var pathExts struct {
	once sync.Once
	list []string
}

func initPathExts() {
	var exts []string
	x := os.Getenv(`PATHEXT`)
	if x != "" {
		for _, e := range strings.Split(strings.ToLower(x), `;`) {
			if e == "" {
				continue
			}
			if e[0] != '.' {
				e = "." + e
			}
			exts = append(exts, e)
		}
	} else {
		exts = []string{".com", ".exe", ".bat", ".cmd"}
	}

	gopath := os.Args[2]
	switch os.Args[3] {
		case "IDENTITY":
		case "REPLACE_SLASH": gopath = strings.ReplaceAll(gopath, `\`, `/`)
		case "UPPER": gopath = strings.ToUpper(gopath)
		case "LOWER": gopath = strings.ToLower(gopath)
		default: fmt.Fprintln(os.Stderr, "bad op"); os.Exit(1)
	}
	cmd := exec.Command("go", os.Args[4:]...)
	cmd.Dir = dir
	cmd.Env = append(os.Environ(), "GOPATH="+gopath)
	cmd.Stdout = os.Stdout

//
// This lets us test a large set of strings for fold-equivalent
// duplicates without making a quadratic number of calls
// to EqualFold. Note that strings.ToUpper and strings.ToLower
// do not have the desired property in some corner cases.
func ToFold(s string) string {
	// Fast path: all ASCII, no upper case.
	// Most paths look like this already.
	for i := 0; i < len(s); i++ {
		c := s[i]

func isGoBinaryCandidate(file string, info fs.FileInfo) bool {
	if info.Mode().IsRegular() && info.Mode()&0111 != 0 {
		return true
	}
	name := strings.ToLower(file)
	switch filepath.Ext(name) {
	case ".so", ".exe", ".dll":
		return true
	default:
		return strings.Contains(name, ".so.")
	}
}

		return
	}

	sort.Strings(names)
	for _, name := range names {
		// Unify presentation by going to lower case.
		// If it's windows, don't show the .exe suffix.
		name = strings.TrimSuffix(strings.ToLower(name), cfg.ToolExeSuffix())

		// The tool directory used by gccgo will have other binaries
		// in addition to go tools. Only display go tools here.
		if cfg.BuildToolchainName == "gccgo" && !isGccgoTool(name) {

	}

	if res.StatusCode != http.StatusOK {
		contentType := res.Header.Get("Content-Type")
		if mediaType, params, _ := mime.ParseMediaType(contentType); mediaType == "text/plain" {
			switch charset := strings.ToLower(params["charset"]); charset {
			case "us-ascii", "utf-8", "":
				// Body claims to be plain text in UTF-8 or a subset thereof.
				// Try to extract a useful error message from it.
				r.errorDetail.r = res.Body

		t.Errorf("invalidRune: expected %q got %q", expect, m)
	}
}

func TestToUpper(t *testing.T) { runStringTests(t, ToUpper, "ToUpper", upperTests) }

func TestToLower(t *testing.T) { runStringTests(t, ToLower, "ToLower", lowerTests) }

func BenchmarkToUpper(b *testing.B) {
	for _, tc := range upperTests {
		tin := []byte(tc.in)
		b.Run(tc.in, func(b *testing.B) {
			for i := 0; i < b.N; i++ {

		if inner == nil {
			t.Errorf("%s: at %s: can't find innermost scope", pos, text)
			return
		}
		got := "undef"
		if _, obj := inner.LookupParent(name, pos); obj != nil {
			kind := strings.ToLower(strings.TrimPrefix(reflect.TypeOf(obj).String(), "*types2."))
			got = fmt.Sprintf("%s:%d", kind, obj.Pos().Line())
		}
		if got != want {
			t.Errorf("%s: at %s: %s resolved to %s, want %s", pos, text, name, got, want)

		parts := re.FindStringSubmatch(line)
		if len(parts) == 0 {
			continue
		}
		addr, err := strconv.ParseUint(parts[1], 16, 64)
		if err != nil {
			continue // not a hex address
		}
		opcode := strings.ToLower(parts[3])
		if !opcodes[opcode] {
			continue
		}
		t.Logf("clobbering instruction %s", line)
		n := (len(parts[2]) - strings.Count(parts[2], " ")) / 2 // number of bytes in instruction encoding

	if fileArch == "" {
		return "", false
	}
	b := fileArch[0]
	if b == '_' || ('a' <= b && b <= 'z') {
		return "", false
	}
	archCaps = fileArch
	fileArch = strings.ToLower(fileArch)
	fileArch = strings.TrimSuffix(fileArch, "splitload")
	fileArch = strings.TrimSuffix(fileArch, "latelower")
	if fileArch == goArch {
		return "", false
	}
	if fileArch == strings.TrimSuffix(goArch, "le") {