since = "CURRENT_RUSTC_VERSION")]
     #[inline]
     pub fn write(mut boxed: Self, value: T) -> Box<T, A> {
         unsafe {

Diff for: library/alloc/src/lib.rs

@@ -102,7 +102,6 @@
 #![feature(assert_matches)]
 #![feature(async_fn_traits)]
 #![feature(async_iterator)]
-#![feature(box_uninit_write)]
 #![feature(bstr)]
 #![feature(bstr_internals)]
 #![feature(char_max_len)]