Auto merge of #79485 - EllenNyan:stabilize_unsafe_cell_get_mut, r=m-ou-se

Stabilize `unsafe_cell_get_mut`

Tracking issue: #76943

r? `@m-ou-se`

Author: bors

Diff for: library/core/src/cell.rs

@@ -1580,7 +1580,7 @@ impl<T: ?Sized + fmt::Display> fmt::Display for RefMut<'_, T> {
 /// `&UnsafeCell<_>` reference); there is no magic whatsoever when dealing with _exclusive_
 /// accesses (_e.g._, through an `&mut UnsafeCell<_>`): neither the cell nor the wrapped value
 /// may be aliased for the duration of that `&mut` borrow.
-/// This is showcased by the [`.get_mut()`] accessor, which is a non-`unsafe` getter that yields
+/// This is showcased by the [`.get_mut()`] accessor, which is a _safe_ getter that yields
 /// a `&mut T`.
 ///
 /// [`.get_mut()`]: `UnsafeCell::get_mut`
@@ -1618,7 +1618,6 @@ impl<T: ?Sized + fmt::Display> fmt::Display for RefMut<'_, T> {
 /// implies exclusive access to its `T`:
 ///
 /// ```rust
-/// #![feature(unsafe_cell_get_mut)]
 /// #![forbid(unsafe_code)] // with exclusive accesses,
 ///                         // `UnsafeCell` is a transparent no-op wrapper,
 ///                         // so no need for `unsafe` here.
@@ -1722,7 +1721,6 @@ impl<T: ?Sized> UnsafeCell<T> {
     /// # Examples
     ///
     /// ```
-    /// #![feature(unsafe_cell_get_mut)]
     /// use std::cell::UnsafeCell;
     ///
     /// let mut c = UnsafeCell::new(5);
@@ -1731,7 +1729,7 @@ impl<T: ?Sized> UnsafeCell<T> {
     /// assert_eq!(*c.get_mut(), 6);
     /// ```
     #[inline]
-    #[unstable(feature = "unsafe_cell_get_mut", issue = "76943")]
+    #[stable(feature = "unsafe_cell_get_mut", since = "1.50.0")]
     pub fn get_mut(&mut self) -> &mut T {
         &mut self.value
     }

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

@@ -325,7 +325,6 @@
 #![feature(try_reserve)]
 #![feature(unboxed_closures)]
 #![feature(unsafe_block_in_unsafe_fn)]
-#![feature(unsafe_cell_get_mut)]
 #![feature(unsafe_cell_raw_get)]
 #![feature(unwind_attributes)]
 #![feature(vec_into_raw_parts)]