From 6c3825e537e15cc7633337e2dababb61b4cb1e97 Mon Sep 17 00:00:00 2001
From: Jack Wrenn <jack@wrenn.fyi>
Date: Mon, 23 Dec 2024 15:20:33 +0000
Subject: [PATCH] Silence `private_bounds` lint in `KnownLayout` derive

For reasons not-yet-known, the `private_bounds` lint flags the
output of `derive(KnownLayout)` on `repr(C)` structs generated
by macros. This is likely a rustc bug, but to preserve a good
experience for our users, we nonetheless, `allow(private_bounds)`.

Fixes #2177
---
 zerocopy-derive/src/lib.rs | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/zerocopy-derive/src/lib.rs b/zerocopy-derive/src/lib.rs
index c7fac7d24e..068cead914 100644
--- a/zerocopy-derive/src/lib.rs
+++ b/zerocopy-derive/src/lib.rs
@@ -320,6 +320,9 @@ fn derive_known_layout_inner(ast: &DeriveInput, _top_level: Trait) -> Result<Tok
                 // `#ty`, not `__ZerocopyKnownLayoutMaybeUninit` (see #2116).
                 #repr
                 #[doc(hidden)]
+                // Required on some rustc versions due to a lint that is only
+                // triggered on macro-generated code. See #2177 for details.
+                #[allow(private_bounds)]
                 #vis struct __ZerocopyKnownLayoutMaybeUninit<#params> (
                     #(::zerocopy::util::macro_util::core_reexport::mem::MaybeUninit<
                         <#ident #ty_generics as