if !f.valid() {
		return "?", 0
	}
	fileno, _ := pcvalue(f, f.pcfile, targetpc, strict)
	line, _ = pcvalue(f, f.pcln, targetpc, strict)
	if fileno == -1 || line == -1 || int(fileno) >= len(datap.filetab) {
		// print("looking for ", hex(targetpc), " in ", funcname(f), " got file=", fileno, " line=", lineno, "\n")
		return "?", 0
	}
	file = funcfile(f, fileno)
	return
}

	Spare         [2]uint32
}

type Statfs_t [0]byte

type Flock_t struct {
	Start  int64
	Len    int64
	Pid    int32
	Type   int16
	Whence int16
}

type Dirent struct {
	Fileno    uint64
	Reclen    uint16
	Namlen    uint16
	Type      uint8
	Name      [512]int8
	Pad_cgo_0 [3]byte
}

type Fsid struct {
	X__fsid_val [2]int32
}

const (
	pathMax = 0x400
)

	Pad_cgo_2     [4]byte
}

type Statfs_t [0]byte

type Flock_t struct {
	Start  int64
	Len    int64
	Pid    int32
	Type   int16
	Whence int16
}

type Dirent struct {
	Fileno    uint64
	Reclen    uint16
	Namlen    uint16
	Type      uint8
	Name      [512]int8
	Pad_cgo_0 [3]byte
}

type Fsid struct {
	X__fsid_val [2]int32
}

const (
	pathMax = 0x400
)

		return nil, err
	}
	return buf[0 : n/siz], nil
}

func direntIno(buf []byte) (uint64, bool) {
	return readInt(buf, unsafe.Offsetof(Dirent{}.Fileno), unsafe.Sizeof(Dirent{}.Fileno))
}

func direntReclen(buf []byte) (uint64, bool) {
	return readInt(buf, unsafe.Offsetof(Dirent{}.Reclen), unsafe.Sizeof(Dirent{}.Reclen))
}

func direntNamlen(buf []byte) (uint64, bool) {

// filename returns a filename suitable for debugging output.
func (check *Checker) filename(fileNo int) string {
	file := check.files[fileNo]
	if pos := file.Pos(); pos.IsKnown() {
		// return check.fset.File(pos).Name()
		// TODO(gri) do we need the actual file name here?
		return pos.RelFilename()
	}
	return fmt.Sprintf("file[%d]", fileNo)
}

func (check *Checker) importPackage(pos syntax.Pos, path, dir string) *Package {

}

// filename returns a filename suitable for debugging output.
func (check *Checker) filename(fileNo int) string {
	file := check.files[fileNo]
	if pos := file.Pos(); pos.IsValid() {
		return check.fset.File(pos).Name()
	}
	return fmt.Sprintf("file[%d]", fileNo)
}

func (check *Checker) importPackage(at positioner, path, dir string) *Package {

		return nil, err
	}
	return buf[0 : n/siz], nil
}

func direntIno(buf []byte) (uint64, bool) {
	return readInt(buf, unsafe.Offsetof(Dirent{}.Fileno), unsafe.Sizeof(Dirent{}.Fileno))
}

func direntReclen(buf []byte) (uint64, bool) {
	namlen, ok := direntNamlen(buf)
	if !ok {
		return 0, false
	}
	return (16 + namlen + 1 + 7) &^ 7, true
}

	Pad_cgo_2     [4]byte
}

type Statfs_t [0]byte

type Flock_t struct {
	Start  int64
	Len    int64
	Pid    int32
	Type   int16
	Whence int16
}

type Dirent struct {
	Fileno    uint64
	Reclen    uint16
	Namlen    uint16
	Type      uint8
	Name      [512]int8
	Pad_cgo_0 [3]byte
}

type Fsid struct {
	X__fsid_val [2]int32
}

const (
	pathMax = 0x400
)

	Pad_cgo_0     [2]byte
	Mount_info    [160]byte
}

type Flock_t struct {
	Start  int64
	Len    int64
	Pid    int32
	Type   int16
	Whence int16
}

type Dirent struct {
	Fileno       uint64
	Off          int64
	Reclen       uint16
	Type         uint8
	Namlen       uint8
	X__d_padding [4]uint8
	Name         [256]int8
}

type Fsid struct {
	Val [2]int32
}

	Pad_cgo_0     [2]byte
	Mount_info    [160]byte
}

type Flock_t struct {
	Start  int64
	Len    int64
	Pid    int32
	Type   int16
	Whence int16
}

type Dirent struct {
	Fileno       uint64
	Off          int64
	Reclen       uint16
	Type         uint8
	Namlen       uint8
	X__d_padding [4]uint8
	Name         [256]int8
}

type Fsid struct {
	Val [2]int32
}