needHeaderOffset := f.headerOffset == int64(^uint32(0))

	// Best effort to find what we need.
	// Other zip authors might not even follow the basic format,
	// and we'll just ignore the Extra content in that case.
	var modified time.Time
parseExtras:
	for extra := readBuf(f.Extra); len(extra) >= 4; { // need at least tag and size
		fieldTag := extra.uint16()
		fieldSize := int(extra.uint16())

//
// Scanning stops unrecoverably at EOF, the first I/O error, or a token too
// large to fit in the [Scanner.Buffer]. When a scan stops, the reader may have
// advanced arbitrarily far past the last token. Programs that need more
// control over error handling or large tokens, or must run sequential scans
// on a reader, should use [bufio.Reader] instead.
type Scanner struct {
	r            io.Reader // The reader provided by the client.

	tok := in.Stack.Next()
	if tok != scanner.Ident {
		in.expectText("expected identifier after '#'")
	}
	if !in.enabled() {
		// Can only start including again if we are at #else or #endif but also
		// need to keep track of nested #if[n]defs.
		// We let #line through because it might affect errors.
		switch in.Stack.Text() {
		case "else", "endif", "ifdef", "ifndef", "line":
			// Press on.
		default:
			return false

		}
	})
	t.Run("uint32max-1_Zip64", func(t *testing.T) {
		t.Parallel()
		if !generatesZip64(t, gen(0xffffffff)) {
			t.Error("expected zip64")
		}
	})
}

// At 16k records, we need to generate a zip64 file.
func TestZip64ManyRecords(t *testing.T) {
	if testing.Short() {
		t.Skip("skipping in short mode")
	}
	t.Parallel()
	gen := func(numRec int) func(*Writer) {
		return func(w *Writer) {

		f.Ref = make([]*Ref, 0, 8)
	}
	f.walk(ast2, ctxProg, (*File).validateIdents)
	f.walk(ast2, ctxProg, (*File).saveExprs)

	// Accumulate exported functions.
	// The comments are only on ast1 but we need to
	// save the function bodies from ast2.
	// The first walk fills in ExpFunc, and the
	// second walk changes the entries to
	// refer to ast2 instead.
	f.walk(ast1, ctxProg, (*File).saveExport)

frame, invokes the system C function (in this case, puts), stores the
result in the frame, and returns.

Linking

Once the _cgo_export.c and *.cgo2.c files have been compiled with gcc,
they need to be linked into the final binary, along with the libraries
they might depend on (in the case of puts, stdio). cmd/link has been
extended to understand basic ELF files, but it does not understand ELF

// invalid usage. opReadRuneX constants are chosen such that
// 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.

				}
				continue
			}
			buf = append(buf, c)
		}

		f := strings.Fields(string(buf))

		// Turn relative (PC) into absolute (PC) automatically,
		// so that most branch instructions don't need comments
		// giving the absolute form.
		if len(f) > 0 && strings.Contains(printed, "(PC)") {
			index := len(f) - 1
			suf := "(PC)"
			for !strings.HasSuffix(f[index], suf) {
				index--
				suf = "(PC),"

				// An "unfortunate" case: the feature was once
				// included in the API (e.g. go1.txt), but was
				// subsequently removed. These are already
				// acknowledged by being in the file
				// "api/except.txt". No need to print them out
				// here.
			} else if portRemoved(feature) {
				// okay.
			} else if featureSet[featureWithoutContext(feature)] {
				// okay.
			} else {
				fmt.Fprintf(w, "-%s\n", feature)

	// However, if the strings require multibyte UTF-8 encoding and is a
	// valid UTF-8 string, then we set the UTF-8 bit.
	//
	// For the case, where the user explicitly wants to specify the encoding
	// as UTF-8, they will need to set the flag bit themselves.
	utf8Valid1, utf8Require1 := detectUTF8(fh.Name)
	utf8Valid2, utf8Require2 := detectUTF8(fh.Comment)
	switch {
	case fh.NonUTF8:
		fh.Flags &^= 0x800