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// There is a bug in Python 3.6 that turned the Index_Check function
// into a macro without taking care of the limited API.
// This leads to the single problem that we don't have
// access to PyLong_Type's nb_index field which is no heap type.
// We cannot easily create this function by inheritance since it is
// not inherited.
//
// Simple solution: Create the structure and write such a function.
// Long term: Submit a patch to python.org .

// Update: I did the long-term solution for python 3.7 in issue 33738.

typedef struct {
    /* Number implementations must check *both*
       arguments for proper type and implement the necessary conversions
       in the slot functions themselves. */

    binaryfunc nb_add;
    binaryfunc nb_subtract;
    binaryfunc nb_multiply;
    binaryfunc nb_remainder;
    binaryfunc nb_divmod;
    ternaryfunc nb_power;
    unaryfunc nb_negative;
    unaryfunc nb_positive;
    unaryfunc nb_absolute;
    inquiry nb_bool;
    unaryfunc nb_invert;
    binaryfunc nb_lshift;
    binaryfunc nb_rshift;
    binaryfunc nb_and;
    binaryfunc nb_xor;
    binaryfunc nb_or;
    unaryfunc nb_int;
    void *nb_reserved;  /* the slot formerly known as nb_long */
    unaryfunc nb_float;

    binaryfunc nb_inplace_add;
    binaryfunc nb_inplace_subtract;
    binaryfunc nb_inplace_multiply;
    binaryfunc nb_inplace_remainder;
    ternaryfunc nb_inplace_power;
    binaryfunc nb_inplace_lshift;
    binaryfunc nb_inplace_rshift;
    binaryfunc nb_inplace_and;
    binaryfunc nb_inplace_xor;
    binaryfunc nb_inplace_or;

    binaryfunc nb_floor_divide;
    binaryfunc nb_true_divide;
    binaryfunc nb_inplace_floor_divide;
    binaryfunc nb_inplace_true_divide;

    unaryfunc nb_index;

    binaryfunc nb_matrix_multiply;
    binaryfunc nb_inplace_matrix_multiply;
} PyNumberMethods;

// temporary structure until we have a generator for the offsets
typedef struct _oldtypeobject {
    PyVarObject ob_base;
    void *X01; // const char *tp_name;
    void *X02; // Py_ssize_t tp_basicsize;
    void *X03; // Py_ssize_t tp_itemsize;
    void *X04; // destructor tp_dealloc;
    void *X05; // printfunc tp_print;
    void *X06; // getattrfunc tp_getattr;
    void *X07; // setattrfunc tp_setattr;
    void *X08; // PyAsyncMethods *tp_as_async;
    void *X09; // reprfunc tp_repr;
    PyNumberMethods *tp_as_number;

} PyOldTypeObject;

int PyIndex_Check(PyObject *obj)
{
    PyOldTypeObject *type = reinterpret_cast<PyOldTypeObject*>(Py_TYPE(obj));
    return type->tp_as_number != NULL &&
           type->tp_as_number->nb_index != NULL;
}