Monkeypatch some more generics. (#1050)

* Add generic monkeypatching for `FileProxyMixin`.

This fixes `TypeError: 'type' object is not subscriptable` for
`django.core.files.File` and `django.core.files.base.ContentFile`.

* Add generic monkeypatching for `ForeignKey`.

This matches the change coming in Django 4.1.

See https://github.com/django/django/pull/15571

django_stubs_ext/django_stubs_ext/patch.py

@@ -4,8 +4,10 @@ from django import VERSION as VERSION
 from django.contrib.admin import ModelAdmin
 from django.contrib.admin.options import BaseModelAdmin
 from django.contrib.syndication.views import Feed
+from django.core.files.utils import FileProxyMixin
 from django.core.paginator import Paginator
 from django.db.models.fields import Field
+from django.db.models.fields.related import ForeignKey
 from django.db.models.manager import BaseManager
 from django.db.models.query import QuerySet
 from django.forms.formsets import BaseFormSet
@@ -54,9 +56,12 @@ _need_generic: List[MPGeneric[Any]] = [
     MPGeneric(BaseModelForm),
     MPGeneric(BaseModelFormSet),
     MPGeneric(Feed),
+    MPGeneric(FileProxyMixin),
     # These types do have native `__class_getitem__` method since django 3.1:
     MPGeneric(QuerySet, (3, 1)),
     MPGeneric(BaseManager, (3, 1)),
+    # These types do have native `__class_getitem__` method since django 4.1:
+    MPGeneric(ForeignKey, (4, 1)),
 ]
 
 

django_stubs_ext/tests/test_monkeypatching.py

@@ -82,6 +82,8 @@ def test_patched_extra_classes_generics(make_generic_classes: _MakeGenericClasse
         (3, 0),
         (3, 1),
         (3, 2),
+        (4, 0),
+        (4, 1),
     ],
 )
 def test_patched_version_specific(