all: replace strings.Split with strings.SplitSeq

misc/ios/go_ios_exec.go

@@ -212,7 +212,7 @@ func copyLocalData(dstbase string) (pkgpath string, err error) {
 	// Copy all immediate files and testdata directories between
 	// the package being tested and the source root.
 	pkgpath = ""
-	for _, element := range strings.Split(finalPkgpath, string(filepath.Separator)) {
+	for element := range strings.SplitSeq(finalPkgpath, string(filepath.Separator)) {
 		if debug {
 			log.Printf("copying %s", pkgpath)
 		}

src/cmd/cgo/gcc.go

@@ -242,7 +242,7 @@ func (f *File) loadDefines(gccOptions []string) bool {
 	stdout := gccDefines(b.Bytes(), gccOptions)
 
 	var gccIsClang bool
-	for _, line := range strings.Split(stdout, "\n") {
+	for line := range strings.SplitSeq(stdout, "\n") {
 		if len(line) < 9 || line[0:7] != "#define" {
 			continue
 		}
@@ -418,7 +418,7 @@ func (p *Package) guessKinds(f *File) []*Name {
 		notDeclared
 	)
 	sawUnmatchedErrors := false
-	for _, line := range strings.Split(stderr, "\n") {
+	for line := range strings.SplitSeq(stderr, "\n") {
 		// Ignore warnings and random comments, with one
 		// exception: newer GCC versions will sometimes emit
 		// an error on a macro #define with a note referring

src/cmd/cgo/internal/test/testx.go

@@ -447,7 +447,7 @@ func issue7978check(t *testing.T, wantFunc string, badFunc string, depth int) {
 	runtime.GC()
 	buf := make([]byte, 65536)
 	trace := string(buf[:runtime.Stack(buf, true)])
-	for _, goroutine := range strings.Split(trace, "\n\n") {
+	for goroutine := range strings.SplitSeq(trace, "\n\n") {
 		if strings.Contains(goroutine, "test.issue7978go") {
 			trace := strings.Split(goroutine, "\n")
 			// look for the expected function in the stack

src/cmd/compile/internal/base/flag.go

@@ -570,7 +570,7 @@ func readEmbedCfg(file string) {
 
 // parseSpectre parses the spectre configuration from the string s.
 func parseSpectre(s string) {
-	for _, f := range strings.Split(s, ",") {
+	for f := range strings.SplitSeq(s, ",") {
 		f = strings.TrimSpace(f)
 		switch f {
 		default:

src/cmd/compile/internal/base/flag_test.go

@@ -0,0 +1,57 @@
+// Copyright 2025 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package base
+
+import (
+	"cmd/internal/obj"
+	"strings"
+	"testing"
+)
+
+func BenchmarkParseSpectreNew(b *testing.B) {
+	if Ctxt == nil {
+		Ctxt = &obj.Link{}
+	}
+
+	testCases := []struct {
+		name  string
+		input string
+	}{{
+		name:  "empty",
+		input: "",
+	}, {
+		name:  "index",
+		input: "index",
+	}, {
+		name:  "ret",
+		input: "ret",
+	}, {
+		name:  "index_ret",
+		input: "index,ret",
+	}, {
+		name:  "all",
+		input: "all",
+	}, {
+		name:  "multiple_indices_ret",
+		input: strings.Repeat("index,", 10) + "ret",
+	}}
+
+	for _, tc := range testCases {
+		b.Run(tc.name, func(b *testing.B) {
+			// Reset variables before each run
+			oldFlagCfgSpectreIndex := Flag.Cfg.SpectreIndex
+			oldCtxtRetpoline := Ctxt.Retpoline
+			defer func() {
+				Flag.Cfg.SpectreIndex = oldFlagCfgSpectreIndex
+				Ctxt.Retpoline = oldCtxtRetpoline
+			}()
+
+			b.ResetTimer()
+			for b.Loop() {
+				parseSpectre(tc.input)
+			}
+		})
+	}
+}

src/cmd/dist/build.go

@@ -380,7 +380,7 @@ func findgoversion() string {
 		if i := strings.Index(b, "\n"); i >= 0 {
 			rest := b[i+1:]
 			b = chomp(b[:i])
-			for _, line := range strings.Split(rest, "\n") {
+			for line := range strings.SplitSeq(rest, "\n") {
 				f := strings.Fields(line)
 				if len(f) == 0 {
 					continue
@@ -1137,7 +1137,7 @@ func shouldbuild(file, pkg string) bool {
 	}
 
 	// Check file contents for //go:build lines.
-	for _, p := range strings.Split(readfile(file), "\n") {
+	for p := range strings.SplitSeq(readfile(file), "\n") {
 		p = strings.TrimSpace(p)
 		if p == "" {
 			continue
@@ -2016,7 +2016,7 @@ func cmdlist() {
 }
 
 func setNoOpt() {
-	for _, gcflag := range strings.Split(gogcflags, " ") {
+	for gcflag := range strings.SplitSeq(gogcflags, " ") {
 		if gcflag == "-N" || gcflag == "-l" {
 			noOpt = true
 			break

src/cmd/distpack/pack.go

@@ -271,7 +271,7 @@ func readVERSION(goroot string) (version string, t time.Time) {
 		log.Fatal(err)
 	}
 	version, rest, _ := strings.Cut(string(data), "\n")
-	for _, line := range strings.Split(rest, "\n") {
+	for line := range strings.SplitSeq(rest, "\n") {
 		f := strings.Fields(line)
 		if len(f) == 0 {
 			continue

src/cmd/fix/main.go

@@ -84,14 +84,14 @@ func main() {
 
 	if *allowedRewrites != "" {
 		allowed = make(map[string]bool)
-		for _, f := range strings.Split(*allowedRewrites, ",") {
+		for f := range strings.SplitSeq(*allowedRewrites, ",") {
 			allowed[f] = true
 		}
 	}
 
 	if *forceRewrites != "" {
 		force = make(map[string]bool)
-		for _, f := range strings.Split(*forceRewrites, ",") {
+		for f := range strings.SplitSeq(*forceRewrites, ",") {
 			force[f] = true
 		}
 	}

src/cmd/go/internal/auth/gitauth.go

@@ -82,7 +82,7 @@ func runGitAuth(client *http.Client, dir, url string) (string, http.Header, erro
 // Any of these values may be empty if parsing fails.
 func parseGitAuth(data []byte) (parsedPrefix, username, password string) {
 	prefix := new(url.URL)
-	for _, line := range strings.Split(string(data), "\n") {
+	for line := range strings.SplitSeq(string(data), "\n") {
 		key, value, ok := strings.Cut(strings.TrimSpace(line), "=")
 		if !ok {
 			continue

src/cmd/go/internal/auth/gitauth_test.go

@@ -5,6 +5,7 @@
 package auth
 
 import (
+	"strings"
 	"testing"
 )
 
@@ -82,3 +83,77 @@ password:secr3t
 		}
 	}
 }
+
+func BenchmarkParseGitAuth(b *testing.B) {
+	// Define different test scenarios to benchmark
+	testCases := []struct {
+		name string
+		data []byte
+	}{{
+		// Standard scenario with all basic fields present
+		name: "standard",
+		data: []byte(`
+protocol=https
+host=example.com
+username=bob
+password=secr3t
+`),
+	}, {
+		// Scenario with URL field included
+		name: "with_url",
+		data: []byte(`
+protocol=https
+host=example.com
+username=bob
+password=secr3t
+url=https://example.com/repo
+`),
+	}, {
+		// Minimal scenario with only required fields
+		name: "minimal",
+		data: []byte(`
+protocol=https
+host=example.com
+`),
+	}, {
+		// Complex scenario with longer values and extra fields
+		name: "complex",
+		data: func() []byte {
+			var builder strings.Builder
+			builder.WriteString("protocol=https\n")
+			builder.WriteString("host=example.com\n")
+			builder.WriteString("username=longusernamenamename\n")
+			builder.WriteString("password=longpasswordwithmanycharacters123456789\n")
+			builder.WriteString("url=https://example.com/very/long/path/to/repository\n")
+			builder.WriteString("extra1=value1\n")
+			builder.WriteString("extra2=value2\n")
+			return []byte(builder.String())
+		}(),
+	}, {
+		// Scenario with empty input
+		name: "empty",
+		data: []byte(``),
+	}, {
+		// Scenario with malformed input (using colon instead of equals)
+		name: "malformed",
+		data: []byte(`
+protocol:https
+host:example.com
+username:bob
+password:secr3t
+`),
+	}}
+
+	for _, tc := range testCases {
+		b.Run(tc.name, func(b *testing.B) {
+			b.ResetTimer()
+			for b.Loop() {
+				prefix, username, password := parseGitAuth(tc.data)
+
+				_ = prefix
+				_ = username
+				_ = password
+			}
+		})
+	}
+}

src/cmd/go/internal/auth/netrc.go

@@ -24,7 +24,7 @@ func parseNetrc(data string) []netrcLine {
 	var nrc []netrcLine
 	var l netrcLine
 	inMacro := false
-	for _, line := range strings.Split(data, "\n") {
+	for line := range strings.SplitSeq(data, "\n") {
 		if inMacro {
 			if line == "" {
 				inMacro = false

src/cmd/go/internal/doc/dirs.go

@@ -241,7 +241,7 @@ func findCodeRoots() []Dir {
 	cmd := exec.Command(goCmd(), "list", "-m", "-f={{.Path}}\t{{.Dir}}", "all")
 	cmd.Stderr = os.Stderr
 	out, _ := cmd.Output()
-	for _, line := range strings.Split(string(out), "\n") {
+	for line := range strings.SplitSeq(string(out), "\n") {
 		path, dir, _ := strings.Cut(line, "\t")
 		if dir != "" {
 			list = append(list, Dir{importPath: path, dir: dir, inModule: true})

src/cmd/go/internal/doc/pkg.go

@@ -920,7 +920,7 @@ func trimUnexportedFields(fields *ast.FieldList, isInterface bool) *ast.FieldLis
 
 			start := doc.List[0].Slash
 			doc.List = doc.List[:0]
-			for _, line := range strings.Split(text, "\n") {
+			for line := range strings.SplitSeq(text, "\n") {
 				prefix := "// "
 				if len(line) > 0 && line[0] == '\t' {
 					prefix = "//"

src/cmd/go/internal/list/list.go

@@ -381,7 +381,7 @@ func (v *jsonFlag) Set(s string) error {
 	if *v == nil {
 		*v = make(map[string]bool)
 	}
-	for _, f := range strings.Split(s, ",") {
+	for f := range strings.SplitSeq(s, ",") {
 		(*v)[f] = true
 	}
 	return nil

src/cmd/go/internal/modfetch/codehost/git.go

@@ -173,7 +173,7 @@ func (r *gitRepo) loadLocalTags(ctx context.Context) {
 		return
 	}
 
-	for _, line := range strings.Split(string(out), "\n") {
+	for line := range strings.SplitSeq(string(out), "\n") {
 		if line != "" {
 			r.localTags.Store(line, true)
 		}
@@ -273,7 +273,7 @@ func (r *gitRepo) loadRefs(ctx context.Context) (map[string]string, error) {
 		}
 
 		refs := make(map[string]string)
-		for _, line := range strings.Split(string(out), "\n") {
+		for line := range strings.SplitSeq(string(out), "\n") {
 			f := strings.Fields(line)
 			if len(f) != 2 {
 				continue
@@ -745,7 +745,7 @@ func (r *gitRepo) RecentTag(ctx context.Context, rev, prefix string, allowed fun
 
 		// prefixed tags aren't valid semver tags so compare without prefix, but only tags with correct prefix
 		var highest string
-		for _, line := range strings.Split(string(out), "\n") {
+		for line := range strings.SplitSeq(string(out), "\n") {
 			line = strings.TrimSpace(line)
 			// git do support lstrip in for-each-ref format, but it was added in v2.13.0. Stripping here
 			// instead gives support for git v2.7.0.

src/cmd/go/internal/modfetch/codehost/vcs.go

@@ -561,7 +561,7 @@ func bzrParseStat(rev, out string) (*RevInfo, error) {
 	var revno int64
 	var tm time.Time
 	var tags []string
-	for _, line := range strings.Split(out, "\n") {
+	for line := range strings.SplitSeq(out, "\n") {
 		if line == "" || line[0] == ' ' || line[0] == '\t' {
 			// End of header, start of commit message.
 			break
@@ -614,7 +614,7 @@ func bzrParseStat(rev, out string) (*RevInfo, error) {
 }
 
 func fossilParseStat(rev, out string) (*RevInfo, error) {
-	for _, line := range strings.Split(out, "\n") {
+	for line := range strings.SplitSeq(out, "\n") {
 		if strings.HasPrefix(line, "uuid:") || strings.HasPrefix(line, "hash:") {
 			f := strings.Fields(line)
 			if len(f) != 5 || len(f[1]) != 40 || f[4] != "UTC" {

src/cmd/go/internal/modindex/build.go

@@ -426,7 +426,7 @@ Lines:
 // These lines set CFLAGS, CPPFLAGS, CXXFLAGS and LDFLAGS and pkg-config directives
 // that affect the way cgo's C code is built.
 func (ctxt *Context) saveCgo(filename string, di *build.Package, text string) error {
-	for _, line := range strings.Split(text, "\n") {
+	for line := range strings.SplitSeq(text, "\n") {
 		orig := line
 
 		// Line is

src/cmd/go/internal/modindex/scan.go

@@ -275,7 +275,7 @@ func importRaw(modroot, reldir string) *rawPackage {
 // which is the comment on import "C".
 func extractCgoDirectives(doc string) []string {
 	var out []string
-	for _, line := range strings.Split(doc, "\n") {
+	for line := range strings.SplitSeq(doc, "\n") {
 		// Line is
 		//	#cgo [GOOS/GOARCH...] LDFLAGS: stuff
 		//

src/cmd/go/internal/modload/buildlist.go

@@ -329,7 +329,7 @@ func readModGraph(ctx context.Context, pruning modPruning, roots []module.Versio
 		// so it wouldn't be useful to log when that occurs (because it happens in
 		// normal operation all the time).
 		readModGraphDebugOnce.Do(func() {
-			for _, f := range strings.Split(os.Getenv("GODEBUG"), ",") {
+			for f := range strings.SplitSeq(os.Getenv("GODEBUG"), ",") {
 				switch f {
 				case "lazymod=log":
 					debug.PrintStack()

src/cmd/go/internal/modload/init.go

@@ -1597,7 +1597,7 @@ func modulesTextIsForWorkspace(vendorDir string) (bool, error) {
 	}
 	line, _, _ := strings.Cut(string(buf[:n]), "\n")
 	if annotations, ok := strings.CutPrefix(line, "## "); ok {
-		for _, entry := range strings.Split(annotations, ";") {
+		for entry := range strings.SplitSeq(annotations, ";") {
 			entry = strings.TrimSpace(entry)
 			if entry == "workspace" {
 				return true, nil

src/cmd/go/internal/modload/vendor.go

@@ -53,7 +53,7 @@ func readVendorList(vendorDir string) {
 		}
 
 		var mod module.Version
-		for _, line := range strings.Split(string(data), "\n") {
+		for line := range strings.SplitSeq(string(data), "\n") {
 			if strings.HasPrefix(line, "# ") {
 				f := strings.Fields(line)
 
@@ -103,7 +103,7 @@ func readVendorList(vendorDir string) {
 			if annotations, ok := strings.CutPrefix(line, "## "); ok {
 				// Metadata. Take the union of annotations across multiple lines, if present.
 				meta := vendorMeta[mod]
-				for _, entry := range strings.Split(annotations, ";") {
+				for entry := range strings.SplitSeq(annotations, ";") {
 					entry = strings.TrimSpace(entry)
 					if entry == "explicit" {
 						meta.Explicit = true

src/cmd/go/internal/test/testflag.go

@@ -149,7 +149,7 @@ func (f *vetFlag) Set(value string) error {
 
 	*f = vetFlag{explicit: true}
 	var single string
-	for _, arg := range strings.Split(value, ",") {
+	for arg := range strings.SplitSeq(value, ",") {
 		switch arg {
 		case "":
 			return fmt.Errorf("-vet argument contains empty list element")