Remove newstyle variable given old-style class support should be removed (pylint-dev#2561)

Author: akamat10

astroid/helpers.py

@@ -67,11 +67,10 @@ def _object_type(
 
     for inferred in node.infer(context=context):
         if isinstance(inferred, scoped_nodes.ClassDef):
-            if inferred.newstyle:
-                metaclass = inferred.metaclass(context=context)
-                if metaclass:
-                    yield metaclass
-                    continue
+            metaclass = inferred.metaclass(context=context)
+            if metaclass:
+                yield metaclass
+                continue
             yield builtins.getattr("type")[0]
         elif isinstance(
             inferred,
@@ -194,8 +193,6 @@ def _type_check(type1, type2) -> bool:
     if not all(map(has_known_bases, (type1, type2))):
         raise _NonDeducibleTypeHierarchy
 
-    if not all([type1.newstyle, type2.newstyle]):
-        return False
     try:
         return type1 in type2.mro()[:-1]
     except MroError as e:

astroid/interpreter/objectmodel.py

@@ -514,19 +514,13 @@ def attr___doc__(self):
 
     @property
     def attr___mro__(self):
-        if not self._instance.newstyle:
-            raise AttributeInferenceError(target=self._instance, attribute="__mro__")
-
         mro = self._instance.mro()
         obj = node_classes.Tuple(parent=self._instance)
         obj.postinit(mro)
         return obj
 
     @property
     def attr_mro(self):
-        if not self._instance.newstyle:
-            raise AttributeInferenceError(target=self._instance, attribute="mro")
-
         other_self = self
 
         # Cls.mro is a method and we need to return one in order to have a proper inference.
@@ -565,10 +559,6 @@ def attr___subclasses__(self):
         This looks only in the current module for retrieving the subclasses,
         thus it might miss a couple of them.
         """
-        if not self._instance.newstyle:
-            raise AttributeInferenceError(
-                target=self._instance, attribute="__subclasses__"
-            )
 
         qname = self._instance.qname()
         root = self._instance.root()

astroid/nodes/scoped_nodes/scoped_nodes.py

@@ -1882,8 +1882,7 @@ def my_meth(self, arg):
         ),
     )
     _other_fields = ("name", "is_dataclass", "position")
-    _other_other_fields = ("locals", "_newstyle")
-    _newstyle: bool | None = None
+    _other_other_fields = "locals"
 
     def __init__(
         self,
@@ -1983,36 +1982,11 @@ def postinit(
         self.bases = bases
         self.body = body
         self.decorators = decorators
-        self._newstyle = newstyle
         self._metaclass = metaclass
         self.position = position
         self.doc_node = doc_node
         self.type_params = type_params or []
 
-    def _newstyle_impl(self, context: InferenceContext | None = None):
-        if context is None:
-            context = InferenceContext()
-        if self._newstyle is not None:
-            return self._newstyle
-        for base in self.ancestors(recurs=False, context=context):
-            if base._newstyle_impl(context):
-                self._newstyle = True
-                break
-        klass = self.declared_metaclass()
-        # could be any callable, we'd need to infer the result of klass(name,
-        # bases, dict).  punt if it's not a class node.
-        if klass is not None and isinstance(klass, ClassDef):
-            self._newstyle = klass._newstyle_impl(context)
-        if self._newstyle is None:
-            self._newstyle = False
-        return self._newstyle
-
-    _newstyle = None
-    newstyle = property(
-        _newstyle_impl,
-        doc=("Whether this is a new style class or not\n\n" ":type: bool or None"),
-    )
-
     @cached_property
     def blockstart_tolineno(self):
         """The line on which the beginning of this block ends.
@@ -2033,14 +2007,12 @@ def block_range(self, lineno: int) -> tuple[int, int]:
         """
         return self.fromlineno, self.tolineno
 
-    def pytype(self) -> Literal["builtins.type", "builtins.classobj"]:
+    def pytype(self) -> Literal["builtins.type"]:
         """Get the name of the type that this node represents.
 
         :returns: The name of the type.
         """
-        if self.newstyle:
-            return "builtins.type"
-        return "builtins.classobj"
+        return "builtins.type"
 
     def display_type(self) -> str:
         """A human readable type of this node.
@@ -2580,7 +2552,6 @@ def _valid_getattr(node):
         try:
             return _valid_getattr(self.getattr("__getattr__", context)[0])
         except AttributeInferenceError:
-            # if self.newstyle: XXX cause an infinite recursion error
             try:
                 getattribute = self.getattr("__getattribute__", context)[0]
                 return _valid_getattr(getattribute)
@@ -2667,16 +2638,12 @@ def mymethods(self):
     def implicit_metaclass(self):
         """Get the implicit metaclass of the current class.
 
-        For newstyle classes, this will return an instance of builtins.type.
-        For oldstyle classes, it will simply return None, since there's
-        no implicit metaclass there.
+        This will return an instance of builtins.type.
 
         :returns: The metaclass.
-        :rtype: builtins.type or None
+        :rtype: builtins.type
         """
-        if self.newstyle:
-            return builtin_lookup("type")[1][0]
-        return None
+        return builtin_lookup("type")[1][0]
 
     def declared_metaclass(
         self, context: InferenceContext | None = None
@@ -2799,10 +2766,6 @@ def _islots(self):
         return None
 
     def _slots(self):
-        if not self.newstyle:
-            raise NotImplementedError(
-                "The concept of slots is undefined for old-style classes."
-            )
 
         slots = self._islots()
         try:
@@ -2842,11 +2805,6 @@ def grouped_slots(
                 else:
                     yield None
 
-        if not self.newstyle:
-            raise NotImplementedError(
-                "The concept of slots is undefined for old-style classes."
-            )
-
         try:
             mro = self.mro()
         except MroError as e:
@@ -2912,17 +2870,8 @@ def _compute_mro(self, context: InferenceContext | None = None):
             if base is self:
                 continue
 
-            try:
-                mro = base._compute_mro(context=context)
-                bases_mro.append(mro)
-            except NotImplementedError:
-                # Some classes have in their ancestors both newstyle and
-                # old style classes. For these we can't retrieve the .mro,
-                # although in Python it's possible, since the class we are
-                # currently working is in fact new style.
-                # So, we fallback to ancestors here.
-                ancestors = list(base.ancestors(context=context))
-                bases_mro.append(ancestors)
+            mro = base._compute_mro(context=context)
+            bases_mro.append(mro)
 
         unmerged_mro: list[list[ClassDef]] = [[self], *bases_mro, inferred_bases]
         unmerged_mro = clean_duplicates_mro(unmerged_mro, self, context)

astroid/objects.py

@@ -109,9 +109,6 @@ def super_mro(self):
                     super_=self,
                 )
 
-        if not mro_type.newstyle:
-            raise SuperError("Unable to call super on old-style classes.", super_=self)
-
         mro = mro_type.mro()
         if self.mro_pointer not in mro:
             raise SuperError(

tests/test_builder.py

@@ -519,36 +519,6 @@ def test_object(self) -> None:
         obj_ast = self.builder.inspect_build(object)
         self.assertIn("__setattr__", obj_ast)
 
-    def test_newstyle_detection(self) -> None:
-        data = """
-            class A:
-                "old style"
-
-            class B(A):
-                "old style"
-
-            class C(object):
-                "new style"
-
-            class D(C):
-                "new style"
-
-            __metaclass__ = type
-
-            class E(A):
-                "old style"
-
-            class F:
-                "new style"
-        """
-        mod_ast = builder.parse(data, __name__)
-        self.assertTrue(mod_ast["A"].newstyle)
-        self.assertTrue(mod_ast["B"].newstyle)
-        self.assertTrue(mod_ast["E"].newstyle)
-        self.assertTrue(mod_ast["C"].newstyle)
-        self.assertTrue(mod_ast["D"].newstyle)
-        self.assertTrue(mod_ast["F"].newstyle)
-
     def test_globals(self) -> None:
         data = """
             CSTE = 1
@@ -833,7 +803,6 @@ def test_class_base_props(self) -> None:
         self.assertEqual(klass.parent.frame(), module)
         self.assertEqual(klass.root(), module)
         self.assertEqual(klass.basenames, [])
-        self.assertTrue(klass.newstyle)
 
     def test_class_locals(self) -> None:
         """Test the 'locals' dictionary of an astroid class."""

tests/test_python3.py

@@ -155,7 +155,6 @@ class SubTest(Test): pass
             )
         )
         klass = astroid["SubTest"]
-        self.assertTrue(klass.newstyle)
         metaclass = klass.metaclass()
         self.assertIsInstance(metaclass, nodes.ClassDef)
         self.assertEqual(metaclass.name, "ABCMeta")

tests/test_scoped_nodes.py

@@ -1002,8 +1002,7 @@ def test_cls_special_attributes_1(self) -> None:
         self.assertIsInstance(cls.getattr("__module__")[0], nodes.Const)
         self.assertEqual(cls.getattr("__module__")[0].value, "data.module")
         self.assertEqual(len(cls.getattr("__dict__")), 1)
-        if not cls.newstyle:
-            self.assertRaises(AttributeInferenceError, cls.getattr, "__mro__")
+
         for cls in (nodes.List._proxied, nodes.Const(1)._proxied):
             self.assertEqual(len(cls.getattr("__bases__")), 1)
             self.assertEqual(len(cls.getattr("__name__")), 1)