all: fix exptostd, ineffassign, unconvert, intrange, predeclared issues

- Replace exp/maps and exp/slices with stdlib (Go 1.21+)
- Fix ineffective assignments by checking errors or using blank identifier
- Remove unnecessary type conversions
- Use integer range syntax for loops (Go 1.22+)
- Rename variables shadowing predeclared identifiers (min, max)

cmd/hi/stats.go

@@ -409,25 +409,25 @@ func calculateStatsSummary(values []float64) StatsSummary {
 		return StatsSummary{}
 	}
 
-	min := values[0]
+	minVal := values[0]
-	max := values[0]
+	maxVal := values[0]
 	sum := 0.0
 
 	for _, value := range values {
-		if value < min {
+		if value < minVal {
-			min = value
+			minVal = value
 		}
 
-		if value > max {
+		if value > maxVal {
-			max = value
+			maxVal = value
 		}
 
 		sum += value
 	}
 
 	return StatsSummary{
-		Min:     min,
+		Min:     minVal,
-		Max:     max,
+		Max:     maxVal,
 		Average: sum / float64(len(values)),
 	}
 }

hscontrol/auth_test.go

@@ -3113,7 +3113,7 @@ func TestWebFlowReauthDifferentUser(t *testing.T) {
 		user1Nodes := 0
 		user2Nodes := 0
 
-		for i := 0; i < allNodesSlice.Len(); i++ {
+		for i := range allNodesSlice.Len() {
 			n := allNodesSlice.At(i)
 			if n.UserID().Get() == user1.ID {
 				user1Nodes++

hscontrol/db/db.go

@@ -173,6 +173,9 @@ AND auth_key_id NOT IN (
 						routes = slices.Compact(routes)
 
 						data, err := json.Marshal(routes)
+						if err != nil {
+							return fmt.Errorf("marshaling routes for node %d: %w", nodeID, err)
+						}
 
 						err = tx.Model(&types.Node{}).Where("id = ?", nodeID).Update("approved_routes", data).Error
 						if err != nil {

hscontrol/db/node_test.go

@@ -754,6 +754,9 @@ func TestNodeNaming(t *testing.T) {
 		}
 
 		_, err = RegisterNodeForTest(tx, nodeInvalidHostname, new(mpp("100.64.0.66/32").Addr()), nil)
+		if err != nil {
+			return err
+		}
 		_, err = RegisterNodeForTest(tx, nodeShortHostname, new(mpp("100.64.0.67/32").Addr()), nil)
 
 		return err

hscontrol/policy/v2/types_test.go

@@ -1860,7 +1860,7 @@ func TestResolvePolicy(t *testing.T) {
 		},
 		{
 			name:      "autogroup-member-comprehensive",
-			toResolve: new(AutoGroup(AutoGroupMember)),
+			toResolve: new(AutoGroupMember),
 			nodes: types.Nodes{
 				// Node with no tags (should be included - is a member)
 				{
@@ -1910,7 +1910,7 @@ func TestResolvePolicy(t *testing.T) {
 		},
 		{
 			name:      "autogroup-tagged",
-			toResolve: new(AutoGroup(AutoGroupTagged)),
+			toResolve: new(AutoGroupTagged),
 			nodes: types.Nodes{
 				// Node with no tags (should be excluded - not tagged)
 				{

hscontrol/state/state.go

@@ -749,7 +749,7 @@ func (s *State) RenameNode(nodeID types.NodeID, newName string) (types.NodeView,
 
 	// Check name uniqueness against NodeStore
 	allNodes := s.nodeStore.ListNodes()
-	for i := 0; i < allNodes.Len(); i++ {
+	for i := range allNodes.Len() {
 		node := allNodes.At(i)
 		if node.ID() != nodeID && node.AsStruct().GivenName == newName {
 			return types.NodeView{}, change.Change{}, fmt.Errorf("%w: %s", ErrNodeNameNotUnique, newName)

integration/auth_web_flow_test.go

@@ -245,7 +245,7 @@ func TestAuthWebFlowLogoutAndReloginNewUser(t *testing.T) {
 	allClients, err := scenario.ListTailscaleClients()
 	requireNoErrListClients(t, err)
 
-	allIps, err := scenario.ListTailscaleClientsIPs()
+	_, err = scenario.ListTailscaleClientsIPs()
 	requireNoErrListClientIPs(t, err)
 
 	err = scenario.WaitForTailscaleSync()
@@ -367,7 +367,7 @@ func TestAuthWebFlowLogoutAndReloginNewUser(t *testing.T) {
 	}
 
 	// Test connectivity after user switch
-	allIps, err = scenario.ListTailscaleClientsIPs()
+	allIps, err := scenario.ListTailscaleClientsIPs()
 	requireNoErrListClientIPs(t, err)
 
 	allAddrs := lo.Map(allIps, func(x netip.Addr, index int) string {

integration/helpers.go

@@ -23,8 +23,8 @@ import (
 	"github.com/oauth2-proxy/mockoidc"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
-	"golang.org/x/exp/maps"
+	"maps"
-	"golang.org/x/exp/slices"
+	"slices"
 	"tailscale.com/tailcfg"
 )
 
@@ -332,7 +332,7 @@ func requireAllClientsOnlineWithSingleTimeout(t *testing.T, headscale ControlSer
 
 		var failureReport strings.Builder
 
-		ids := types.NodeIDs(maps.Keys(nodeStatus))
+		ids := slices.Collect(maps.Keys(nodeStatus))
 		slices.Sort(ids)
 
 		for _, nodeID := range ids {

integration/scenario.go

@@ -1158,7 +1158,7 @@ var errParseAuthPage = errors.New("failed to parse auth page")
 
 func (s *Scenario) runHeadscaleRegister(userStr string, body string) error {
 	// see api.go HTML template
-	codeSep := strings.Split(string(body), "</code>")
+	codeSep := strings.Split(body, "</code>")
 	if len(codeSep) != expectedHTMLSplitParts {
 		return errParseAuthPage
 	}

integration/tsic/tsic.go

@@ -731,12 +731,12 @@ func (t *TailscaleInContainer) LoginWithURL(
 
 // Logout runs the logout routine on the given Tailscale instance.
 func (t *TailscaleInContainer) Logout() error {
-	stdout, stderr, err := t.Execute([]string{"tailscale", "logout"})
+	_, _, err := t.Execute([]string{"tailscale", "logout"})
 	if err != nil {
 		return err
 	}
 
-	stdout, stderr, _ = t.Execute([]string{"tailscale", "status"})
+	stdout, stderr, _ := t.Execute([]string{"tailscale", "status"})
 	if !strings.Contains(stdout+stderr, "Logged out.") {
 		return fmt.Errorf("%w: stdout: %s, stderr: %s", errLogoutFailed, stdout, stderr)
 	}