Make UnsafeCell::value private

Author: petrochenkov

Diff for: src/libcore/cell.rs

@@ -631,18 +631,10 @@ impl<'b, T: ?Sized> DerefMut for RefMut<'b, T> {
 ///
 /// unsafe impl<T> Sync for NotThreadSafe<T> {}
 /// ```
-///
-/// **NOTE:** `UnsafeCell<T>`'s fields are public to allow static initializers. It is not
-/// recommended to access its fields directly, `get` should be used instead.
 #[lang = "unsafe_cell"]
 #[stable(feature = "rust1", since = "1.0.0")]
 pub struct UnsafeCell<T: ?Sized> {
-    /// Wrapped value
-    ///
-    /// This field should not be accessed directly, it is made public for static
-    /// initializers.
-    #[unstable(feature = "core")]
-    pub value: T,
+    value: T,
 }
 
 impl<T: ?Sized> !Sync for UnsafeCell<T> {}
@@ -651,8 +643,7 @@ impl<T> UnsafeCell<T> {
     /// Constructs a new instance of `UnsafeCell` which will wrap the specified
     /// value.
     ///
-    /// All access to the inner value through methods is `unsafe`, and it is highly discouraged to
-    /// access the fields directly.
+    /// All access to the inner value through methods is `unsafe`.
     ///
     /// # Examples
     ///