Allow subclasses of APIView to override get_permissions with return type implementing _SupportsHasPermission (#320)

Issue is that list is invariant, which makes the protocol not work.

Changing it so a sequence of course breaks stuff that relies on the result being mutable, but I am assuming that that should not be supported anyways.

Author: guldfisk

rest_framework-stubs/views.pyi

@@ -71,7 +71,7 @@ class APIView(View):
     def get_renderers(self) -> list[BaseRenderer]: ...
     def get_parsers(self) -> list[BaseParser]: ...
     def get_authenticators(self) -> list[BaseAuthentication]: ...
-    def get_permissions(self) -> list[_SupportsHasPermission]: ...
+    def get_permissions(self) -> Sequence[_SupportsHasPermission]: ...
     def get_throttles(self) -> list[BaseThrottle]: ...
     def get_content_negotiator(self) -> BaseContentNegotiation: ...
     def get_exception_handler(self) -> Callable: ...

tests/typecheck/test_views.yml

@@ -55,3 +55,14 @@
         pass
 
     reveal_type(MyRetrieveViewSet().get_object())  # N: Revealed type is "main.MyModel"
+
+- case: test_override_get_permissions
+  main: |
+    from typing import List
+
+    from rest_framework.viewsets import GenericViewSet
+    from rest_framework.permissions import BasePermission
+
+    class MyView(GenericViewSet):
+        def get_permissions(self) -> List[BasePermission]:
+            ...