Adding Features Rc::clone_raw() and Arc::clone_raw()

library/alloc/src/rc.rs

@@ -743,6 +743,16 @@ impl<T: ?Sized> Rc<T> {
         unsafe { Self::from_ptr(rc_ptr) }
     }
 
+    /// Obtains a new reference to a raw [`Rc`] pointer, without taking ownership.
+    #[unstable(feature = "rc_clone_raw", issue = "48108")]
+    pub unsafe fn clone_raw(ptr: *const T) -> Self {
+        let result = unsafe { Rc::from_raw(ptr) };
+
+        forget(result.clone());
+
+        result
+    }
+
     /// Creates a new [`Weak`] pointer to this allocation.
     ///
     /// # Examples

library/alloc/src/sync.rs

@@ -14,7 +14,7 @@ use core::hint;
 use core::intrinsics::abort;
 use core::iter;
 use core::marker::{PhantomData, Unpin, Unsize};
-use core::mem::{self, align_of_val, size_of_val};
+use core::mem::{self, align_of_val, forget, size_of_val};
 use core::ops::{CoerceUnsized, Deref, DispatchFromDyn, Receiver};
 use core::pin::Pin;
 use core::ptr::{self, NonNull};
@@ -760,6 +760,16 @@ impl<T: ?Sized> Arc<T> {
         }
     }
 
+    /// Obtains a new reference to a raw [`Arc`] pointer, without taking ownership.
+    #[unstable(feature = "rc_clone_raw", issue = "48108")]
+    pub fn clone_raw(ptr: *const T) -> Self {
+        let result = unsafe { Arc::from_raw(ptr) };
+
+        forget(result.clone());
+
+        result
+    }
+
     /// Creates a new [`Weak`] pointer to this allocation.
     ///
     /// # Examples