When creatingint instances, wealways allocate space for and initialise at least one digit, since themedium_value function that's used for fast pathsassumes the existence of that digit. This change was introduced for Python 3.11 in PR#27832.

However, the corresponding change inlong_subtype_new was missed; this results in us asking for zero digits in the case of creating an instance of a subclass ofint with value zero - e.g.,

classMyInt(int):passmyint=MyInt()# problem

That's then a problem ifmyint is used in a context wheremedium_value might be called on it, for example as inint(myint).

We've got away with this so far because of a compensatingoverallocation issue: see#81381; this bug blocked an attempt to address#81381 in#100855. But I believe this should still be fixed.

I'll make a PR shortly.

Linked PRs

• gh-101037: Fix potential memory underallocation for zeros of int subtypes #101038
• [3.11] gh-101037: Fix potential memory underallocation for zeros of int subtypes (GH-101038) #101219