Cache types.GenericAlias in getitems

The "old-style" generic classes from the typing module (List, Dict, etc) cached typing._GenericAlias instances retuned from __getitem__:

>>> from typing import List
>>> List[int] is List[int]
True

But when this functionality was ported to built-in types, caching was not implemented:

>>> list[int] is list[int]
False

Since it is very common to subscript the same types with the same arguments, caching will be very beneficial here and will reduce memory footprint of heavily type-annotated modules.

Linked PRs

• gh-103541

Comece revisando o comportamento de cache existente do módulo typing para getitem e o PR vinculado gh-103541. Confirme o resultado desejado com o exemplo list[int] is list[int]; considera-se concluído quando aliases genéricos integrados equivalentes são armazenados em cache sem alterar o comportamento declarado de typing.