Order-dependent overload resolution failure due to memorised Protocol conformance check on generic class #11644

from typing import TYPE_CHECKING, Generic, Protocol, TypeVar, assert_type, overload

T_contra = TypeVar("T_contra", contravariant=True)
T = TypeVar("T")
S = TypeVar("S")
S_contra = TypeVar("S_contra", contravariant=True)

class ElementOpsMixin(Generic[S]):
    @overload
    def _proto_add(self: "ElementOpsMixin[bool]", other: bool, /) -> "ElementOpsMixin[bool]": ...
    @overload
    def _proto_add(self: "ElementOpsMixin[int]", other: int, /) -> "ElementOpsMixin[int]": ...
    def _proto_add(self, other: object, /) -> object:
        return self

class Supports_ProtoAdd(Protocol[T_contra, T]):
    def _proto_add(self, other: T_contra, /) -> ElementOpsMixin[T]: ...

class Series(ElementOpsMixin[S], Generic[S]):
    @overload
    def __add__(self: Supports_ProtoAdd[S_contra, S], other: S_contra, /) -> "Series[S]": ...
    @overload
    def __add__(self: "Series[bool]", other: int, /) -> "Series[int]": ...
    def __add__(self, other: object, /) -> object:
        return self

class A: ...
class B: ...

# Step 1: Evaluate mismatched operation on Series[A] + B
# Series[A] does NOT implement _proto_add for B.
s_a: Series[A] = Series()
b: B = B()
if TYPE_CHECKING:
    _ = s_a + b  # type: ignore[operator] # pyright: ignore[reportOperatorIssue,reportUnknownVariableType] # pyrefly: ignore[unsupported-operation] # ty: ignore[unsupported-operator]

# Step 2: Now evaluate valid operation Series[bool] + True
s_bool: Series[bool] = Series()

# EXPECTED: Series[bool] (via Supports_ProtoAdd[bool, bool])
# ACTUAL:   Series[int]  (Supports_ProtoAdd was cached as invalid, falling back to Series[bool] + int because bool is a subtype of int)
res = s_bool + True
assert_type(res, Series[bool])  # only pyright raises here