Describe the Bug

Minimal repro:

from typing import Annotated

A = Annotated

def test(x: A[int, 0]) -> None:
    pass

Expected: No type error
Actual:

• Expected a type argument for Annotated
• type[Annotated] is not subscriptable

In practice people probably won't do this kind of trivial aliasing within the same file. What would happen instead is that they tend to do it in version-compatibility shims, e.g.

# my_library.py
import sys
import typing

if sys.version_info < (3, 9):
  Annotated = SOME_CUSTOM_IMPLEMENTATION_OF_ANNOTATED
else:
  Annotated = typing.Annotated

# my_app.py
from my_library import Annotated
def test(x: Annotated[int, 0]) -> None:
    pass

The pattern is currently (as of 11/14/2025) recognized by both Pyright and Ty, but not Mypy.

Sandbox Link

https://pyrefly.org/sandbox/?project=N4IgZglgNgpgziAXKOBDAdgEwEYHsAeAdAA4CeS4ATrgLYAEALqcROgOZ0Q3G6UN0BBdOlwNUDGJgA66GQLoBeQcNHjJMmZhhhG8BgAp8iQQG1WDADR0ADAF0AlHQC0APjoA5XOhiIZdf3TEqHAIFiAArgzQcCTkiFS0jMysHFw8fMqkGuhguLiKmSBhZJTaUKSEDLRQFADEdAAKpKVg5XRoWHj4dADGXpBs4ZTiEF6EMvUAyjAwdAAWDAzEcIgA9KslZRW8bKsw6KuYuD1wq305EIPDUV6rdLmUdKgAbqjQqNiwvf2XQyNedFwxBu6BiMjIDDmXiczxglDgo3QBSkIAAzIQAIwAJhRMhAAF8wqgelFYQAxaAwCgdHAEWIEoA

(Only applicable for extension issues) IDE Information

No response