types/ptr: deprecate ptr.To, use Go 1.26 new

Updates #18682

Change-Id: I62f6aa0de2a15ef8c1435032c6aa74a181c25f8f
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>

types/prefs/item.go

@@ -9,7 +9,6 @@ import (
 	jsonv2 "github.com/go-json-experiment/json"
 	"github.com/go-json-experiment/json/jsontext"
 	"tailscale.com/types/opt"
-	"tailscale.com/types/ptr"
 	"tailscale.com/types/views"
 	"tailscale.com/util/must"
 )
@@ -47,7 +46,7 @@ func (i *Item[T]) SetManagedValue(val T) {
 // It is a runtime error to call [Item.Clone] if T contains pointers
 // but does not implement [views.Cloner].
 func (i Item[T]) Clone() *Item[T] {
-	res := ptr.To(i)
+	res := new(i)
 	if v, ok := i.ValueOk(); ok {
 		res.s.Value.Set(must.Get(deepClone(v)))
 	}

types/prefs/list.go

@@ -12,7 +12,6 @@ import (
 	"github.com/go-json-experiment/json/jsontext"
 	"golang.org/x/exp/constraints"
 	"tailscale.com/types/opt"
-	"tailscale.com/types/ptr"
 	"tailscale.com/types/views"
 )
 
@@ -62,7 +61,7 @@ func (ls *List[T]) View() ListView[T] {
 
 // Clone returns a copy of l that aliases no memory with l.
 func (ls List[T]) Clone() *List[T] {
-	res := ptr.To(ls)
+	res := new(ls)
 	if v, ok := ls.s.Value.GetOk(); ok {
 		res.s.Value.Set(append(v[:0:0], v...))
 	}

types/prefs/map.go

@@ -11,7 +11,6 @@ import (
 	"github.com/go-json-experiment/json/jsontext"
 	"golang.org/x/exp/constraints"
 	"tailscale.com/types/opt"
-	"tailscale.com/types/ptr"
 	"tailscale.com/types/views"
 )
 
@@ -44,7 +43,7 @@ func (m *Map[K, V]) View() MapView[K, V] {
 
 // Clone returns a copy of m that aliases no memory with m.
 func (m Map[K, V]) Clone() *Map[K, V] {
-	res := ptr.To(m)
+	res := new(m)
 	if v, ok := m.s.Value.GetOk(); ok {
 		res.s.Value.Set(maps.Clone(v))
 	}

types/prefs/prefs_clone_test.go

@@ -7,8 +7,6 @@ package prefs
 
 import (
 	"net/netip"
-
-	"tailscale.com/types/ptr"
 )
 
 // Clone makes a deep copy of TestPrefs.
@@ -67,7 +65,7 @@ func (src *TestBundle) Clone() *TestBundle {
 	dst := new(TestBundle)
 	*dst = *src
 	if dst.Nested != nil {
-		dst.Nested = ptr.To(*src.Nested)
+		dst.Nested = new(*src.Nested)
 	}
 	return dst
 }

types/prefs/struct_list.go

@@ -11,7 +11,6 @@ import (
 	jsonv2 "github.com/go-json-experiment/json"
 	"github.com/go-json-experiment/json/jsontext"
 	"tailscale.com/types/opt"
-	"tailscale.com/types/ptr"
 	"tailscale.com/types/views"
 )
 
@@ -45,7 +44,7 @@ func (ls *StructList[T]) SetManagedValue(val []T) {
 
 // Clone returns a copy of l that aliases no memory with l.
 func (ls StructList[T]) Clone() *StructList[T] {
-	res := ptr.To(ls)
+	res := new(ls)
 	if v, ok := ls.s.Value.GetOk(); ok {
 		res.s.Value.Set(deepCloneSlice(v))
 	}

types/prefs/struct_map.go

@@ -9,7 +9,6 @@ import (
 	jsonv2 "github.com/go-json-experiment/json"
 	"github.com/go-json-experiment/json/jsontext"
 	"tailscale.com/types/opt"
-	"tailscale.com/types/ptr"
 	"tailscale.com/types/views"
 )
 
@@ -43,7 +42,7 @@ func (m *StructMap[K, V]) SetManagedValue(val map[K]V) {
 
 // Clone returns a copy of m that aliases no memory with m.
 func (m StructMap[K, V]) Clone() *StructMap[K, V] {
-	res := ptr.To(m)
+	res := new(m)
 	if v, ok := m.s.Value.GetOk(); ok {
 		res.s.Value.Set(deepCloneMap(v))
 	}