bytes: add Clone function

The new Clone function returns a copy of b[:len(b)]
for the input byte slice b.
The result may have additional unused capacity.
Clone(nil) returns nil.

Fixes #45038

Change-Id: I0469a202d77a7b491f1341c08915d07ddd1f0300
Reviewed-on: https://go-review.googlesource.com/c/go/+/359675
Run-TryBot: Martin Möhrmann <martin@golang.org>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Joseph Tsai <joetsai@digital-static.net>
Reviewed-by: Martin Möhrmann <moehrmann@google.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>

1 files changed, 10 insertions, 0 deletions

diff --git a/src/bytes/bytes.go b/src/bytes/bytes.go
index 659a82bcc8..27834fc6db 100644
--- a/src/bytes/bytes.go
+++ b/src/bytes/bytes.go
@@ -1299,3 +1299,13 @@ func Cut(s, sep []byte) (before, after []byte, found bool) {
 	}
 	return s, nil, false
 }
+
+// Clone returns a copy of b[:len(b)].
+// The result may have additional unused capacity.
+// Clone(nil) returns nil.
+func Clone(b []byte) []byte {
+	if b == nil {
+		return nil
+	}
+	return append([]byte{}, b...)
+}