[unused-private-member] Handle the case with Call node

As seen in issue #4638

3 files changed, 34 insertions, 4 deletions

diff --git a/ChangeLog b/ChangeLog
index 5a4f700ee..c84b2620b 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -17,6 +17,10 @@ Release date: TBA
 ..
   Put bug fixes that should not wait for a new minor version here
 
+* Fix a crash that happened when analysing code using ``type(self)`` to access
+  a class attribute in the ``unused-private-member`` checker.
+
+  Closes #4638
 
 
 What's New in Pylint 2.9.1?
diff --git a/pylint/checkers/classes.py b/pylint/checkers/classes.py
index 6fffd2b16..a85e216c5 100644
--- a/pylint/checkers/classes.py
+++ b/pylint/checkers/classes.py
@@ -909,14 +909,29 @@ a metaclass class method.",
                 continue
             for attribute in node.nodes_of_class(astroid.Attribute):
                 attribute = cast(astroid.Attribute, attribute)
-                if attribute.expr is None:  # attribute.expr is probably not really an Optional ?
+                if attribute.expr is None:
+                    # attribute.expr is an Optional[NodeNG] it can be None
                     continue
                 if (
-                    attribute.attrname == function_def.name
-                    and attribute.scope() != function_def  # We ignore recursive calls
-                    and attribute.expr.name in ("self", node.name)
+                    attribute.attrname != function_def.name
+                    or attribute.scope() == function_def
                 ):
+                    # We ignore recursive calls
+                    continue
+                if isinstance(attribute.expr, astroid.Name) and attribute.expr.name in (
+                    "self",
+                    node.name,
+                ):
+                    # self.__attrname / node_name.__attrname
                     break
+                if isinstance(attribute.expr, astroid.Call):
+                    # type(self).__attrname
+                    inferred = safe_infer(attribute.expr)
+                    if (
+                        isinstance(inferred, astroid.ClassDef)
+                        and inferred.name == node.name
+                    ):
+                        break
             else:
                 function_repr = f"{function_def.name}({function_def.args.as_string()})"
                 self.add_message(
diff --git a/tests/functional/u/unused/unused_private_member.py b/tests/functional/u/unused/unused_private_member.py
index d65478503..35c5801e4 100644
--- a/tests/functional/u/unused/unused_private_member.py
+++ b/tests/functional/u/unused/unused_private_member.py
@@ -66,3 +66,14 @@ class MyCls:
     @classmethod
     def get_class_var(cls):
         return cls.__class_var
+
+
+class Bla:
+    """Regression test for issue 4638"""
+
+    def __init__(self):
+        type(self).__a()
+
+    @classmethod
+    def __a(cls):
+        pass