extraneous reportArgumentType when calling super().__init__

[Alan-Chen99]

class Parameter:
    def __init__(self, name):
        pass


class testclass:
    def __init__(
        self, x: list[Parameter] = None
    ):  # error: Expression of type "None" cannot be assigned to parameter of type "list[Parameter]
        pass


class testclass2(testclass):
    def __init__(self):
        # I expect no error here
        super().__init__()  # error: Argument of type "None" cannot be assigned to parameter "x" of type "list[Parameter]" in function "__init__"

This is annoying when testclass is from a dependency.

$ pyright --version
pyright 1.1.394

[erictraut]

Pyright is working as intended here. The default value has type None which is not assignable to the type list[Parameter].

Your options are:

1. Fix the bug in the testclass.__init__ method. (While this is the recommended option, it sounds like this may not be possible if it's coming from a dependency that you don't have control over.)
2. In your pyright config file for this project, set strictParameterNoneValue to false. This tells pyright to use the (now obsolete) convention that a None default argument value should imply an Optional parameter type.
3. Suppress the error in testclass2.__init__ using a # type: ignore or # pragma: ignore.

[Alan-Chen99]

It is inconsistent though; it no longer errors if you do

class Parameter:
    def __init__(self):
        pass

instead.

[erictraut]

Yeah, that's inconsistent. I'll reopen and investigate further.

[erictraut]

This is addressed in pyright 1.1.395.

[erictraut]

The fix for this inconsistency resulted in a regression that is affecting many pyright users. I'm going to back out this change and reopen the issue so I have time to reconsider the approach.