From e27bfb6e23774b61619b0d83a66e7f079c3ada37 Mon Sep 17 00:00:00 2001
From: John Kugelman <john@kugelman.name>
Date: Fri, 8 Oct 2021 23:31:57 -0400
Subject: [PATCH] Add #[must_use] to stdin/stdout/stderr locks

---
 library/std/src/io/stdio.rs | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/library/std/src/io/stdio.rs b/library/std/src/io/stdio.rs
index 14a63303711..1ac3bbc95c6 100644
--- a/library/std/src/io/stdio.rs
+++ b/library/std/src/io/stdio.rs
@@ -256,6 +256,7 @@ pub struct Stdin {
 ///     Ok(())
 /// }
 /// ```
+#[must_use = "if unused stdin will immediately unlock"]
 #[stable(feature = "rust1", since = "1.0.0")]
 pub struct StdinLock<'a> {
     inner: MutexGuard<'a, BufReader<StdinRaw>>,
@@ -624,6 +625,7 @@ pub struct Stdout {
 /// When operating in a console, the Windows implementation of this stream does not support
 /// non-UTF-8 byte sequences. Attempting to write bytes that are not valid UTF-8 will return
 /// an error.
+#[must_use = "if unused stdout will immediately unlock"]
 #[stable(feature = "rust1", since = "1.0.0")]
 pub struct StdoutLock<'a> {
     inner: ReentrantMutexGuard<'a, RefCell<LineWriter<StdoutRaw>>>,
@@ -907,6 +909,7 @@ pub struct Stderr {
 /// When operating in a console, the Windows implementation of this stream does not support
 /// non-UTF-8 byte sequences. Attempting to write bytes that are not valid UTF-8 will return
 /// an error.
+#[must_use = "if unused stderr will immediately unlock"]
 #[stable(feature = "rust1", since = "1.0.0")]
 pub struct StderrLock<'a> {
     inner: ReentrantMutexGuard<'a, RefCell<StderrRaw>>,