__eq__ Method Fails for QuantLib.Date with None Comparison

[sergioUjo]

Description:

I recently updated QuantLib from version 1.32 to 1.35, and noticed that a comparison in my code suddenly broke. The issue suggests that the eq method for QuantLib.Date may not be working as expected.

Steps to Reproduce:

Here's a minimal reproducible example:

import QuantLib as ql

ql_date = ql.Date(1, 1, 2021)

is_false = ql_date == None

Expected Behavior: The comparison ql_date == None should return False, indicating that the ql_date is not equal to None, as None is not a valid Date object.

Actual Behavior: Instead, the code raises the following error:

ValueError: invalid null reference in method 'Date_eq', argument 2 of type 'Date const &'

[boring-cyborg[bot]]

Thanks for posting! It might take a while before we look at your issue, so don't worry if there seems to be no feedback. We'll get to it.

[lballabio]

Hi—it turns out this changed with release 1.34 due to upgrading to SWIG 4.2 (which was necessary to enable Python stable API). I've opened an issue with the SWIG people (https://github.com/swig/swig/issues/2987) to see if that's an intentional change.

In the meantime, if you want to compare with None explicitly, the idiomatic if date is None works.