buf := bytes.NewBuffer(nil)
		cmd.Stdout = buf
		cmd.Stderr = buf
		if err := cmd.Start(); err != nil {
			// We are starting so many processes that on
			// some systems (problem seen on Darwin,
			// Dragonfly, OpenBSD) the fork call will fail
			// with EAGAIN.
			if pe, ok := err.(*os.PathError); ok {
				err = pe.Err
			}

	for _, c := range s {
		if c < 0x80 && c != 0x00 {
			b = append(b, byte(c))
		}
	}
	return string(b)
}

type parser struct {
	err error // Last error seen
}

type formatter struct {
	err error // Last error seen
}

// parseString parses bytes as a NUL-terminated C-style string.
// If a NUL byte is not found then the whole slice is returned as a string.
func (*parser) parseString(b []byte) string {

	for _, f := range fs {
		tf := fmt.Sprintf("/proc/%s/status", f.Name())
		d, err := os.ReadFile(tf)
		if err != nil {
			// There are a surprising number of ways this
			// can error out on linux.  We've seen all of
			// the following, so treat any error here as
			// equivalent to the "process is gone":
			//    os.IsNotExist(err),
			//    "... : no such process",
			//    "... : bad file descriptor.
			continue
		}

			"#endif",
			"C",
		),
		"1234.\n",
	},
	{
		"nested taken/not-taken #ifdef",
		lines(
			"#define A",
			"#ifdef A",
			"#ifdef B",
			"#define C 1234",
			"#else",
			"#define C 5678",
			"#endif",
			"#endif",
			"C",
		),
		"5678.\n",
	},
	{
		"nested not-taken/would-be-taken #ifdef",
		lines(
			"#define B",
			"#ifdef A",
			"#ifdef B",