2 files changed, 31 insertions, 13 deletions

diff --git a/src/testing/testing.go b/src/testing/testing.go
index dec39d24da..a53d5745cb 100644
--- a/src/testing/testing.go
+++ b/src/testing/testing.go
@@ -251,6 +251,8 @@ import (
 	"sync"
 	"sync/atomic"
 	"time"
+	"unicode"
+	"unicode/utf8"
 )
 
 var initRan bool
@@ -906,11 +908,6 @@ func (c *common) Cleanup(f func()) {
 	c.cleanups = append(c.cleanups, fn)
 }
 
-var tempDirReplacer struct {
-	sync.Once
-	r *strings.Replacer
-}
-
 // TempDir returns a temporary directory for the test to use.
 // The directory is automatically removed by Cleanup when the test and
 // all its subtests complete.
@@ -934,13 +931,26 @@ func (c *common) TempDir() string {
 	if nonExistent {
 		c.Helper()
 
-		// os.MkdirTemp doesn't like path separators in its pattern,
-		// so mangle the name to accommodate subtests.
-		tempDirReplacer.Do(func() {
-			tempDirReplacer.r = strings.NewReplacer("/", "_", "\\", "_", ":", "_")
-		})
-		pattern := tempDirReplacer.r.Replace(c.Name())
-
+		// Drop unusual characters (such as path separators or
+		// characters interacting with globs) from the directory name to
+		// avoid surprising os.MkdirTemp behavior.
+		mapper := func(r rune) rune {
+			if r < utf8.RuneSelf {
+				const allowed = "!#$%&()+,-.=@^_{}~ "
+				if '0' <= r && r <= '9' ||
+					'a' <= r && r <= 'z' ||
+					'A' <= r && r <= 'Z' {
+					return r
+				}
+				if strings.ContainsRune(allowed, r) {
+					return r
+				}
+			} else if unicode.IsLetter(r) || unicode.IsNumber(r) {
+				return r
+			}
+			return -1
+		}
+		pattern := strings.Map(mapper, c.Name())
 		c.tempDir, c.tempDirErr = os.MkdirTemp("", pattern)
 		if c.tempDirErr == nil {
 			c.Cleanup(func() {
diff --git a/src/testing/testing_test.go b/src/testing/testing_test.go
index 0f096980ca..42058ae449 100644
--- a/src/testing/testing_test.go
+++ b/src/testing/testing_test.go
@@ -58,6 +58,9 @@ func TestTempDir(t *testing.T) {
 	t.Run("test:subtest", testTempDir)
 	t.Run("test/..", testTempDir)
 	t.Run("../test", testTempDir)
+	t.Run("test[]", testTempDir)
+	t.Run("test*", testTempDir)
+	t.Run("äöüéè", testTempDir)
 }
 
 func testTempDir(t *testing.T) {
@@ -74,7 +77,7 @@ func testTempDir(t *testing.T) {
 			if err != nil {
 				t.Fatal(err)
 			}
-			t.Errorf("directory %q stil exists: %v, isDir=%v", dir, fi, fi.IsDir())
+			t.Errorf("directory %q still exists: %v, isDir=%v", dir, fi, fi.IsDir())
 		default:
 			if !t.Failed() {
 				t.Fatal("never received dir channel")
@@ -108,4 +111,9 @@ func testTempDir(t *testing.T) {
 	if len(files) > 0 {
 		t.Errorf("unexpected %d files in TempDir: %v", len(files), files)
 	}
+
+	glob := filepath.Join(dir, "*.txt")
+	if _, err := filepath.Glob(glob); err != nil {
+		t.Error(err)
+	}
 }