Jun 11, 2025 · Jun 10, 2025 · Jun 10, 2025 · Jun 10, 2025
diff --git a/mypy/checker.py b/mypy/checker.py
        if (
            isinstance(supertype, Instance)
            and supertype.type.is_protocol
            and isinstance(subtype, (CallableType, Instance, TupleType, TypedDictType))
            and isinstance(subtype, (CallableType, Instance, TupleType, TypedDictType, TypeType))
        ):
            self.msg.report_protocol_problems(subtype, supertype, context, code=msg.code)
        if isinstance(supertype, CallableType) and isinstance(subtype, Instance):
diff --git a/mypy/messages.py b/mypy/messages.py
    assert right.type.is_protocol
    all_flags: list[tuple[str, set[int], set[int]]] = []
    for member in right.type.protocol_members:
        if find_member(member, left, left):
            item = (member, get_member_flags(member, left), get_member_flags(member, right))
            all_flags.append(item)
        if find_member(member, left, left, class_obj=class_obj):
            all_flags.append(
                (
                    member,
                    get_member_flags(member, left, class_obj=class_obj),
                    get_member_flags(member, right),
                )
            )
    bad_flags = []
    for name, subflags, superflags in all_flags:
        if (
diff --git a/mypy/subtypes.py b/mypy/subtypes.py
        is_lvalue=is_lvalue,
        is_super=False,
        is_operator=is_operator,
        original_type=itype,
        self_type=subtype,
        original_type=TypeType.make_normalized(itype) if class_obj elseitype,
        self_type=TypeType.make_normalized(subtype) if class_obj elsesubtype,
        context=Context(),  # all errors are filtered, but this is a required argument
        chk=type_checker,
        suppress_errors=True,
diff --git a/test-data/unit/check-protocols.test b/test-data/unit/check-protocols.test
 t = Test(Mock())
 reveal_type(t)  # N: Revealed type is "__main__.Test[Any]"
 [builtins fixtures/dict.pyi]

 [case testProtocolClassObjectDescriptor]
 from typing import Any, Protocol, overload

 class Desc:
    @overload
    def __get__(self, instance: None, owner: Any) -> Desc: ...
    @overload
    def __get__(self, instance: object, owner: Any) -> int: ...
    def __get__(self, instance, owner):
        pass

 class HasDesc(Protocol):
    attr: Desc

 class HasInt(Protocol):
    attr: int

 class C:
    attr = Desc()

 x: HasInt = C()
 y: HasDesc = C
 z: HasInt = C  # E: Incompatible types in assignment (expression has type "type[C]", variable has type "HasInt") \
               # N: Following member(s) of "C" have conflicts: \
               # N:     attr: expected "int", got "Desc"
Original file line number	Diff line number	Diff line change
Expand Up		@@ -7190,7 +7190,7 @@ def check_subtype(
		if (
		isinstance(supertype, Instance)
		and supertype.type.is_protocol
		and isinstance(subtype, (CallableType, Instance, TupleType, TypedDictType))
		and isinstance(subtype, (CallableType, Instance, TupleType, TypedDictType, TypeType))
		):
		self.msg.report_protocol_problems(subtype, supertype, context, code=msg.code)
		if isinstance(supertype, CallableType) and isinstance(subtype, Instance):
Expand Down
Original file line number	Diff line number	Diff line change
Expand Up		@@ -3109,9 +3109,14 @@ def get_bad_protocol_flags(
		assert right.type.is_protocol
		all_flags: list[tuple[str, set[int], set[int]]] = []
		for member in right.type.protocol_members:
		if find_member(member, left, left):
		item = (member, get_member_flags(member, left), get_member_flags(member, right))
		all_flags.append(item)
		if find_member(member, left, left, class_obj=class_obj):
		all_flags.append(
		(
		member,
		get_member_flags(member, left, class_obj=class_obj),
		get_member_flags(member, right),
		)
		)
		bad_flags = []
		for name, subflags, superflags in all_flags:
		if (
Expand Down
Original file line number	Diff line number	Diff line change
Expand Up		@@ -1319,8 +1319,8 @@ def find_member(
		is_lvalue=is_lvalue,
		is_super=False,
		is_operator=is_operator,
		original_type=itype,
		self_type=subtype,
		original_type=TypeType.make_normalized(itype) if class_obj elseitype,
		self_type=TypeType.make_normalized(subtype) if class_obj elsesubtype,
		context=Context(), # all errors are filtered, but this is a required argument
		chk=type_checker,
		suppress_errors=True,
Expand Down
Original file line number	Diff line number	Diff line change
Expand Up		@@ -4551,3 +4551,29 @@ class Test(Generic[T]):
		t = Test(Mock())
		reveal_type(t) # N: Revealed type is "__main__.Test[Any]"
		[builtins fixtures/dict.pyi]

		[case testProtocolClassObjectDescriptor]
		from typing import Any, Protocol, overload

		class Desc:
		@overload
		def __get__(self, instance: None, owner: Any) -> Desc: ...
		@overload
		def __get__(self, instance: object, owner: Any) -> int: ...
		def __get__(self, instance, owner):
		pass

		class HasDesc(Protocol):
		attr: Desc

		class HasInt(Protocol):
		attr: int

		class C:
		attr = Desc()

		x: HasInt = C()
		y: HasDesc = C
		z: HasInt = C # E: Incompatible types in assignment (expression has type "type[C]", variable has type "HasInt") \
		# N: Following member(s) of "C" have conflicts: \
		# N: attr: expected "int", got "Desc"