Empty list of lists crashes at runtime with njit

[GaidaiIgor]

The following code reproduces the issue:

from numba import njit
import numpy as np


@njit
def test():
    a = [[0, 1]]
    a.clear()
    b = np.array(a)


test()

This code crashes with the following error message:

IndexError: getitem out of range

Without @njit this code finishes successfully.

Numba version: 0.56.4
Numpy version: 1.23.5
Python version: 3.10
OS: Windows 10

[stuartarchibald]

Thanks for the report and MWR. This reproduces exactly as described. Numba infers that a is a list-of-lists-of-integers from which it then determines that b must be a 2d array of integers, i.e. the a.clear() isn't acknowledged. I'd guess it's this which leads to the IndexError as the np.array() constructor code expects a list-of-lists but just gets a list.