s.Whitespace = 1<<'\t' | 1<<'\r' | 1<<' '
	// Don't skip comments: we need to count newlines.
	s.Mode = scanner.ScanChars |
		scanner.ScanFloats |
		scanner.ScanIdents |
		scanner.ScanInts |
		scanner.ScanStrings |
		scanner.ScanComments
	s.Position.Filename = name
	s.IsIdentRune = isIdentRune
	return &Tokenizer{
		s:    &s,

	for _, test := range []struct {
		in, want string
		mode     uint
	}{
		{"foo01.bar31.xx-0-1-1-0", "01 31 0 1 1 0", ScanInts},
		{"foo0/12/0/5.67", "0 12 0 5 67", ScanInts},
		{"xxx1e0yyy", "1 0", ScanInts},
		{"1_2", "1_2", ScanInts},
		{"xxx1.0yyy2e3ee", "1 0 2 3", ScanInts},
		{"xxx1.0yyy2e3ee", "1.0 2e3", ScanFloats},
	} {
		got := extractInts(test.in, test.mode)
		if got != test.want {

// Predefined mode bits to control recognition of tokens. For instance,
// to configure a [Scanner] such that it only recognizes (Go) identifiers,
// integers, and skips comments, set the Scanner's Mode field to:
//
//	ScanIdents | ScanInts | SkipComments
//
// With the exceptions of comments, which are skipped if SkipComments is
// set, unrecognized tokens are not ignored. Instead, the scanner simply

		if err == io.ErrUnexpectedEOF {
			err = nil
		}
		return
	}
	r.next = next
	return
}

// scanInts performs the same scanning task as RecursiveInt.Scan
// but without recurring through scanner, so we can compare
// performance more directly.
func scanInts(r *RecursiveInt, b *bytes.Buffer) (err error) {
	r.next = nil
	_, err = Fscan(b, &r.i)
	if err != nil {
		return
	}

}

func (p *parser) initScanner(filename string, src io.Reader) {
	p.scanner.Init(src)
	p.scanner.Error = func(_ *scanner.Scanner, msg string) { p.error(msg) }
	p.scanner.Mode = scanner.ScanIdents | scanner.ScanInts | scanner.ScanFloats | scanner.ScanStrings
	p.scanner.Whitespace = 1<<'\t' | 1<<' '
	p.scanner.Filename = filename // for good error messages
	p.next()
}

type importError struct {
	pos scanner.Position

	case *complex128:
		*v = s.scanComplex(verb, 128)
	case *int:
		*v = int(s.scanInt(verb, intBits))
	case *int8:
		*v = int8(s.scanInt(verb, 8))
	case *int16:
		*v = int16(s.scanInt(verb, 16))
	case *int32:
		*v = int32(s.scanInt(verb, 32))
	case *int64:
		*v = s.scanInt(verb, 64)
	case *uint:
		*v = uint(s.scanUint(verb, intBits))
	case *uint8:
		*v = uint8(s.scanUint(verb, 8))

		{s: "256", d: &scanuint8, wanterr: "converting driver.Value type string (\"256\") to a uint8: value out of range"},
		{s: "256", d: &scanuint16, wantuint: 256},
		{s: "-1", d: &scanint, wantint: -1},
		{s: "foo", d: &scanint, wanterr: "converting driver.Value type string (\"foo\") to a int: invalid syntax"},

		// int64 to smaller integers
		{s: int64(5), d: &scanuint8, wantuint: 5},

	cmd = testenv.Command(t, testenv.GoToolPath(t), "tool", "nm", dst)
	out, err = cmd.CombinedOutput()
	if err != nil {
		t.Fatalf("could not read target: %v", err)
	}
	if bytes.Contains(out, []byte("scanInt")) {
		t.Fatalf("scanf code not removed from helloworld")
	}
}

// Make sure -S prints assembly code. See issue 14515.
func TestDashS(t *testing.T) {
	testenv.MustHaveGoBuild(t)
	t.Parallel()

		{"Position.Offset", Field, 0},
		{"RawString", Const, 0},
		{"ScanChars", Const, 0},
		{"ScanComments", Const, 0},
		{"ScanFloats", Const, 0},
		{"ScanIdents", Const, 0},
		{"ScanInts", Const, 0},
		{"ScanRawStrings", Const, 0},
		{"ScanStrings", Const, 0},
		{"Scanner", Type, 0},
		{"Scanner.Error", Field, 0},
		{"Scanner.ErrorCount", Field, 0},
		{"Scanner.IsIdentRune", Field, 4},

pkg text/scanner, const ScanChars ideal-int
pkg text/scanner, const ScanComments ideal-int
pkg text/scanner, const ScanFloats ideal-int
pkg text/scanner, const ScanIdents ideal-int
pkg text/scanner, const ScanInts ideal-int
pkg text/scanner, const ScanRawStrings ideal-int
pkg text/scanner, const ScanStrings ideal-int
pkg text/scanner, const SkipComments ideal-int
pkg text/scanner, const String ideal-int