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

Updates #18682

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

util/deephash/deephash_test.go

@@ -24,7 +24,6 @@ import (
 	"go4.org/netipx"
 	"tailscale.com/tailcfg"
 	"tailscale.com/types/key"
-	"tailscale.com/types/ptr"
 	"tailscale.com/util/deephash/testtype"
 	"tailscale.com/util/hashx"
 	"tailscale.com/version"
@@ -382,7 +381,7 @@ func TestGetTypeHasher(t *testing.T) {
 		},
 		{
 			name: "time_ptr", // addressable, as opposed to "time" test above
-			val:  ptr.To(time.Unix(1234, 5678).In(time.UTC)),
+			val:  new(time.Unix(1234, 5678).In(time.UTC)),
 			out:  u8(1) + u64(1234) + u32(5678) + u32(0),
 		},
 		{
@@ -412,7 +411,7 @@ func TestGetTypeHasher(t *testing.T) {
 		},
 		{
 			name: "array_ptr_memhash",
-			val:  ptr.To([4]byte{1, 2, 3, 4}),
+			val:  new([4]byte{1, 2, 3, 4}),
 			out:  "\x01\x01\x02\x03\x04",
 		},
 		{
@@ -640,7 +639,7 @@ var filterRules = []tailcfg.FilterRule{
 		SrcIPs: []string{"*", "10.1.3.4/32", "10.0.0.0/24"},
 		DstPorts: []tailcfg.NetPortRange{{
 			IP:    "1.2.3.4/32",
-			Bits:  ptr.To(32),
+			Bits:  new(32),
 			Ports: tailcfg.PortRange{First: 1, Last: 2},
 		}},
 		IPProto: []int{1, 2, 3, 4},
@@ -823,7 +822,7 @@ func TestHashThroughView(t *testing.T) {
 		SSHPolicy: &sshPolicyOut{
 			Rules: []tailcfg.SSHRuleView{
 				(&tailcfg.SSHRule{
-					RuleExpires: ptr.To(time.Unix(123, 0)),
+					RuleExpires: new(time.Unix(123, 0)),
 				}).View(),
 			},
 		},

util/linuxfw/nftables_runner.go

@@ -20,7 +20,6 @@ import (
 	"golang.org/x/sys/unix"
 	"tailscale.com/net/tsaddr"
 	"tailscale.com/types/logger"
-	"tailscale.com/types/ptr"
 )
 
 const (
@@ -955,7 +954,7 @@ const (
 // via netfilter via nftables, as a last resort measure to detect that nftables
 // can be used. It cleans up the dummy chains after creation.
 func (n *nftablesRunner) createDummyPostroutingChains() (retErr error) {
-	polAccept := ptr.To(nftables.ChainPolicyAccept)
+	polAccept := new(nftables.ChainPolicyAccept)
 	for _, table := range n.getTables() {
 		nat, err := createTableIfNotExist(n.conn, table.Proto, tsDummyTableName)
 		if err != nil {

util/pool/pool.go

@@ -12,8 +12,6 @@ package pool
 import (
 	"fmt"
 	"math/rand/v2"
-
-	"tailscale.com/types/ptr"
 )
 
 // consistencyCheck enables additional runtime checks to ensure that the pool
@@ -77,7 +75,7 @@ func (p *Pool[V]) AppendTakeAll(dst []V) []V {
 func (p *Pool[V]) Add(item V) Handle[V] {
 	// Store the index in a pointer, so that we can pass it to both the
 	// handle and store it in the itemAndIndex.
-	idx := ptr.To(len(p.s))
+	idx := new(len(p.s))
 	p.s = append(p.s, itemAndIndex[V]{
 		item:  item,
 		index: idx,

util/syspolicy/setting/errors.go

@@ -5,8 +5,6 @@ package setting
 
 import (
 	"errors"
-
-	"tailscale.com/types/ptr"
 )
 
 var (
@@ -39,7 +37,7 @@ type ErrorText string
 
 // NewErrorText returns a [ErrorText] with the specified error message.
 func NewErrorText(text string) *ErrorText {
-	return ptr.To(ErrorText(text))
+	return new(ErrorText(text))
 }
 
 // MaybeErrorText returns an [ErrorText] with the text of the specified error,
@@ -51,7 +49,7 @@ func MaybeErrorText(err error) *ErrorText {
 	if err, ok := err.(*ErrorText); ok {
 		return err
 	}
-	return ptr.To(ErrorText(err.Error()))
+	return new(ErrorText(err.Error()))
 }
 
 // Error implements error.

util/syspolicy/setting/setting_test.go

@@ -9,7 +9,6 @@ import (
 	"testing"
 
 	"tailscale.com/types/lazy"
-	"tailscale.com/types/ptr"
 	"tailscale.com/util/syspolicy/internal"
 	"tailscale.com/util/syspolicy/pkey"
 )
@@ -138,7 +137,7 @@ func TestSettingDefinition(t *testing.T) {
 			if !tt.setting.Equal(tt.setting) {
 				t.Errorf("the setting should be equal to itself")
 			}
-			if tt.setting != nil && !tt.setting.Equal(ptr.To(*tt.setting)) {
+			if tt.setting != nil && !tt.setting.Equal(new(*tt.setting)) {
 				t.Errorf("the setting should be equal to its shallow copy")
 			}
 			if gotKey := tt.setting.Key(); gotKey != tt.wantKey {