Resolve configured AUTH_USER_MODEL with a get_type_analyze_hook

mypy_django_plugin/config.py

@@ -123,9 +123,10 @@ def parse_ini_file(self, filepath: Path) -> None:
         except ValueError:
             exit_with_error(INVALID_BOOL_SETTING.format(key="strict_settings"))
 
-    def to_json(self) -> Dict[str, Any]:
+    def to_json(self, extra_data: Dict[str, Any]) -> Dict[str, Any]:
         """We use this method to reset mypy cache via `report_config_data` hook."""
         return {
             "django_settings_module": self.django_settings_module,
             "strict_settings": self.strict_settings,
+            **dict(sorted(extra_data.items())),
         }

mypy_django_plugin/django/context.py

@@ -535,3 +535,7 @@ def resolve_lookup_expected_type(
 
     def resolve_f_expression_type(self, f_expression_type: Instance) -> ProperType:
         return AnyType(TypeOfAny.explicit)
+
+    @cached_property
+    def is_contrib_auth_installed(self) -> bool:
+        return "django.contrib.auth" in self.settings.INSTALLED_APPS

mypy_django_plugin/main.py

@@ -35,6 +35,7 @@
     request,
     settings,
 )
+from mypy_django_plugin.transformers.auth import update_authenticate_hook
 from mypy_django_plugin.transformers.functional import resolve_str_promise_attribute
 from mypy_django_plugin.transformers.managers import (
     add_as_manager_to_queryset_class,
@@ -110,15 +111,14 @@ def get_additional_deps(self, file: MypyFile) -> List[Tuple[int, str, int]]:
             return [self._new_dependency("typing"), self._new_dependency("django_stubs_ext")]
 
         # for `get_user_model()`
-        if self.django_context.settings:
-            if file.fullname == "django.contrib.auth" or file.fullname in {"django.http", "django.http.request"}:
-                auth_user_model_name = self.django_context.settings.AUTH_USER_MODEL
-                try:
-                    auth_user_module = self.django_context.apps_registry.get_model(auth_user_model_name).__module__
-                except LookupError:
-                    # get_user_model() model app is not installed
-                    return []
-                return [self._new_dependency(auth_user_module), self._new_dependency("django_stubs_ext")]
+        if file.fullname == "django.contrib.auth" or file.fullname in {"django.http", "django.http.request"}:
+            auth_user_model_name = self.django_context.settings.AUTH_USER_MODEL
+            try:
+                auth_user_module = self.django_context.apps_registry.get_model(auth_user_model_name).__module__
+            except LookupError:
+                # get_user_model() model app is not installed
+                return []
+            return [self._new_dependency(auth_user_module), self._new_dependency("django_stubs_ext")]
 
         # ensure that all mentioned to='someapp.SomeModel' are loaded with corresponding related Fields
         defined_model_classes = self.django_context.model_modules.get(file.fullname)
@@ -148,9 +148,21 @@ def get_additional_deps(self, file: MypyFile) -> List[Tuple[int, str, int]]:
             self._new_dependency("django.db.models.query"),
         ]
 
+    @cached_property
+    def contrib_auth_hooks(self) -> Dict[str, Callable[[FunctionContext], MypyType]]:
+        authenticate_hook = partial(update_authenticate_hook, django_context=self.django_context)
+        return {
+            "django.contrib.auth.get_user_model": partial(
+                settings.get_user_model_hook, django_context=self.django_context
+            ),
+            "django.contrib.auth.authenticate": authenticate_hook,
+            "django.contrib.auth.aauthenticate": authenticate_hook,
+        }
+
     def get_function_hook(self, fullname: str) -> Optional[Callable[[FunctionContext], MypyType]]:
-        if fullname == "django.contrib.auth.get_user_model":
-            return partial(settings.get_user_model_hook, django_context=self.django_context)
+        auth_hook = self.contrib_auth_hooks.get(fullname)
+        if auth_hook is not None:
+            return auth_hook
 
         info = self._get_typeinfo_or_none(fullname)
         if info:
@@ -313,7 +325,10 @@ def get_dynamic_class_hook(self, fullname: str) -> Optional[Callable[[DynamicCla
 
     def report_config_data(self, ctx: ReportConfigContext) -> Dict[str, Any]:
         # Cache would be cleared if any settings do change.
-        return self.plugin_config.to_json()
+        extra_data = {}
+        if ctx.id == "django.contrib.auth":
+            extra_data["AUTH_USER_MODEL"] = self.django_context.settings.AUTH_USER_MODEL
+        return self.plugin_config.to_json(extra_data)
 
 
 def plugin(version: str) -> Type[NewSemanalDjangoPlugin]:

mypy_django_plugin/transformers/auth.py

@@ -0,0 +1,30 @@
+from mypy.plugin import FunctionContext
+from mypy.types import Instance, NoneType, UnionType, get_proper_type
+from mypy.types import Type as MypyType
+from mypy.typevars import fill_typevars_with_any
+
+from mypy_django_plugin.django.context import DjangoContext
+from mypy_django_plugin.lib import helpers
+
+
+def update_authenticate_hook(ctx: FunctionContext, django_context: DjangoContext) -> MypyType:
+    if not django_context.is_contrib_auth_installed:
+        return ctx.default_return_type
+
+    auth_user_model = django_context.settings.AUTH_USER_MODEL
+    api = helpers.get_typechecker_api(ctx)
+    model_info = helpers.resolve_lazy_reference(
+        auth_user_model, api=api, django_context=django_context, ctx=ctx.context
+    )
+    if model_info is None:
+        return ctx.default_return_type
+
+    optional_model = UnionType([fill_typevars_with_any(model_info), NoneType()], ctx.context.line, ctx.context.column)
+    default_return_type = get_proper_type(ctx.default_return_type)
+    if isinstance(default_return_type, Instance) and default_return_type.type.fullname == "typing.Coroutine":
+        if len(default_return_type.args) == 3:
+            return default_return_type.copy_modified(
+                args=[default_return_type.args[0], default_return_type.args[1], optional_model]
+            )
+        return ctx.default_return_type
+    return optional_model

tests/typecheck/contrib/auth/test_auth.yml

@@ -0,0 +1,51 @@
+-   case: test_authenticate_returns_configured_auth_user_model
+    main: |
+        from django.contrib.auth import authenticate, aauthenticate
+        reveal_type(authenticate())  # N: Revealed type is "Union[myapp.models.MyUser, None]"
+        async def f() -> None:
+            reveal_type(await aauthenticate())  # N: Revealed type is "Union[myapp.models.MyUser, None]"
+    custom_settings: |
+        INSTALLED_APPS = ("django.contrib.contenttypes", "django.contrib.auth", "myapp")
+        AUTH_USER_MODEL = "myapp.MyUser"
+    files:
+        - path: myapp/__init__.py
+        - path: myapp/models.py
+          content: |
+              from django.db import models
+
+              class MyUser(models.Model):
+                  ...
+
+-   case: test_authenticate_returns_stubs_types_when_contrib_auth_is_not_installed
+    main: |
+        from django.contrib.auth import authenticate, aauthenticate
+        reveal_type(authenticate())  # N: Revealed type is "Union[django.contrib.auth.base_user.AbstractBaseUser, None]"
+        async def f() -> None:
+            reveal_type(await aauthenticate())  # N: Revealed type is "Union[django.contrib.auth.base_user.AbstractBaseUser, None]"
+    custom_settings: |
+        INSTALLED_APPS = ("django.contrib.contenttypes", "myapp")
+    files:
+        - path: myapp/__init__.py
+        - path: myapp/models.py
+          content: |
+              from django.db import models
+
+              class MyUser(models.Model):
+                  ...
+
+-   case: test_authenticate_returns_builtin_auth_user_per_default
+    main: |
+        from django.contrib.auth import authenticate, aauthenticate
+        reveal_type(authenticate())  # N: Revealed type is "Union[django.contrib.auth.models.User, None]"
+        async def f() -> None:
+            reveal_type(await aauthenticate())  # N: Revealed type is "Union[django.contrib.auth.models.User, None]"
+    custom_settings: |
+        INSTALLED_APPS = ("django.contrib.contenttypes", "django.contrib.auth", "myapp")
+    files:
+        - path: myapp/__init__.py
+        - path: myapp/models.py
+          content: |
+              from django.db import models
+
+              class MyUser(models.Model):
+                  ...