From 602e660eb486ceadb7492448a1570604785d9ad9 Mon Sep 17 00:00:00 2001
From: Kadir Can Ozden <101993364+bysiber@users.noreply.github.com>
Date: Fri, 20 Feb 2026 10:50:39 +0300
Subject: [PATCH] Allow on_setattr=setters.NO_OP on frozen classes

---
 src/attr/_make.py | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/src/attr/_make.py b/src/attr/_make.py
index 32e42976e..0f2ef48cc 100644
--- a/src/attr/_make.py
+++ b/src/attr/_make.py
@@ -2014,11 +2014,13 @@ def _make_init_script(
         attr_dict[a.name] = a
 
         if a.on_setattr is not None:
-            if frozen is True:
+            if a.on_setattr is setters.NO_OP:
+                pass
+            elif frozen is True:
                 msg = "Frozen classes can't use on_setattr."
                 raise ValueError(msg)
-
-            needs_cached_setattr = True
+            else:
+                needs_cached_setattr = True
         elif has_cls_on_setattr and a.on_setattr is not setters.NO_OP:
             needs_cached_setattr = True