alloc: impl fmt::Pointer for Rc, Arc and Box

Closes #24091

3 files changed, 24 insertions, 0 deletions

diff --git a/src/liballoc/arc.rs b/src/liballoc/arc.rs
index 68bde147611..ff176d81591 100644
--- a/src/liballoc/arc.rs
+++ b/src/liballoc/arc.rs
@@ -669,6 +669,13 @@ impl<T: fmt::Debug> fmt::Debug for Arc<T> {
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
+impl<T> fmt::Pointer for Arc<T> {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        fmt::Pointer::fmt(&*self._ptr, f)
+    }
+}
+
+#[stable(feature = "rust1", since = "1.0.0")]
 impl<T: Default + Sync + Send> Default for Arc<T> {
     #[stable(feature = "rust1", since = "1.0.0")]
     fn default() -> Arc<T> { Arc::new(Default::default()) }
diff --git a/src/liballoc/boxed.rs b/src/liballoc/boxed.rs
index 2801cf38cb7..4468e425a85 100644
--- a/src/liballoc/boxed.rs
+++ b/src/liballoc/boxed.rs
@@ -276,6 +276,16 @@ impl<T: fmt::Debug + ?Sized> fmt::Debug for Box<T> {
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
+impl<T> fmt::Pointer for Box<T> {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        // It's not possible to extract the inner Uniq directly from the Box,
+        // instead we cast it to a *const which aliases the Unique
+        let ptr: *const T = &**self;
+        fmt::Pointer::fmt(&ptr, f)
+    }
+}
+
+#[stable(feature = "rust1", since = "1.0.0")]
 impl<T: ?Sized> Deref for Box<T> {
     type Target = T;
 
diff --git a/src/liballoc/rc.rs b/src/liballoc/rc.rs
index 56822cfe28a..67805d10a4a 100644
--- a/src/liballoc/rc.rs
+++ b/src/liballoc/rc.rs
@@ -634,6 +634,13 @@ impl<T: fmt::Debug> fmt::Debug for Rc<T> {
     }
 }
 
+#[stable(feature = "rust1", since = "1.0.0")]
+impl<T> fmt::Pointer for Rc<T> {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        fmt::Pointer::fmt(&*self._ptr, f)
+    }
+}
+
 /// A weak version of `Rc<T>`.
 ///
 /// Weak references do not count when determining if the inner value should be