>>> import typing
>>> def f(x: typing.ClassVar[int]): pass
... 
>>> typing.get_type_hints(f)
{'x': typing.ClassVar[int]}
>>> def f(x: "typing.ClassVar[int]"): pass
... 
>>> typing.get_type_hints(f)
Traceback (most recent call last):
  File "<python-input-4>", line 1, in <module>
    typing.get_type_hints(f)
    ~~~~~~~~~~~~~~~~~~~~~^^^
  File "/Users/jelle/py/cpython/Lib/typing.py", line 2390, in get_type_hints
    hints[name] = _eval_type(value, globalns, localns, type_params, format=format, owner=obj)
                  ~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/jelle/py/cpython/Lib/typing.py", line 448, in _eval_type
    return evaluate_forward_ref(t, globals=globalns, locals=localns,
                                type_params=type_params, owner=owner,
                                _recursive_guard=recursive_guard, format=format)
  File "/Users/jelle/py/cpython/Lib/typing.py", line 993, in evaluate_forward_ref
    type_ = _type_check(
        value,
    ...<2 lines>...
        allow_special_forms=forward_ref.__forward_is_class__,
    )
  File "/Users/jelle/py/cpython/Lib/typing.py", line 204, in _type_check
    raise TypeError(f"{arg} is not valid as type argument")
TypeError: typing.ClassVar[int] is not valid as type argument