X-Git-Url: https://git.lizzy.rs/?a=blobdiff_plain;f=src%2Flibcore%2Fcell.rs;h=e3292ecc1d1871c0cd8bb4efb1e50a013250b5ed;hb=aba385abbd69146387893c84951a06ec283f4d10;hp=817c04d0af924db10119d86dd9765ae28cb739d3;hpb=de401900b4d25b4a01c5f3e34554f9a656f89f84;p=rust.git

diff --git a/src/libcore/cell.rs b/src/libcore/cell.rs
index 817c04d0af9..e3292ecc1d1 100644
--- a/src/libcore/cell.rs
+++ b/src/libcore/cell.rs
@@ -187,6 +187,8 @@
 //! ```
 //!
 
+// ignore-tidy-undocumented-unsafe
+
 #![stable(feature = "rust1", since = "1.0.0")]
 
 use crate::cmp::Ordering;
@@ -1546,6 +1548,36 @@ pub const fn get(&self) -> *mut T {
         // #[repr(transparent)]
         self as *const UnsafeCell<T> as *const T as *mut T
     }
+
+    /// Gets a mutable pointer to the wrapped value.
+    ///
+    /// This can be cast to a pointer of any kind.
+    /// Ensure that the access is unique (no active references, mutable or not)
+    /// when casting to `&mut T`, and ensure that there are no mutations
+    /// or mutable aliases going on when casting to `&T`.
+    ///
+    /// # Examples
+    ///
+    /// Gradual initialization of an `UnsafeCell`:
+    ///
+    /// ```
+    /// #![feature(unsafe_cell_raw_get)]
+    /// use std::cell::UnsafeCell;
+    /// use std::mem::MaybeUninit;
+    ///
+    /// let m = MaybeUninit::<UnsafeCell<i32>>::uninit();
+    /// unsafe { m.as_ptr().raw_get().write(5); }
+    /// let uc = unsafe { m.assume_init() };
+    ///
+    /// assert_eq!(uc.into_inner(), 5);
+    /// ```
+    #[inline]
+    #[unstable(feature = "unsafe_cell_raw_get", issue = "0")]
+    pub const fn raw_get(self: *const Self) -> *mut T {
+        // We can just cast the pointer from `UnsafeCell<T>` to `T` because of
+        // #[repr(transparent)]
+        self as *const T as *mut T
+    }
 }
 
 #[stable(feature = "unsafe_cell_default", since = "1.10.0")]