From bb8afd7265af41a75e8889774aa26f157f146380 Mon Sep 17 00:00:00 2001
From: Alan Wu <XrXr@users.noreply.github.com>
Date: Tue, 6 Dec 2022 12:06:25 -0500
Subject: Freeze singleton class, not its origin

Previously, when we froze an object, we froze
`RCLASS_ORIGIN(object.singleton_class)`, which didn't freeze
`object.singleton_class` when it has some prepended modules.

Origin iclass are internal objects and users can't interact with
them through Kernel#freeze?, Kernel#freeze, or any mutation method
that checks the frozen status. So we shouldn't touch the origin
iclasses when the frozen status should be visible.

[Bug #19169]
---
 test/ruby/test_object.rb | 13 +++++++++++++
 1 file changed, 13 insertions(+)

(limited to 'test/ruby')

diff --git a/test/ruby/test_object.rb b/test/ruby/test_object.rb
index a9d5d4b13e..891ceff0c9 100644
--- a/test/ruby/test_object.rb
+++ b/test/ruby/test_object.rb
@@ -925,6 +925,19 @@ class TestObject < Test::Unit::TestCase
     end
   end
 
+  def test_singleton_class_freeze
+    x = Object.new
+    xs = x.singleton_class
+    x.freeze
+    assert_predicate(xs, :frozen?)
+
+    y = Object.new
+    ys = y.singleton_class
+    ys.prepend(Module.new)
+    y.freeze
+    assert_predicate(ys, :frozen?, '[Bug #19169]')
+  end
+
   def test_redef_method_missing
     bug5473 = '[ruby-core:40287]'
     ['ArgumentError.new("bug5473")', 'ArgumentError, "bug5473"', '"bug5473"'].each do |code|
-- 
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