Improve types of ConnectionProxy (#2246)

Author: Viicos

django-stubs/core/cache/__init__.pyi

@@ -17,5 +17,6 @@ class CacheHandler(BaseConnectionHandler[BaseCache]):
 
 def close_caches(**kwargs: Any) -> None: ...
 
-cache: BaseCache
 caches: CacheHandler
+# Actually ConnectionProxy, but quacks exactly like BaseCache, it's not worth distinguishing the two.
+cache: BaseCache

django-stubs/db/__init__.pyi

@@ -16,7 +16,7 @@ from .utils import ProgrammingError as ProgrammingError
 
 connections: ConnectionHandler
 router: ConnectionRouter
-# Actually DefaultConnectionProxy, but quacks exactly like BaseDatabaseWrapper, it's not worth distinguishing the two.
+# Actually ConnectionProxy, but quacks exactly like BaseDatabaseWrapper, it's not worth distinguishing the two.
 connection: BaseDatabaseWrapper
 
 def close_old_connections(**kwargs: Any) -> None: ...

django-stubs/utils/connection.pyi

@@ -1,20 +1,20 @@
-from collections.abc import Iterator, Mapping, Sequence
+from collections.abc import Iterator, Sequence
 from typing import Any, Generic, TypeVar
 
 from django.utils.functional import cached_property
 
-class ConnectionProxy:
-    def __init__(self, connections: Mapping[str, Any], alias: str) -> None: ...
-    def __getattr__(self, item: str) -> Any: ...
-    def __setattr__(self, name: str, value: Any) -> None: ...
+_T = TypeVar("_T")
+
+class ConnectionProxy(Generic[_T]):
+    def __init__(self, connections: BaseConnectionHandler[_T], alias: str) -> None: ...
+    def __getattr__(self, item: str) -> _T: ...
+    def __setattr__(self, name: str, value: _T) -> None: ...
     def __delattr__(self, name: str) -> None: ...
     def __contains__(self, key: str) -> bool: ...
     def __eq__(self, other: object) -> bool: ...
 
 class ConnectionDoesNotExist(Exception): ...
 
-_T = TypeVar("_T")
-
 class BaseConnectionHandler(Generic[_T]):
     settings_name: str | None
     exception_class: type[Exception]