The following code works fine with python 3.7 but breaks with 3.8:```import dataclassesfrom typing import Optional@dataclasses.dataclassclass TestingDataclass:    base_path: dataclasses.InitVar[Optional[str]] = None```Exception traceback:```Traceback (most recent call last):  File "test.py", line 6, in <module>    class TestingDataclass:  File "/usr/local/lib/python3.8/dataclasses.py", line 995, in dataclass    return wrap(cls)  File "/usr/local/lib/python3.8/dataclasses.py", line 987, in wrap    return _process_class(cls, init, repr, eq, order, unsafe_hash, frozen)  File "/usr/local/lib/python3.8/dataclasses.py", line 967, in _process_class    str(inspect.signature(cls)).replace(' -> None', ''))  File "/usr/local/lib/python3.8/inspect.py", line 3050, in __str__    formatted = str(param)  File "/usr/local/lib/python3.8/inspect.py", line 2568, in __str__    formatannotation(self._annotation))  File "/usr/local/lib/python3.8/inspect.py", line 1202, in formatannotation    return repr(annotation)  File "/usr/local/lib/python3.8/dataclasses.py", line 213, in __repr__    return f'dataclasses.InitVar[{self.type.__name__}]'  File "/usr/local/lib/python3.8/typing.py", line 757, in __getattr__    raise AttributeError(attr)AttributeError: __name__```The code runs fine with `str` instead of `Optional[str]`.Tested locally with `Python 3.8.0rc1 (tags/v3.8.0rc1:34214de6ab, Oct 10 2019, 16:15:14)`. The same error can be seen (in a more involved context) on travis [here](https://travis-ci.org/samuelcolvin/pydantic/jobs/596131963)

This is a bug with the `__repr__` method on `InitVar`.I'm working on a PR now.

git blame points tohttps://github.com/python/cpython/commit/01ee12ba35a333e8a6a25c4153c4a21838e9585c . I am tagging this as a 3.8 regression since the commit was not backported and 3.7 works fine. Feel free to remove it if it's a mistake.

Oh, Samuel already made a PR. Then I withdrawPR 16701.

New changeset793cb85437299a3da3d74fe65480d720af330cbb by Serhiy Storchaka (Samuel Colvin) in branch 'master':bpo-38431: Fix __repr__ method of InitVar to work with typing objects. (GH-16702)https://github.com/python/cpython/commit/793cb85437299a3da3d74fe65480d720af330cbb

New changeset6da52ac411947d1a7958bbad831fcf8dfc8c95fe by Miss Islington (bot) in branch '3.8':bpo-38431: Fix __repr__ method of InitVar to work with typing objects. (GH-16702)https://github.com/python/cpython/commit/6da52ac411947d1a7958bbad831fcf8dfc8c95fe

Thank you for your contribution Samuel!