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>

2 files changed, 16 insertions, 7 deletions

diff --git a/src/cmd/gofmt/gofmt.go b/src/cmd/gofmt/gofmt.go
index dba2411eed..719c681a3e 100644
--- a/src/cmd/gofmt/gofmt.go
+++ b/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() {
diff --git a/src/cmd/gofmt/long_test.go b/src/cmd/gofmt/long_test.go
index 28306ce83e..4a821705f1 100644
--- a/src/cmd/gofmt/long_test.go
+++ b/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 }