bpo-39627: Fix TypedDict totality check for inherited keys

[vemel]

I realized that the inheritance of TypedDict does not work as it should.

class BaseAnimal(TypedDict):
     name: str

class Animal(BaseAnimal, total=False):
     voice: str

class Cat(Animal):
     fur_color: str

I would assume that Cat should have required keys name and fur_color and optional voice.
But in reality, it will have required fur_color and optional name and voice, because Animal has total=False

Fixed

• __required_keys__ and __optional_keys__ are copied from base classes
• Own TypedDict annotations are added to __annotations__ after base annotations

https://bugs.python.org/issue39627

[gvanrossum]

Can you fix the test? To run locally, build python.exe or python (by running ./configure; make -j) and then /.python[.exe] -m test test_typing -v

Also, please add a news item, and a reference to the fix in the python/typing repo.

[vemel]

I forgot to copy a couple of lines, now tests are passing.

[gvanrossum]

Thanks!

[bedevere-bot]

@gvanrossum: Please replace # with GH- in the commit message next time. Thanks!