Support bool with Literal in --warn-unreachable by kreathon · Pull Request #15645 · python/mypy (original) (raw)

MyPy Primer Analysis

- steam/package.py:396: error: Return value expected [return-value]

if self.flags & LicenseFlag.Expired:
    return
if self.time_limit is None:                      <- This code is unreachable
    return                                                <- 396
return self.time_limit - self.time_used

self.flags is an Instance of LicenceFlag (which inherits from Flags, which inherits from IntEnum).

See below for an explanation of IntEnum.

- steam/state.py:2565: error: Item "None" of "Language | None" has no attribute "api_name" [union-attr]

    player.GetGameAchievementsRequest(appid=app_id, language=(self.language or language).api_name)

The type of language is Language | None and the type of self.language is Language (which inherits from IntEnum).

See below for an explanation of IntEnum.

IntEnum

This class is a custom enum implementation which has:

def __bool__(self) -> Literal[True]:
    return True  # an enum member with a zero value would return False otherwise

I am confused by this comment, because:

>>> bool(LicenseFlag.NONE)
True

>>> bool(LicenseFlag.Renew)
True

With:

class LicenseFlag(Flags):
    """Flags for a license."""
    NONE                         = 0
    """No flags."""
    Renew                        = 1 << 0
    ...

I am not sure if this is a bug, or I am missing something ...

Edit: I will ask the steam.py maintainer.

Edit 2: Both issues were discussed on the steam.py Discord:

• self.flags & LicenseFlag.Expired creates a new LicenseFlag which will evaluate to True again
• self.language or language should be language or self.language

So the change already found two bugs 🎉