libgo: update to Go1.16beta1 release

This does not yet include support for the //go:embed directive added
in this release.

	* Makefile.am (check-runtime): Don't create check-runtime-dir.
	(mostlyclean-local): Don't remove check-runtime-dir.
	(check-go-tool, check-vet): Copy in go.mod and modules.txt.
	(check-cgo-test, check-carchive-test): Add go.mod file.
	* Makefile.in: Regenerate.

Reviewed-on: https://go-review.googlesource.com/c/gofrontend/+/280172

8 files changed, 289 insertions, 116 deletions

diff --git a/libgo/go/path/filepath/example_unix_test.go b/libgo/go/path/filepath/example_unix_test.go
index 23f2138..c9d6944 100644
--- a/libgo/go/path/filepath/example_unix_test.go
+++ b/libgo/go/path/filepath/example_unix_test.go
@@ -72,12 +72,16 @@ func ExampleJoin() {
 	fmt.Println(filepath.Join("a", "b/c"))
 	fmt.Println(filepath.Join("a/b", "c"))
 	fmt.Println(filepath.Join("a/b", "/c"))
+
+	fmt.Println(filepath.Join("a/b", "../../../xyz"))
+
 	// Output:
 	// On Unix:
 	// a/b/c
 	// a/b/c
 	// a/b/c
 	// a/b/c
+	// ../xyz
 }
 
 func ExampleMatch() {
diff --git a/libgo/go/path/filepath/example_unix_walk_test.go b/libgo/go/path/filepath/example_unix_walk_test.go
index fa8b8e3..c8a818f 100644
--- a/libgo/go/path/filepath/example_unix_walk_test.go
+++ b/libgo/go/path/filepath/example_unix_walk_test.go
@@ -8,13 +8,13 @@ package filepath_test
 
 import (
 	"fmt"
-	"io/ioutil"
+	"io/fs"
 	"os"
 	"path/filepath"
 )
 
 func prepareTestDirTree(tree string) (string, error) {
-	tmpDir, err := ioutil.TempDir("", "")
+	tmpDir, err := os.MkdirTemp("", "")
 	if err != nil {
 		return "", fmt.Errorf("error creating temp directory: %v\n", err)
 	}
@@ -40,7 +40,7 @@ func ExampleWalk() {
 	subDirToSkip := "skip"
 
 	fmt.Println("On Unix:")
-	err = filepath.Walk(".", func(path string, info os.FileInfo, err error) error {
+	err = filepath.Walk(".", func(path string, info fs.FileInfo, err error) error {
 		if err != nil {
 			fmt.Printf("prevent panic by handling failure accessing a path %q: %v\n", path, err)
 			return err
diff --git a/libgo/go/path/filepath/match.go b/libgo/go/path/filepath/match.go
index 20a3348..c77a269 100644
--- a/libgo/go/path/filepath/match.go
+++ b/libgo/go/path/filepath/match.go
@@ -122,25 +122,28 @@ Scan:
 // If so, it returns the remainder of s (after the match).
 // Chunk is all single-character operators: literals, char classes, and ?.
 func matchChunk(chunk, s string) (rest string, ok bool, err error) {
+	// failed records whether the match has failed.
+	// After the match fails, the loop continues on processing chunk,
+	// checking that the pattern is well-formed but no longer reading s.
+	failed := false
 	for len(chunk) > 0 {
-		if len(s) == 0 {
-			return
+		if !failed && len(s) == 0 {
+			failed = true
 		}
 		switch chunk[0] {
 		case '[':
 			// character class
-			r, n := utf8.DecodeRuneInString(s)
-			s = s[n:]
-			chunk = chunk[1:]
-			// We can't end right after '[', we're expecting at least
-			// a closing bracket and possibly a caret.
-			if len(chunk) == 0 {
-				err = ErrBadPattern
-				return
+			var r rune
+			if !failed {
+				var n int
+				r, n = utf8.DecodeRuneInString(s)
+				s = s[n:]
 			}
+			chunk = chunk[1:]
 			// possibly negated
-			negated := chunk[0] == '^'
-			if negated {
+			negated := false
+			if len(chunk) > 0 && chunk[0] == '^' {
+				negated = true
 				chunk = chunk[1:]
 			}
 			// parse all ranges
@@ -153,12 +156,12 @@ func matchChunk(chunk, s string) (rest string, ok bool, err error) {
 				}
 				var lo, hi rune
 				if lo, chunk, err = getEsc(chunk); err != nil {
-					return
+					return "", false, err
 				}
 				hi = lo
 				if chunk[0] == '-' {
 					if hi, chunk, err = getEsc(chunk[1:]); err != nil {
-						return
+						return "", false, err
 					}
 				}
 				if lo <= r && r <= hi {
@@ -167,35 +170,41 @@ func matchChunk(chunk, s string) (rest string, ok bool, err error) {
 				nrange++
 			}
 			if match == negated {
-				return
+				failed = true
 			}
 
 		case '?':
-			if s[0] == Separator {
-				return
+			if !failed {
+				if s[0] == Separator {
+					failed = true
+				}
+				_, n := utf8.DecodeRuneInString(s)
+				s = s[n:]
 			}
-			_, n := utf8.DecodeRuneInString(s)
-			s = s[n:]
 			chunk = chunk[1:]
 
 		case '\\':
 			if runtime.GOOS != "windows" {
 				chunk = chunk[1:]
 				if len(chunk) == 0 {
-					err = ErrBadPattern
-					return
+					return "", false, ErrBadPattern
 				}
 			}
 			fallthrough
 
 		default:
-			if chunk[0] != s[0] {
-				return
+			if !failed {
+				if chunk[0] != s[0] {
+					failed = true
+				}
+				s = s[1:]
 			}
-			s = s[1:]
 			chunk = chunk[1:]
 		}
 	}
+	if failed {
+		return "", false, nil
+	}
 	return s, true, nil
 }
 
@@ -232,6 +241,10 @@ func getEsc(chunk string) (r rune, nchunk string, err error) {
 // The only possible returned error is ErrBadPattern, when pattern
 // is malformed.
 func Glob(pattern string) (matches []string, err error) {
+	// Check pattern is well-formed.
+	if _, err := Match(pattern, ""); err != nil {
+		return nil, err
+	}
 	if !hasMeta(pattern) {
 		if _, err = os.Lstat(pattern); err != nil {
 			return nil, nil
diff --git a/libgo/go/path/filepath/match_test.go b/libgo/go/path/filepath/match_test.go
index 70db359..0204225 100644
--- a/libgo/go/path/filepath/match_test.go
+++ b/libgo/go/path/filepath/match_test.go
@@ -7,7 +7,6 @@ package filepath_test
 import (
 	"fmt"
 	"internal/testenv"
-	"io/ioutil"
 	"os"
 	. "path/filepath"
 	"reflect"
@@ -75,8 +74,10 @@ var matchTests = []MatchTest{
 	{"[", "a", false, ErrBadPattern},
 	{"[^", "a", false, ErrBadPattern},
 	{"[^bc", "a", false, ErrBadPattern},
-	{"a[", "a", false, nil},
+	{"a[", "a", false, ErrBadPattern},
 	{"a[", "ab", false, ErrBadPattern},
+	{"a[", "x", false, ErrBadPattern},
+	{"a/b[", "x", false, ErrBadPattern},
 	{"*x", "xxx", true, nil},
 }
 
@@ -156,9 +157,11 @@ func TestGlob(t *testing.T) {
 }
 
 func TestGlobError(t *testing.T) {
-	_, err := Glob("[]")
-	if err == nil {
-		t.Error("expected error for bad pattern; got none")
+	bad := []string{`[]`, `nonexist/[]`}
+	for _, pattern := range bad {
+		if _, err := Glob(pattern); err != ErrBadPattern {
+			t.Errorf("Glob(%#q) returned err=%v, want ErrBadPattern", pattern, err)
+		}
 	}
 }
 
@@ -179,7 +182,7 @@ var globSymlinkTests = []struct {
 func TestGlobSymlink(t *testing.T) {
 	testenv.MustHaveSymlink(t)
 
-	tmpDir, err := ioutil.TempDir("", "globsymlink")
+	tmpDir, err := os.MkdirTemp("", "globsymlink")
 	if err != nil {
 		t.Fatal("creating temp dir:", err)
 	}
@@ -265,7 +268,7 @@ func TestWindowsGlob(t *testing.T) {
 		t.Skipf("skipping windows specific test")
 	}
 
-	tmpDir, err := ioutil.TempDir("", "TestWindowsGlob")
+	tmpDir, err := os.MkdirTemp("", "TestWindowsGlob")
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -299,7 +302,7 @@ func TestWindowsGlob(t *testing.T) {
 		}
 	}
 	for _, file := range files {
-		err := ioutil.WriteFile(Join(tmpDir, file), nil, 0666)
+		err := os.WriteFile(Join(tmpDir, file), nil, 0666)
 		if err != nil {
 			t.Fatal(err)
 		}
diff --git a/libgo/go/path/filepath/path.go b/libgo/go/path/filepath/path.go
index 26f1833..2e7b439 100644
--- a/libgo/go/path/filepath/path.go
+++ b/libgo/go/path/filepath/path.go
@@ -13,6 +13,7 @@ package filepath
 
 import (
 	"errors"
+	"io/fs"
 	"os"
 	"sort"
 	"strings"
@@ -333,29 +334,82 @@ func Rel(basepath, targpath string) (string, error) {
 // SkipDir is used as a return value from WalkFuncs to indicate that
 // the directory named in the call is to be skipped. It is not returned
 // as an error by any function.
-var SkipDir = errors.New("skip this directory")
+var SkipDir error = fs.SkipDir
 
-// WalkFunc is the type of the function called for each file or directory
-// visited by Walk. The path argument contains the argument to Walk as a
-// prefix; that is, if Walk is called with "dir", which is a directory
-// containing the file "a", the walk function will be called with argument
-// "dir/a". The info argument is the os.FileInfo for the named path.
+// WalkFunc is the type of the function called by Walk to visit each each
+// file or directory.
 //
-// If there was a problem walking to the file or directory named by path, the
-// incoming error will describe the problem and the function can decide how
-// to handle that error (and Walk will not descend into that directory). In the
-// case of an error, the info argument will be nil. If an error is returned,
-// processing stops. The sole exception is when the function returns the special
-// value SkipDir. If the function returns SkipDir when invoked on a directory,
-// Walk skips the directory's contents entirely. If the function returns SkipDir
-// when invoked on a non-directory file, Walk skips the remaining files in the
-// containing directory.
-type WalkFunc func(path string, info os.FileInfo, err error) error
+// The path argument contains the argument to Walk as a prefix.
+// That is, if Walk is called with root argument "dir" and finds a file
+// named "a" in that directory, the walk function will be called with
+// argument "dir/a".
+//
+// The directory and file are joined with Join, which may clean the
+// directory name: if Walk is called with the root argument "x/../dir"
+// and finds a file named "a" in that directory, the walk function will
+// be called with argument "dir/a", not "x/../dir/a".
+//
+// The info argument is the fs.FileInfo for the named path.
+//
+// The error result returned by the function controls how Walk continues.
+// If the function returns the special value SkipDir, Walk skips the
+// current directory (path if info.IsDir() is true, otherwise path's
+// parent directory). Otherwise, if the function returns a non-nil error,
+// Walk stops entirely and returns that error.
+//
+// The err argument reports an error related to path, signaling that Walk
+// will not walk into that directory. The function can decide how to
+// handle that error; as described earlier, returning the error will
+// cause Walk to stop walking the entire tree.
+//
+// Walk calls the function with a non-nil err argument in two cases.
+//
+// First, if an os.Lstat on the root directory or any directory or file
+// in the tree fails, Walk calls the function with path set to that
+// directory or file's path, info set to nil, and err set to the error
+// from os.Lstat.
+//
+// Second, if a directory's Readdirnames method fails, Walk calls the
+// function with path set to the directory's path, info, set to an
+// fs.FileInfo describing the directory, and err set to the error from
+// Readdirnames.
+type WalkFunc func(path string, info fs.FileInfo, err error) error
 
 var lstat = os.Lstat // for testing
 
+// walkDir recursively descends path, calling walkDirFn.
+func walkDir(path string, d fs.DirEntry, walkDirFn fs.WalkDirFunc) error {
+	if err := walkDirFn(path, d, nil); err != nil || !d.IsDir() {
+		if err == SkipDir && d.IsDir() {
+			// Successfully skipped directory.
+			err = nil
+		}
+		return err
+	}
+
+	dirs, err := readDir(path)
+	if err != nil {
+		// Second call, to report ReadDir error.
+		err = walkDirFn(path, d, err)
+		if err != nil {
+			return err
+		}
+	}
+
+	for _, d1 := range dirs {
+		path1 := Join(path, d1.Name())
+		if err := walkDir(path1, d1, walkDirFn); err != nil {
+			if err == SkipDir {
+				break
+			}
+			return err
+		}
+	}
+	return nil
+}
+
 // walk recursively descends path, calling walkFn.
-func walk(path string, info os.FileInfo, walkFn WalkFunc) error {
+func walk(path string, info fs.FileInfo, walkFn WalkFunc) error {
 	if !info.IsDir() {
 		return walkFn(path, info, nil)
 	}
@@ -392,18 +446,59 @@ func walk(path string, info os.FileInfo, walkFn WalkFunc) error {
 	return nil
 }
 
-// Walk walks the file tree rooted at root, calling walkFn for each file or
-// directory in the tree, including root. All errors that arise visiting files
-// and directories are filtered by walkFn. The files are walked in lexical
-// order, which makes the output deterministic but means that for very
-// large directories Walk can be inefficient.
+// WalkDir walks the file tree rooted at root, calling fn for each file or
+// directory in the tree, including root.
+//
+// All errors that arise visiting files and directories are filtered by fn:
+// see the fs.WalkDirFunc documentation for details.
+//
+// The files are walked in lexical order, which makes the output deterministic
+// but requires WalkDir to read an entire directory into memory before proceeding
+// to walk that directory.
+//
+// WalkDir does not follow symbolic links.
+func WalkDir(root string, fn fs.WalkDirFunc) error {
+	info, err := os.Lstat(root)
+	if err != nil {
+		err = fn(root, nil, err)
+	} else {
+		err = walkDir(root, &statDirEntry{info}, fn)
+	}
+	if err == SkipDir {
+		return nil
+	}
+	return err
+}
+
+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 }
+
+// Walk walks the file tree rooted at root, calling fn for each file or
+// directory in the tree, including root.
+//
+// All errors that arise visiting files and directories are filtered by fn:
+// see the WalkFunc documentation for details.
+//
+// The files are walked in lexical order, which makes the output deterministic
+// but requires Walk to read an entire directory into memory before proceeding
+// to walk that directory.
+//
 // Walk does not follow symbolic links.
-func Walk(root string, walkFn WalkFunc) error {
+//
+// Walk is less efficient than WalkDir, introduced in Go 1.16,
+// which avoids calling os.Lstat on every visited file or directory.
+func Walk(root string, fn WalkFunc) error {
 	info, err := os.Lstat(root)
 	if err != nil {
-		err = walkFn(root, nil, err)
+		err = fn(root, nil, err)
 	} else {
-		err = walk(root, info, walkFn)
+		err = walk(root, info, fn)
 	}
 	if err == SkipDir {
 		return nil
@@ -411,8 +506,24 @@ func Walk(root string, walkFn WalkFunc) error {
 	return err
 }
 
-// readDirNames reads the directory named by dirname and returns
+// readDir reads the directory named by dirname and returns
 // a sorted list of directory entries.
+func readDir(dirname string) ([]fs.DirEntry, error) {
+	f, err := os.Open(dirname)
+	if err != nil {
+		return nil, err
+	}
+	dirs, err := f.ReadDir(-1)
+	f.Close()
+	if err != nil {
+		return nil, err
+	}
+	sort.Slice(dirs, func(i, j int) bool { return dirs[i].Name() < dirs[j].Name() })
+	return dirs, nil
+}
+
+// readDirNames reads the directory named by dirname and returns
+// a sorted list of directory entry names.
 func readDirNames(dirname string) ([]string, error) {
 	f, err := os.Open(dirname)
 	if err != nil {
diff --git a/libgo/go/path/filepath/path_test.go b/libgo/go/path/filepath/path_test.go
index 537d848..51ea684 100644
--- a/libgo/go/path/filepath/path_test.go
+++ b/libgo/go/path/filepath/path_test.go
@@ -8,7 +8,7 @@ import (
 	"errors"
 	"fmt"
 	"internal/testenv"
-	"io/ioutil"
+	"io/fs"
 	"os"
 	"path/filepath"
 	"reflect"
@@ -396,8 +396,8 @@ func checkMarks(t *testing.T, report bool) {
 // Assumes that each node name is unique. Good enough for a test.
 // If clear is true, any incoming error is cleared before return. The errors
 // are always accumulated, though.
-func mark(info os.FileInfo, err error, errors *[]error, clear bool) error {
-	name := info.Name()
+func mark(d fs.DirEntry, err error, errors *[]error, clear bool) error {
+	name := d.Name()
 	walkTree(tree, tree.name, func(path string, n *Node) {
 		if n.name == name {
 			n.mark++
@@ -418,7 +418,7 @@ func chtmpdir(t *testing.T) (restore func()) {
 	if err != nil {
 		t.Fatalf("chtmpdir: %v", err)
 	}
-	d, err := ioutil.TempDir("", "test")
+	d, err := os.MkdirTemp("", "test")
 	if err != nil {
 		t.Fatalf("chtmpdir: %v", err)
 	}
@@ -434,12 +434,34 @@ func chtmpdir(t *testing.T) (restore func()) {
 }
 
 func TestWalk(t *testing.T) {
-	if runtime.GOOS == "darwin" && runtime.GOARCH == "arm64" {
+	walk := func(root string, fn fs.WalkDirFunc) error {
+		return filepath.Walk(root, func(path string, info fs.FileInfo, err error) error {
+			return fn(path, &statDirEntry{info}, err)
+		})
+	}
+	testWalk(t, walk, 1)
+}
+
+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 }
+
+func TestWalkDir(t *testing.T) {
+	testWalk(t, filepath.WalkDir, 2)
+}
+
+func testWalk(t *testing.T, walk func(string, fs.WalkDirFunc) error, errVisit int) {
+	if runtime.GOOS == "ios" {
 		restore := chtmpdir(t)
 		defer restore()
 	}
 
-	tmpDir, err := ioutil.TempDir("", "TestWalk")
+	tmpDir, err := os.MkdirTemp("", "TestWalk")
 	if err != nil {
 		t.Fatal("creating temp dir:", err)
 	}
@@ -457,11 +479,11 @@ func TestWalk(t *testing.T) {
 	makeTree(t)
 	errors := make([]error, 0, 10)
 	clear := true
-	markFn := func(path string, info os.FileInfo, err error) error {
-		return mark(info, err, &errors, clear)
+	markFn := func(path string, d fs.DirEntry, err error) error {
+		return mark(d, err, &errors, clear)
 	}
 	// Expect no errors.
-	err = filepath.Walk(tree.name, markFn)
+	err = walk(tree.name, markFn)
 	if err != nil {
 		t.Fatalf("no error expected, found: %s", err)
 	}
@@ -471,10 +493,20 @@ func TestWalk(t *testing.T) {
 	checkMarks(t, true)
 	errors = errors[0:0]
 
-	// Test permission errors. Only possible if we're not root
-	// and only on some file systems (AFS, FAT).  To avoid errors during
-	// all.bash on those file systems, skip during go test -short.
-	if os.Getuid() > 0 && !testing.Short() {
+	t.Run("PermErr", func(t *testing.T) {
+		// Test permission errors. Only possible if we're not root
+		// and only on some file systems (AFS, FAT).  To avoid errors during
+		// all.bash on those file systems, skip during go test -short.
+		if runtime.GOOS == "windows" {
+			t.Skip("skipping on Windows")
+		}
+		if os.Getuid() == 0 {
+			t.Skip("skipping as root")
+		}
+		if testing.Short() {
+			t.Skip("skipping in short mode")
+		}
+
 		// introduce 2 errors: chmod top-level directories to 0
 		os.Chmod(filepath.Join(tree.name, tree.entries[1].name), 0)
 		os.Chmod(filepath.Join(tree.name, tree.entries[3].name), 0)
@@ -484,9 +516,9 @@ func TestWalk(t *testing.T) {
 		markTree(tree.entries[1])
 		markTree(tree.entries[3])
 		// correct double-marking of directory itself
-		tree.entries[1].mark--
-		tree.entries[3].mark--
-		err := filepath.Walk(tree.name, markFn)
+		tree.entries[1].mark -= errVisit
+		tree.entries[3].mark -= errVisit
+		err := walk(tree.name, markFn)
 		if err != nil {
 			t.Fatalf("expected no error return from Walk, got %s", err)
 		}
@@ -502,10 +534,10 @@ func TestWalk(t *testing.T) {
 		markTree(tree.entries[1])
 		markTree(tree.entries[3])
 		// correct double-marking of directory itself
-		tree.entries[1].mark--
-		tree.entries[3].mark--
+		tree.entries[1].mark -= errVisit
+		tree.entries[3].mark -= errVisit
 		clear = false // error will stop processing
-		err = filepath.Walk(tree.name, markFn)
+		err = walk(tree.name, markFn)
 		if err == nil {
 			t.Fatalf("expected error return from Walk")
 		}
@@ -519,7 +551,7 @@ func TestWalk(t *testing.T) {
 		// restore permissions
 		os.Chmod(filepath.Join(tree.name, tree.entries[1].name), 0770)
 		os.Chmod(filepath.Join(tree.name, tree.entries[3].name), 0770)
-	}
+	})
 }
 
 func touch(t *testing.T, name string) {
@@ -533,7 +565,7 @@ func touch(t *testing.T, name string) {
 }
 
 func TestWalkSkipDirOnFile(t *testing.T) {
-	td, err := ioutil.TempDir("", "walktest")
+	td, err := os.MkdirTemp("", "walktest")
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -546,7 +578,7 @@ func TestWalkSkipDirOnFile(t *testing.T) {
 	touch(t, filepath.Join(td, "dir/foo2"))
 
 	sawFoo2 := false
-	walker := func(path string, info os.FileInfo, err error) error {
+	walker := func(path string) error {
 		if strings.HasSuffix(path, "foo2") {
 			sawFoo2 = true
 		}
@@ -555,26 +587,35 @@ func TestWalkSkipDirOnFile(t *testing.T) {
 		}
 		return nil
 	}
+	walkFn := func(path string, _ fs.FileInfo, _ error) error { return walker(path) }
+	walkDirFn := func(path string, _ fs.DirEntry, _ error) error { return walker(path) }
 
-	err = filepath.Walk(td, walker)
-	if err != nil {
-		t.Fatal(err)
-	}
-	if sawFoo2 {
-		t.Errorf("SkipDir on file foo1 did not block processing of foo2")
+	check := func(t *testing.T, walk func(root string) error, root string) {
+		t.Helper()
+		sawFoo2 = false
+		err = walk(root)
+		if err != nil {
+			t.Fatal(err)
+		}
+		if sawFoo2 {
+			t.Errorf("SkipDir on file foo1 did not block processing of foo2")
+		}
 	}
 
-	err = filepath.Walk(filepath.Join(td, "dir"), walker)
-	if err != nil {
-		t.Fatal(err)
-	}
-	if sawFoo2 {
-		t.Errorf("SkipDir on file foo1 did not block processing of foo2")
-	}
+	t.Run("Walk", func(t *testing.T) {
+		Walk := func(root string) error { return filepath.Walk(td, walkFn) }
+		check(t, Walk, td)
+		check(t, Walk, filepath.Join(td, "dir"))
+	})
+	t.Run("WalkDir", func(t *testing.T) {
+		WalkDir := func(root string) error { return filepath.WalkDir(td, walkDirFn) }
+		check(t, WalkDir, td)
+		check(t, WalkDir, filepath.Join(td, "dir"))
+	})
 }
 
 func TestWalkFileError(t *testing.T) {
-	td, err := ioutil.TempDir("", "walktest")
+	td, err := os.MkdirTemp("", "walktest")
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -592,14 +633,14 @@ func TestWalkFileError(t *testing.T) {
 		*filepath.LstatP = os.Lstat
 	}()
 	statErr := errors.New("some stat error")
-	*filepath.LstatP = func(path string) (os.FileInfo, error) {
+	*filepath.LstatP = func(path string) (fs.FileInfo, error) {
 		if strings.HasSuffix(path, "stat-error") {
 			return nil, statErr
 		}
 		return os.Lstat(path)
 	}
 	got := map[string]error{}
-	err = filepath.Walk(td, func(path string, fi os.FileInfo, err error) error {
+	err = filepath.Walk(td, func(path string, fi fs.FileInfo, err error) error {
 		rel, _ := filepath.Rel(td, path)
 		got[filepath.ToSlash(rel)] = err
 		return nil
@@ -853,7 +894,7 @@ func testEvalSymlinksAfterChdir(t *testing.T, wd, path, want string) {
 func TestEvalSymlinks(t *testing.T) {
 	testenv.MustHaveSymlink(t)
 
-	tmpDir, err := ioutil.TempDir("", "evalsymlink")
+	tmpDir, err := os.MkdirTemp("", "evalsymlink")
 	if err != nil {
 		t.Fatal("creating temp dir:", err)
 	}
@@ -939,7 +980,7 @@ func TestEvalSymlinksIsNotExist(t *testing.T) {
 func TestIssue13582(t *testing.T) {
 	testenv.MustHaveSymlink(t)
 
-	tmpDir, err := ioutil.TempDir("", "issue13582")
+	tmpDir, err := os.MkdirTemp("", "issue13582")
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -956,7 +997,7 @@ func TestIssue13582(t *testing.T) {
 		t.Fatal(err)
 	}
 	file := filepath.Join(linkToDir, "file")
-	err = ioutil.WriteFile(file, nil, 0644)
+	err = os.WriteFile(file, nil, 0644)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -1026,7 +1067,7 @@ var absTests = []string{
 }
 
 func TestAbs(t *testing.T) {
-	root, err := ioutil.TempDir("", "TestAbs")
+	root, err := os.MkdirTemp("", "TestAbs")
 	if err != nil {
 		t.Fatal("TempDir failed: ", err)
 	}
@@ -1097,7 +1138,7 @@ func TestAbs(t *testing.T) {
 // We test it separately from all other absTests because the empty string is not
 // a valid path, so it can't be used with os.Stat.
 func TestAbsEmptyString(t *testing.T) {
-	root, err := ioutil.TempDir("", "TestAbsEmptyString")
+	root, err := os.MkdirTemp("", "TestAbsEmptyString")
 	if err != nil {
 		t.Fatal("TempDir failed: ", err)
 	}
@@ -1282,7 +1323,7 @@ func TestDriveLetterInEvalSymlinks(t *testing.T) {
 
 func TestBug3486(t *testing.T) { // https://golang.org/issue/3486
 	t.Skip("skipping test because gccgo sources are arranged differently.")
-	if runtime.GOOS == "darwin" && runtime.GOARCH == "arm64" {
+	if runtime.GOOS == "ios" {
 		t.Skipf("skipping on %s/%s", runtime.GOOS, runtime.GOARCH)
 	}
 	root, err := filepath.EvalSymlinks(runtime.GOROOT() + "/test")
@@ -1293,7 +1334,7 @@ func TestBug3486(t *testing.T) { // https://golang.org/issue/3486
 	ken := filepath.Join(root, "ken")
 	seenBugs := false
 	seenKen := false
-	err = filepath.Walk(root, func(pth string, info os.FileInfo, err error) error {
+	err = filepath.Walk(root, func(pth string, info fs.FileInfo, err error) error {
 		if err != nil {
 			t.Fatal(err)
 		}
@@ -1319,7 +1360,7 @@ func TestBug3486(t *testing.T) { // https://golang.org/issue/3486
 }
 
 func testWalkSymlink(t *testing.T, mklink func(target, link string) error) {
-	tmpdir, err := ioutil.TempDir("", "testWalkSymlink")
+	tmpdir, err := os.MkdirTemp("", "testWalkSymlink")
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -1342,7 +1383,7 @@ func testWalkSymlink(t *testing.T, mklink func(target, link string) error) {
 	}
 
 	var visited []string
-	err = filepath.Walk(tmpdir, func(path string, info os.FileInfo, err error) error {
+	err = filepath.Walk(tmpdir, func(path string, info fs.FileInfo, err error) error {
 		if err != nil {
 			t.Fatal(err)
 		}
@@ -1369,14 +1410,14 @@ func TestWalkSymlink(t *testing.T) {
 }
 
 func TestIssue29372(t *testing.T) {
-	tmpDir, err := ioutil.TempDir("", "TestIssue29372")
+	tmpDir, err := os.MkdirTemp("", "TestIssue29372")
 	if err != nil {
 		t.Fatal(err)
 	}
 	defer os.RemoveAll(tmpDir)
 
 	path := filepath.Join(tmpDir, "file.txt")
-	err = ioutil.WriteFile(path, nil, 0644)
+	err = os.WriteFile(path, nil, 0644)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -1405,7 +1446,7 @@ func TestEvalSymlinksAboveRoot(t *testing.T) {
 
 	t.Parallel()
 
-	tmpDir, err := ioutil.TempDir("", "TestEvalSymlinksAboveRoot")
+	tmpDir, err := os.MkdirTemp("", "TestEvalSymlinksAboveRoot")
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -1422,7 +1463,7 @@ func TestEvalSymlinksAboveRoot(t *testing.T) {
 	if err := os.Symlink(filepath.Join(evalTmpDir, "a"), filepath.Join(evalTmpDir, "b")); err != nil {
 		t.Fatal(err)
 	}
-	if err := ioutil.WriteFile(filepath.Join(evalTmpDir, "a", "file"), nil, 0666); err != nil {
+	if err := os.WriteFile(filepath.Join(evalTmpDir, "a", "file"), nil, 0666); err != nil {
 		t.Fatal(err)
 	}
 
@@ -1453,7 +1494,7 @@ func TestEvalSymlinksAboveRoot(t *testing.T) {
 func TestEvalSymlinksAboveRootChdir(t *testing.T) {
 	testenv.MustHaveSymlink(t)
 
-	tmpDir, err := ioutil.TempDir("", "TestEvalSymlinksAboveRootChdir")
+	tmpDir, err := os.MkdirTemp("", "TestEvalSymlinksAboveRootChdir")
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -1476,7 +1517,7 @@ func TestEvalSymlinksAboveRootChdir(t *testing.T) {
 	if err := os.Symlink(subdir, "c"); err != nil {
 		t.Fatal(err)
 	}
-	if err := ioutil.WriteFile(filepath.Join(subdir, "file"), nil, 0666); err != nil {
+	if err := os.WriteFile(filepath.Join(subdir, "file"), nil, 0666); err != nil {
 		t.Fatal(err)
 	}
 
diff --git a/libgo/go/path/filepath/symlink.go b/libgo/go/path/filepath/symlink.go
index 335b315..6fefd15 100644
--- a/libgo/go/path/filepath/symlink.go
+++ b/libgo/go/path/filepath/symlink.go
@@ -6,6 +6,7 @@ package filepath
 
 import (
 	"errors"
+	"io/fs"
 	"os"
 	"runtime"
 	"syscall"
@@ -85,7 +86,7 @@ func walkSymlinks(path string) (string, error) {
 			return "", err
 		}
 
-		if fi.Mode()&os.ModeSymlink == 0 {
+		if fi.Mode()&fs.ModeSymlink == 0 {
 			if !fi.Mode().IsDir() && end < len(path) {
 				return "", syscall.ENOTDIR
 			}
diff --git a/libgo/go/path/filepath/symlink_windows.go b/libgo/go/path/filepath/symlink_windows.go
index a799488..d72279e 100644
--- a/libgo/go/path/filepath/symlink_windows.go
+++ b/libgo/go/path/filepath/symlink_windows.go
@@ -68,7 +68,7 @@ func toNorm(path string, normBase func(string) (string, error)) (string, error)
 	path = path[len(volume):]
 
 	// skip special cases
-	if path == "." || path == `\` {
+	if path == "" || path == "." || path == `\` {
 		return volume + path, nil
 	}