Argh! The self-tests cause

mypy/typeshed/stdlib/2and3/argparse.pyi:128: error: Overloaded function signatures 2 and 3 overlap with incompatible return types
mypy/typeshed/stdlib/2and3/argparse.pyi:132: error: Overloaded function signatures 4 and 5 overlap with incompatible return types

even though type-checking something (like my example above) that imports argparse does not give this.

Any ideas?

The signatures are overlapping if --strict-optional is False.

Hm, it fails even with strict optional, a simple repro:

from typing import overload, TypeVar
  
T = TypeVar('T')

@overload
def f(x: None) -> int: ...
@overload
def f(x: T) -> T: ...
def f(x):
    pass

I would say this is a bug.

Well this is not a bug, sorry, if T is Optional[str], there is an unsafe overlap, there must be a bound for T.

I remember we discussed this with @Michael0x2a and were at the boundary of allowing this, because in practice the unsafety is quite minor. So I think it is fine to just # type: ignore this, if there is no way to put a bound on variable.