fix: fix safe_issubclass for NewType

src/magicgui/_util.py

@@ -187,6 +187,8 @@ def _safe_isinstance_tuple(obj: object, superclass: object) -> bool:
 
 def safe_issubclass(obj: object, superclass: object) -> bool:
     """Safely check if obj is a subclass of superclass."""
+    if obj == superclass:
+        return True
     if isinstance(superclass, tuple):
         return any(safe_issubclass(obj, s) for s in superclass)
     obj_origin = get_origin(obj)

tests/test_magicgui.py

@@ -940,3 +940,18 @@ def func() -> Union[None, int]:
 
     func()
     mock.assert_called_once()
+
+
+def test_list_builtin_and_typing():
+    mock = Mock()
+
+    new_int = NewType("new_int", int)
+
+    register_type(list[new_int], return_callback=mock)
+
+    @magicgui
+    def func() -> list[new_int]:
+        return [1]
+
+    func()
+    mock.assert_called_once()