Fix couple inconsistencies in protocols vs TypeType (#19267)

Author: ilevkivskyi

mypy/checker.py

@@ -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, parent_error=error)
         if isinstance(supertype, CallableType) and isinstance(subtype, Instance):

mypy/messages.py

@@ -3090,9 +3090,14 @@ 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 (

mypy/subtypes.py

@@ -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 else itype,
+        self_type=TypeType.make_normalized(subtype) if class_obj else subtype,
         context=Context(),  # all errors are filtered, but this is a required argument
         chk=type_checker,
         suppress_errors=True,

test-data/unit/check-protocols.test

@@ -4552,6 +4552,32 @@ 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"
+
 [case testProtocolErrorReportingNoDuplicates]
 from typing import Callable, Protocol, TypeVar