f.walk(ast1, ctxProg, (*File).saveExport)
	f.walk(ast2, ctxProg, (*File).saveExport2)

	f.Comments = ast1.Comments
	f.AST = ast2
}

// Like ast.CommentGroup's Text method but preserves
// leading blank lines, so that line numbers line up.
func commentText(g *ast.CommentGroup) string {
	var pieces []string
	for _, com := range g.List {
		c := com.Text
		// Remove comment markers.

	{"4", func(b *Reader) string { return reads(b, 4) }},
	{"5", func(b *Reader) string { return reads(b, 5) }},
	{"7", func(b *Reader) string { return reads(b, 7) }},
	{"bytes", readBytes},
	{"lines", readLines},
}

const minReadBufferSize = 16

var bufsizes = []int{
	0, minReadBufferSize, 23, 32, 46, 64, 93, 128, 1024, 4096,
}

func TestReader(t *testing.T) {
	var texts [31]string

pkg syscall (netbsd-arm64-cgo), const ETHERTYPE_VGLAB ideal-int
pkg syscall (netbsd-arm64-cgo), const ETHERTYPE_VINES = 2989
pkg syscall (netbsd-arm64-cgo), const ETHERTYPE_VINESECHO = 2991
pkg syscall (netbsd-arm64-cgo), const ETHERTYPE_VINESECHO ideal-int
pkg syscall (netbsd-arm64-cgo), const ETHERTYPE_VINES ideal-int
pkg syscall (netbsd-arm64-cgo), const ETHERTYPE_VINESLOOP = 2990

			// equivalent to the "process is gone":
			//    os.IsNotExist(err),
			//    "... : no such process",
			//    "... : bad file descriptor.
			continue
		}
		lines := strings.Split(string(d), "\n")
		for _, line := range lines {
			// Different kernel vintages pad differently.
			line = strings.TrimSpace(line)
			if strings.HasPrefix(line, "Pid:\t") {
				// On loaded systems, it is possible

		b = strconv.AppendInt(b, i, 10)
		b = append(b, ' ')
		w.Write(b)
	}
	w.Flush()
	// Output: 1 2 3 4
}

// The simplest use of a Scanner, to read standard input as a set of lines.
func ExampleScanner_lines() {
	scanner := bufio.NewScanner(os.Stdin)
	for scanner.Scan() {
		fmt.Println(scanner.Text()) // Println will add back the final '\n'
	}
	if err := scanner.Err(); err != nil {

`}}

Only differences from the base Go toolchain defaults are reported.

When testing a package, `//go:debug` lines in the `*_test.go`
files are treated as directives for the test's main package.
In any other context, `//go:debug` lines are ignored by the toolchain;
`go` `vet` reports such lines as misplaced.

## GODEBUG History {#history}

// a file of newline-delimited lines of text. Successive calls to
// the [Scanner.Scan] method will step through the 'tokens' of a file, skipping
// the bytes between the tokens. The specification of a token is
// defined by a split function of type [SplitFunc]; the default split
// function breaks the input into lines with line termination stripped. [Scanner.Split]

  (the latter if this is not a complete fix) to this comment
+ If referring to a repo other than `golang/go` you can use the
  `owner/repo#issue_number` syntax: `Fixes golang/tools#1234`
+ We do not use Signed-off-by lines in Go. Please don't add them.
  Our Gerrit server & GitHub bots enforce CLA compliance instead.

      Please draft the record entry for your proposal here.
      If multiple records need to be included, separate them with `---` lines.
      You can check the list of the approved counters and their current configuration in [config.txt](https://go.googlesource.com/telemetry/+/master/internal/configgen/config.txt).
    render: Text
    value: |

	// behavior too closely to specific versions of the compilers.
	// Instead, arrange that we can infer what we need from only the presence or absence
	// of an error on a specific line.
	//
	// For each name, we generate these lines, where xxx is the index in toSniff plus one.
	//
	//	#line xxx "not-declared"
	//	void __cgo_f_xxx_1(void) { __typeof__(name) *__cgo_undefined__1; }
	//	#line xxx "not-type"