all: update to use filepath.WalkDir instead of filepath.Walk

Now that filepath.WalkDir is available, it is more efficient
and should be used in place of filepath.Walk.
Update the tree to reflect best practices.

As usual, the code compiled with Go 1.4 during bootstrap is excluded.
(In this CL, that's only cmd/dist.)

For #42027.

Change-Id: Ib0f7b1e43e50b789052f9835a63ced701d8c411c
Reviewed-on: https://go-review.googlesource.com/c/go/+/267719
Trust: Russ Cox <rsc@golang.org>
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Rob Pike <r@golang.org>

src/cmd/compile/fmt_test.go

@@ -52,6 +52,7 @@ import (
 	"go/types"
 	"internal/testenv"
 	"io"
+	"io/fs"
 	"io/ioutil"
 	"log"
 	"os"
@@ -89,7 +90,7 @@ func TestFormats(t *testing.T) {
 	testenv.MustHaveGoBuild(t) // more restrictive than necessary, but that's ok
 
 	// process all directories
-	filepath.Walk(".", func(path string, info os.FileInfo, err error) error {
+	filepath.WalkDir(".", func(path string, info fs.DirEntry, err error) error {
 		if info.IsDir() {
 			if info.Name() == "testdata" {
 				return filepath.SkipDir

src/cmd/dist/test.go

@@ -1509,6 +1509,7 @@ func (t *tester) makeGOROOTUnwritable() (undo func()) {
 	}
 	gocacheSubdir, _ := filepath.Rel(dir, gocache)
 
+	// Note: Can't use WalkDir here, because this has to compile with Go 1.4.
 	filepath.Walk(dir, func(path string, info os.FileInfo, err error) error {
 		if suffix := strings.TrimPrefix(path, dir+string(filepath.Separator)); suffix != "" {
 			if suffix == gocacheSubdir {

src/cmd/fix/main.go

@@ -234,10 +234,10 @@ func report(err error) {
 }
 
 func walkDir(path string) {
-	filepath.Walk(path, visitFile)
+	filepath.WalkDir(path, visitFile)
 }
 
-func visitFile(path string, f fs.FileInfo, err error) error {
+func visitFile(path string, f fs.DirEntry, err error) error {
 	if err == nil && isGoFile(f) {
 		err = processFile(path, false)
 	}
@@ -247,7 +247,7 @@ func visitFile(path string, f fs.FileInfo, err error) error {
 	return nil
 }
 
-func isGoFile(f fs.FileInfo) bool {
+func isGoFile(f fs.DirEntry) bool {
 	// ignore non-Go files
 	name := f.Name()
 	return !f.IsDir() && !strings.HasPrefix(name, ".") && strings.HasSuffix(name, ".go")

src/cmd/go/go_test.go

@@ -774,7 +774,7 @@ func (tg *testgoData) cleanup() {
 func removeAll(dir string) error {
 	// module cache has 0444 directories;
 	// make them writable in order to remove content.
-	filepath.Walk(dir, func(path string, info fs.FileInfo, err error) error {
+	filepath.WalkDir(dir, func(path string, info fs.DirEntry, err error) error {
 		// chmod not only directories, but also things that we couldn't even stat
 		// due to permission errors: they may also be unreadable directories.
 		if err != nil || info.IsDir() {
@@ -820,8 +820,8 @@ func TestNewReleaseRebuildsStalePackagesInGOPATH(t *testing.T) {
 	} {
 		srcdir := filepath.Join(testGOROOT, copydir)
 		tg.tempDir(filepath.Join("goroot", copydir))
-		err := filepath.Walk(srcdir,
+		err := filepath.WalkDir(srcdir,
-			func(path string, info fs.FileInfo, err error) error {
+			func(path string, info fs.DirEntry, err error) error {
 				if err != nil {
 					return err
 				}
@@ -838,9 +838,6 @@ func TestNewReleaseRebuildsStalePackagesInGOPATH(t *testing.T) {
 					return err
 				}
 				tg.tempFile(dest, string(data))
-				if err := os.Chmod(tg.path(dest), info.Mode()|0200); err != nil {
-					return err
-				}
 				return nil
 			})
 		if err != nil {

src/cmd/go/internal/modfetch/fetch.go

@@ -318,9 +318,10 @@ func makeDirsReadOnly(dir string) {
 		mode fs.FileMode
 	}
 	var dirs []pathMode // in lexical order
-	filepath.Walk(dir, func(path string, info fs.FileInfo, err error) error {
+	filepath.WalkDir(dir, func(path string, d fs.DirEntry, err error) error {
-		if err == nil && info.Mode()&0222 != 0 {
+		if err == nil && d.IsDir() {
-			if info.IsDir() {
+			info, err := d.Info()
+			if err == nil && info.Mode()&0222 != 0 {
 				dirs = append(dirs, pathMode{path, info.Mode()})
 			}
 		}
@@ -337,7 +338,7 @@ func makeDirsReadOnly(dir string) {
 // any permission changes needed to do so.
 func RemoveAll(dir string) error {
 	// Module cache has 0555 directories; make them writable in order to remove content.
-	filepath.Walk(dir, func(path string, info fs.FileInfo, err error) error {
+	filepath.WalkDir(dir, func(path string, info fs.DirEntry, err error) error {
 		if err != nil {
 			return nil // ignore errors walking in file system
 		}

src/cmd/go/internal/version/version.go

@@ -88,8 +88,15 @@ func runVersion(ctx context.Context, cmd *base.Command, args []string) {
 
 // scanDir scans a directory for executables to run scanFile on.
 func scanDir(dir string) {
-	filepath.Walk(dir, func(path string, info fs.FileInfo, err error) error {
+	filepath.WalkDir(dir, func(path string, d fs.DirEntry, err error) error {
-		if info.Mode().IsRegular() || info.Mode()&fs.ModeSymlink != 0 {
+		if d.Type().IsRegular() || d.Type()&fs.ModeSymlink != 0 {
+			info, err := d.Info()
+			if err != nil {
+				if *versionV {
+					fmt.Fprintf(os.Stderr, "%s: %v\n", path, err)
+				}
+				return nil
+			}
 			scanFile(path, info, *versionV)
 		}
 		return nil
@@ -120,6 +127,7 @@ func scanFile(file string, info fs.FileInfo, mustPrint bool) {
 		}
 		info = i
 	}
+
 	if !isExe(file, info) {
 		if mustPrint {
 			fmt.Fprintf(os.Stderr, "%s: not executable file\n", file)

src/cmd/go/testdata/addmod.go

@@ -122,8 +122,8 @@ func main() {
 			{Name: ".info", Data: info},
 		}
 		dir = filepath.Clean(dir)
-		err = filepath.Walk(dir, func(path string, info fs.FileInfo, err error) error {
+		err = filepath.WalkDir(dir, func(path string, info fs.DirEntry, err error) error {
-			if !info.Mode().IsRegular() {
+			if !info.Type().IsRegular() {
 				return nil
 			}
 			name := info.Name()

src/cmd/go/testdata/savedir.go

@@ -49,7 +49,7 @@ func main() {
 
 	a := new(txtar.Archive)
 	dir = filepath.Clean(dir)
-	filepath.Walk(dir, func(path string, info fs.FileInfo, err error) error {
+	filepath.WalkDir(dir, func(path string, info fs.DirEntry, err error) error {
 		if path == dir {
 			return nil
 		}
@@ -60,7 +60,7 @@ func main() {
 			}
 			return nil
 		}
-		if !info.Mode().IsRegular() {
+		if !info.Type().IsRegular() {
 			return nil
 		}
 		data, err := ioutil.ReadFile(path)

src/cmd/gofmt/gofmt.go

@@ -74,7 +74,7 @@ func initParserMode() {
 	}
 }
 
-func isGoFile(f fs.FileInfo) bool {
+func isGoFile(f fs.DirEntry) bool {
 	// ignore non-Go files
 	name := f.Name()
 	return !f.IsDir() && !strings.HasPrefix(name, ".") && strings.HasSuffix(name, ".go")
@@ -164,7 +164,7 @@ func processFile(filename string, in io.Reader, out io.Writer, stdin bool) error
 	return err
 }
 
-func visitFile(path string, f fs.FileInfo, err error) error {
+func visitFile(path string, f fs.DirEntry, err error) error {
 	if err == nil && isGoFile(f) {
 		err = processFile(path, nil, os.Stdout, false)
 	}
@@ -177,7 +177,7 @@ func visitFile(path string, f fs.FileInfo, err error) error {
 }
 
 func walkDir(path string) {
-	filepath.Walk(path, visitFile)
+	filepath.WalkDir(path, visitFile)
 }
 
 func main() {

src/cmd/gofmt/long_test.go

@@ -108,12 +108,12 @@ func testFiles(t *testing.T, filenames <-chan string, done chan<- int) {
 func genFilenames(t *testing.T, filenames chan<- string) {
 	defer close(filenames)
 
-	handleFile := func(filename string, fi fs.FileInfo, err error) error {
+	handleFile := func(filename string, d fs.DirEntry, err error) error {
 		if err != nil {
 			t.Error(err)
 			return nil
 		}
-		if isGoFile(fi) {
+		if isGoFile(d) {
 			filenames <- filename
 			nfiles++
 		}
@@ -124,13 +124,13 @@ func genFilenames(t *testing.T, filenames chan<- string) {
 	if *files != "" {
 		for _, filename := range strings.Split(*files, ",") {
 			fi, err := os.Stat(filename)
-			handleFile(filename, fi, err)
+			handleFile(filename, &statDirEntry{fi}, err)
 		}
 		return // ignore files under -root
 	}
 
 	// otherwise, test all Go files under *root
-	filepath.Walk(*root, handleFile)
+	filepath.WalkDir(*root, handleFile)
 }
 
 func TestAll(t *testing.T) {
@@ -164,3 +164,12 @@ func TestAll(t *testing.T) {
 		fmt.Printf("processed %d files\n", nfiles)
 	}
 }
+
+type statDirEntry struct {
+	info fs.FileInfo
+}
+
+func (d *statDirEntry) Name() string               { return d.info.Name() }
+func (d *statDirEntry) IsDir() bool                { return d.info.IsDir() }
+func (d *statDirEntry) Type() fs.FileMode          { return d.info.Mode().Type() }
+func (d *statDirEntry) Info() (fs.FileInfo, error) { return d.info, nil }

src/cmd/internal/moddeps/moddeps_test.go

@@ -33,7 +33,7 @@ func findGorootModules(t *testing.T) []gorootModule {
 	goBin := testenv.GoToolPath(t)
 
 	goroot.once.Do(func() {
-		goroot.err = filepath.Walk(runtime.GOROOT(), func(path string, info fs.FileInfo, err error) error {
+		goroot.err = filepath.WalkDir(runtime.GOROOT(), func(path string, info fs.DirEntry, err error) error {
 			if err != nil {
 				return err
 			}

src/compress/gzip/issue14937_test.go

@@ -31,7 +31,7 @@ func TestGZIPFilesHaveZeroMTimes(t *testing.T) {
 		t.Fatal("error evaluating GOROOT: ", err)
 	}
 	var files []string
-	err = filepath.Walk(goroot, func(path string, info fs.FileInfo, err error) error {
+	err = filepath.WalkDir(goroot, func(path string, info fs.DirEntry, err error) error {
 		if err != nil {
 			return err
 		}

src/go/build/deps_test.go

@@ -510,8 +510,8 @@ func listStdPkgs(goroot string) ([]string, error) {
 	var pkgs []string
 
 	src := filepath.Join(goroot, "src") + string(filepath.Separator)
-	walkFn := func(path string, fi fs.FileInfo, err error) error {
+	walkFn := func(path string, d fs.DirEntry, err error) error {
-		if err != nil || !fi.IsDir() || path == src {
+		if err != nil || !d.IsDir() || path == src {
 			return nil
 		}
 
@@ -528,7 +528,7 @@ func listStdPkgs(goroot string) ([]string, error) {
 		pkgs = append(pkgs, strings.TrimPrefix(name, "vendor/"))
 		return nil
 	}
-	if err := filepath.Walk(src, walkFn); err != nil {
+	if err := filepath.WalkDir(src, walkFn); err != nil {
 		return nil, err
 	}
 	return pkgs, nil

src/go/doc/headscan.go

@@ -69,8 +69,8 @@ func main() {
 	flag.Parse()
 	fset := token.NewFileSet()
 	nheadings := 0
-	err := filepath.Walk(*root, func(path string, fi fs.FileInfo, err error) error {
+	err := filepath.WalkDir(*root, func(path string, info fs.DirEntry, err error) error {
-		if !fi.IsDir() {
+		if !info.IsDir() {
 			return nil
 		}
 		pkgs, err := parser.ParseDir(fset, path, isGoFile, parser.ParseComments)

src/index/suffixarray/suffixarray_test.go

@@ -503,7 +503,7 @@ func makeText(name string) ([]byte, error) {
 			return nil, err
 		}
 	case "go":
-		err := filepath.Walk("../..", func(path string, info fs.FileInfo, err error) error {
+		err := filepath.WalkDir("../..", func(path string, info fs.DirEntry, err error) error {
 			if err == nil && strings.HasSuffix(path, ".go") && !info.IsDir() {
 				file, err := ioutil.ReadFile(path)
 				if err != nil {

test/run.go

@@ -14,6 +14,7 @@ import (
 	"fmt"
 	"hash/fnv"
 	"io"
+	"io/fs"
 	"io/ioutil"
 	"log"
 	"os"
@@ -1793,7 +1794,7 @@ func overlayDir(dstRoot, srcRoot string) error {
 		return err
 	}
 
-	return filepath.Walk(srcRoot, func(srcPath string, info os.FileInfo, err error) error {
+	return filepath.WalkDir(srcRoot, func(srcPath string, d fs.DirEntry, err error) error {
 		if err != nil || srcPath == srcRoot {
 			return err
 		}
@@ -1804,14 +1805,16 @@ func overlayDir(dstRoot, srcRoot string) error {
 		}
 		dstPath := filepath.Join(dstRoot, suffix)
 
-		perm := info.Mode() & os.ModePerm
+		var info fs.FileInfo
-		if info.Mode()&os.ModeSymlink != 0 {
+		if d.Type()&os.ModeSymlink != 0 {
 			info, err = os.Stat(srcPath)
-			if err != nil {
+		} else {
-				return err
+			info, err = d.Info()
-			}
-			perm = info.Mode() & os.ModePerm
 		}
+		if err != nil {
+			return err
+		}
+		perm := info.Mode() & os.ModePerm
 
 		// Always copy directories (don't symlink them).
 		// If we add a file in the overlay, we don't want to add it in the original.

test/winbatch.go

@@ -27,11 +27,11 @@ func main() {
 	// Walk the entire Go repository source tree (without GOROOT/pkg),
 	// skipping directories that start with "." and named "testdata",
 	// and ensure all .bat files found have exact CRLF line endings.
-	err := filepath.Walk(runtime.GOROOT(), func(path string, fi os.FileInfo, err error) error {
+	err := filepath.WalkDir(runtime.GOROOT(), func(path string, d os.DirEntry, err error) error {
 		if err != nil {
 			return err
 		}
-		if fi.IsDir() && (strings.HasPrefix(fi.Name(), ".") || fi.Name() == "testdata") {
+		if d.IsDir() && (strings.HasPrefix(d.Name(), ".") || d.Name() == "testdata") {
 			return filepath.SkipDir
 		}
 		if path == filepath.Join(runtime.GOROOT(), "pkg") {
@@ -39,7 +39,7 @@ func main() {
 			// Skip it to avoid false positives. (Also see golang.org/issue/37929.)
 			return filepath.SkipDir
 		}
-		if filepath.Ext(fi.Name()) == ".bat" {
+		if filepath.Ext(d.Name()) == ".bat" {
 			enforceBatchStrictCRLF(path)
 		}
 		return nil