Fix false positive for useless-super-delegation for variadics (#6949)

Author: DanielNoord

doc/whatsnew/2/2.14/full.rst

@@ -5,7 +5,10 @@ What's New in Pylint 2.14.3?
 ----------------------------
 Release date: TBA
 
+* Fixed a false positive for ``useless-super-delegation`` for subclasses that specify the number of
+  of parameters against a parent that uses a variadic argument.
 
+  Closes #2270
 
 What's New in Pylint 2.14.2?
 ----------------------------

pylint/checkers/classes/class_checker.py

@@ -1276,6 +1276,12 @@ def _check_useless_super_delegation(self, function: nodes.FunctionDef) -> None:
         args = _signature_from_call(call)
 
         if meth_node is not None:
+            # Detect if the super method uses varargs and the function doesn't or makes some of those explicit
+            if meth_node.args.vararg and (
+                not function.args.vararg
+                or len(function.args.args) > len(meth_node.args.args)
+            ):
+                return
 
             def form_annotations(arguments):
                 annotations = chain(

tests/functional/u/useless/useless_super_delegation.py

@@ -303,3 +303,34 @@ def __str__(self):
 
     def __hash__(self): # [useless-super-delegation]
         return super().__hash__()
+
+
+# Reported in https://github.com/PyCQA/pylint/issues/2270
+class Super:
+    def __init__(self, *args):
+        self.args = args
+
+
+class Sub(Super):
+    def __init__(self, a, b):
+        super().__init__(a, b)
+
+
+class SubTwo(Super):
+    def __init__(self, a, *args):
+        super().__init__(a, *args)
+
+
+class SuperTwo:
+    def __init__(self, a, *args):
+        self.args = args
+
+
+class SubTwoOne(SuperTwo):
+    def __init__(self, a, *args):  # [useless-super-delegation]
+        super().__init__(a, *args)
+
+
+class SubTwoTwo(SuperTwo):
+    def __init__(self, a, b, *args):
+        super().__init__(a, b, *args)

tests/functional/u/useless/useless_super_delegation.txt

@@ -18,3 +18,4 @@ useless-super-delegation:264:4:264:28:UselessSuper.with_default_arg_bis:Useless
 useless-super-delegation:267:4:267:28:UselessSuper.with_default_arg_ter:Useless super delegation in method 'with_default_arg_ter':UNDEFINED
 useless-super-delegation:270:4:270:29:UselessSuper.with_default_arg_quad:Useless super delegation in method 'with_default_arg_quad':UNDEFINED
 useless-super-delegation:304:4:304:16:DecoratedList.__hash__:Useless super delegation in method '__hash__':UNDEFINED
+useless-super-delegation:330:4:330:16:SubTwoOne.__init__:Useless super delegation in method '__init__':UNDEFINED