From 1e445f48d4d0880d4c158c3ae96be8f0d9ad2e02 Mon Sep 17 00:00:00 2001
From: Henry Sloan <henryksloan@gmail.com>
Date: Mon, 12 Aug 2024 18:48:03 -0700
Subject: [PATCH] Add must_use attribute to Coroutine trait

---
 library/core/src/ops/coroutine.rs | 1 +
 tests/ui/coroutine/issue-58888.rs | 5 +++--
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/library/core/src/ops/coroutine.rs b/library/core/src/ops/coroutine.rs
index 13df888d24c..c7d596d74c3 100644
--- a/library/core/src/ops/coroutine.rs
+++ b/library/core/src/ops/coroutine.rs
@@ -69,6 +69,7 @@ pub enum CoroutineState<Y, R> {
 #[lang = "coroutine"]
 #[unstable(feature = "coroutine_trait", issue = "43122")]
 #[fundamental]
+#[must_use = "coroutines are lazy and do nothing unless resumed"]
 pub trait Coroutine<R = ()> {
     /// The type of value this coroutine yields.
     ///
diff --git a/tests/ui/coroutine/issue-58888.rs b/tests/ui/coroutine/issue-58888.rs
index 6266f97ce8c..e4fada0cd43 100644
--- a/tests/ui/coroutine/issue-58888.rs
+++ b/tests/ui/coroutine/issue-58888.rs
@@ -13,7 +13,8 @@ fn get_connection(&self) -> impl Iterator<Item = ()> {
     }
 
     fn check_connection(&self) -> impl Coroutine<Yield = (), Return = ()> + '_ {
-        #[coroutine] move || {
+        #[coroutine]
+        move || {
             let iter = self.get_connection();
             for i in iter {
                 yield i
@@ -23,5 +24,5 @@ fn check_connection(&self) -> impl Coroutine<Yield = (), Return = ()> + '_ {
 }
 
 fn main() {
-    Database.check_connection();
+    let _ = Database.check_connection();
 }