From d7341f3c4bfd814a778461a465365e78a15e4de7 Mon Sep 17 00:00:00 2001
From: Giacomo Stevanato <giaco.stevanato@gmail.com>
Date: Sun, 23 May 2021 21:43:11 +0200
Subject: [PATCH] Don't reborrow self when computing the dest pointer in
 <[T]>::copy_within

---
 library/core/src/slice/mod.rs | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/library/core/src/slice/mod.rs b/library/core/src/slice/mod.rs
index 0923175414edd..3bcea4e6d25ed 100644
--- a/library/core/src/slice/mod.rs
+++ b/library/core/src/slice/mod.rs
@@ -3096,7 +3096,11 @@ impl<T> [T] {
         // SAFETY: the conditions for `ptr::copy` have all been checked above,
         // as have those for `ptr::add`.
         unsafe {
-            ptr::copy(self.as_ptr().add(src_start), self.as_mut_ptr().add(dest), count);
+            // Derive both `src_ptr` and `dest_ptr` from the same loan
+            let ptr = self.as_mut_ptr();
+            let src_ptr = ptr.add(src_start);
+            let dest_ptr = ptr.add(dest);
+            ptr::copy(src_ptr, dest_ptr, count);
         }
     }