func stack2000() { var buf [2000]byte; use(buf[:]); C.callGoStackCheck() }
func stack2004() { var buf [2004]byte; use(buf[:]); C.callGoStackCheck() }
func stack2008() { var buf [2008]byte; use(buf[:]); C.callGoStackCheck() }
func stack2012() { var buf [2012]byte; use(buf[:]); C.callGoStackCheck() }
func stack2016() { var buf [2016]byte; use(buf[:]); C.callGoStackCheck() }

		wantValid:    true,
		wantAligned:  []sparseEntry{{0, 1536}, {8192, 1808}},
		wantInverted: []sparseEntry{{2000, 6000}, {10000, 0}},
	}, {
		in: []sparseEntry{{0, 2000}, {2000, 2000}, {4000, 0}, {4000, 3000}, {7000, 1000}, {8000, 0}, {8000, 2000}}, size: 10000,
		wantValid:    true,
		wantAligned:  []sparseEntry{{0, 1536}, {2048, 1536}, {4096, 2560}, {7168, 512}, {8192, 1808}},

		t.Fatal("after scan:", s.Err())
	}
}

func TestBlankLines(t *testing.T) {
	s := NewScanner(strings.NewReader(strings.Repeat("\n", 1000)))
	for count := 0; s.Scan(); count++ {
		if count > 2000 {
			t.Fatal("looping")
		}
	}
	if s.Err() != nil {
		t.Fatal("after scan:", s.Err())
	}
}

type countdown int