Keep abstract Django models internally in the plugin (#2017)

Renders `class Meta` declarations unnecessary in any .pyi files, for
database models.

Ref: #2000

django-stubs/contrib/auth/base_user.pyi

@@ -20,9 +20,6 @@ class AbstractBaseUser(models.Model):
     last_login = models.DateTimeField(blank=True, null=True)
     is_active: bool | BooleanField[bool | Combinable, bool]
 
-    class Meta:
-        abstract: Literal[True]
-
     def get_username(self) -> str: ...
     def natural_key(self) -> tuple[str]: ...
     @property

django-stubs/contrib/auth/models.pyi

@@ -61,9 +61,6 @@ class PermissionsMixin(models.Model):
     groups = models.ManyToManyField(Group)
     user_permissions = models.ManyToManyField(Permission)
 
-    class Meta:
-        abstract: Literal[True]
-
     def get_user_permissions(self, obj: _AnyUser | None = ...) -> set[str]: ...
     def get_group_permissions(self, obj: _AnyUser | None = ...) -> set[str]: ...
     def get_all_permissions(self, obj: _AnyUser | None = ...) -> set[str]: ...
@@ -87,9 +84,6 @@ class AbstractUser(AbstractBaseUser, PermissionsMixin):
     EMAIL_FIELD: str
     USERNAME_FIELD: str
 
-    class Meta:
-        abstract: Literal[True]
-
     def get_full_name(self) -> str: ...
     def get_short_name(self) -> str: ...
     def email_user(

django-stubs/contrib/sessions/base_session.pyi

@@ -1,5 +1,5 @@
 from datetime import datetime
-from typing import Any, Literal, TypeVar
+from typing import Any, TypeVar
 
 from django.contrib.sessions.backends.base import SessionBase
 from django.db import models
@@ -16,9 +16,6 @@ class AbstractBaseSession(models.Model):
     session_key: str
     objects: Any
 
-    class Meta:
-        abstract: Literal[True]
-
     @classmethod
     def get_session_store_class(cls) -> type[SessionBase] | None: ...
     def get_decoded(self) -> dict[str, Any]: ...

mypy_django_plugin/lib/fullnames.py

@@ -58,3 +58,12 @@
 
 OBJECT_DOES_NOT_EXIST = "django.core.exceptions.ObjectDoesNotExist"
 MULTIPLE_OBJECTS_RETURNED = "django.core.exceptions.MultipleObjectsReturned"
+
+DJANGO_ABSTRACT_MODELS = frozenset(
+    (
+        "django.contrib.auth.base_user.AbstractBaseUser",
+        ABSTRACT_USER_MODEL_FULLNAME,
+        PERMISSION_MIXIN_CLASS_FULLNAME,
+        "django.contrib.sessions.base_session.AbstractBaseSession",
+    )
+)

mypy_django_plugin/lib/helpers.py

@@ -416,6 +416,9 @@ def add_new_manager_base(api: SemanticAnalyzerPluginInterface, fullname: str) ->
 
 
 def is_abstract_model(model: TypeInfo) -> bool:
+    if model.fullname in fullnames.DJANGO_ABSTRACT_MODELS:
+        return True
+
     if not is_model_type(model):
         return False