fix Django: Instance vs Class access of attributes should return different types #4080

[asukaminato0721]

Summary

Fixes #4080

Django fields now preserve descriptor semantics for class access while retaining inferred instance types, _ST/_GT parameters are specialized from Django stubs.

Test Plan

add test

[meta-codesync]

This pull request has been imported. If you are a Meta employee, you can view this in D114011430. (Because this pull request was imported automatically, there will not be any future comments.)

[codspeed-hq]

Merging this PR will not alter performance

✅ 15 untouched benchmarks
⏩ 3 skipped benchmarks¹

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_{Comparing asukaminato0721:4080 (c3da2b2) with main (344edea)}

Footnotes

1. 3 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩

[github-actions]

Diff from mypy_primer, showing the effect of this PR on open source code:

django-stubs (https://github.com/typeddjango/django-stubs)
+ ERROR django-stubs/contrib/auth/models.pyi:113:5-14: Class member `AbstractUser.is_active` overrides parent class `AbstractBaseUser` in an inconsistent manner [bad-override]
+ ERROR django-stubs/contrib/auth/models.pyi:113:5-14: Class member `AbstractUser.is_active` overrides a member in a parent class but is missing an `@override` decorator [missing-override-decorator]

zulip (https://github.com/zulip/zulip)
+ ERROR corporate/lib/stripe.py:1450:22-66: `-` is not supported between `int` and `None` [unsupported-operation]
+ ERROR zerver/actions/data_import.py:147:17-150:18: The type of this argument is unknown [unknown-argument-type]
- ERROR zerver/actions/data_import.py:156:17-85: The type of this argument is unknown [unknown-argument-type]
+ ERROR zerver/lib/import_realm.py:2208:25-63: The type of this argument is unknown [unknown-argument-type]
+ ERROR zerver/lib/realm_description.py:39:12-38: Returned type `str | None` is not assignable to declared return type `str` [bad-return]
- ERROR zerver/lib/send_email.py:547:5-549:15: Result of call expression is of type `tuple[int, dict[str, int]]` and is not used; assign to `_` if this is intentional [unused-call-result]
+ ERROR zerver/lib/send_email.py:554:16-78: The type of `subquery` is unknown; it is inferred as an implicit `Any` [unknown-variable-type]
+ ERROR zerver/lib/send_email.py:555:67-75: The type of this argument is unknown [unknown-argument-type]
- ERROR zerver/lib/test_classes.py:2833:28-44: `Literal['6cde5f7a-1f7e-4978-9716-49f69ebfc9fe']` is not assignable to attribute `uuid` with type `UUID` [bad-assignment]
+ ERROR zerver/models/presence.py:104:5-17: Class member `UserStatus.user_profile` overrides a member in a parent class but is missing an `@override` decorator [missing-override-decorator]
+ ERROR zerver/models/presence.py:111:5-15: Class member `UserStatus.emoji_name` overrides a member in a parent class but is missing an `@override` decorator [missing-override-decorator]
+ ERROR zerver/models/presence.py:112:5-15: Class member `UserStatus.emoji_code` overrides a member in a parent class but is missing an `@override` decorator [missing-override-decorator]
+ ERROR zerver/models/users.py:491:5-7: Class member `UserProfile.id` overrides parent class `AbstractBaseUser` in an inconsistent manner [bad-override]
+ ERROR zerver/models/users.py:491:5-7: Class member `UserProfile.id` overrides parent class `PermissionsMixin` in an inconsistent manner [bad-override]
+ ERROR zerver/models/users.py:491:5-7: Class member `UserProfile.id` overrides parent class `UserBaseSettings` in an inconsistent manner [bad-override]
+ ERROR zerver/models/users.py:491:5-7: Class member `UserProfile.id` overrides a member in a parent class but is missing an `@override` decorator [missing-override-decorator]
+ ERROR zerver/tests/test_zulip_update_announcements.py:242:36-78: Object of class `NoneType` has no attribute `id` [missing-attribute]
+ ERROR zerver/tests/test_zulip_update_announcements.py:261:26-68: Object of class `NoneType` has no attribute `id` [missing-attribute]
+ ERROR zerver/tests/test_zulip_update_announcements.py:262:34-73: Argument `Any | None` is not assignable to parameter `stream` with type `Stream` in function `zerver.actions.streams.do_deactivate_stream` [bad-argument-type]
- ERROR zerver/views/registration.py:387:49-51: Cannot infer type of empty container; it will be treated as containing `Any` [implicit-any-empty-container]