From 602401c4d49753dfd9d351ffcf0c72c00ff4c62f Mon Sep 17 00:00:00 2001
From: Ralf Jung <post@ralfj.de>
Date: Sun, 31 Mar 2024 12:46:37 +0200
Subject: [PATCH] warn against implementing Freeze

---
 library/core/src/marker.rs | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/library/core/src/marker.rs b/library/core/src/marker.rs
index 385c288db12..1d073a6d649 100644
--- a/library/core/src/marker.rs
+++ b/library/core/src/marker.rs
@@ -817,6 +817,13 @@ pub trait DiscriminantKind {
 /// This can be used to declare that a constant with a generic type
 /// will not contain interior mutability, and subsequently allow
 /// placing the constant behind references.
+///
+/// # Safety
+///
+/// This trait is a core part of the language, it is just expressed as a trait in libcore for
+/// convenience. Do *not* implement it for other types.
+// FIXME: Eventually this trait should become `#[rustc_deny_explicit_impl]`.
+// That requires porting the impls below to native internal impls.
 #[lang = "freeze"]
 #[unstable(feature = "freeze", issue = "121675")]
 pub unsafe auto trait Freeze {}