1 files changed, 9 insertions, 6 deletions
diff --git a/library/alloc/src/sync.rs b/library/alloc/src/sync.rs
index 8eee7cff208..dba1449347a 100644
--- a/library/alloc/src/sync.rs
+++ b/library/alloc/src/sync.rs
@@ -2740,7 +2740,7 @@ impl<T: ?Sized> Weak<T> {
     /// # Safety
     ///
     /// The pointer must have originated from the [`into_raw`] and must still own its potential
-    /// weak reference.
+    /// weak reference, and must point to a block of memory allocated by global allocator.
     ///
     /// It is allowed for the strong count to be 0 at the time of calling this. Nevertheless, this
     /// takes ownership of one weak reference currently represented as a raw pointer (the weak
@@ -3466,11 +3466,14 @@ impl<T: Default> Default for Arc<T> {
     fn default() -> Arc<T> {
         unsafe {
             Self::from_inner(
-                Box::leak(Box::write(Box::new_uninit(), ArcInner {
-                    strong: atomic::AtomicUsize::new(1),
-                    weak: atomic::AtomicUsize::new(1),
-                    data: T::default(),
-                }))
+                Box::leak(Box::write(
+                    Box::new_uninit(),
+                    ArcInner {
+                        strong: atomic::AtomicUsize::new(1),
+                        weak: atomic::AtomicUsize::new(1),
+                        data: T::default(),
+                    },
+                ))
                 .into(),
             )
         }