Update

vendor/tailscale.com/util/checkchange/checkchange.go

@@ -0,0 +1,25 @@
+// Copyright (c) Tailscale Inc & AUTHORS
+// SPDX-License-Identifier: BSD-3-Clause
+
+// Package checkchange defines a utility for determining whether a value
+// has changed since the last time it was checked.
+package checkchange
+
+// EqualCloner is an interface for types that can be compared for equality
+// and can be cloned.
+type EqualCloner[T any] interface {
+	Equal(T) bool
+	Clone() T
+}
+
+// Update sets *old to a clone of new if they are not equal, returning whether
+// they were different.
+//
+// It only modifies *old if they are different. old must be non-nil.
+func Update[T EqualCloner[T]](old *T, new T) (changed bool) {
+	if (*old).Equal(new) {
+		return false
+	}
+	*old = new.Clone()
+	return true
+}