Confusing error message when assigning to `SomeType.__class__`

class X:
    pass

X.__class__ = type
# Cannot assign to a method
# Incompatible types in assignment (expression has type "Type[type]", variable has type overloaded function)

Bug Report
X.__class__ isnt an overloaded function nor method, it is property defined in object class:

>>> object.__dict__['__class__']
<attribute '__class__' of 'object' objects>

Expected Behavior
I expect to get something like this:
Incompatible types in assignment (expression has type "type[type]", variable has type "type[type[X]]")
or
"X.__class__" doesnt support assignment
or
Cannot determine type of "X" after ".__class__" assignment
or
Cannot change type of class "X"

With variables it gives good error message:

class X: pass
class Y: pass
x = X()
x.__class__ = Y # Incompatible types in assignment (expression has type "Type[Y]", variable has type "Type[X]")

My Environment

• mypy 0.961 (compiled: no)
• no command-line flags, no config file
• CPython 3.10.4
• Windows 10

Start with the minimal class-assignment reproduction in the report and compare it with the instance-assignment example. Trace mypy's handling of __class__ assignment and ensure the class case produces a type-specific or clearly unsupported-assignment diagnostic without misidentifying __class__ as a method.