Empty lists result in overly broad types

[DRMacIver]

All of the following is tested on MonkeyType 23.3.0.

Suppose I have the following function as foo.py:

def bar(nums):
    return 0

And run the following code in test_foo.py:

from foo import bar

if __name__ == '__main__':
    bar([1])
    bar([])

Then apply this with:

monkeytype run test_foo.py
monkeytype apply foo

This results in the following type:

from typing import Any, List, Union

def bar(nums: List[Union[Any, int]]) -> int:
    return 0

Presumably the root cause of this is that an empty list does not have an obvious type associated with its element, so it is being typed as List[Any], but this results in fairly non-ideal behaviour because it means that if a function that takes a list of a specific type is ever called with an empty list, it will instead get this over broad type

[carljm]

Hmm, thanks for the report. Seems like this must have regressed at some point, since I'm fairly sure it wasn't the case when I used MonkeyType more actively. Will investigate.