Improve system check registry hints

django-stubs/core/checks/registry.pyi

@@ -1,6 +1,7 @@
-from typing import Any, Callable, List, Optional, Sequence, Set, TypeVar, Union
+from typing import Any, Callable, List, Optional, Sequence, Set, TypeVar, Union, overload
 
 from django.apps.config import AppConfig
+from django.apps.registry import Apps
 from django.core.checks.messages import CheckMessage
 from typing_extensions import Protocol
 
@@ -18,7 +19,9 @@ class Tags:
     translation: str = ...
     urls: str = ...
 
-_CheckCallable = Callable[..., Sequence[CheckMessage]]
+class _CheckCallable(Protocol):
+    def __call__(self, app_configs: Apps, **kwargs: Any) -> Sequence[CheckMessage]: ...
+
 _C = TypeVar("_C", bound=_CheckCallable)
 
 class _ProcessedCheckCallable(Protocol[_C]):
@@ -29,9 +32,10 @@ class CheckRegistry:
     registered_checks: Set[_ProcessedCheckCallable] = ...
     deployment_checks: Set[_ProcessedCheckCallable] = ...
     def __init__(self) -> None: ...
-    def register(
-        self, check: Optional[Union[_CheckCallable, str]] = ..., *tags: str, **kwargs: Any
-    ) -> Union[Callable[[_CheckCallable], _ProcessedCheckCallable], _ProcessedCheckCallable]: ...
+    @overload
+    def register(self, __check: _C) -> _ProcessedCheckCallable[_C]: ...
+    @overload
+    def register(self, *tags: str, **kwargs: Any) -> Callable[[_C], _ProcessedCheckCallable[_C]]: ...
     def run_checks(
         self,
         app_configs: Optional[Sequence[AppConfig]] = ...,
@@ -44,6 +48,6 @@ class CheckRegistry:
     def get_checks(self, include_deployment_checks: bool = ...) -> List[_ProcessedCheckCallable]: ...
 
 registry: CheckRegistry = ...
-register: Any = ...
-run_checks: Any = ...
-tag_exists: Any = ...
+register = registry.register
+run_checks = registry.run_checks
+tag_exists = registry.tag_exists

tests/typecheck/core/test_checks.yml

@@ -0,0 +1,20 @@
+- case: test_checks_register
+  main: |
+    from typing import Any, List, Sequence
+
+    from django.apps.registry import Apps
+    from django.core.checks import register, Warning, CheckMessage
+
+    @register("foo", deploy=True)
+    def check_foo(app_configs: Apps, **kwargs: Any) -> List[Warning]: ...
+
+    reveal_type(check_foo)  # N: Revealed type is "django.core.checks.registry._ProcessedCheckCallable[def (app_configs: django.apps.registry.Apps, **kwargs: Any) -> builtins.list[django.core.checks.messages.Warning]]"
+    reveal_type(check_foo.tags)  # N: Revealed type is "typing.Sequence[builtins.str]"
+
+    @register
+    def check_bar(app_configs: Apps, **kwargs: Any) -> Sequence[CheckMessage]: ...
+
+    reveal_type(check_bar)  # N: Revealed type is "django.core.checks.registry._ProcessedCheckCallable[def (app_configs: django.apps.registry.Apps, **kwargs: Any) -> typing.Sequence[django.core.checks.messages.CheckMessage]]"
+
+    @register()  # E: Value of type variable "_C" of function cannot be "Callable[[int], Sequence[CheckMessage]]"
+    def wrong_args(bla: int) -> Sequence[CheckMessage]: ...