How do I use a struct with a pointer to struct?

like this, adapted from here (btw, that could use an update since cffi_utils moved)

from cffi import FFI
from numba.core.typing import cffi_utils

src = """
typedef struct nested_struct {
    float  x;
} nested_struct;

/* Define the C struct */
typedef struct my_struct {
    nested_struct*    nested;
} my_struct;

ffi = FFI()

print(cffi_utils.map_type(ffi.typeof('my_struct'), use_record_dtype=True))

error is

NotImplementedError: Record(x[type=float32;offset=0];4;True)* cannot be represented as a Numpy dtype

with use_record_dtype=False, error is

File “/home/test/PycharmProjects/test1/venv/lib/python3.7/site-packages/numba/core/typing/”, line 134, in map_type
raise TypeError(cffi_type)
TypeError: <ctype ‘my_struct’>