Don't emit super-init-not-called for abstract __init__ methods

Author: DanielNoord

doc/whatsnew/fragments/3975.false_positive

@@ -0,0 +1,3 @@
+Don't report ``super-init-not-called`` for abstract ``__init__`` methods.
+
+Closes #3975

pylint/checkers/classes/class_checker.py

@@ -2034,7 +2034,7 @@ def _check_init(self, node: nodes.FunctionDef, klass_node: nodes.ClassDef) -> No
                         # Record that the class' init has been called
                         parents_with_called_inits.add(node_frame_class(method))
                     except KeyError:
-                        if klass not in to_call:
+                        if klass not in klass_node.ancestors(recurs=False):
                             self.add_message(
                                 "non-parent-init-called", node=expr, args=klass.name
                             )
@@ -2061,9 +2061,6 @@ def _check_init(self, node: nodes.FunctionDef, klass_node: nodes.ClassDef) -> No
 
             if decorated_with(node, ["typing.overload"]):
                 continue
-            cls = node_frame_class(method)
-            if klass.name == "object" or (cls and cls.name == "object"):
-                continue
             self.add_message(
                 "super-init-not-called",
                 args=klass.name,
@@ -2196,7 +2193,10 @@ def _ancestors_to_call(
     to_call: dict[nodes.ClassDef, bases.UnboundMethod] = {}
     for base_node in klass_node.ancestors(recurs=False):
         try:
-            to_call[base_node] = next(base_node.igetattr(method))
+            init_node: bases.UnboundMethod = next(base_node.igetattr(method))
+            if init_node.is_abstract():
+                continue
+            to_call[base_node] = init_node
         except astroid.InferenceError:
             continue
     return to_call

tests/functional/i/init_not_called.py

@@ -59,9 +59,9 @@ def xx_init(self):
 
 
 class AssignedInit(NewStyleC):
-    """No init called."""
+    """No init called, but abstract so that is fine."""
 
-    def __init__(self):  # [super-init-not-called]
+    def __init__(self):
         self.arg = 0
 
 

tests/functional/i/init_not_called.txt

@@ -1,2 +1 @@
 super-init-not-called:32:4:32:16:ZZZZ.__init__:__init__ method from base class 'BBBB' is not called:INFERENCE
-super-init-not-called:64:4:64:16:AssignedInit.__init__:__init__ method from base class 'NewStyleC' is not called:INFERENCE

tests/functional/n/non/non_init_parent_called.py

@@ -46,6 +46,6 @@ class Super2(dict):
     """ Using the same idiom as Super, but without calling
     the __init__ method.
     """
-    def __init__(self):  # [super-init-not-called]
+    def __init__(self):
         base = super()
         base.__woohoo__()  # [no-member]

tests/functional/n/non/non_init_parent_called.txt

@@ -2,5 +2,4 @@ import-error:7:0:7:18::Unable to import 'nonexistant':UNDEFINED
 non-parent-init-called:15:8:15:26:AAAA.__init__:__init__ method from a non direct base class 'BBBBMixin' is called:UNDEFINED
 no-member:23:50:23:77:CCC:Module 'functional.n.non.non_init_parent_called' has no 'BBBB' member:INFERENCE
 no-member:28:8:28:35:CCC.__init__:Module 'functional.n.non.non_init_parent_called' has no 'BBBB' member:INFERENCE
-super-init-not-called:49:4:49:16:Super2.__init__:__init__ method from base class 'dict' is not called:INFERENCE
 no-member:51:8:51:23:Super2.__init__:Super of 'Super2' has no '__woohoo__' member:INFERENCE

tests/functional/s/super/super_init_not_called.py

@@ -1,6 +1,7 @@
 """Tests for super-init-not-called."""
 # pylint: disable=too-few-public-methods, missing-class-docstring
 
+import abc
 import ctypes
 
 
@@ -53,5 +54,45 @@ def __init__(self):  # [super-init-not-called]
 # Regression test as reported in
 # https://github.com/PyCQA/pylint/issues/6027
 class MyUnion(ctypes.Union):
-    def __init__(self):  # [super-init-not-called]
+    def __init__(self):
         pass
+
+
+# Should not be called on abstract __init__ methods
+# https://github.com/PyCQA/pylint/issues/3975
+class Base:
+    def __init__(self, param: int, param_two: str) -> None:
+        raise NotImplementedError()
+
+
+class Derived(Base):
+    def __init__(self, param: int, param_two: str) -> None:
+        self.param = param + 1
+        self.param_two = param_two[::-1]
+
+
+class AbstractBase(abc.ABC):
+    def __init__(self, param: int) -> None:
+        self.param = param + 1
+
+    def abstract_method(self) -> str:
+        """This needs to be implemented."""
+        raise NotImplementedError()
+
+
+class DerivedFromAbstract(AbstractBase):
+    def __init__(self, param: int) -> None:  # [super-init-not-called]
+        print("Called")
+
+    def abstract_method(self) -> str:
+        return "Implemented"
+
+
+class DerivedFrom(UnknownParent):  # [undefined-variable]
+    def __init__(self) -> None:
+        print("Called")
+
+
+class DerivedFromUnknownGrandparent(DerivedFrom):
+    def __init__(self) -> None:
+        DerivedFrom.__init__(self)

tests/functional/s/super/super_init_not_called.rc

@@ -0,0 +1,4 @@
+[testoptions]
+# ctypes has a different implementation in PyPy and does have an inferable
+# __init__ method for ctypes.Union.
+except_implementations=PyPy

tests/functional/s/super/super_init_not_called.txt

@@ -1,3 +1,4 @@
-undefined-variable:18:23:18:40:UninferableChild:Undefined variable 'UninferableParent':UNDEFINED
-super-init-not-called:49:4:49:16:ChildThree.__init__:__init__ method from base class 'ParentWithoutInit' is not called:INFERENCE
-super-init-not-called:56:4:56:16:MyUnion.__init__:__init__ method from base class 'Union' is not called:INFERENCE
+undefined-variable:19:23:19:40:UninferableChild:Undefined variable 'UninferableParent':UNDEFINED
+super-init-not-called:50:4:50:16:ChildThree.__init__:__init__ method from base class 'ParentWithoutInit' is not called:INFERENCE
+super-init-not-called:84:4:84:16:DerivedFromAbstract.__init__:__init__ method from base class 'AbstractBase' is not called:INFERENCE
+undefined-variable:91:18:91:31:DerivedFrom:Undefined variable 'UnknownParent':UNDEFINED