pyre error: Incompatible parameter type [6]: In call `simple_parsing.parsing.parse`, for 1st positional argument, expected `Type[Variable[DataclassT (bound to Dataclass)]]` but got `Type[Opts]`

[alexanderlobov]

Describe the bug

pyre check
ƛ Found 1 type error!
src/test.py:9:21 Incompatible parameter type [6]: In call `simple_parsing.parsing.parse`, for 1st positional argument, expected `Type[Variable[DataclassT (bound to Dataclass)]]` but got `Type[Opts]`.

To Reproduce

from dataclasses import dataclass
import simple_parsing

@dataclass
class Opts:
    foo: int

simple_parsing.parse(Opts)

pyre init
pyre check

Expected behavior No errors are expected from pyre.

Actual behavior

pyre check
ƛ Found 1 type error!
src/test.py:9:21 Incompatible parameter type [6]: In call `simple_parsing.parsing.parse`, for 1st positional argument, expected `Type[Variable[DataclassT (bound to Dataclass)]]` but got `Type[Opts]`.

Desktop (please complete the following information):

pyre --version
Binary version: d5ff1b0a39e2b09e3873a3131373a7f466c77d5d
Client version: 0.9.18

pip list | grep simple
simple-parsing    0.1.3

python --version
Python 3.9.13

Additional context

The same happens for ArgumentParser.add_arguments:

Incompatible parameter type [6]: In call `simple_parsing.parsing.ArgumentParser.add_arguments`, for 1st positional argument, expected `Type[Variable[DataclassT (bound to Dataclass)]]` but got `Type[Options]`

The reason may be that a private method is used in the Dataclass declaration:

class Dataclass(Protocol):
    __dataclass_fields__: ClassVar[dict[str, Field]]

That is prohibited in pyre: https://pyre-check.org/docs/errors/#52-private-protocol-property

[lebrice]

Then that's a problem with Pyre, no?

Otherwise, how are you supposed to make a TypeVar with a bound set to a Dataclass protocol? I do want to keep the bound of Dataclass, otherwise any non-dataclass type could be passed.

[alexanderlobov]

Thanks for the answer! Sounds reasonable. I'll discuss it with the pyre team.

[lebrice]

Closing this for now, since the DataclassInstance protocol from dataclasses is also following this structure.