From 83d601d38cb11edee01fd6cbd3b7635db5bed337 Mon Sep 17 00:00:00 2001
From: Ammar Askar <ammar@ammaraskar.com>
Date: Sat, 31 Oct 2020 15:55:07 -0700
Subject: [PATCH] Add a Sync bound for GenericMutexGuard. Fixes #53.

---
 src/sync/mutex.rs | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/src/sync/mutex.rs b/src/sync/mutex.rs
index c301548..a26f472 100644
--- a/src/sync/mutex.rs
+++ b/src/sync/mutex.rs
@@ -310,6 +310,13 @@ impl<MutexType: RawMutex, T> DerefMut for GenericMutexGuard<'_, MutexType, T> {
     }
 }
 
+// Safety: GenericMutexGuard may only be used across threads if the underlying
+// type is Sync.
+unsafe impl<MutexType: RawMutex, T: Sync> Sync
+    for GenericMutexGuard<'_, MutexType, T>
+{
+}
+
 /// A future which resolves when the target mutex has been successfully acquired.
 #[must_use = "futures do nothing unless polled"]
 pub struct GenericMutexLockFuture<'a, MutexType: RawMutex, T: 'a> {