[Python] Data class with argument optional only in init

I have the following simple class in Python:

class Point:
def __init__(x: int, y: int | None = None):
self.x = x
self.y = y if y is not None else x


How can the same thing be implemented using a @dataclass? The obvious would be to do the following:

from dataclasses import dataclass

@dataclass
class Point:
x: int
y: int | None

def __post_init__(self):
if self.y is None:
self.y = self.x


This appears to work, but changes type of y to an optional, resulting in false positive warning issued by e.g. Point(1, 2).y + 0.

How can I make y optional only in __init__? The only thing that comes to mind is to split it in half:

@dataclass
class Point:
x: int
y: int = field(init=False)
_y: InitVar[int | None]

def __post_init__(self, _y: int | None):
self.y = _y if _y is not None else self.x


but it seems overly verbose

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