From 46decd4feb0e286ad59c6ebf7eb7e2a67f85b876 Mon Sep 17 00:00:00 2001
From: Dan Parizher <105245560+danparizher@users.noreply.github.com>
Date: Tue, 23 Sep 2025 10:56:39 -0400
Subject: [PATCH] [`pyupgrade`] Fix `UP008` to not apply when `__class__` is a
 local variable (`UP008`) (#20497)

## Summary

Fixes #20491
---
 .../resources/test/fixtures/pyupgrade/UP008.py   | 16 ++++++++++++++++
 .../rules/super_call_with_parameters.rs          | 10 +++++-----
 2 files changed, 21 insertions(+), 5 deletions(-)

diff --git a/crates/ruff_linter/resources/test/fixtures/pyupgrade/UP008.py b/crates/ruff_linter/resources/test/fixtures/pyupgrade/UP008.py
index dd46c6c4d0..96c3acc75d 100644
--- a/crates/ruff_linter/resources/test/fixtures/pyupgrade/UP008.py
+++ b/crates/ruff_linter/resources/test/fixtures/pyupgrade/UP008.py
@@ -287,3 +287,19 @@ class C(B):
     def f(self):
         C = B  # Local variable C shadows the class name
         return super(C, self).f()  # Should NOT trigger UP008
+
+
+# See: https://github.com/astral-sh/ruff/issues/20491
+# UP008 should not apply when __class__ is a local variable
+class A:
+    def f(self):
+        return 1
+
+class B(A):
+    def f(self):
+        return 2
+
+class C(B):
+    def f(self):
+        __class__ = B  # Local variable __class__ shadows the implicit __class__
+        return super(__class__, self).f()  # Should NOT trigger UP008
diff --git a/crates/ruff_linter/src/rules/pyupgrade/rules/super_call_with_parameters.rs b/crates/ruff_linter/src/rules/pyupgrade/rules/super_call_with_parameters.rs
index 30ff93d6be..9f7f31a2f8 100644
--- a/crates/ruff_linter/src/rules/pyupgrade/rules/super_call_with_parameters.rs
+++ b/crates/ruff_linter/src/rules/pyupgrade/rules/super_call_with_parameters.rs
@@ -139,11 +139,11 @@ pub(crate) fn super_call_with_parameters(checker: &Checker, call: &ast::ExprCall
         return;
     };
 
-    if !((first_arg_id == "__class__"
-        || (first_arg_id == parent_name.as_str()
-            // If the first argument matches the class name, check if it's a local variable
-            // that shadows the class name. If so, don't apply UP008.
-            && !checker.semantic().current_scope().has(first_arg_id)))
+    // The `super(__class__, self)` and `super(ParentClass, self)` patterns are redundant in Python 3
+    // when the first argument refers to the implicit `__class__` cell or to the enclosing class.
+    // Avoid triggering if a local variable shadows either name.
+    if !(((first_arg_id == "__class__") || (first_arg_id == parent_name.as_str()))
+        && !checker.semantic().current_scope().has(first_arg_id)
         && second_arg_id == parent_arg.name().as_str())
     {
         return;