// is tricky because we'd have to run updateExprType on the argument first.
// (go.dev/issue/21982.)

// convertibleTo reports whether T(x) is valid. In the failure case, *cause
// may be set to the cause for the failure.
// The check parameter may be nil if convertibleTo is invoked through an
// exported API call, i.e., when all methods have been type-checked.

}

// consumeToken consumes a token from the beginning of provided
// string, per RFC 2045 section 5.1 (referenced from 2183), and return
// the token consumed and the rest of the string. Returns ("", v) on
// failure to consume at least one character.
func consumeToken(v string) (token, rest string) {
	notPos := strings.IndexFunc(v, isNotTokenChar)
	if notPos == -1 {
		return v, ""
	}
	if notPos == 0 {
		return "", v

	// (4) Organize batchCursors in a min-heap, ordered by the timestamp of the next event for each M.
	// (5) Try to advance the next event for the M at the top of the min-heap.
	//   (a) On success, select that M.
	//   (b) On failure, sort the min-heap and try to advance other Ms. Select the first M that advances.
	//   (c) If there's nothing left to advance, goto (1).
	// (6) Select the latest event for the selected M and get it ready to be returned.

	}

	// Write generations.
	for _, g := range t.gens {
		g.writeEventsTo(tw)
	}

	// Expectation file contents.
	expect := []byte("SUCCESS\n")
	if t.bad {
		expect = []byte(fmt.Sprintf("FAILURE %q\n", t.badMatch))
	}

	// Create the test file's contents.
	return txtar.Format(&txtar.Archive{
		Files: []txtar.File{
			{Name: "expect", Data: expect},
			{Name: "trace", Data: buf.Bytes()},
		},

var (
	doDiff    = flag.Bool("diff", false, "display diffs instead of rewriting files")
	goVersion = flag.String("go", "", "go language version for files")
)

// enable for debugging fix failures
const debug = false // display incorrectly reformatted source and exit

func usage() {
	fmt.Fprintf(os.Stderr, "usage: go tool fix [-diff] [-r fixname,...] [-force fixname,...] [path ...]\n")
	flag.PrintDefaults()

	} else {
		if cfg.BuildV {
			fmt.Printf("failed to run gdb --version: %v\n", err)
		}
	}
}

// printCmdOut prints the output of running the given command.
// It ignores failures; 'go bug' is best effort.
func printCmdOut(w io.Writer, prefix, path string, args ...string) {
	cmd := exec.Command(path, args...)
	out, err := cmd.Output()
	if err != nil {
		if cfg.BuildV {