From: Brad Fitzpatrick <bradfitz@golang.org>
Date: Sat, 19 Aug 2023 16:08:38 +0000 (-0700)
Subject: slices: simplify Clone a bit
X-Git-Tag: go1.22rc1~1192
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=b581e447394b4ba7a08ea64b214781cae0f4ef6c;p=gostls13.git

slices: simplify Clone a bit

No need for an explicit nil check. Slicing the input slice
down to zero capacity also preserves nil.

Change-Id: I1f53cc485373d0e65971cd87b6243650ac72612c
Reviewed-on: https://go-review.googlesource.com/c/go/+/521037
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@google.com>
---

diff --git a/src/slices/slices.go b/src/slices/slices.go
index a4d9f7e3f5..252a8eecfc 100644
--- a/src/slices/slices.go
+++ b/src/slices/slices.go
@@ -333,11 +333,8 @@ func Replace[S ~[]E, E any](s S, i, j int, v ...E) S {
 // Clone returns a copy of the slice.
 // The elements are copied using assignment, so this is a shallow clone.
 func Clone[S ~[]E, E any](s S) S {
-	// Preserve nil in case it matters.
-	if s == nil {
-		return nil
-	}
-	return append(S([]E{}), s...)
+	// The s[:0:0] preserves nil in case it matters.
+	return append(s[:0:0], s...)
 }
 
 // Compact replaces consecutive runs of equal elements with a single copy.