From c3f0577002b5c158c63dab92476d94af954086f1 Mon Sep 17 00:00:00 2001
From: John Kugelman <john@kugelman.name>
Date: Mon, 11 Oct 2021 20:40:03 -0400
Subject: Add #[must_use] to non-mutating verb methods

---
 library/alloc/src/rc.rs | 2 ++
 1 file changed, 2 insertions(+)

(limited to 'library/alloc/src/rc.rs')

diff --git a/library/alloc/src/rc.rs b/library/alloc/src/rc.rs
index 2f4a131136e..4023d7b21ed 100644
--- a/library/alloc/src/rc.rs
+++ b/library/alloc/src/rc.rs
@@ -2229,6 +2229,8 @@ 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()?;
-- 
cgit 1.4.1-3-g733a5