switch err := recover().(type) {
		case nil:
			t.Fatal("bytes.Buffer.ReadFrom didn't panic")
		case error:
			// this is the error string of errNegativeRead
			wantError := "bytes.Buffer: reader returned negative count from Read"
			if err.Error() != wantError {
				t.Fatalf("recovered panic: got %v, want %v", err.Error(), wantError)
			}
		default:
			t.Fatalf("unexpected panic value: %#v", err)
		}
	}()

	if zt.File == nil {
		return
	}

	if z.Comment != zt.Comment {
		t.Errorf("comment=%q, want %q", z.Comment, zt.Comment)
	}
	if len(z.File) != len(zt.File) {
		t.Fatalf("file count=%d, want %d", len(z.File), len(zt.File))
	}

	// test read of each file
	for i, ft := range zt.File {
		readTestFile(t, zt, ft, z.File[i], raw)
	}
	if t.Failed() {
		return
	}

	b := NewReader(new(negativeReader))
	defer func() {
		switch err := recover().(type) {
		case nil:
			t.Fatal("read did not panic")
		case error:
			if !strings.Contains(err.Error(), "reader returned negative count from Read") {
				t.Fatalf("wrong panic: %v", err)
			}
		default:
			t.Fatalf("unexpected panic value: %T(%v)", err, err)
		}
	}()
	b.Read(make([]byte, 100))
}

The shift operators shift the left operand by the shift count specified by the
right operand, which must be non-negative. If the shift count is negative at run time,
a <a href="#Run_time_panics">run-time panic</a> occurs.
The shift operators implement arithmetic shifts if the left operand is a signed
integer and logical shifts if it is an unsigned integer.
There is no upper limit on the shift count. Shifts behave

}

func TestCountNearPageBoundary(t *testing.T) {
	t.Parallel()
	b := dangerousSlice(t)
	for i := range b {
		c := Count(b[i:], []byte{1})
		if c != 0 {
			t.Fatalf("Count(b[%d:], {1})=%d, want 0\n", i, c)
		}
		c = Count(b[:i], []byte{0})
		if c != i {
			t.Fatalf("Count(b[:%d], {0})=%d, want %d\n", i, c, i)
		}
	}

	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
	s.IsIdentRune = isIdentRune

)

// ErrTooLarge is passed to panic if memory cannot be allocated to store data in a buffer.
var ErrTooLarge = errors.New("bytes.Buffer: too large")
var errNegativeRead = errors.New("bytes.Buffer: reader returned negative count from Read")

const maxInt = int(^uint(0) >> 1)

// Bytes returns a slice of length b.Len() holding the unread portion of the buffer.
// The slice is valid for use only until the next buffer modification (that is,

			t.Go = c.Opaque(t.Size)
			break
		}
		count := dt.Count
		if count == -1 {
			// Indicates flexible array member, which Go doesn't support.
			// Translate to zero-length array instead.
			count = 0
		}
		sub := c.Type(dt.Type, pos)
		t.Align = sub.Align
		t.Go = &ast.ArrayType{
			Len: c.intExpr(count),
			Elt: sub.Go,
		}

	// Set the split function for the scanning operation.
	scanner.Split(bufio.ScanWords)
	// Count the words.
	count := 0
	for scanner.Scan() {
		count++
	}
	if err := scanner.Err(); err != nil {
		fmt.Fprintln(os.Stderr, "reading input:", err)
	}
	fmt.Printf("%d\n", count)
	// Output: 15
}

// Use a Scanner with a custom split function (built by wrapping ScanWords) to validate

	{"3%0", "modulo by zero"},
	{"(1<<63)%0", "modulo of value with high bit set"},
	{"3<<-4", "negative left shift count"},
	{"3<<(1<<63)", "negative left shift count"},
	{"3>>-4", "negative right shift count"},
	{"3>>(1<<63)", "negative right shift count"},
	{"(1<<63)>>2", "right shift of value with high bit set"},
	{"(1<<62)>>2", ""},
	{`'\x80'`, "illegal UTF-8 encoding for character constant"},