From 6b016d7e592798610f6313891cbc3ba81906f894 Mon Sep 17 00:00:00 2001
From: Yotam Ofek <yotam.ofek@gmail.com>
Date: Mon, 3 Feb 2025 19:18:07 +0000
Subject: [PATCH] Mark `std::fmt::from_fn` as `#[must_use]`

---
 library/core/src/fmt/builders.rs | 1 +
 1 file changed, 1 insertion(+)

diff --git a/library/core/src/fmt/builders.rs b/library/core/src/fmt/builders.rs
index 1862be0e86c5d..665b05b12ec07 100644
--- a/library/core/src/fmt/builders.rs
+++ b/library/core/src/fmt/builders.rs
@@ -1228,6 +1228,7 @@ impl<'a, 'b: 'a> DebugMap<'a, 'b> {
 /// assert_eq!(format!("{:?}", wrapped), "'a'");
 /// ```
 #[unstable(feature = "debug_closure_helpers", issue = "117729")]
+#[must_use = "returns a type implementing Debug and Display, which do not have any effects unless they are used"]
 pub fn from_fn<F: Fn(&mut fmt::Formatter<'_>) -> fmt::Result>(f: F) -> FromFn<F> {
     FromFn(f)
 }