Take the following simple structure:

    class Foo(ctypes.Structure):
        _fields_ = [('f', ctypes.uint32_t)]

And construct some arrays with it:

    def get_array_view(N):
        return memoryview((Foo * N)())

In most cases, this works as expected, returning the size of one item:

    >>> get_array_view(10).itemsize
    4
    >>> get_array_view(1).itemsize
    4

But when N=0, it returns the wrong result

    >>> get_array_view(0).itemsize
    0

Which contradicts its `.format`, which still describes a 4-byte struct

    >>> get_array_view(0).format
    'T{>I:one:}'

This causes a downstream problem in numpy:

    >>> np.array(get_array_view(0))
    RuntimeWarning: Item size computed from the PEP 3118 buffer format string does not match the actual item size.