1 files changed, 3 insertions, 0 deletions
diff --git a/library/alloc/src/rc.rs b/library/alloc/src/rc.rs
index 2f4a131136e..493cf3117ed 100644
--- a/library/alloc/src/rc.rs
+++ b/library/alloc/src/rc.rs
@@ -2093,6 +2093,7 @@ impl<T: ?Sized> Weak<T> {
     /// ```
     ///
     /// [`null`]: ptr::null
+    #[must_use]
     #[stable(feature = "rc_as_ptr", since = "1.45.0")]
     pub fn as_ptr(&self) -> *const T {
         let ptr: *mut RcBox<T> = NonNull::as_ptr(self.ptr);
@@ -2229,6 +2230,8 @@ impl<T: ?Sized> Weak<T> {
     ///
     /// assert!(weak_five.upgrade().is_none());
     /// ```
+    #[must_use = "this returns a new `Rc`, \
+                  without modifying the original weak pointer"]
     #[stable(feature = "rc_weak", since = "1.4.0")]
     pub fn upgrade(&self) -> Option<Rc<T>> {
         let inner = self.inner()?;