if err != nil {
		t.Errorf("read error: %v", err)
	}
	if n != 0 {
		t.Errorf("wrong count; got %d want 0", n)
	}
}

func TestUnreadByte(t *testing.T) {
	b := new(Buffer)

	// check at EOF
	if err := b.UnreadByte(); err == nil {
		t.Fatal("UnreadByte at EOF: got no error")
	}
	if _, err := b.ReadByte(); err == nil {
		t.Fatal("ReadByte at EOF: got no error")
	}

An error on not-int-const:1 indicates that foo is not an integer constant.
An error on not-num-const:1 indicates that foo is not a number constant.
An error on not-str-lit:1 indicates that foo is not a string literal.
An error on not-signed-int-const:1 indicates that foo is not a signed integer constant.

The line number specifies the name involved. In the example, 1 is foo.

Next, cgo must learn the details of each type, variable, function, or

		t.Fatalf("error creating header: %v", err)
	}
	if _, err := f.Write([]byte("hi")); err != nil {
		t.Fatalf("error writing content: %v", err)
	}
	if err := z.Close(); err != nil {
		t.Fatalf("error closing zip writer: %v", err)
	}

	b := buf.Bytes()
	zf, err := NewReader(bytes.NewReader(b), int64(len(b)))
	if err != nil {
		t.Fatalf("got %v, expected nil", err)
	}
	zh := zf.File[0].FileHeader

var (
	ErrHeader          = errors.New("archive/tar: invalid tar header")
	ErrWriteTooLong    = errors.New("archive/tar: write too long")
	ErrFieldTooLong    = errors.New("archive/tar: header field too long")
	ErrWriteAfterClose = errors.New("archive/tar: write after close")
	ErrInsecurePath    = errors.New("archive/tar: insecure file path")
	errMissData        = errors.New("archive/tar: sparse file references non-existent data")

	}
}

// panicOnError is enabled when testing to abort execution on the first error
// and turn it into a recoverable panic.
var panicOnError bool

func (p *Parser) errorf(format string, args ...interface{}) {
	if panicOnError {
		panic(fmt.Errorf(format, args...))
	}
	if p.lineNum == p.errorLine {
		// Only one error per line.
		return
	}
	p.errorLine = p.lineNum
	if p.lex != nil {

// to stay in the language.
func println(args ...Type)

// The error built-in interface type is the conventional interface for
// representing an error condition, with the nil value representing no error.
type error interface {
	Error() string

[`x509usepolicies` setting.](/pkg/crypto/x509/#CreateCertificate).


### Go 1.21

Go 1.21 made it a run-time error to call `panic` with a nil interface value,
controlled by the [`panicnil` setting](/pkg/builtin/#panic).

Go 1.21 made it an error for html/template actions to appear inside of an ECMAScript 6
template literal, controlled by the

						if err := tw.WriteHeader(file.hdr); err != nil {
							b.Errorf("unexpected WriteHeader error: %v", err)
						}
						if _, err := tw.Write(file.body); err != nil {
							b.Errorf("unexpected Write error: %v", err)
						}
					}
					if err := tw.Close(); err != nil {
						b.Errorf("unexpected Close error: %v", err)
					}
				}
			})
		}
	})

func (w *Writer) AddFS(fsys fs.FS) error {
	return fs.WalkDir(fsys, ".", func(name string, d fs.DirEntry, err error) error {
		if err != nil {
			return err
		}
		if d.IsDir() {
			return nil
		}
		info, err := d.Info()
		if err != nil {
			return err
		}
		if !info.Mode().IsRegular() {
			return errors.New("zip: cannot add non-regular file")
		}

	blk  block      // Buffer to use as temporary local storage

	// err is a persistent error.
	// It is only the responsibility of every exported method of Reader to
	// ensure that this error is sticky.
	err error
}

type fileReader interface {
	io.Reader
	fileState

	WriteTo(io.Writer) (int64, error)
}

// NewReader creates a new [Reader] reading from r.
func NewReader(r io.Reader) *Reader {