From 4d05b759b2857ac192f9ad4f09295408a89d8301 Mon Sep 17 00:00:00 2001
From: Guillaume Lessard <guillaume.lessard@apple.com>
Date: Thu, 14 Oct 2021 19:03:30 -0600
Subject: [PATCH] [stdlib] a minor optimization

We have already done the hard work of unwrapping the optionals
that represent the first and last pointer, and calling `self.count` does it all over again. Use the distance between the unwrapped pointers instead.
---
 stdlib/public/core/UnsafeRawBufferPointer.swift.gyb | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/stdlib/public/core/UnsafeRawBufferPointer.swift.gyb b/stdlib/public/core/UnsafeRawBufferPointer.swift.gyb
index c01039cb7b9a6..4fec4b4e52936 100644
--- a/stdlib/public/core/UnsafeRawBufferPointer.swift.gyb
+++ b/stdlib/public/core/UnsafeRawBufferPointer.swift.gyb
@@ -161,7 +161,7 @@ extension Unsafe${Mutable}RawBufferPointer: Sequence {
     }
     let destinationAddress = destination.baseAddress._unsafelyUnwrappedUnchecked
     let d = UnsafeMutableRawPointer(destinationAddress)
-    let n = Swift.min(destination.count, self.count)
+    let n = Swift.min(destination.count, s.distance(to: e))
     d.copyMemory(from: s, byteCount: n)
     return (Iterator(_position: s.advanced(by: n), _end: e), n)
   }