if err == nil || !wantErr.MatchString(err.Error()) {
			t.Errorf("want error matching %s, got %s", wantErr, err)
		}
		// And it should flush all output (even if it looks
		// like we may be getting an exit code)
		if got := out.String(); text != got {
			t.Errorf("want full output %q, got %q", text, got)
		}
	}
	wantErr = regexp.MustCompile("^no exit code")
	check("abc")
	check("exitcode")
	check("exitcode=")

	-dynlink
		Support references to Go symbols defined in other shared libraries.
	-e
		No limit on number of errors reported.
	-gensymabis
		Write symbol ABI information to output file. Don't assemble.
	-o file
		Write output to file. The default is foo.o for /a/b/c/foo.s.
	-p pkgpath
		Set expected package import to pkgpath.
	-shared
		Generate code that can be linked into a shared library.
	-spectre list

	out, err := cmd.Output()
	if err != nil {
		if ee, ok := err.(*exec.ExitError); ok && len(ee.Stderr) > 0 {
			return errorf("%v: %s", cmd, ee.Stderr)
		}
		return errorf("%v: %w", cmd, err)
	}

	parts := strings.SplitN(string(bytes.TrimSpace(out)), ":", 4)
	if len(parts) < 2 {
		return errorf("%v: missing ':' in output: %q", cmd, out)
	}
	importPath = parts[0]

//
// Usage:
//
//	go tool addr2line binary
//
// Addr2line reads hexadecimal addresses, one per line and with optional 0x prefix,
// from standard input. For each input address, addr2line prints two output lines,
// first the name of the function containing the address and second the file:line
// of the source code corresponding to that address.
//
// This tool is intended for use only by pprof; its interface may change or

	return nil
}

// findDevImage use the device iOS version and build to locate a suitable
// developer image.
func findDevImage() (string, error) {
	cmd := idevCmd(exec.Command("ideviceinfo"))
	out, err := cmd.Output()
	if err != nil {
		return "", fmt.Errorf("ideviceinfo: %v", err)
	}
	var iosVer, buildVer string
	lines := bytes.Split(out, []byte("\n"))
	for _, line := range lines {

func (b *Reader) writeBuf(w io.Writer) (int64, error) {
	n, err := w.Write(b.buf[b.r:b.w])
	if n < 0 {
		panic(errNegativeWrite)
	}
	b.r += n
	return int64(n), err
}

// buffered output

// Writer implements buffering for an [io.Writer] object.
// If an error occurs writing to a [Writer], no more data will be
// accepted and all subsequent writes, and [Writer.Flush], will return the error.

		}
	})
}

func TestSplitUSTARPath(t *testing.T) {
	sr := strings.Repeat

	vectors := []struct {
		input  string // Input path
		prefix string // Expected output prefix
		suffix string // Expected output suffix
		ok     bool   // Split success?
	}{
		{"", "", "", false},
		{"abc", "", "", false},
		{"用戶名", "", "", false},
		{sr("a", nameSize), "", "", false},

This is a syntactically valid Go program—it can be parsed with the Go
parser and processed by godoc—but it is not compiled directly by gc.
Instead, a separate tool, cgo, processes it to produce three output
files.  The first two, 6g.go and 6c.c, are a Go source file for 6g and
a C source file for 6c; both compile as part of the named package
(gmp, in this example).  The third, gcc.c, is a C source file for gcc;

		cmd := exec.Command(goCmd(), "list", "-e", "-deps", "-json", "std")
		cmd.Env = listEnv(w.context)
		if w.context.Dir != "" {
			cmd.Dir = w.context.Dir
		}
		cmd.Stderr = os.Stderr
		out, err := cmd.Output()
		if err != nil {
			log.Fatalf("loading imports: %v\n%s", err, out)
		}

		var stdPackages []string
		importMap := make(map[string]map[string]string)
		importDir := make(map[string]string)

pkg encoding/xml, type TokenReader interface, Token() (Token, error)
pkg flag, method (*FlagSet) ErrorHandling() ErrorHandling
pkg flag, method (*FlagSet) Name() string
pkg flag, method (*FlagSet) Output() io.Writer
pkg html/template, type Srcset string
pkg math, func Erfcinv(float64) float64
pkg math, func Erfinv(float64) float64
pkg math, func Round(float64) float64
pkg math, func RoundToEven(float64) float64