Incorrect handling of methods whose name shadows an existing name

[elprans]

Given the following module structure:

top
|-- __init__.py
`-- bar.py

And the following module contents:

• top/__init__.py:

from . import bar

class Foo:
    def bar(arg: bar.Spam):
        pass

• top/bar.py:

class Spam:
    pass

mypy -m top fails:

top/__init__.py:4: error: Invalid type "top.Foo.bar"

This is because it prematurely assumes that bar is a function, not a module.
Interestingly, regular functions do not exhibit this behaviour. The following works fine:

from . import bar

def bar(arg: bar.Spam):
    pass

[ezyang]

An even simpler repro is:

class foo: ...

class bar:
    foo: foo = ...

[ezyang]

A simple workaround is to just give the type a different name and refer to it that way:

class foo: ...
_foo = foo # NB: workaround https://github.com/python/mypy/issues/4146

class bar:
    foo: _foo = ...