From 23a4050f7dbc8675df6305b9968a3d5648518ff4 Mon Sep 17 00:00:00 2001
From: David Tolnay <dtolnay@gmail.com>
Date: Thu, 20 May 2021 19:43:41 -0700
Subject: [PATCH] Weak's type parameter may dangle on drop

---
 library/alloc/src/rc.rs   | 2 +-
 library/alloc/src/sync.rs | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/library/alloc/src/rc.rs b/library/alloc/src/rc.rs
index 800952f7a5ece..f19a13c8defef 100644
--- a/library/alloc/src/rc.rs
+++ b/library/alloc/src/rc.rs
@@ -2303,7 +2303,7 @@ impl<T: ?Sized> Weak<T> {
 }
 
 #[stable(feature = "rc_weak", since = "1.4.0")]
-impl<T: ?Sized> Drop for Weak<T> {
+unsafe impl<#[may_dangle] T: ?Sized> Drop for Weak<T> {
     /// Drops the `Weak` pointer.
     ///
     /// # Examples
diff --git a/library/alloc/src/sync.rs b/library/alloc/src/sync.rs
index 17927f5f5fdc4..02a739309cde0 100644
--- a/library/alloc/src/sync.rs
+++ b/library/alloc/src/sync.rs
@@ -2015,7 +2015,7 @@ impl<T> Default for Weak<T> {
 }
 
 #[stable(feature = "arc_weak", since = "1.4.0")]
-impl<T: ?Sized> Drop for Weak<T> {
+unsafe impl<#[may_dangle] T: ?Sized> Drop for Weak<T> {
     /// Drops the `Weak` pointer.
     ///
     /// # Examples