Go 1.26 and golangci-lint updates (#2146)

Keep Go 1.24 compatibility for now (by not using `wg.Go()`).

stackless/func.go

@@ -27,7 +27,7 @@ func NewFunc(f func(ctx any)) func(ctx any) bool {
 	funcWorkCh := make(chan *funcWork, runtime.GOMAXPROCS(-1)*2048)
 	onceInit := func() {
 		n := runtime.GOMAXPROCS(-1)
-		for i := 0; i < n; i++ {
+		for range n {
 			go funcWorker(funcWorkCh, f)
 		}
 	}

stackless/func_test.go

@@ -16,7 +16,7 @@ func TestNewFuncSimple(t *testing.T) {
 	})
 
 	iterations := 4 * 1024
-	for i := 0; i < iterations; i++ {
+	for range iterations {
 		if !f(2) {
 			t.Fatalf("f mustn't return false")
 		}
@@ -42,7 +42,7 @@ func TestNewFuncMulti(t *testing.T) {
 	f1Done := make(chan error, 1)
 	go func() {
 		var err error
-		for i := 0; i < iterations; i++ {
+		for range iterations {
 			if !f1(3) {
 				err = errors.New("f1 mustn't return false")
 				break
@@ -54,7 +54,7 @@ func TestNewFuncMulti(t *testing.T) {
 	f2Done := make(chan error, 1)
 	go func() {
 		var err error
-		for i := 0; i < iterations; i++ {
+		for range iterations {
 			if !f2(5) {
 				err = errors.New("f2 mustn't return false")
 				break

stackless/writer_test.go

@@ -70,7 +70,7 @@ func testWriter(newWriter NewWriterFunc, newReader func(io.Reader) io.Reader) er
 	dstW := &bytes.Buffer{}
 	w := NewWriter(dstW, newWriter)
 
-	for i := 0; i < 5; i++ {
+	for i := range 5 {
 		if err := testWriterReuse(w, dstW, newReader); err != nil {
 			return fmt.Errorf("unexpected error when re-using writer on iteration %d: %w", i, err)
 		}
@@ -84,7 +84,7 @@ func testWriter(newWriter NewWriterFunc, newReader func(io.Reader) io.Reader) er
 func testWriterReuse(w Writer, r io.Reader, newReader func(io.Reader) io.Reader) error {
 	wantW := &bytes.Buffer{}
 	mw := io.MultiWriter(w, wantW)
-	for i := 0; i < 30; i++ {
+	for i := range 30 {
 		fmt.Fprintf(mw, "foobar %d\n", i)
 		if i%13 == 0 {
 			if err := w.Flush(); err != nil {
@@ -110,12 +110,12 @@ func testWriterReuse(w Writer, r io.Reader, newReader func(io.Reader) io.Reader)
 
 func testConcurrent(testFunc func() error, concurrency int) error {
 	ch := make(chan error, concurrency)
-	for i := 0; i < concurrency; i++ {
+	for range concurrency {
 		go func() {
 			ch <- testFunc()
 		}()
 	}
-	for i := 0; i < concurrency; i++ {
+	for i := range concurrency {
 		select {
 		case err := <-ch:
 			if err != nil {