From 1615634f7bc44157b4ee74148f9af6d392d84bb6 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Dani=C3=ABl=20van=20Noord?=
 <13665637+DanielNoord@users.noreply.github.com>
Date: Fri, 17 Dec 2021 21:37:40 +0100
Subject: [PATCH 1/3] Fix crash on uninferable decorators on Python 3.6 and 3.7

---
 ChangeLog                                                 | 2 ++
 doc/whatsnew/2.13.rst                                     | 2 ++
 pylint/checkers/utils.py                                  | 6 +++++-
 tests/functional/o/overridden_final_method_regression.py  | 6 ++++++
 tests/functional/o/overridden_final_method_regression.txt | 1 +
 5 files changed, 16 insertions(+), 1 deletion(-)
 create mode 100644 tests/functional/o/overridden_final_method_regression.py
 create mode 100644 tests/functional/o/overridden_final_method_regression.txt

diff --git a/ChangeLog b/ChangeLog
index 68ec3a7829..7b312ff495 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -79,6 +79,8 @@ Release date: TBA
 
   Closes #5323
 
+* Fixed crash on uninferable decorators on Python 3.6 and 3.7
+
 * Add checker ``unnecessary-ellipsis``: Emitted when the ellipsis constant is used unnecessarily.
 
   Closes #5460
diff --git a/doc/whatsnew/2.13.rst b/doc/whatsnew/2.13.rst
index ef72d58552..8f71a4b122 100644
--- a/doc/whatsnew/2.13.rst
+++ b/doc/whatsnew/2.13.rst
@@ -73,6 +73,8 @@ Other Changes
 
   Closes #5065
 
+* Fixed crash on uninferable decorators on Python 3.6 and 3.7
+
 * Fatal errors now emit a score of 0.0 regardless of whether the linted module
   contained any statements
 
diff --git a/pylint/checkers/utils.py b/pylint/checkers/utils.py
index 1f85399a7d..9deee663e3 100644
--- a/pylint/checkers/utils.py
+++ b/pylint/checkers/utils.py
@@ -876,7 +876,11 @@ def uninferable_final_decorators(
             except AttributeError:
                 continue
         elif isinstance(decorator, nodes.Name):
-            import_node = decorator.lookup(decorator.name)[1][0]
+            lookup_values = decorator.lookup(decorator.name)
+            if lookup_values[1]:
+                import_node = decorator.lookup(decorator.name)[1][0]
+            else:
+                continue
         else:
             continue
 
diff --git a/tests/functional/o/overridden_final_method_regression.py b/tests/functional/o/overridden_final_method_regression.py
new file mode 100644
index 0000000000..a1f72b3807
--- /dev/null
+++ b/tests/functional/o/overridden_final_method_regression.py
@@ -0,0 +1,6 @@
+"""Test a crash regression for the overridden-final-method checker on uninferable decorators"""
+
+
+@unknown_decorator  # [undefined-variable]
+def crash_test():
+    """A docstring"""
diff --git a/tests/functional/o/overridden_final_method_regression.txt b/tests/functional/o/overridden_final_method_regression.txt
new file mode 100644
index 0000000000..a8cb239542
--- /dev/null
+++ b/tests/functional/o/overridden_final_method_regression.txt
@@ -0,0 +1 @@
+undefined-variable:4:1:4:18:crash_test:Undefined variable 'unknown_decorator':UNDEFINED

From a815957b8dd95dc567710f86e03843faa121ae59 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Dani=C3=ABl=20van=20Noord?=
 <13665637+DanielNoord@users.noreply.github.com>
Date: Fri, 17 Dec 2021 22:45:32 +0100
Subject: [PATCH 2/3] Add pragma

---
 pylint/checkers/utils.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/pylint/checkers/utils.py b/pylint/checkers/utils.py
index 9deee663e3..90654b4d21 100644
--- a/pylint/checkers/utils.py
+++ b/pylint/checkers/utils.py
@@ -880,7 +880,7 @@ def uninferable_final_decorators(
             if lookup_values[1]:
                 import_node = decorator.lookup(decorator.name)[1][0]
             else:
-                continue
+                continue  # pragma: no cover # Covered on Python < 3.8
         else:
             continue
 

From d5c0ddb1bdfe0b2c7342e42134dcafe18e845491 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Dani=C3=ABl=20van=20Noord?=
 <13665637+DanielNoord@users.noreply.github.com>
Date: Fri, 17 Dec 2021 22:48:24 +0100
Subject: [PATCH 3/3] Update pylint/checkers/utils.py

Co-authored-by: Mark Byrne <31762852+mbyrnepr2@users.noreply.github.com>
---
 pylint/checkers/utils.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/pylint/checkers/utils.py b/pylint/checkers/utils.py
index 90654b4d21..cb04c21190 100644
--- a/pylint/checkers/utils.py
+++ b/pylint/checkers/utils.py
@@ -878,7 +878,7 @@ def uninferable_final_decorators(
         elif isinstance(decorator, nodes.Name):
             lookup_values = decorator.lookup(decorator.name)
             if lookup_values[1]:
-                import_node = decorator.lookup(decorator.name)[1][0]
+                import_node = lookup_values[1][0]
             else:
                 continue  # pragma: no cover # Covered on Python < 3.8
         else: