Protect against `AttributeError` when checking `cell-var-from-loop`

Close #3646

4 files changed, 25 insertions, 9 deletions

diff --git a/ChangeLog b/ChangeLog
index aefef4bf0..94d8f5f2e 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -52,6 +52,10 @@ Release date: TBA
 
   Close #3547
 
+* Protect against `AttributeError` when checking `cell-var-from-loop`
+
+  Close #3646
+
 
 What's New in Pylint 2.5.2?
 ===========================
diff --git a/pylint/checkers/variables.py b/pylint/checkers/variables.py
index 28dc2178f..a6208f146 100644
--- a/pylint/checkers/variables.py
+++ b/pylint/checkers/variables.py
@@ -1716,13 +1716,14 @@ class VariablesChecker(BaseChecker):
         else:
             assign_scope = assignment_node.scope()
             maybe_for = assignment_node
-            while not isinstance(maybe_for, astroid.For):
+            while maybe_for and not isinstance(maybe_for, astroid.For):
                 if maybe_for is assign_scope:
                     break
                 maybe_for = maybe_for.parent
             else:
                 if (
-                    maybe_for.parent_of(node_scope)
+                    maybe_for
+                    and maybe_for.parent_of(node_scope)
                     and not _is_direct_lambda_call()
                     and not isinstance(node_scope.statement(), astroid.Return)
                 ):
diff --git a/tests/functional/c/cellvar_escaping_loop.py b/tests/functional/c/cellvar_escaping_loop.py
index 193f289ac..48d2291dd 100644
--- a/tests/functional/c/cellvar_escaping_loop.py
+++ b/tests/functional/c/cellvar_escaping_loop.py
@@ -1,7 +1,10 @@
-# pylint: disable=print-statement, unnecessary-comprehension
+# pylint: disable=print-statement, unnecessary-comprehension,missing-docstring,too-few-public-methods
 """Tests for loopvar-in-closure."""
 from __future__ import print_function
 
+from enum import Enum
+
+
 def good_case():
     """No problems here."""
     lst = []
@@ -118,3 +121,11 @@ def bad_case6():
         print(j)
         lst.append(lambda: i)  # [cell-var-from-loop]
     return lst
+
+
+class Test(Enum):
+    TEST = (40, 160)
+
+    @staticmethod
+    def new_test(minimum=TEST[0], maximum=TEST[1]):
+        return minimum, maximum
diff --git a/tests/functional/c/cellvar_escaping_loop.txt b/tests/functional/c/cellvar_escaping_loop.txt
index 2ac0b58ef..d9fc6d025 100644
--- a/tests/functional/c/cellvar_escaping_loop.txt
+++ b/tests/functional/c/cellvar_escaping_loop.txt
@@ -1,6 +1,6 @@
-cell-var-from-loop:67:bad_case.<lambda>:Cell variable i defined in loop
-cell-var-from-loop:72:bad_case2.<lambda>:Cell variable i defined in loop
-cell-var-from-loop:80:bad_case3.<lambda>:Cell variable j defined in loop
-cell-var-from-loop:90:bad_case4.nested:Cell variable i defined in loop
-cell-var-from-loop:111:bad_case5.<lambda>:Cell variable i defined in loop
-cell-var-from-loop:119:bad_case6.<lambda>:Cell variable i defined in loop
+cell-var-from-loop:70:bad_case.<lambda>:Cell variable i defined in loop
+cell-var-from-loop:75:bad_case2.<lambda>:Cell variable i defined in loop
+cell-var-from-loop:83:bad_case3.<lambda>:Cell variable j defined in loop
+cell-var-from-loop:93:bad_case4.nested:Cell variable i defined in loop
+cell-var-from-loop:114:bad_case5.<lambda>:Cell variable i defined in loop
+cell-var-from-loop:122:bad_case6.<lambda>:Cell variable i defined in loop