Ignore cached_property in method-hidden check (#8753)

doc/whatsnew/fragments/8753.bugfix

@@ -0,0 +1,3 @@
+Fix a false positive for ``method-hidden`` when using ``cached_property`` decorator.
+
+Closes #8753

pylint/checkers/classes/class_checker.py

@@ -49,6 +49,7 @@
 _AccessNodes = Union[nodes.Attribute, nodes.AssignAttr]
 
 INVALID_BASE_CLASSES = {"bool", "range", "slice", "memoryview"}
+ALLOWED_PROPERTIES = {"bultins.property", "functools.cached_property"}
 BUILTIN_DECORATORS = {"builtins.property", "builtins.classmethod"}
 ASTROID_TYPE_COMPARATORS = {
     nodes.Const: lambda a, b: a.value == b.value,
@@ -1252,11 +1253,15 @@ def visit_functiondef(self, node: nodes.FunctionDef) -> None:
                     # attribute affectation will call this method, not hiding it
                     return
                 if isinstance(decorator, nodes.Name):
-                    if decorator.name == "property":
+                    if decorator.name in ALLOWED_PROPERTIES:
                         # attribute affectation will either call a setter or raise
                         # an attribute error, anyway not hiding the function
                         return
 
+                if isinstance(decorator, nodes.Attribute):
+                    if self._check_functools_or_not(decorator):
+                        return
+
                 # Infer the decorator and see if it returns something useful
                 inferred = safe_infer(decorator)
                 if not inferred:
@@ -1454,6 +1459,24 @@ def _check_invalid_overridden_method(
                 node=function_node,
             )
 
+    def _check_functools_or_not(self, decorator: nodes.Attribute) -> bool:
+        if decorator.attrname != "cached_property":
+            return False
+
+        if not isinstance(decorator.expr, nodes.Name):
+            return False
+
+        _, import_nodes = decorator.expr.lookup(decorator.expr.name)
+
+        if not import_nodes:
+            return False
+        import_node = import_nodes[0]
+
+        if not isinstance(import_node, (astroid.Import, astroid.ImportFrom)):
+            return False
+
+        return "functools" in dict(import_node.names)
+
     def _check_slots(self, node: nodes.ClassDef) -> None:
         if "__slots__" not in node.locals:
             return

tests/functional/m/method_hidden.py

@@ -1,7 +1,10 @@
 # pylint: disable=too-few-public-methods,missing-docstring
 # pylint: disable=unused-private-member
+# pylint: disable=import-error
 """check method hiding ancestor attribute
 """
+import functools as ft
+import something_else as functools
 
 
 class Abcd:
@@ -106,13 +109,24 @@ def default(self, o):
 class Parent:
     def __init__(self):
         self._protected = None
+        self._protected_two = None
 
 
 class Child(Parent):
     def _protected(self):  # [method-hidden]
         pass
 
 
+class CachedChild(Parent):
+    @ft.cached_property
+    def _protected(self):
+        pass
+
+    @functools.cached_property
+    def _protected_two(self):
+        pass
+
+
 class ParentTwo:
     def __init__(self):
         self.__private = None

tests/functional/m/method_hidden.txt

@@ -1,3 +1,3 @@
-method-hidden:17:4:17:12:Cdef.abcd:An attribute defined in functional.m.method_hidden line 11 hides this method:UNDEFINED
-method-hidden:85:4:85:11:One.one:An attribute defined in functional.m.method_hidden line 83 hides this method:UNDEFINED
-method-hidden:112:4:112:18:Child._protected:An attribute defined in functional.m.method_hidden line 108 hides this method:UNDEFINED
+method-hidden:20:4:20:12:Cdef.abcd:An attribute defined in functional.m.method_hidden line 14 hides this method:UNDEFINED
+method-hidden:88:4:88:11:One.one:An attribute defined in functional.m.method_hidden line 86 hides this method:UNDEFINED
+method-hidden:116:4:116:18:Child._protected:An attribute defined in functional.m.method_hidden line 111 hides this method:UNDEFINED

tests/functional/m/method_hidden_py39.py

@@ -0,0 +1,142 @@
+# pylint: disable=too-few-public-methods,missing-docstring
+# pylint: disable=unused-private-member
+# pylint: disable=import-error
+"""check method hiding ancestor attribute
+"""
+import functools as ft
+import something_else as functools
+
+
+class Abcd:
+    """dummy"""
+
+    def __init__(self):
+        self.abcd = 1
+
+
+class Cdef(Abcd):
+    """dummy"""
+
+    def abcd(self):  # [method-hidden]
+        """test"""
+        print(self)
+
+
+class AbcdMixin:
+    def abcd(self):
+        pass
+
+
+class Dabc(AbcdMixin, Abcd):
+    def abcd(self):
+        pass
+
+
+class CustomProperty:
+    """dummy"""
+
+    def __init__(self, _):
+        pass
+
+    def __get__(self, obj, __):
+        if not obj:
+            return self
+        return 5
+
+    def __set__(self, _, __):
+        pass
+
+
+class Ddef:
+    """dummy"""
+
+    def __init__(self):
+        self.five = "five"
+
+    @CustomProperty
+    def five(self):
+        """Always 5."""
+        return self
+
+
+def my_decorator(*args, **kwargs):
+    return CustomProperty(*args, **kwargs)
+
+
+class Foo:
+    def __init__(self):
+        self._bar = 42
+        self._baz = 84
+
+    @my_decorator
+    def method(self):  # E0202
+        return self._baz
+
+    @method.setter
+    def method(self, value):
+        self._baz = value
+
+    def do_something_with_baz(self, value):
+        self.method = value
+
+
+class One:
+    def __init__(self, one=None):
+        if one is not None:
+            self.one = one
+
+    def one(self):  # [method-hidden]
+        pass
+
+
+class Two(One):
+    def one(self):
+        pass
+
+
+try:
+    import unknown as js
+except ImportError:
+    import json as js
+
+
+class JsonEncoder(js.JSONEncoder):
+    # pylint: disable=useless-super-delegation,super-with-arguments
+    def default(self, o):
+        return super(JsonEncoder, self).default(o)
+
+
+class Parent:
+    def __init__(self):
+        self._protected = None
+        self._protected_two = None
+        self._protected_three = None
+
+
+class Child(Parent):
+    def _protected(self):  # [method-hidden]
+        pass
+
+
+class CachedChild(Parent):
+    @ft.cached_property
+    def _protected(self):
+        pass
+
+    @functools.cached_property
+    def _protected_two(self):
+        pass
+
+    @functools().cached_property
+    def _protected_three(self):
+        pass
+
+
+class ParentTwo:
+    def __init__(self):
+        self.__private = None
+
+
+class ChildTwo(ParentTwo):
+    def __private(self):
+        pass

tests/functional/m/method_hidden_py39.rc

@@ -0,0 +1,2 @@
+[testoptions]
+min_pyver = 3.9

tests/functional/m/method_hidden_py39.txt

@@ -0,0 +1,3 @@
+method-hidden:20:4:20:12:Cdef.abcd:An attribute defined in functional.m.method_hidden_py39 line 14 hides this method:UNDEFINED
+method-hidden:88:4:88:11:One.one:An attribute defined in functional.m.method_hidden_py39 line 86 hides this method:UNDEFINED
+method-hidden:117:4:117:18:Child._protected:An attribute defined in functional.m.method_hidden_py39 line 111 hides this method:UNDEFINED