numba CFFI class method C wrapper

mylib.cc

//compile with  g++ -fPIC mylib.cc -shared -o mylib.dylib
class MyClass {
public:
  
  MyClass(const char* filename) {
    //do something with filename
  }
  
  double func(int a) {
    //an expensive C++ function
    return 0.0;
  }
  
};

extern "C" {
  void* new_class(const char* filename) {
    return new MyClass(filename);
  }

  double class_func(void* cls, int a) {
    return ((MyClass*)cls)->func(a);
  }
}

test.py

import numba
from cffi import FFI

ffi = FFI()
ffi.cdef("""
void* new_class(const char* filename);
double class_func(void* cls, int a);
""")
mylib = ffi.dlopen("mylib.dylib")

class_func = mylib.class_func

c = mylib.new_class("asd")

@numba.njit
def call_myfunc(a):
    x = class_func(c, a)

#throws exception as the type of c ('_cffi_backend.CData') is not known to Numba
call_myfunc(1)