Rule to force var = <default> if value is None else value instead of var = value or <default> for value: int | None = None

[adriangb]

Description

I often see the pattern of a function taking a parameter such as value: int | None = None and then having an internal default by doing var = value or 1. This is problematic because 0 and None are both falsy:

def f(value: int | None) -> int:
    return value or 1

f(0)  # returns 1

I guess one might do this intentionally, but unless you are explicit the meaning is unclear. I would rather see one of:

def f(value: int | None) -> int:
    return 1 if value is None else value

def f(value: int | None) -> int:
    return 1 if value is None or value == 0 else value

Arguably in these simple cases just making the parameter value: int = 1 would be better, but I believe there are use cases for this pattern or it is at least a pattern that exists