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Prohibit parameterized generics in isinstance #3037
Description
As @ilevkivskyi commented (#3005 (comment)), it would be nice to fail type check on this code:
obj = 1
if isinstance(obj, Iterable[int]):
1
because it fails in runtime with TypeError.
I can easily see this situation inside checker.py:get_isinstance_type() by verifying that len(type.items()[0].ret_type.args) == 0; but is it the right place to message about type validation problems?
Activity
ilevkivskyi commentedon Mar 20, 2017
Maybe the right place is in
visit_call_exprincheckexpr.py? If the name of function called isbuiltins.isinstanceorbuiltins.issubclassand there is, for example, anyCallableTypeargument with.is_class_obj()returningTrueand having type arguments, then you issue a warning.