Modernize Go code with go fix

Apply the modernize analyzers integrated into go1.26's `go fix`
across the codebase: strings.SplitSeq/CutSuffix/CutPrefix, slices.Contains,
maps.Copy/Clone, fmt.Appendf, new(expr), for-range over integers, and any.

Author: nemunaire

checkers/domain_contact.go

@@ -74,7 +74,7 @@ func (r *domainContactRule) ValidateOptions(opts happydns.CheckerOptions) error
 
 	if v, ok := opts["checkRoles"].(string); ok && v != "" {
 		hasOne := false
-		for _, p := range strings.Split(v, ",") {
+		for p := range strings.SplitSeq(v, ",") {
 			role := strings.TrimSpace(p)
 			if role == "" {
 				continue

checkers/domain_lock.go

@@ -65,7 +65,7 @@ func (r *domainLockRule) ValidateOptions(opts happydns.CheckerOptions) error {
 	if !ok {
 		return fmt.Errorf("requiredStatuses must be a string")
 	}
-	for _, p := range strings.Split(s, ",") {
+	for p := range strings.SplitSeq(s, ",") {
 		if strings.TrimSpace(p) != "" {
 			return nil
 		}
@@ -89,7 +89,7 @@ func (r *domainLockRule) Evaluate(ctx context.Context, obs happydns.ObservationG
 	}
 
 	var required []string
-	for _, s := range strings.Split(requiredStr, ",") {
+	for s := range strings.SplitSeq(requiredStr, ",") {
 		s = strings.TrimSpace(s)
 		if s != "" {
 			required = append(required, s)

internal/adapters/libdns-providers_test.go

@@ -24,6 +24,7 @@ package adapter
 import (
 	"context"
 	"net/netip"
+	"slices"
 	"testing"
 	"time"
 
@@ -303,27 +304,15 @@ func TestGetLibdnsProviderCapabilities(t *testing.T) {
 	caps := GetLibdnsProviderCapabilities(config)
 
 	// Should include ListDomains since mock implements ZoneLister
-	found := false
-	for _, c := range caps {
-		if c == "ListDomains" {
-			found = true
-			break
-		}
-	}
+	found := slices.Contains(caps, "ListDomains")
 	if !found {
 		t.Error("expected ListDomains capability")
 	}
 
 	// Should include common RR types
 	expectedTypes := []string{"rr-1-A", "rr-28-AAAA", "rr-5-CNAME", "rr-15-MX", "rr-16-TXT"}
 	for _, expected := range expectedTypes {
-		found = false
-		for _, c := range caps {
-			if c == expected {
-				found = true
-				break
-			}
-		}
+		found = slices.Contains(caps, expected)
 		if !found {
 			t.Errorf("expected capability %s", expected)
 		}

internal/dnschecker/observation.go

@@ -42,6 +42,7 @@ import (
 	"encoding/json"
 	"fmt"
 	"log"
+	"maps"
 	"sync"
 	"time"
 
@@ -288,8 +289,6 @@ func (oc *ObservationContext) Data() map[happydns.ObservationKey]json.RawMessage
 	defer oc.mu.Unlock()
 
 	data := make(map[happydns.ObservationKey]json.RawMessage, len(oc.cache))
-	for k, v := range oc.cache {
-		data[k] = v
-	}
+	maps.Copy(data, oc.cache)
 	return data
 }

internal/dnschecker/observation_test.go

@@ -126,7 +126,7 @@ func TestObservationContext_DedupesSameKey(t *testing.T) {
 	const N = 8
 	var wg sync.WaitGroup
 	wg.Add(N)
-	for i := 0; i < N; i++ {
+	for range N {
 		go func() {
 			defer wg.Done()
 			var dst map[string]string

internal/helpers/dns.go

@@ -92,8 +92,8 @@ func DomainRelative(subdomain string, origin string) string {
 		origin += "."
 	}
 
-	if strings.HasSuffix(subdomain, origin) {
-		subdomain = strings.TrimSuffix(strings.TrimSuffix(subdomain, origin), ".")
+	if before, ok := strings.CutSuffix(subdomain, origin); ok {
+		subdomain = strings.TrimSuffix(before, ".")
 	}
 
 	if subdomain == "" {
@@ -143,8 +143,8 @@ func RRRelative(rr happydns.Record, origin string) happydns.Record {
 	}
 
 	// Make header relative
-	if strings.HasSuffix(rr.Header().Name, origin) {
-		rr.Header().Name = strings.TrimSuffix(strings.TrimSuffix(rr.Header().Name, origin), ".")
+	if before, ok := strings.CutSuffix(rr.Header().Name, origin); ok {
+		rr.Header().Name = strings.TrimSuffix(before, ".")
 	}
 
 	return RDataRelative(rr, origin)
@@ -159,8 +159,8 @@ func RRRelativeSubdomain(rr happydns.Record, origin, subdomain string) happydns.
 	subdomain = DomainFQDN(subdomain, origin)
 
 	// Make header relative
-	if strings.HasSuffix(rr.Header().Name, subdomain) {
-		rr.Header().Name = strings.TrimSuffix(strings.TrimSuffix(rr.Header().Name, subdomain), ".")
+	if before, ok := strings.CutSuffix(rr.Header().Name, subdomain); ok {
+		rr.Header().Name = strings.TrimSuffix(before, ".")
 	}
 
 	return RDataRelative(rr, origin)

internal/helpers/dnssec_test.go

@@ -425,7 +425,7 @@ func TestIsDNSSECTypeNonDNSSECTypes(t *testing.T) {
 func TestIsDNSSECTypeConsistency(t *testing.T) {
 	testType := dns.TypeNSEC
 
-	for i := 0; i < 100; i++ {
+	for i := range 100 {
 		result := IsDNSSECType(testType)
 		if !result {
 			t.Errorf("IsDNSSECType returned inconsistent result on iteration %d", i)

internal/mailer/mailer.go

@@ -24,6 +24,7 @@ package mailer
 import (
 	"bytes"
 	"io"
+	"maps"
 	"net/mail"
 	"text/template"
 
@@ -104,10 +105,7 @@ func (r *Mailer) SendMail(to *mail.Address, subject, content string) (err error)
 	if err != nil {
 		return err
 	}
-	htmlData := map[string]string{}
-	for k, v := range tplData {
-		htmlData[k] = v
-	}
+	htmlData := maps.Clone(tplData)
 	htmlData["Content"] = buf.String()
 	m.AddAlternativeWriter("text/html", func(w io.Writer) error {
 		return htmlTpl.Execute(w, htmlData)

internal/serviceanalyzer/registry.go

@@ -92,7 +92,7 @@ func RegisterSubServices(t reflect.Type) {
 		for i := 0; i < t.NumField(); i += 1 {
 			RegisterSubServices(t.Field(i).Type)
 		}
-	} else if t.Kind() == reflect.Array || t.Kind() == reflect.Map || t.Kind() == reflect.Ptr || t.Kind() == reflect.Slice {
+	} else if t.Kind() == reflect.Array || t.Kind() == reflect.Map || t.Kind() == reflect.Pointer || t.Kind() == reflect.Slice {
 		RegisterSubServices(t.Elem())
 	} else if t.PkgPath() == pathToSvcsModule {
 		if _, ok := subServices[t.String()]; ok {

internal/storage/kvtpl/discovery_test.go

@@ -131,12 +131,12 @@ type fakeIter struct {
 	idx  int
 }
 
-func (i *fakeIter) Release()      {}
-func (i *fakeIter) Next() bool    { i.idx++; return i.idx < len(i.keys) }
-func (i *fakeIter) Valid() bool   { return i.idx >= 0 && i.idx < len(i.keys) }
-func (i *fakeIter) Key() string   { return i.keys[i.idx] }
-func (i *fakeIter) Value() any    { return i.data[i.keys[i.idx]] }
-func (i *fakeIter) Err() error    { return nil }
+func (i *fakeIter) Release()    {}
+func (i *fakeIter) Next() bool  { i.idx++; return i.idx < len(i.keys) }
+func (i *fakeIter) Valid() bool { return i.idx >= 0 && i.idx < len(i.keys) }
+func (i *fakeIter) Key() string { return i.keys[i.idx] }
+func (i *fakeIter) Value() any  { return i.data[i.keys[i.idx]] }
+func (i *fakeIter) Err() error  { return nil }
 
 func newDiscoveryTestStore() *KVStorage {
 	return &KVStorage{db: newFakeKV()}
@@ -325,11 +325,9 @@ func TestPutDiscoveryObservationRefConcurrentSamePrimary(t *testing.T) {
 	const N = 16
 	var wg sync.WaitGroup
 	errs := make(chan error, N)
-	for i := 0; i < N; i++ {
+	for i := range N {
 		i := i
-		wg.Add(1)
-		go func() {
-			defer wg.Done()
+		wg.Go(func() {
 			errs <- s.PutDiscoveryObservationRef(&happydns.DiscoveryObservationRef{
 				ProducerID:  "p",
 				Target:      target,
@@ -339,7 +337,7 @@ func TestPutDiscoveryObservationRefConcurrentSamePrimary(t *testing.T) {
 				SnapshotID:  happydns.Identifier{byte(i + 1)},
 				CollectedAt: time.Now(),
 			})
-		}()
+		})
 	}
 	wg.Wait()
 	close(errs)