// printed.
func (f *File) ParseGo(abspath string, src []byte) {
	// Two different parses: once with comments, once without.
	// The printer is not good enough at printing comments in the
	// right place when we start editing the AST behind its back,
	// so we use ast1 to look for the doc comments on import "C"
	// and on exported functions, and we use ast2 for translating
	// and reprinting.

"C? Go? Cgo!" for an introduction to using cgo:
https://golang.org/doc/articles/c_go_cgo.html.

CFLAGS, CPPFLAGS, CXXFLAGS, FFLAGS and LDFLAGS may be defined with pseudo
#cgo directives within these comments to tweak the behavior of the C, C++
or Fortran compiler. Values defined in multiple directives are concatenated
together. The directive can include a list of build constraints limiting its

	COMISD X11, X11                         // 66450f2fdb
	COMISS (BX), X2                         // 0f2f13
	COMISS (R11), X2                        // 410f2f13
	COMISS X2, X2                           // 0f2fd2
	COMISS X11, X2                          // 410f2fd3
	COMISS (BX), X11                        // 440f2f1b
	COMISS (R11), X11                       // 450f2f1b
	COMISS X2, X11                          // 440f2fda

</pre>

<h2 id="Lexical_elements">Lexical elements</h2>

<h3 id="Comments">Comments</h3>

<p>
Comments serve as program documentation. There are two forms:
</p>

<ol>
<li>
<i>Line comments</i> start with the character sequence <code>//</code>
and stop at the end of the line.
</li>
<li>
<i>General comments</i> start with the character sequence <code>/*</code>

	echo No updates needed.
	exit 0
fi

echo Updated for $CODE/$DATA: $files

commitmsg="lib/time: update to $CODE/$DATA

Commit generated by update.bash.

For #22487.
"

if [ "$1" = "-commit" ]; then
	echo "Creating commit. Run 'git reset HEAD^' to undo commit."
	echo
	git commit -m "$commitmsg" $files
	echo
	git log -n1 --stat
	echo

func NewTokenizer(name string, r io.Reader, file *os.File) *Tokenizer {
	var s scanner.Scanner
	s.Init(r)
	// Newline is like a semicolon; other space characters are fine.
	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

// converted to int they correspond to the rune size that was read.
type readOp int8

// Don't use iota for these, as the values need to correspond with the
// names and comments, which is easier to see when being explicit.
const (
	opRead      readOp = -1 // Any other read operation.
	opInvalid   readOp = 0  // Non-read operation.
	opReadRune1 readOp = 1  // Read rune of size 1.

	// able to treat them as byte arrays, so the godefs
	// inputs in package syscall say
	//
	//	// +godefs map struct_in_addr [4]byte
	//	// +godefs map struct_in_addr6 [16]byte
	//
	for _, g := range f.Comments {
		for _, c := range g.List {
			i := strings.Index(c.Text, "+godefs map")
			if i < 0 {
				continue
			}
			s := strings.TrimSpace(c.Text[i+len("+godefs map"):])
			i = strings.Index(s, " ")
			if i < 0 {

func ExampleScanner_emptyFinalToken() {
	// Comma-separated list; last entry is empty.
	const input = "1,2,3,4,"
	scanner := bufio.NewScanner(strings.NewReader(input))
	// Define a split function that separates on commas.
	onComma := func(data []byte, atEOF bool) (advance int, token []byte, err error) {
		for i := 0; i < len(data); i++ {
			if data[i] == ',' {
				return i + 1, data[:i], nil
			}
		}
		if !atEOF {

		notType = 1 << iota
		notIntConst
		notNumConst
		notStrLiteral
		notDeclared
	)
	sawUnmatchedErrors := false
	for _, line := range strings.Split(stderr, "\n") {
		// Ignore warnings and random comments, with one
		// exception: newer GCC versions will sometimes emit
		// an error on a macro #define with a note referring
		// to where the expansion occurs. We care about where