Segfault when pickling array >2G size

[iynehz]

See below for reproducing code. I studied it a little bit and found it caused by this line You see it converts iter->index to int which is 4 bytes

numpy/numpy/core/src/multiarray/methods.c

Line 1619 in 00a45b4

PyList_SET_ITEM(list, (int) iter->index, theobject);

btw seems this (int) conversion is used at multiple places like

numpy/numpy/core/src/multiarray/methods.c

Line 1639 in 00a45b4

theobject = PyList_GET_ITEM(list, (int) iter->index);

Reproducing code example:

To try this you probably need a machine of large memory. Mine is 64GB and I believe 32GB is not enough.

import numpy as np
x = np.empty(2**31+1, dtype='object')
x.__reduce__()

Numpy/Python version information:

1.19.1 3.8.2 (default, Jul 16 2020, 14:00:26)
[GCC 9.3.0]

[eric-wieser]

I suspect this is a holdover from when PyList_GET_ITEM accepted int and not Py_ssize_t.

This looks like a very easy fix (remove the casts), want to make a PR?