Failing to recognize generic constraints in tuples #7702

from dataclasses import dataclass
from typing import Generic, Tuple, TypeVar
from typing_extensions import Protocol


M = TypeVar("M", covariant=True)
class Mapping(Protocol[M]):
    def map(self) -> M:
        ...


W = TypeVar("W", contravariant=True)
class Writer(Protocol[W]):
    def write(self, shape: W):
        ...


class Circle:
    pass


class CircleMapping:
    def map(self) -> Circle:
        return Circle()


class CircleWriter:
    def write(self, shape: Circle):
        print("in CircleWriter.write")


class Square:
    pass


class SquareMapping:
    def map(self) -> Square:
        return Square()


class SquareWriter:
    def write(self, shape: Square):
        print("in SquareWriter.write")


E = TypeVar("E")


## Tuple strategy
Tools = Tuple[Mapping[E], Writer[E]]

def get_tools(shape_name: str) -> Tools:
    if shape_name == "square":
        return (SquareMapping(), CircleWriter())   # mypy does not flag an error here!
    else:
        return (CircleMapping(), CircleWriter())

def run_1(tools: Tools):
    (mapping, writer) = tools
    shape = mapping.map()
    writer.write(shape)



## Dataclass strategy
@dataclass
class EtlTools(Generic[E]):
    mapping: Mapping[E]
    writer: Writer[E]

def get_etl_tools(shape_name: str) -> EtlTools:
    if shape_name == "square":
        return EtlTools(mapping=SquareMapping(), writer=CircleWriter()) # mypy error, cannot infer type argument 1 of EtlTools
    else:
        return EtlTools(mapping=CircleMapping(), writer=CircleWriter())

def run_2(etl_tools: EtlTools):
    shape = etl_tools.mapping.map()
    etl_tools.writer.write(shape)