Recover after #909 (#925)

* Fix stubs related to `(Async)RequestFactory` and `(Async)Client`

* Revert incorrect removal.

* Allow set as `unique_together`, use shared type alias.

* Revert `Q.__init__` to use only `*args, **kwargs` to remove false-positive with `Q(**{...})`

* Add abstract methods to `HttpResponseBase` to create common interface.

* Remove monkey-patched attributes from `HttpResponseBase` subclasses.

* Add QueryDict mutability checks (+ plugin support)

* Fix lint

* Return back GenericForeignKey to `Options.get_fields`

* Minor fixup

* Make plugin code typecheck with `--warn-unreachable`, minor performance increase.

* Better types for `{unique, index}_together` and Options.

* Fix odd type of `URLResolver.urlconf_name` which isn't a str actually.

* Better types for field migration operations.

* Revert form.files to `MultiValueDict[str, UploadedFile]`

* Compatibility fix (#916)

* Do not assume that `Annotated` is always related to django-stubs (fixes #893)

* Restrict `FormView.get_form` return type to `_FormT` (class type argument). Now it is resolved to `form_class` argument if present, but also errors if it is not subclass of _FormT

* Fix CI (make test runnable on 3.8)

* Fix CI (make test runnable on 3.8 _again_)

mypy_django_plugin/transformers/fields.py

@@ -1,4 +1,4 @@
-from typing import Optional, Tuple, Union, cast
+from typing import TYPE_CHECKING, Optional, Tuple, Union, cast
 
 from django.db.models.fields import AutoField, Field
 from django.db.models.fields.related import RelatedField
@@ -12,10 +12,13 @@ from mypy.types import TypeOfAny, UnionType
 from mypy_django_plugin.django.context import DjangoContext
 from mypy_django_plugin.lib import fullnames, helpers
 
+if TYPE_CHECKING:
+    from django.contrib.contenttypes.fields import GenericForeignKey
+
 
 def _get_current_field_from_assignment(
     ctx: FunctionContext, django_context: DjangoContext
-) -> Optional[Union[Field, ForeignObjectRel]]:
+) -> Optional[Union[Field, ForeignObjectRel, "GenericForeignKey"]]:
     outer_model_info = helpers.get_typechecker_api(ctx).scope.active_class()
     if outer_model_info is None or not helpers.is_model_subclass_info(outer_model_info, django_context):
         return None