From dfcf764d093445d1c5eedbc7ef1f72c7fa5dcac8 Mon Sep 17 00:00:00 2001
From: Konrad Borowski <konrad@borowski.pw>
Date: Thu, 5 Dec 2019 10:28:11 +0100
Subject: Document why Pin implementations aren't derived

---
 src/libcore/pin.rs | 6 ++++++
 1 file changed, 6 insertions(+)

(limited to 'src/libcore')

diff --git a/src/libcore/pin.rs b/src/libcore/pin.rs
index f4e0e647434..015a75ba3dc 100644
--- a/src/libcore/pin.rs
+++ b/src/libcore/pin.rs
@@ -403,6 +403,12 @@ pub struct Pin<P> {
     pointer: P,
 }
 
+// The following implementations aren't derived in order to avoid soundness
+// issues. `&self.pointer` should not be accessible to untrusted trait
+// implementations.
+//
+// See <https://internals.rust-lang.org/t/unsoundness-in-pin/11311/73> for more details.
+
 #[stable(feature = "pin_trait_impls", since = "1.41.0")]
 impl<P: Deref, Q: Deref> PartialEq<Pin<Q>> for Pin<P>
 where
-- 
cgit 1.4.1-3-g733a5