// We have a '#'; it must be followed by a known word (define, include, etc.).
	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() {

		t.Skip("skipping for non-gc toolchain")
	}
	if runtime.GOARCH != "amd64" {
		// TODO: support SEH on other architectures.
		t.Skip("skipping on non-amd64")
	}
	// Only frames in the test package are checked.
	want := []string{
		"test._Cfunc_backtrace",
		"test.testCallbackCallersSEH.func1.1",
		"test.testCallbackCallersSEH.func1",
		"test.goCallback",
		"test._Cfunc_callback",

otherwise it is <i>bidirectional</i>.
A channel may be constrained only to send or only to receive by
<a href="#Assignment_statements">assignment</a> or
explicit <a href="#Conversions">conversion</a>.
</p>

<pre>
chan T          // can be used to send and receive values of type T
chan&lt;- float64  // can only be used to send float64s
&lt;-chan int      // can only be used to receive ints
</pre>

<p>

// AST expression onto a single line. The lexer normally inserts a
// semicolon at each newline, so we can replace newline with semicolon.
// However, we can't do that in cases where the lexer would not insert
// a semicolon. We only have to worry about cases that can occur in an
// expression passed through gofmt, which means composite literals and
// (due to the printer possibly inserting newlines because of position
// information) operators.

// and the maximum size of buffer that may be allocated during scanning.
// The maximum token size must be less than the larger of max and cap(buf).
// If max <= cap(buf), [Scanner.Scan] will use this buffer only and do no allocation.
//
// By default, [Scanner.Scan] uses an internal buffer and sets the
// maximum token size to [MaxScanTokenSize].
//
// Buffer panics if it is called after scanning has started.

	"unicode/utf8"
)

// A Reader implements the io.Reader, io.ReaderAt, io.WriterTo, io.Seeker,
// io.ByteScanner, and io.RuneScanner interfaces by reading from
// a byte slice.
// Unlike a [Buffer], a Reader is read-only and supports seeking.
// The zero value for Reader operates like a Reader of an empty slice.
type Reader struct {
	s        []byte
	i        int64 // current reading index
	prevRune int   // index of previous rune; or < 0

// It splits the slice s around each instance of one or more consecutive white space
// characters, as defined by unicode.IsSpace, returning a slice of subslices of s or an
// empty slice if s contains only white space.
func Fields(s []byte) [][]byte {
	// First count the fields.
	// This is an exact count if s is ASCII, otherwise it is an approximation.
	n := 0
	wasSpace := 1

	// arbitrary file sizes, filenames of arbitrary encoding and length,
	// sparse files, and other features.
	//
	// It is recommended that PAX be chosen over GNU unless the target
	// application can only parse GNU formatted archives.
	//
	// Reference:
	//	https://www.gnu.org/software/tar/manual/html_node/Standard.html
	FormatGNU

	// Schily's tar format, which is incompatible with USTAR.

	//       This only captures the MOVD. Should the SLD be appended to the encoding by the test?
	// Hex constant 0x20004000000
	MOVD $2199090364416, R5         // 60058001
	// Hex constant 0xFFFFFE0004000000
	MOVD $-2198956146688, R5        // 38a08001
	// TODO: On GOPPC64={power8,power9}, this is preprocessed into MOVD $-1, R5; RLDC R5, $33, $63, R5.

					i, s1, s2, cnt, v.cnt)
			}
		}
	}
}

// TestReadHeaderOnly tests that Reader does not attempt to read special
// header-only files.
func TestReadHeaderOnly(t *testing.T) {
	f, err := os.Open("testdata/hdr-only.tar")
	if err != nil {
		t.Fatalf("unexpected error: %v", err)
	}
	defer f.Close()

	var hdrs []*Header
	tr := NewReader(f)
	for {
		hdr, err := tr.Next()