Here’s simple example of code:

class meta(type): pass
class Test(str, metaclass = meta): pass

When I run mypy on it (just from cli, without any flags or other additional setup) I’m seeing next output:

test.py:2: error: Metaclass conflict: the metaclass of a derived class must be a (non-strict) subclass of the metaclasses of all its bases  [misc]

I know that similar error appears at runtime when metaclass of derived class is not a subtype of all parents metaclasses. But type(str) is type, and my class meta derived from type, so I cannot understand what’s incorrect here.

Provided example isn’t working only with str parent class. Mypy says everything is correct when inheriting from int or float.

So, how to get rid of such error message? Or it is just a mypy bug?