From f2172ea4e25021cae0efb9ef078373a8cca43885 Mon Sep 17 00:00:00 2001
From: Ralf Jung <post@ralfj.de>
Date: Mon, 14 Aug 2023 10:15:25 +0200
Subject: [PATCH] avoid transmuting Box when we can just cast raw pointers
 instead

---
 library/alloc/src/boxed.rs | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/library/alloc/src/boxed.rs b/library/alloc/src/boxed.rs
index 8697a77db3b..96b93830f96 100644
--- a/library/alloc/src/boxed.rs
+++ b/library/alloc/src/boxed.rs
@@ -2183,7 +2183,7 @@ impl dyn Error + Send {
         let err: Box<dyn Error> = self;
         <dyn Error>::downcast(err).map_err(|s| unsafe {
             // Reapply the `Send` marker.
-            mem::transmute::<Box<dyn Error>, Box<dyn Error + Send>>(s)
+            Box::from_raw(Box::into_raw(s) as *mut (dyn Error + Send))
         })
     }
 }
@@ -2197,7 +2197,7 @@ impl dyn Error + Send + Sync {
         let err: Box<dyn Error> = self;
         <dyn Error>::downcast(err).map_err(|s| unsafe {
             // Reapply the `Send + Sync` marker.
-            mem::transmute::<Box<dyn Error>, Box<dyn Error + Send + Sync>>(s)
+            Box::from_raw(Box::into_raw(s) as *mut (dyn Error + Send + Sync))
         })
     }
 }