Class __get__ method is not working for generic specialization overload cases  #15921

from __future__ import annotations

from typing import Sequence, Generic, TypeVar, TYPE_CHECKING, Any, overload, Mapping, Type, Optional

from typing_extensions import reveal_type

T_co = TypeVar("T_co", covariant=True)
TSequence_co = TypeVar("TSequence_co", bound=Sequence[Any], covariant=True)


class Field(Generic[T_co]):
    type: Optional[Type[T_co]]

    if TYPE_CHECKING:
        @overload
        def __get__(self: Field[bool], instance: None, owner: Any) -> BoolField:
            pass

        @overload
        def __get__(self: Field[int], instance: None, owner: Any) -> NumField:
            pass

        @overload
        def __get__(self: Field[str], instance: None, owner: Any) -> StrField:
            pass

        @overload
        def __get__(self: Field[TSequence_co], instance: None, owner: Any) -> SeqField[TSequence_co]:
            pass

        @overload
        def __get__(self: Field[Any], instance: None, owner: Any) -> AnyField[T_co]:
            pass

        @overload
        def __get__(self, instance: Any, owner: Any) -> T_co:
            pass

        def __get__(self, instance: Any, owner: Any) -> Any:
            pass


class BoolField(Field[bool]):
    pass


class NumField(Field[int]):
    pass


class StrField(Field[str]):
    pass


class SeqField(Field[TSequence_co]):
    pass


class AnyField(Field[T_co]):
    pass


class Fields:
    bool_f: Field[bool]
    cmp_f: Field[int]
    str_f: Field[str]
    seq_f: Field[Sequence[int]]
    any_f: Field[Mapping[int, int]]


reveal_type(Fields.bool_f)
reveal_type(Fields.cmp_f)
reveal_type(Fields.str_f)
reveal_type(Fields.seq_f)
reveal_type(Fields.any_f)

temp.py
  temp.py:71:13 - information: Type of "Fields.bool_f" is "BoolField"
  temp.py:72:13 - information: Type of "Fields.cmp_f" is "NumField"
  temp.py:73:13 - information: Type of "Fields.str_f" is "StrField"
  temp.py:74:13 - information: Type of "Fields.seq_f" is "SeqField[Sequence[int]]"
  temp.py:75:13 - information: Type of "Fields.any_f" is "AnyField[Mapping[int, int]]"
0 errors, 0 warnings, 5 informations 

temp.py:71:13: note: Revealed type is "temp.BoolField"
temp.py:72:13: note: Revealed type is "temp.BoolField"
temp.py:73:13: note: Revealed type is "temp.BoolField"
temp.py:74:13: note: Revealed type is "temp.BoolField"
temp.py:75:13: note: Revealed type is "temp.BoolField"
Success: no issues found in 1 source file