resolve http handler conflicts

litestar/handlers/http_handlers/base.py

@@ -53,7 +53,7 @@
 )
 from litestar.types.builtin_types import NoneType
 from litestar.utils import ensure_async_callable
-from litestar.utils.predicates import is_async_callable
+from litestar.utils.predicates import is_async_callable, is_class_and_subclass
 from litestar.utils.scope.state import ScopeState
 from litestar.utils.warnings import warn_implicit_sync_to_thread, warn_sync_to_thread_with_async_callable
 
@@ -615,7 +615,15 @@ def _validate_handler_function(self) -> None:
         if self.http_methods == {HttpMethod.HEAD} and not self.parsed_fn_signature.return_type.is_subclass_of(
             (NoneType, File, ASGIFileResponse)
         ):
-            raise ImproperlyConfiguredException("A response to a head request should not have a body")
+            field_definition = self.parsed_fn_signature.return_type
+            if not (
+                is_empty_response_annotation(field_definition)
+                or is_class_and_subclass(field_definition.annotation, File)
+                or is_class_and_subclass(field_definition.annotation, ASGIFileResponse)
+            ):
+                raise ImproperlyConfiguredException(
+                    f"{self}: Handlers for 'HEAD' requests must not return a value. Either return 'None' or a response type without a body."
+                )
 
     async def handle(self, connection: Request[Any, Any, Any]) -> None:
         """ASGI app that creates a :class:`~.connection.Request` from the passed in args, determines which handler function to call and then

tests/unit/test_handlers/test_http_handlers/test_head.py

@@ -50,16 +50,6 @@ def handler_subclass() -> MyResponse[None]:
     Litestar(route_handlers=[handler, handler_subclass])
 
 
-def test_head_decorator_raises_validation_error_if_method_is_passed() -> None:
-    with pytest.raises(ImproperlyConfiguredException):
-
-        @head("/", http_method=HttpMethod.HEAD)
-        def handler() -> None:
-            return
-
-        handler.on_registration(Litestar(), HTTPRoute(path="/", route_handlers=[handler]))
-
-
 def test_head_decorator_does_not_raise_for_file_response() -> None:
     @head("/")
     def handler() -> "File":