Fix ``protected-access`` for attributes and methods of nested classes (#5232)

* Fix access to private function in inner class on protected-access bug

* Add functional test for protected-access from inner class

* Add Ikraduya to CONTRIBUTORS file

* Add if statement to avoid potential bug

* Fix ``protected-access`` for attributes and methods of nested classes
This closes #3066

Co-authored-by: ikraduya <ikraduya@gmail.com>
Co-authored-by: Pierre Sassoulas <pierre.sassoulas@gmail.com>

1 files changed, 15 insertions, 1 deletions

diff --git a/pylint/checkers/classes.py b/pylint/checkers/classes.py
index f6db8a73f..730f2e659 100644
--- a/pylint/checkers/classes.py
+++ b/pylint/checkers/classes.py
@@ -63,6 +63,7 @@ from pylint.checkers.utils import (
     class_is_abstract,
     decorated_with,
     decorated_with_property,
+    get_outer_class,
     has_known_bases,
     is_attr_private,
     is_attr_protected,
@@ -1606,9 +1607,22 @@ a metaclass class method.",
             if self._is_type_self_call(node.expr):
                 return
 
+            # Check if we are inside the scope of a class or nested inner class
+            inside_klass = True
+            outer_klass = klass
+            parents_callee = callee.split(".")
+            parents_callee.reverse()
+            for callee in parents_callee:
+                if callee != outer_klass.name:
+                    inside_klass = False
+                    break
+
+                # Move up one level within the nested classes
+                outer_klass = get_outer_class(outer_klass)
+
             # We are in a class, one remaining valid cases, Klass._attr inside
             # Klass
-            if not (callee == klass.name or callee in klass.basenames):
+            if not (inside_klass or callee in klass.basenames):
                 # Detect property assignments in the body of the class.
                 # This is acceptable:
                 #