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>

2 files changed, 91 insertions, 15 deletions

diff --git a/tests/functional/a/access/access_to_protected_members.py b/tests/functional/a/access/access_to_protected_members.py
index ffbfabf15..7d732dcc5 100644
--- a/tests/functional/a/access/access_to_protected_members.py
+++ b/tests/functional/a/access/access_to_protected_members.py
@@ -211,3 +211,67 @@ class Issue1159Subclass(Issue1159):
         instance = Issue1159OtherClass()
         instance._bar = 3  # [protected-access]
         _ = instance._foo  # [protected-access]
+
+
+class Issue3066:
+    """Test for GitHub issue 3066
+    Accessing of attributes/methods of inner and outer classes
+    https://github.com/PyCQA/pylint/issues/3066"""
+
+    attr = 0
+    _attr = 1
+
+    @staticmethod
+    def _bar(i):
+        """Docstring."""
+
+    @staticmethod
+    def foobar(i):
+        """Test access from outer class"""
+        Issue3066._attr = 2
+        Issue3066.Aclass._attr = "y"  # [protected-access]
+        Issue3066.Aclass.Bclass._attr = "b"  # [protected-access]
+
+        Issue3066._bar(i)
+        Issue3066.Aclass._bar(i)  # [protected-access]
+        Issue3066.Aclass.Bclass._bar(i)  # [protected-access]
+
+    class Aclass:
+        """Inner class for GitHub issue 3066"""
+
+        _attr = "x"
+
+        @staticmethod
+        def foobar(i):
+            """Test access from inner class"""
+            Issue3066._attr = 2  # [protected-access]
+            Issue3066.Aclass._attr = "y"
+            Issue3066.Aclass.Bclass._attr = "b"  # [protected-access]
+
+            Issue3066._bar(i)  # [protected-access]
+            Issue3066.Aclass._bar(i)
+            Issue3066.Aclass.Bclass._bar(i)  # [protected-access]
+
+        @staticmethod
+        def _bar(i):
+            """Docstring."""
+
+        class Bclass:
+            """Inner inner class for GitHub issue 3066"""
+
+            _attr = "a"
+
+            @staticmethod
+            def foobar(i):
+                """Test access from inner inner class"""
+                Issue3066._attr = 2  # [protected-access]
+                Issue3066.Aclass._attr = "y"  # [protected-access]
+                Issue3066.Aclass.Bclass._attr = "b"
+
+                Issue3066._bar(i)  # [protected-access]
+                Issue3066.Aclass._bar(i)  # [protected-access]
+                Issue3066.Aclass.Bclass._bar(i)
+
+            @staticmethod
+            def _bar(i):
+                """Docstring."""
diff --git a/tests/functional/a/access/access_to_protected_members.txt b/tests/functional/a/access/access_to_protected_members.txt
index 1b93683db..3f127f70c 100644
--- a/tests/functional/a/access/access_to_protected_members.txt
+++ b/tests/functional/a/access/access_to_protected_members.txt
@@ -1,16 +1,28 @@
-protected-access:19:14:MyClass.test:Access to a protected member _haha of a client class
-protected-access:41:0::Access to a protected member _protected of a client class
-protected-access:42:6::Access to a protected member _protected of a client class
-protected-access:43:0::Access to a protected member _cls_protected of a client class
-protected-access:44:6::Access to a protected member _cls_protected of a client class
-protected-access:58:19:Issue1031.incorrect_access:Access to a protected member _protected of a client class
-protected-access:72:48:Issue1802.__eq__:Access to a protected member __private of a client class
-protected-access:80:32:Issue1802.not_in_special:Access to a protected member _foo of a client class
-protected-access:100:32:Issue1802.__fake_special__:Access to a protected member _foo of a client class
-protected-access:162:8:Issue1159.access_other_attr:Access to a protected member _bar of a client class
-protected-access:163:12:Issue1159.access_other_attr:Access to a protected member _foo of a client class
+protected-access:19:14:MyClass.test:Access to a protected member _haha of a client class:HIGH
+protected-access:41:0::Access to a protected member _protected of a client class:HIGH
+protected-access:42:6::Access to a protected member _protected of a client class:HIGH
+protected-access:43:0::Access to a protected member _cls_protected of a client class:HIGH
+protected-access:44:6::Access to a protected member _cls_protected of a client class:HIGH
+protected-access:58:19:Issue1031.incorrect_access:Access to a protected member _protected of a client class:HIGH
+protected-access:72:48:Issue1802.__eq__:Access to a protected member __private of a client class:HIGH
+protected-access:80:32:Issue1802.not_in_special:Access to a protected member _foo of a client class:HIGH
+protected-access:100:32:Issue1802.__fake_special__:Access to a protected member _foo of a client class:HIGH
+protected-access:162:8:Issue1159.access_other_attr:Access to a protected member _bar of a client class:HIGH
+protected-access:163:12:Issue1159.access_other_attr:Access to a protected member _foo of a client class:HIGH
 no-member:194:12:Issue1159Subclass.access_missing_member:Instance of 'Issue1159Subclass' has no '_baz' member; maybe '_bar'?:INFERENCE
-protected-access:194:12:Issue1159Subclass.access_missing_member:Access to a protected member _baz of a client class
-attribute-defined-outside-init:203:8:Issue1159Subclass.assign_missing_member:Attribute '_qux' defined outside __init__
-protected-access:212:8:Issue1159Subclass.access_other_attr:Access to a protected member _bar of a client class
-protected-access:213:12:Issue1159Subclass.access_other_attr:Access to a protected member _foo of a client class
+protected-access:194:12:Issue1159Subclass.access_missing_member:Access to a protected member _baz of a client class:HIGH
+attribute-defined-outside-init:203:8:Issue1159Subclass.assign_missing_member:Attribute '_qux' defined outside __init__:HIGH
+protected-access:212:8:Issue1159Subclass.access_other_attr:Access to a protected member _bar of a client class:HIGH
+protected-access:213:12:Issue1159Subclass.access_other_attr:Access to a protected member _foo of a client class:HIGH
+protected-access:232:8:Issue3066.foobar:Access to a protected member _attr of a client class:HIGH
+protected-access:233:8:Issue3066.foobar:Access to a protected member _attr of a client class:HIGH
+protected-access:236:8:Issue3066.foobar:Access to a protected member _bar of a client class:HIGH
+protected-access:237:8:Issue3066.foobar:Access to a protected member _bar of a client class:HIGH
+protected-access:247:12:Issue3066.Aclass.foobar:Access to a protected member _attr of a client class:HIGH
+protected-access:249:12:Issue3066.Aclass.foobar:Access to a protected member _attr of a client class:HIGH
+protected-access:251:12:Issue3066.Aclass.foobar:Access to a protected member _bar of a client class:HIGH
+protected-access:253:12:Issue3066.Aclass.foobar:Access to a protected member _bar of a client class:HIGH
+protected-access:267:16:Issue3066.Aclass.Bclass.foobar:Access to a protected member _attr of a client class:HIGH
+protected-access:268:16:Issue3066.Aclass.Bclass.foobar:Access to a protected member _attr of a client class:HIGH
+protected-access:271:16:Issue3066.Aclass.Bclass.foobar:Access to a protected member _bar of a client class:HIGH
+protected-access:272:16:Issue3066.Aclass.Bclass.foobar:Access to a protected member _bar of a client class:HIGH