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,
		base: src.NewFileBase(name, objabi.AbsFile(objabi.WorkingDir(), name, *flags.TrimPath)),
		line: 1,

	ScanFloats     = 1 << -Float // includes Ints and hexadecimal floats
	ScanChars      = 1 << -Char
	ScanStrings    = 1 << -String
	ScanRawStrings = 1 << -RawString
	ScanComments   = 1 << -Comment
	SkipComments   = 1 << -skipComment // if set with ScanComments, comments become white space
	GoTokens       = ScanIdents | ScanFloats | ScanChars | ScanStrings | ScanRawStrings | ScanComments | SkipComments
)

	// the floats in the source look like (invalid) octal ints
	// and ScanNumbers may return either Int or Float.
	testScanSelectedMode(t, ScanChars, Char)
	testScanSelectedMode(t, ScanStrings, String)
	testScanSelectedMode(t, SkipComments, 0)
	testScanSelectedMode(t, ScanComments, Comment)
}

func TestScanCustomIdent(t *testing.T) {
	const src = "faab12345 a12b123 a12 3b"

	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
	err error
}

		{"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},
		{"Scanner.Mode", Field, 0},

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
pkg text/scanner, func TokenString(int32) string
pkg text/scanner, method (*Position) IsValid() bool

pkg text/scanner, const ScanFloats = 16
pkg text/scanner, const ScanIdents = 4
pkg text/scanner, const ScanInts = 8
pkg text/scanner, const ScanRawStrings = 128
pkg text/scanner, const ScanStrings = 64
pkg text/scanner, const SkipComments = 512
pkg text/scanner, const String = -6
pkg text/tabwriter, const AlignRight = 4
pkg text/tabwriter, const Debug = 32