all: cleanup unused code, part 1 (#10661)

Run `staticcheck` with `U1000` to find unused code. This cleans up about
a half of it. I'll do the other half separately to keep PRs manageable.

Updates #cleanup

Signed-off-by: Andrew Lytvynov <awly@tailscale.com>

util/deephash/deephash_test.go

@@ -342,11 +342,11 @@ func getVal() *tailscaleTypes {
 }
 
 type IntThenByte struct {
-	i int
-	b byte
+	_ int
+	_ byte
 }
 
-type TwoInts struct{ a, b int }
+type TwoInts struct{ _, _ int }
 
 type IntIntByteInt struct {
 	i1, i2 int32
@@ -355,7 +355,6 @@ type IntIntByteInt struct {
 }
 
 func u8(n uint8) string   { return string([]byte{n}) }
-func u16(n uint16) string { return string(binary.LittleEndian.AppendUint16(nil, n)) }
 func u32(n uint32) string { return string(binary.LittleEndian.AppendUint32(nil, n)) }
 func u64(n uint64) string { return string(binary.LittleEndian.AppendUint64(nil, n)) }
 func ux(n uint) string {

util/deephash/types_test.go

@@ -78,7 +78,7 @@ func TestTypeIsMemHashable(t *testing.T) {
 
 func TestTypeIsRecursive(t *testing.T) {
 	type RecursiveStruct struct {
-		v *RecursiveStruct
+		_ *RecursiveStruct
 	}
 	type RecursiveChan chan *RecursiveChan
 

util/syspolicy/policy_keys.go

@@ -73,33 +73,3 @@ const (
 	// The default is "user-decides" unless otherwise stated.
 	PostureChecking Key = "PostureChecking"
 )
-
-var stringKeys = []Key{
-	ControlURL,
-	LogTarget,
-	Tailnet,
-	ExitNodeID,
-	ExitNodeIP,
-	EnableIncomingConnections,
-	EnableServerMode,
-	ExitNodeAllowLANAccess,
-	EnableTailscaleDNS,
-	EnableTailscaleSubnets,
-	AdminConsoleVisibility,
-	NetworkDevicesVisibility,
-	TestMenuVisibility,
-	UpdateMenuVisibility,
-	RunExitNodeVisibility,
-	PreferencesMenuVisibility,
-	ExitNodeMenuVisibility,
-	AutoUpdateVisibility,
-	KeyExpirationNoticeTime,
-	PostureChecking,
-}
-
-var boolKeys = []Key{
-	LogSCMInteractions,
-	FlushDNSOnSessionUnlock,
-}
-
-var uint64Keys = []Key{}

util/syspolicy/policy_keys_windows.go

@@ -0,0 +1,34 @@
+// Copyright (c) Tailscale Inc & AUTHORS
+// SPDX-License-Identifier: BSD-3-Clause
+
+package syspolicy
+
+var stringKeys = []Key{
+	ControlURL,
+	LogTarget,
+	Tailnet,
+	ExitNodeID,
+	ExitNodeIP,
+	EnableIncomingConnections,
+	EnableServerMode,
+	ExitNodeAllowLANAccess,
+	EnableTailscaleDNS,
+	EnableTailscaleSubnets,
+	AdminConsoleVisibility,
+	NetworkDevicesVisibility,
+	TestMenuVisibility,
+	UpdateMenuVisibility,
+	RunExitNodeVisibility,
+	PreferencesMenuVisibility,
+	ExitNodeMenuVisibility,
+	AutoUpdateVisibility,
+	KeyExpirationNoticeTime,
+	PostureChecking,
+}
+
+var boolKeys = []Key{
+	LogSCMInteractions,
+	FlushDNSOnSessionUnlock,
+}
+
+var uint64Keys = []Key{}