Remove old-style classes code, remove check for new-style class (#9925)

Python 3 is only new style classes.

Author: akamat10

doc/user_guide/checkers/features.rst

@@ -474,9 +474,8 @@ Exceptions checker Messages
 :raising-bad-type (E0702): *Raising %s while only classes or instances are allowed*
   Used when something which is neither a class nor an instance is raised (i.e.
   a `TypeError` will be raised).
-:raising-non-exception (E0710): *Raising a new style class which doesn't inherit from BaseException*
-  Used when a new style class which doesn't inherit from BaseException is
-  raised.
+:raising-non-exception (E0710): *Raising a class which doesn't inherit from BaseException*
+  Used when a class which doesn't inherit from BaseException is raised.
 :misplaced-bare-raise (E0704): *The raise statement is not inside an except clause*
   Used when a bare raise is not used inside an except clause. This generates an
   error, since there are no active exceptions to be reraised. An exception to

doc/whatsnew/fragments/9925.internal

@@ -0,0 +1,3 @@
+Remove old-style classes (Python 2) code and remove check for new-style class since everything is new-style in Python 3. Updated doc for exception checker to remove reference to new style class.
+
+Refs #9925

pylint/checkers/classes/class_checker.py

@@ -1778,7 +1778,7 @@ def _check_in_slots(self, node: nodes.AssignAttr) -> None:
         klass = inferred._proxied
         if not has_known_bases(klass):
             return
-        if "__slots__" not in klass.locals or not klass.newstyle:
+        if "__slots__" not in klass.locals:
             return
         # If `__setattr__` is defined on the class, then we can't reason about
         # what will happen when assigning to an attribute.

pylint/checkers/exceptions.py

@@ -92,10 +92,9 @@ def _is_raising(body: list[nodes.NodeNG]) -> bool:
         {"old_names": [("E0703", "bad-exception-context")]},
     ),
     "E0710": (
-        "Raising a new style class which doesn't inherit from BaseException",
+        "Raising a class which doesn't inherit from BaseException",
         "raising-non-exception",
-        "Used when a new style class which doesn't inherit from "
-        "BaseException is raised.",
+        "Used when a class which doesn't inherit from BaseException is raised.",
     ),
     "E0711": (
         "NotImplemented raised - should raise NotImplementedError",
@@ -262,12 +261,11 @@ def visit_instance(self, instance: objects.ExceptionInstance) -> None:
 
     def visit_classdef(self, node: nodes.ClassDef) -> None:
         if not utils.inherit_from_std_ex(node) and utils.has_known_bases(node):
-            if node.newstyle:
-                self._checker.add_message(
-                    "raising-non-exception",
-                    node=self._node,
-                    confidence=INFERENCE,
-                )
+            self._checker.add_message(
+                "raising-non-exception",
+                node=self._node,
+                confidence=INFERENCE,
+            )
 
     def visit_tuple(self, _: nodes.Tuple) -> None:
         self._checker.add_message(

pylint/checkers/newstyle.py

@@ -12,11 +12,7 @@
 from astroid import nodes
 
 from pylint.checkers import BaseChecker
-from pylint.checkers.utils import (
-    has_known_bases,
-    node_frame_class,
-    only_required_for_messages,
-)
+from pylint.checkers.utils import node_frame_class, only_required_for_messages
 from pylint.typing import MessageDefinitionTuple
 
 if TYPE_CHECKING:
@@ -72,55 +68,51 @@ def visit_functiondef(self, node: nodes.FunctionDef) -> None:
             ):
                 continue
 
-            # super should not be used on an old style class
-            if klass.newstyle or not has_known_bases(klass):
-                # super first arg should not be the class
-                if not call.args:
-                    continue
-
-                # calling super(type(self), self) can lead to recursion loop
-                # in derived classes
-                arg0 = call.args[0]
-                if (
-                    isinstance(arg0, nodes.Call)
-                    and isinstance(arg0.func, nodes.Name)
-                    and arg0.func.name == "type"
-                ):
-                    self.add_message("bad-super-call", node=call, args=("type",))
-                    continue
-
-                # calling super(self.__class__, self) can lead to recursion loop
-                # in derived classes
-                if (
-                    len(call.args) >= 2
-                    and isinstance(call.args[1], nodes.Name)
-                    and call.args[1].name == "self"
-                    and isinstance(arg0, nodes.Attribute)
-                    and arg0.attrname == "__class__"
-                ):
-                    self.add_message(
-                        "bad-super-call", node=call, args=("self.__class__",)
-                    )
-                    continue
-
-                try:
-                    supcls = call.args and next(call.args[0].infer(), None)
-                except astroid.InferenceError:
-                    continue
-
-                # If the supcls is in the ancestors of klass super can be used to skip
-                # a step in the mro() and get a method from a higher parent
-                if klass is not supcls and all(i != supcls for i in klass.ancestors()):
-                    name = None
-                    # if supcls is not Uninferable, then supcls was inferred
-                    # and use its name. Otherwise, try to look
-                    # for call.args[0].name
-                    if supcls:
-                        name = supcls.name
-                    elif call.args and hasattr(call.args[0], "name"):
-                        name = call.args[0].name
-                    if name:
-                        self.add_message("bad-super-call", node=call, args=(name,))
+            # super first arg should not be the class
+            if not call.args:
+                continue
+
+            # calling super(type(self), self) can lead to recursion loop
+            # in derived classes
+            arg0 = call.args[0]
+            if (
+                isinstance(arg0, nodes.Call)
+                and isinstance(arg0.func, nodes.Name)
+                and arg0.func.name == "type"
+            ):
+                self.add_message("bad-super-call", node=call, args=("type",))
+                continue
+
+            # calling super(self.__class__, self) can lead to recursion loop
+            # in derived classes
+            if (
+                len(call.args) >= 2
+                and isinstance(call.args[1], nodes.Name)
+                and call.args[1].name == "self"
+                and isinstance(arg0, nodes.Attribute)
+                and arg0.attrname == "__class__"
+            ):
+                self.add_message("bad-super-call", node=call, args=("self.__class__",))
+                continue
+
+            try:
+                supcls = call.args and next(call.args[0].infer(), None)
+            except astroid.InferenceError:
+                continue
+
+            # If the supcls is in the ancestors of klass super can be used to skip
+            # a step in the mro() and get a method from a higher parent
+            if klass is not supcls and all(i != supcls for i in klass.ancestors()):
+                name = None
+                # if supcls is not Uninferable, then supcls was inferred
+                # and use its name. Otherwise, try to look
+                # for call.args[0].name
+                if supcls:
+                    name = supcls.name
+                elif call.args and hasattr(call.args[0], "name"):
+                    name = call.args[0].name
+                if name:
+                    self.add_message("bad-super-call", node=call, args=(name,))
 
     visit_asyncfunctiondef = visit_functiondef
 

tests/functional/i/invalid/invalid_exceptions/invalid_exceptions_raised.py

@@ -1,17 +1,13 @@
 # pylint:disable=too-few-public-methods,import-error,missing-docstring, not-callable, import-outside-toplevel
-"""test pb with exceptions and old/new style classes"""
+"""test pb with exceptions and classes"""
 
 
 class ValidException(Exception):
     """Valid Exception."""
 
-class OldStyleClass:
-    """Not an exception."""
-
 class NewStyleClass:
     """Not an exception."""
 
-
 def good_case():
     """raise"""
     raise ValidException('hop')
@@ -31,22 +27,10 @@ def good_case3():
     import io
     raise io.BlockingIOError
 
-def bad_case0():
-    """raise"""
-    # +2:<3.0:[nonstandard-exception]
-    # +1:>=3.0:[raising-non-exception]
-    raise OldStyleClass('hop')
-
 def bad_case1():
     """raise"""
     raise NewStyleClass()  # [raising-non-exception]
 
-def bad_case2():
-    """raise"""
-    # +2:<3.0:[nonstandard-exception]
-    # +1:>=3.0:[raising-non-exception]
-    raise OldStyleClass('hop')
-
 def bad_case3():
     """raise"""
     raise NewStyleClass  # [raising-non-exception]

tests/functional/i/invalid/invalid_exceptions/invalid_exceptions_raised.txt

@@ -1,11 +1,9 @@
-raising-non-exception:38:4:38:30:bad_case0:Raising a new style class which doesn't inherit from BaseException:INFERENCE
-raising-non-exception:42:4:42:25:bad_case1:Raising a new style class which doesn't inherit from BaseException:INFERENCE
-raising-non-exception:48:4:48:30:bad_case2:Raising a new style class which doesn't inherit from BaseException:INFERENCE
-raising-non-exception:52:4:52:23:bad_case3:Raising a new style class which doesn't inherit from BaseException:INFERENCE
-notimplemented-raised:56:4:56:31:bad_case4:NotImplemented raised - should raise NotImplementedError:HIGH
-raising-bad-type:60:4:60:11:bad_case5:Raising int while only classes or instances are allowed:INFERENCE
-raising-bad-type:64:4:64:14:bad_case6:Raising NoneType while only classes or instances are allowed:INFERENCE
-raising-non-exception:68:4:68:14:bad_case7:Raising a new style class which doesn't inherit from BaseException:INFERENCE
-raising-non-exception:72:4:72:15:bad_case8:Raising a new style class which doesn't inherit from BaseException:INFERENCE
-raising-non-exception:76:4:76:14:bad_case9:Raising a new style class which doesn't inherit from BaseException:INFERENCE
-raising-bad-type:110:4:110:18:bad_case10:Raising str while only classes or instances are allowed:INFERENCE
+raising-non-exception:32:4:32:25:bad_case1:Raising a class which doesn't inherit from BaseException:INFERENCE
+raising-non-exception:36:4:36:23:bad_case3:Raising a class which doesn't inherit from BaseException:INFERENCE
+notimplemented-raised:40:4:40:31:bad_case4:NotImplemented raised - should raise NotImplementedError:HIGH
+raising-bad-type:44:4:44:11:bad_case5:Raising int while only classes or instances are allowed:INFERENCE
+raising-bad-type:48:4:48:14:bad_case6:Raising NoneType while only classes or instances are allowed:INFERENCE
+raising-non-exception:52:4:52:14:bad_case7:Raising a class which doesn't inherit from BaseException:INFERENCE
+raising-non-exception:56:4:56:15:bad_case8:Raising a class which doesn't inherit from BaseException:INFERENCE
+raising-non-exception:60:4:60:14:bad_case9:Raising a class which doesn't inherit from BaseException:INFERENCE
+raising-bad-type:94:4:94:18:bad_case10:Raising str while only classes or instances are allowed:INFERENCE

tests/functional/r/raising/raising_non_exception.txt

@@ -1 +1 @@
-raising-non-exception:13:0:13:22::Raising a new style class which doesn't inherit from BaseException:INFERENCE
+raising-non-exception:13:0:13:22::Raising a class which doesn't inherit from BaseException:INFERENCE