From ab19cd3dea151cf070d504c605c618c1d05b91e9 Mon Sep 17 00:00:00 2001
From: Folkert de Vries <folkert@folkertdev.nl>
Date: Sun, 26 Apr 2026 14:00:51 +0200
Subject: [PATCH] c-variadic: add a `Copy` bound to `VaArgSafe`

because a VaList can be cloned, the same c-variadic argument can be read twice and that is only safe if the argument type is copy
---
 library/core/src/ffi/va_list.rs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/library/core/src/ffi/va_list.rs b/library/core/src/ffi/va_list.rs
index fe6fae478957..afd166d4931e 100644
--- a/library/core/src/ffi/va_list.rs
+++ b/library/core/src/ffi/va_list.rs
@@ -333,7 +333,7 @@ impl<T> Sealed for *const T {}
 // types with an alignment larger than 8, or with a non-scalar layout. Inline assembly can be used
 // to accept unsupported types in the meantime.
 #[lang = "va_arg_safe"]
-pub unsafe trait VaArgSafe: sealed::Sealed {}
+pub unsafe trait VaArgSafe: Copy + sealed::Sealed {}
 
 crate::cfg_select! {
     any(target_arch = "avr", target_arch = "msp430") => {