h.Reset()
		h.Write(in)
		out = h.Sum(out[:0])
	}))
	if n > 0 {
		t.Errorf("allocs = %d, want 0", n)
	}
}

type cgoData struct {
	Data [16]byte
	Ptr  *cgoData
}

func TestCgo(t *testing.T) {
	// Test that Write does not cause cgo to scan the entire cgoData struct for pointers.
	// The scan (if any) should be limited to the [16]byte.
	d := new(cgoData)
	d.Ptr = d
	h := New()