cmd/cloner: support cloning arbitrarily-nested maps

Fixes #17870

Signed-off-by: Andrew Dunham <andrew@tailscale.com>

cmd/cloner/clonerex/clonerex.go

@@ -1,7 +1,7 @@
 // Copyright (c) Tailscale Inc & AUTHORS
 // SPDX-License-Identifier: BSD-3-Clause
 
-//go:generate go run tailscale.com/cmd/cloner  -clonefunc=true -type SliceContainer,InterfaceContainer
+//go:generate go run tailscale.com/cmd/cloner  -clonefunc=true -type SliceContainer,InterfaceContainer,MapWithPointers,DeeplyNestedMap
 
 // Package clonerex is an example package for the cloner tool.
 package clonerex
@@ -32,3 +32,15 @@ func (c *CloneableImpl) Clone() Cloneable {
 type InterfaceContainer struct {
 	Interface Cloneable
 }
+
+type MapWithPointers struct {
+	Nested          map[string]*int
+	WithCloneMethod map[string]*SliceContainer
+	CloneInterface  map[string]Cloneable
+}
+
+// DeeplyNestedMap tests arbitrary depth of map nesting (3+ levels)
+type DeeplyNestedMap struct {
+	ThreeLevels map[string]map[string]map[string]int
+	FourLevels  map[string]map[string]map[string]map[string]*SliceContainer
+}