Fix a crash in `undefined-variable` caused by chained attributes in metaclassfix-crash-in-attribute-check

Close #3742

3 files changed, 14 insertions, 1 deletions

diff --git a/ChangeLog b/ChangeLog
index 97ebf5f55..9dfd94060 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -28,6 +28,10 @@ What's New in Pylint 2.6.1?
 ===========================
 Release date: TBA
 
+* Fix a crash in `undefined-variable` caused by chained attributes in metaclass
+
+  Close #3742
+
 * Fix false positive for `not-async-context-manager` when `contextlib.asynccontextmanager` is used
 
   Close #3862
diff --git a/pylint/checkers/variables.py b/pylint/checkers/variables.py
index b6a2978a5..986f76fd2 100644
--- a/pylint/checkers/variables.py
+++ b/pylint/checkers/variables.py
@@ -2037,7 +2037,10 @@ class VariablesChecker(BaseChecker):
         if isinstance(klass._metaclass, astroid.Name):
             name = klass._metaclass.name
         elif isinstance(klass._metaclass, astroid.Attribute) and klass._metaclass.expr:
-            name = klass._metaclass.expr.name
+            attr = klass._metaclass.expr
+            while not isinstance(attr, astroid.Name):
+                attr = attr.expr
+            name = attr.name
         elif metaclass:
             name = metaclass.root().name
 
diff --git a/tests/functional/u/undefined_variable_crash_on_attribute.py b/tests/functional/u/undefined_variable_crash_on_attribute.py
new file mode 100644
index 000000000..571efab1c
--- /dev/null
+++ b/tests/functional/u/undefined_variable_crash_on_attribute.py
@@ -0,0 +1,6 @@
+# pylint: disable=import-error,missing-module-docstring,missing-class-docstring,too-few-public-methods
+import unknown
+
+
+class Cls(metaclass=unknown.path.MetaFoo):
+    pass