Ensure that all registered checks return a list of CheckMessage (#508)

* Ensure that all registered checks return a list of CheckMessage

This changes missing and Any return types on registered checks to always
return "List[CheckMessage]".

In many cases, check functions were already annotated to return in a more
specific type than CheckMessage (e.g. Error). In these cases, it's assumed
that the existing annotation is correct, and the more specific type is kept.

* Update model_checks.pyi

Co-authored-by: Nikita Sobolev <mail@sobolevn.me>

django-stubs/contrib/admin/checks.pyi

@@ -1,14 +1,12 @@
-from typing import Any, List, Union, Optional, Sequence
+from typing import Any, List, Optional, Sequence
 
 from django.contrib.admin.options import BaseModelAdmin
 from django.core.checks.messages import CheckMessage, Error
 
 from django.apps.config import AppConfig
 
-_CheckError = Union[str, Error]
-
-def check_admin_app(app_configs: Optional[Sequence[AppConfig]] = ..., **kwargs: Any) -> List[_CheckError]: ...
-def check_dependencies(**kwargs: Any) -> List[_CheckError]: ...
+def check_admin_app(app_configs: Optional[Sequence[AppConfig]] = ..., **kwargs: Any) -> List[Error]: ...
+def check_dependencies(app_configs: Optional[Sequence[AppConfig]] = ..., **kwargs: Any) -> List[Error]: ...
 
 class BaseModelAdminChecks:
     def check(self, admin_obj: BaseModelAdmin, **kwargs: Any) -> List[CheckMessage]: ...

django-stubs/contrib/auth/checks.pyi

@@ -5,4 +5,4 @@ from django.core.checks.messages import CheckMessage
 from django.apps.config import AppConfig
 
 def check_user_model(app_configs: Optional[Sequence[AppConfig]] = ..., **kwargs: Any) -> List[CheckMessage]: ...
-def check_models_permissions(app_configs: Optional[Sequence[AppConfig]] = ..., **kwargs: Any) -> List[Any]: ...
+def check_models_permissions(app_configs: Optional[Sequence[AppConfig]] = ..., **kwargs: Any) -> List[CheckMessage]: ...

django-stubs/contrib/contenttypes/checks.pyi

@@ -1,6 +1,10 @@
 from typing import Any, List, Optional, Sequence
 
+from django.core.checks.messages import CheckMessage
+
 from django.apps.config import AppConfig
 
-def check_generic_foreign_keys(app_configs: Optional[Sequence[AppConfig]] = ..., **kwargs: Any) -> List[Any]: ...
-def check_model_name_lengths(app_configs: Optional[Sequence[AppConfig]] = ..., **kwargs: Any) -> List[Any]: ...
+def check_generic_foreign_keys(
+    app_configs: Optional[Sequence[AppConfig]] = ..., **kwargs: Any
+) -> List[CheckMessage]: ...
+def check_model_name_lengths(app_configs: Optional[Sequence[AppConfig]] = ..., **kwargs: Any) -> List[CheckMessage]: ...

django-stubs/core/checks/async_checks.pyi

@@ -1,7 +1,9 @@
-from typing import Any, Optional, Sequence
+from typing import Any, List, Optional, Sequence
+
+from django.core.checks.messages import CheckMessage
 
 from django.apps.config import AppConfig
 
 E001: Any
 
-def check_async_unsafe(app_configs: Optional[Sequence[AppConfig]] = ..., **kwargs: Any): ...
+def check_async_unsafe(app_configs: Optional[Sequence[AppConfig]] = ..., **kwargs: Any) -> List[CheckMessage]: ...

django-stubs/core/checks/model_checks.pyi

@@ -1,8 +1,8 @@
 from typing import Any, List, Optional, Sequence
 
-from django.core.checks.messages import Warning
+from django.core.checks.messages import CheckMessage, Warning
 
 from django.apps.config import AppConfig
 
-def check_all_models(app_configs: Optional[Sequence[AppConfig]] = ..., **kwargs: Any) -> List[Warning]: ...
-def check_lazy_references(app_configs: Optional[Sequence[AppConfig]] = ..., **kwargs: Any) -> List[Any]: ...
+def check_all_models(app_configs: Optional[Sequence[AppConfig]] = ..., **kwargs: Any) -> List[CheckMessage]: ...
+def check_lazy_references(app_configs: Optional[Sequence[AppConfig]] = ..., **kwargs: Any) -> List[CheckMessage]: ...