all: modernize (#5498)

* modernize string cut usage

* modernize string cut prefix usage

* modernize slices helper usage

* modernize min and max usage

* modernize loop variable copies

* modernize integer range loops

* modernize map copy loops

* modernize go types iterator usage

* modernize empty interface usage

* modernize atomic type usage

* modernize string builders

* modernize string split iteration

* modernize remaining loop variable copies

* modernize usb cdc min usage

* modernize src integer range loops

* modernize example empty interface usage

* modernize src min and max usage

* modernize src integer range loops

* modernize src empty interface usage

* modernize src atomic type usage

* modernize reflect type lookups

* modernize review nits

builder/build.go

@@ -14,6 +14,7 @@ import (
 	"fmt"
 	"go/types"
 	"hash/crc32"
+	"maps"
 	"math/bits"
 	"os"
 	"os/exec"
@@ -137,9 +138,7 @@ func Build(pkgName, outpath, tmpdir string, config *compileopts.Config) (BuildRe
 		if _, ok := globalValues[pkgPath]; !ok {
 			globalValues[pkgPath] = map[string]string{}
 		}
-		for k, v := range vals {
-			globalValues[pkgPath][k] = v
-		}
+		maps.Copy(globalValues[pkgPath], vals)
 	}
 
 	// Check for a libc dependency.
@@ -278,7 +277,6 @@ func Build(pkgName, outpath, tmpdir string, config *compileopts.Config) (BuildRe
 
 	var embedFileObjects []*compileJob
 	for _, pkg := range lprogram.Sorted() {
-		pkg := pkg // necessary to avoid a race condition
 
 		var undefinedGlobals []string
 		for name := range globalValues[pkg.Pkg.Path()] {
@@ -775,7 +773,6 @@ func Build(pkgName, outpath, tmpdir string, config *compileopts.Config) (BuildRe
 	// TODO: do this as part of building the package to be able to link the
 	// bitcode files together.
 	for _, pkg := range lprogram.Sorted() {
-		pkg := pkg
 		for _, filename := range pkg.CFiles {
 			abspath := filepath.Join(pkg.OriginalDir(), filename)
 			job := &compileJob{
@@ -914,7 +911,7 @@ func Build(pkgName, outpath, tmpdir string, config *compileopts.Config) (BuildRe
 			}
 
 			// Run wasm-opt for wasm binaries
-			if arch := strings.Split(config.Triple(), "-")[0]; arch == "wasm32" {
+			if arch, _, _ := strings.Cut(config.Triple(), "-"); arch == "wasm32" {
 				optLevel, _, _ := config.OptLevel()
 				opt := "-" + optLevel
 

builder/builder_test.go

@@ -47,7 +47,6 @@ func TestClangAttributes(t *testing.T) {
 		targetNames = append(targetNames, "esp32", "esp8266")
 	}
 	for _, targetName := range targetNames {
-		targetName := targetName
 		t.Run(targetName, func(t *testing.T) {
 			testClangAttributes(t, &compileopts.Options{Target: targetName})
 		})

builder/cc.go

@@ -281,7 +281,7 @@ func parseDepFile(s string) ([]string, error) {
 	s = strings.ReplaceAll(s, "\\\n", " ")
 
 	// Only use the first line, which is expected to begin with "deps:".
-	line := strings.SplitN(s, "\n", 2)[0]
+	line, _, _ := strings.Cut(s, "\n")
 	if !strings.HasPrefix(line, "deps:") {
 		return nil, errors.New("readDepFile: expected 'deps:' prefix")
 	}

builder/commands.go

@@ -17,7 +17,7 @@ import (
 var commands = map[string][]string{}
 
 func init() {
-	llvmMajor := strings.Split(llvm.Version, ".")[0]
+	llvmMajor, _, _ := strings.Cut(llvm.Version, ".")
 	commands["clang"] = []string{"clang-" + llvmMajor}
 	commands["ld.lld"] = []string{"ld.lld-" + llvmMajor, "ld.lld"}
 	commands["wasm-ld"] = []string{"wasm-ld-" + llvmMajor, "wasm-ld"}

builder/darwin-libsystem.go

@@ -15,7 +15,7 @@ func makeDarwinLibSystemJob(config *compileopts.Config, tmpdir string) *compileJ
 	return &compileJob{
 		description: "compile Darwin libSystem.dylib",
 		run: func(job *compileJob) (err error) {
-			arch := strings.Split(config.Triple(), "-")[0]
+			arch, _, _ := strings.Cut(config.Triple(), "-")
 			job.result = filepath.Join(tmpdir, "libSystem.dylib")
 			objpath := filepath.Join(tmpdir, "libSystem.o")
 			inpath := filepath.Join(goenv.Get("TINYGOROOT"), "lib/macos-minimal-sdk/src", arch, "libSystem.s")

builder/jobs.go

@@ -195,11 +195,11 @@ type intHeap struct {
 	sort.IntSlice
 }
 
-func (h *intHeap) Push(x interface{}) {
+func (h *intHeap) Push(x any) {
 	h.IntSlice = append(h.IntSlice, x.(int))
 }
 
-func (h *intHeap) Pop() interface{} {
+func (h *intHeap) Pop() any {
 	x := h.IntSlice[len(h.IntSlice)-1]
 	h.IntSlice = h.IntSlice[:len(h.IntSlice)-1]
 	return x

builder/library.go

@@ -232,7 +232,6 @@ func (l *Library) load(config *compileopts.Config, tmpdir string) (job *compileJ
 	}
 	for _, path := range paths {
 		// Strip leading "../" parts off the path.
-		path := path
 		cleanpath := path
 		for strings.HasPrefix(cleanpath, "../") {
 			cleanpath = cleanpath[3:]

builder/musl.go

@@ -28,8 +28,8 @@ func buildMuslAllTypes(arch, muslDir, outputBitsDir string) error {
 		if err != nil {
 			return err
 		}
-		lines := strings.Split(string(data), "\n")
-		for _, line := range lines {
+		lines := strings.SplitSeq(string(data), "\n")
+		for line := range lines {
 			if strings.HasPrefix(line, "TYPEDEF ") {
 				matches := regexp.MustCompile(`TYPEDEF (.*) ([^ ]*);`).FindStringSubmatch(line)
 				value := matches[1]

builder/sizes_test.go

@@ -51,7 +51,6 @@ func TestBinarySize(t *testing.T) {
 		// output varies by binaryen version.
 	}
 	for _, tc := range tests {
-		tc := tc
 		t.Run(tc.target+"/"+tc.path, func(t *testing.T) {
 			t.Parallel()
 
@@ -85,7 +84,6 @@ func TestSizeFull(t *testing.T) {
 	pkgMatch := regexp.MustCompile(`^[a-z/]+$`)    // example: "internal/task"
 
 	for _, target := range tests {
-		target := target
 		t.Run(target, func(t *testing.T) {
 			t.Parallel()
 

builder/tools.go

@@ -116,7 +116,7 @@ func parseLLDErrors(text string) error {
 		// This can happen in some cases like with CGo and //go:linkname tricker.
 		if matches := regexp.MustCompile(`^ld.lld(-[0-9]+)?: error: undefined symbol: (.*)\n`).FindStringSubmatch(message); matches != nil {
 			symbolName := matches[2]
-			for _, line := range strings.Split(message, "\n") {
+			for line := range strings.SplitSeq(message, "\n") {
 				matches := regexp.MustCompile(`referenced by .* \(((.*):([0-9]+))\)`).FindStringSubmatch(line)
 				if matches != nil {
 					parsedError = true

builder/uf2.go

@@ -40,7 +40,7 @@ func convertBinToUF2(input []byte, targetAddr uint32, uf2FamilyID string) ([]byt
 	}
 	bl.SetNumBlocks(len(blocks))
 
-	for i := 0; i < len(blocks); i++ {
+	for i := range blocks {
 		bl.SetBlockNo(i)
 		bl.SetData(blocks[i])