From 28a77c4de1e5992f3004bbd4a5074b92a1a3ca8a Mon Sep 17 00:00:00 2001
From: LeSeulArtichaut <leseulartichaut@gmail.com>
Date: Wed, 21 Oct 2020 21:56:25 +0200
Subject: [PATCH] Make `ControlFlow` `#[must_use]`

---
 library/core/src/ops/control_flow.rs | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/library/core/src/ops/control_flow.rs b/library/core/src/ops/control_flow.rs
index b0c7dc1a5187..798e3f670624 100644
--- a/library/core/src/ops/control_flow.rs
+++ b/library/core/src/ops/control_flow.rs
@@ -3,6 +3,7 @@ use crate::ops::Try;
 /// Used to make try_fold closures more like normal loops
 #[unstable(feature = "control_flow_enum", reason = "new API", issue = "75744")]
 #[derive(Debug, Clone, Copy, PartialEq)]
+#[must_use = "this `ControlFlow` may be a `Break` variant, which should be handled"]
 pub enum ControlFlow<C, B> {
     /// Continue in the loop, using the given value for the next iteration
     Continue(C),
@@ -99,7 +100,7 @@ impl<C> ControlFlow<C, ()> {
     /// use std::ops::ControlFlow;
     ///
     /// let mut partial_sum = 0;
-    /// (1..10).chain(20..25).try_for_each(|x| {
+    /// let _ = (1..10).chain(20..25).try_for_each(|x| {
     ///     if partial_sum > 100 { ControlFlow::BREAK }
     ///     else { partial_sum += x; ControlFlow::CONTINUE }
     /// });