all: update to use os.ReadDir where appropriate

os.ReadDir is a replacement for ioutil.ReadDir that returns
a slice of fs.DirEntry instead of fs.FileInfo, meaning it is the
more efficient form.

This CL updates call sites throughout the Go source tree
wherever possible. As usual, code built using the Go 1.4
bootstrap toolchain is not included. There is also a use in
go/build that appears in the public API and can't be changed,
at least not without additional changes.

Fixes #42026.

Change-Id: Icfc9dd52c6045020f6830e22c72128499462d561
Reviewed-on: https://go-review.googlesource.com/c/go/+/266366
Trust: Russ Cox <[email protected]>
Run-TryBot: Russ Cox <[email protected]>
TryBot-Result: Go Bot <[email protected]>
Reviewed-by: Ian Lance Taylor <[email protected]>

Author: rsc

src/cmd/go/internal/clean/clean.go

@@ -9,7 +9,6 @@ import (
 	"context"
 	"fmt"
 	"io"
-	"io/ioutil"
 	"os"
 	"path/filepath"
 	"strconv"
@@ -244,7 +243,7 @@ func clean(p *load.Package) {
 		base.Errorf("%v", p.Error)
 		return
 	}
-	dirs, err := ioutil.ReadDir(p.Dir)
+	dirs, err := os.ReadDir(p.Dir)
 	if err != nil {
 		base.Errorf("go clean %s: %v", p.Dir, err)
 		return

src/cmd/go/internal/imports/scan_test.go

@@ -7,7 +7,6 @@ package imports
 import (
 	"bytes"
 	"internal/testenv"
-	"io/ioutil"
 	"os"
 	"path"
 	"path/filepath"
@@ -58,7 +57,7 @@ func TestScan(t *testing.T) {
 func TestScanDir(t *testing.T) {
 	testenv.MustHaveGoBuild(t)
 
-	dirs, err := ioutil.ReadDir("testdata")
+	dirs, err := os.ReadDir("testdata")
 	if err != nil {
 		t.Fatal(err)
 	}

src/cmd/go/internal/load/pkg.go

@@ -15,7 +15,6 @@ import (
 	"go/scanner"
 	"go/token"
 	"io/fs"
-	"io/ioutil"
 	"os"
 	"path"
 	pathpkg "path"
@@ -1296,9 +1295,9 @@ HaveGoMod:
 // Otherwise it is not possible to vendor just a/b/c and still import the
 // non-vendored a/b. See golang.org/issue/13832.
 func hasGoFiles(dir string) bool {
-	fis, _ := ioutil.ReadDir(dir)
-	for _, fi := range fis {
-		if !fi.IsDir() && strings.HasSuffix(fi.Name(), ".go") {
+	files, _ := os.ReadDir(dir)
+	for _, f := range files {
+		if !f.IsDir() && strings.HasSuffix(f.Name(), ".go") {
 			return true
 		}
 	}

src/cmd/go/internal/modcmd/vendor.go

@@ -10,7 +10,6 @@ import (
 	"fmt"
 	"io"
 	"io/fs"
-	"io/ioutil"
 	"os"
 	"path/filepath"
 	"sort"
@@ -244,7 +243,7 @@ var metaPrefixes = []string{
 }
 
 // matchMetadata reports whether info is a metadata file.
-func matchMetadata(dir string, info fs.FileInfo) bool {
+func matchMetadata(dir string, info fs.DirEntry) bool {
 	name := info.Name()
 	for _, p := range metaPrefixes {
 		if strings.HasPrefix(name, p) {
@@ -255,7 +254,7 @@ func matchMetadata(dir string, info fs.FileInfo) bool {
 }
 
 // matchPotentialSourceFile reports whether info may be relevant to a build operation.
-func matchPotentialSourceFile(dir string, info fs.FileInfo) bool {
+func matchPotentialSourceFile(dir string, info fs.DirEntry) bool {
 	if strings.HasSuffix(info.Name(), "_test.go") {
 		return false
 	}
@@ -281,16 +280,16 @@ func matchPotentialSourceFile(dir string, info fs.FileInfo) bool {
 }
 
 // copyDir copies all regular files satisfying match(info) from src to dst.
-func copyDir(dst, src string, match func(dir string, info fs.FileInfo) bool) {
-	files, err := ioutil.ReadDir(src)
+func copyDir(dst, src string, match func(dir string, info fs.DirEntry) bool) {
+	files, err := os.ReadDir(src)
 	if err != nil {
 		base.Fatalf("go mod vendor: %v", err)
 	}
 	if err := os.MkdirAll(dst, 0777); err != nil {
 		base.Fatalf("go mod vendor: %v", err)
 	}
 	for _, file := range files {
-		if file.IsDir() || !file.Mode().IsRegular() || !match(src, file) {
+		if file.IsDir() || !file.Type().IsRegular() || !match(src, file) {
 			continue
 		}
 		r, err := os.Open(filepath.Join(src, file.Name()))

src/cmd/go/internal/modfetch/cache.go

@@ -11,7 +11,6 @@ import (
 	"fmt"
 	"io"
 	"io/fs"
-	"io/ioutil"
 	"os"
 	"path/filepath"
 	"strings"
@@ -598,7 +597,7 @@ func rewriteVersionList(dir string) {
 	}
 	defer unlock()
 
-	infos, err := ioutil.ReadDir(dir)
+	infos, err := os.ReadDir(dir)
 	if err != nil {
 		return
 	}

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

@@ -12,7 +12,6 @@ import (
 	"fmt"
 	"go/build"
 	"internal/lazyregexp"
-	"io/ioutil"
 	"os"
 	"path"
 	"path/filepath"
@@ -445,13 +444,13 @@ func CreateModFile(ctx context.Context, modPath string) {
 	// this is an existing project. Walking the tree for packages would be more
 	// accurate, but could take much longer.
 	empty := true
-	fis, _ := ioutil.ReadDir(modRoot)
-	for _, fi := range fis {
-		name := fi.Name()
+	files, _ := os.ReadDir(modRoot)
+	for _, f := range files {
+		name := f.Name()
 		if strings.HasPrefix(name, ".") || strings.HasPrefix(name, "_") {
 			continue
 		}
-		if strings.HasSuffix(name, ".go") || fi.IsDir() {
+		if strings.HasSuffix(name, ".go") || f.IsDir() {
 			empty = false
 			break
 		}
@@ -731,19 +730,19 @@ func findModulePath(dir string) (string, error) {
 
 	// Cast about for import comments,
 	// first in top-level directory, then in subdirectories.
-	list, _ := ioutil.ReadDir(dir)
+	list, _ := os.ReadDir(dir)
 	for _, info := range list {
-		if info.Mode().IsRegular() && strings.HasSuffix(info.Name(), ".go") {
+		if info.Type().IsRegular() && strings.HasSuffix(info.Name(), ".go") {
 			if com := findImportComment(filepath.Join(dir, info.Name())); com != "" {
 				return com, nil
 			}
 		}
 	}
 	for _, info1 := range list {
 		if info1.IsDir() {
-			files, _ := ioutil.ReadDir(filepath.Join(dir, info1.Name()))
+			files, _ := os.ReadDir(filepath.Join(dir, info1.Name()))
 			for _, info2 := range files {
-				if info2.Mode().IsRegular() && strings.HasSuffix(info2.Name(), ".go") {
+				if info2.Type().IsRegular() && strings.HasSuffix(info2.Name(), ".go") {
 					if com := findImportComment(filepath.Join(dir, info1.Name(), info2.Name())); com != "" {
 						return path.Dir(com), nil
 					}

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

@@ -13,7 +13,6 @@ import (
 	"go/build"
 	"io"
 	"io/fs"
-	"io/ioutil"
 	"os"
 	"os/exec"
 	"path"
@@ -1561,13 +1560,18 @@ func hashOpen(name string) (cache.ActionID, error) {
 	}
 	hashWriteStat(h, info)
 	if info.IsDir() {
-		names, err := ioutil.ReadDir(name)
+		files, err := os.ReadDir(name)
 		if err != nil {
 			fmt.Fprintf(h, "err %v\n", err)
 		}
-		for _, f := range names {
+		for _, f := range files {
 			fmt.Fprintf(h, "file %s ", f.Name())
-			hashWriteStat(h, f)
+			finfo, err := f.Info()
+			if err != nil {
+				fmt.Fprintf(h, "err %v\n", err)
+			} else {
+				hashWriteStat(h, finfo)
+			}
 		}
 	} else if info.Mode().IsRegular() {
 		// Because files might be very large, do not attempt

src/cmd/go/proxy_test.go

@@ -13,7 +13,6 @@ import (
 	"fmt"
 	"io"
 	"io/fs"
-	"io/ioutil"
 	"log"
 	"net"
 	"net/http"
@@ -75,12 +74,12 @@ func StartProxy() {
 var modList []module.Version
 
 func readModList() {
-	infos, err := ioutil.ReadDir("testdata/mod")
+	files, err := os.ReadDir("testdata/mod")
 	if err != nil {
 		log.Fatal(err)
 	}
-	for _, info := range infos {
-		name := info.Name()
+	for _, f := range files {
+		name := f.Name()
 		if !strings.HasSuffix(name, ".txt") {
 			continue
 		}

src/crypto/x509/root_unix.go

@@ -8,7 +8,6 @@ package x509
 
 import (
 	"io/fs"
-	"io/ioutil"
 	"os"
 	"path/filepath"
 	"strings"
@@ -82,28 +81,28 @@ func loadSystemRoots() (*CertPool, error) {
 	return nil, firstErr
 }
 
-// readUniqueDirectoryEntries is like ioutil.ReadDir but omits
+// readUniqueDirectoryEntries is like os.ReadDir but omits
 // symlinks that point within the directory.
-func readUniqueDirectoryEntries(dir string) ([]fs.FileInfo, error) {
-	fis, err := ioutil.ReadDir(dir)
+func readUniqueDirectoryEntries(dir string) ([]fs.DirEntry, error) {
+	files, err := os.ReadDir(dir)
 	if err != nil {
 		return nil, err
 	}
-	uniq := fis[:0]
-	for _, fi := range fis {
-		if !isSameDirSymlink(fi, dir) {
-			uniq = append(uniq, fi)
+	uniq := files[:0]
+	for _, f := range files {
+		if !isSameDirSymlink(f, dir) {
+			uniq = append(uniq, f)
 		}
 	}
 	return uniq, nil
 }
 
 // isSameDirSymlink reports whether fi in dir is a symlink with a
 // target not containing a slash.
-func isSameDirSymlink(fi fs.FileInfo, dir string) bool {
-	if fi.Mode()&fs.ModeSymlink == 0 {
+func isSameDirSymlink(f fs.DirEntry, dir string) bool {
+	if f.Type()&fs.ModeSymlink == 0 {
 		return false
 	}
-	target, err := os.Readlink(filepath.Join(dir, fi.Name()))
+	target, err := os.Readlink(filepath.Join(dir, f.Name()))
 	return err == nil && !strings.Contains(target, "/")
 }

src/go/build/deps_test.go

@@ -12,7 +12,6 @@ import (
 	"fmt"
 	"internal/testenv"
 	"io/fs"
-	"io/ioutil"
 	"os"
 	"path/filepath"
 	"runtime"
@@ -597,7 +596,7 @@ func findImports(pkg string) ([]string, error) {
 		vpkg = "vendor/" + pkg
 	}
 	dir := filepath.Join(Default.GOROOT, "src", vpkg)
-	files, err := ioutil.ReadDir(dir)
+	files, err := os.ReadDir(dir)
 	if err != nil {
 		return nil, err
 	}

src/go/internal/gcimporter/gcimporter_test.go

@@ -8,7 +8,6 @@ import (
 	"bytes"
 	"fmt"
 	"internal/testenv"
-	"io/ioutil"
 	"os"
 	"os/exec"
 	"path/filepath"
@@ -66,7 +65,7 @@ const maxTime = 30 * time.Second
 
 func testDir(t *testing.T, dir string, endTime time.Time) (nimports int) {
 	dirname := filepath.Join(runtime.GOROOT(), "pkg", runtime.GOOS+"_"+runtime.GOARCH, dir)
-	list, err := ioutil.ReadDir(dirname)
+	list, err := os.ReadDir(dirname)
 	if err != nil {
 		t.Fatalf("testDir(%s): %s", dirname, err)
 	}
@@ -144,7 +143,7 @@ func TestVersionHandling(t *testing.T) {
 	}
 
 	const dir = "./testdata/versions"
-	list, err := ioutil.ReadDir(dir)
+	list, err := os.ReadDir(dir)
 	if err != nil {
 		t.Fatal(err)
 	}

src/go/internal/srcimporter/srcimporter_test.go

@@ -10,7 +10,6 @@ import (
 	"go/token"
 	"go/types"
 	"internal/testenv"
-	"io/ioutil"
 	"os"
 	"path"
 	"path/filepath"
@@ -59,7 +58,7 @@ func walkDir(t *testing.T, path string, endTime time.Time) (int, bool) {
 		return 0, false
 	}
 
-	list, err := ioutil.ReadDir(filepath.Join(runtime.GOROOT(), "src", path))
+	list, err := os.ReadDir(filepath.Join(runtime.GOROOT(), "src", path))
 	if err != nil {
 		t.Fatalf("walkDir %s failed (%v)", path, err)
 	}

src/go/parser/error_test.go

@@ -25,7 +25,7 @@ package parser
 import (
 	"go/scanner"
 	"go/token"
-	"io/ioutil"
+	"os"
 	"path/filepath"
 	"regexp"
 	"strings"
@@ -174,13 +174,13 @@ func checkErrors(t *testing.T, filename string, input interface{}) {
 }
 
 func TestErrors(t *testing.T) {
-	list, err := ioutil.ReadDir(testdata)
+	list, err := os.ReadDir(testdata)
 	if err != nil {
 		t.Fatal(err)
 	}
-	for _, fi := range list {
-		name := fi.Name()
-		if !fi.IsDir() && !strings.HasPrefix(name, ".") && strings.HasSuffix(name, ".src") {
+	for _, d := range list {
+		name := d.Name()
+		if !d.IsDir() && !strings.HasPrefix(name, ".") && strings.HasSuffix(name, ".src") {
 			checkErrors(t, filepath.Join(testdata, name), nil)
 		}
 	}