Subject

when attempting to subclass urllib3.Retry -- one would want to implement def increment(...) -> Self: as both increment and new preserve the type but label the return value as Retry (essentially breaking subclassing types):

if the codebase were python 3.11+ I would use from typing import Self -- it appears elsewhere in the codebase one-off SelfT TypeVars are created -- that pattern could be followed here

alternatively the TYPE_CHECKING trick could be used and is understood by the current major type checkers:

if TYPE_CHECKING:
    from typing_extensions import Self

Environment

N/A -- latest primary branch source, mypy 1.9

Steps to Reproduce

from typing import Any, Self
import urllib3
class MyRetry(urllib3.Retry):
    def increment(self, *a: Any, **k: Any) -> Self:  # type error on this line!
        return super().increment(*a, **k)

$ mypy t.py
t.py:5: error: Incompatible return value type (got "Retry", expected "Self")  [return-value]
Found 1 error in 1 file (checked 1 source file)

Expected Behavior

no errors

Actual Behavior

shown above