🥕 dns, slicehelper: prefer slices package

slices.Grow is better because it exposes all additional capacity from rounding up to the next size class.

dns/dns.go

@@ -749,11 +749,7 @@ func (r *Resolver) LookupIPs(ctx context.Context, name string) ([]netip.Addr, er
 	if err != nil {
 		return nil, err
 	}
-
-	ips := make([]netip.Addr, 0, len(result.IPv6)+len(result.IPv4))
-	ips = append(ips, result.IPv6...)
-	ips = append(ips, result.IPv4...)
-	return ips, nil
+	return slices.Concat(result.IPv6, result.IPv4), nil
 }
 
 // SystemResolver resolves names using [net.DefaultResolver].

slicehelper/slicehelper.go

@@ -1,15 +1,11 @@
 package slicehelper
 
+import "slices"
+
 // Extend extends the input slice by n elements. head is the full extended
 // slice, while tail is the appended part. If the original slice has sufficient
 // capacity no allocation is performed.
 func Extend[S ~[]E, E any](in S, n int) (head, tail S) {
-	if total := len(in) + n; cap(in) >= total {
-		head = in[:total]
-	} else {
-		head = make(S, total)
-		copy(head, in)
-	}
-	tail = head[len(in):]
-	return
+	head = slices.Grow(in, n)[:len(in)+n]
+	return head, head[len(in):]
 }