From ec8900e3eb7f0008a635fb6fbabde3eb7802536b Mon Sep 17 00:00:00 2001
From: Jean Boussier <jean.boussier@gmail.com>
Date: Thu, 15 May 2025 14:04:36 +0200
Subject: [PATCH] rb_gc_impl_copy_finalizer: generate a new object id

Fix a regression introduced by: https://github.com/ruby/ruby/pull/13155
---
 gc/default/default.c          |  3 ++-
 gc/mmtk/mmtk.c                |  3 ++-
 object.c                      |  2 +-
 test/ruby/test_objectspace.rb | 21 ++++++++++++++++++++-
 4 files changed, 25 insertions(+), 4 deletions(-)

diff --git a/gc/default/default.c b/gc/default/default.c
index 5c6c2a9417..131086c338 100644
--- a/gc/default/default.c
+++ b/gc/default/default.c
@@ -2805,7 +2805,8 @@ rb_gc_impl_copy_finalizer(void *objspace_ptr, VALUE dest, VALUE obj)
 
     int lev = rb_gc_vm_lock();
     if (RB_LIKELY(st_lookup(finalizer_table, obj, &data))) {
-        table = (VALUE)data;
+        table = rb_ary_dup((VALUE)data);
+        RARRAY_ASET(table, 0, rb_obj_id(dest));
         st_insert(finalizer_table, dest, table);
         FL_SET(dest, FL_FINALIZE);
     }
diff --git a/gc/mmtk/mmtk.c b/gc/mmtk/mmtk.c
index 09a8c0bc5c..70cd5f405c 100644
--- a/gc/mmtk/mmtk.c
+++ b/gc/mmtk/mmtk.c
@@ -985,7 +985,8 @@ rb_gc_impl_copy_finalizer(void *objspace_ptr, VALUE dest, VALUE obj)
 
     int lev = rb_gc_vm_lock();
     if (RB_LIKELY(st_lookup(objspace->finalizer_table, obj, &data))) {
-        table = (VALUE)data;
+        table = rb_ary_dup((VALUE)data);
+        RARRAY_ASET(table, 0, rb_obj_id(dest));
         st_insert(objspace->finalizer_table, dest, table);
         FL_SET(dest, FL_FINALIZE);
     }
diff --git a/object.c b/object.c
index 85b96fe31a..15eeda8689 100644
--- a/object.c
+++ b/object.c
@@ -409,11 +409,11 @@ init_copy(VALUE dest, VALUE obj)
     RBASIC(dest)->flags &= ~(T_MASK|FL_EXIVAR);
     // Copies the shape id from obj to dest
     RBASIC(dest)->flags |= RBASIC(obj)->flags & (T_MASK|FL_EXIVAR);
-    rb_gc_copy_attributes(dest, obj);
     rb_copy_generic_ivar(dest, obj);
     if (RB_TYPE_P(obj, T_OBJECT)) {
         rb_obj_copy_ivar(dest, obj);
     }
+    rb_gc_copy_attributes(dest, obj);
 }
 
 static VALUE immutable_obj_clone(VALUE obj, VALUE kwfreeze);
diff --git a/test/ruby/test_objectspace.rb b/test/ruby/test_objectspace.rb
index ef85edc5ee..f27f586ab7 100644
--- a/test/ruby/test_objectspace.rb
+++ b/test/ruby/test_objectspace.rb
@@ -94,7 +94,7 @@ End
   end
 
   def test_finalizer
-    assert_in_out_err(["-e", <<-END], "", %w(:ok :ok :ok :ok), [])
+    assert_in_out_err(["-e", <<-END], "", %w(:ok :ok :ok), [])
       a = []
       ObjectSpace.define_finalizer(a) { p :ok }
       b = a.dup
@@ -137,6 +137,25 @@ End
     }
   end
 
+  def test_finalizer_copy
+    assert_in_out_err(["-e", <<~'RUBY'], "", %w(:ok), [])
+      def fin
+        ids = Set.new
+        ->(id) { puts "object_id (#{id}) reused" unless ids.add?(id) }
+      end
+
+      OBJ = Object.new
+      ObjectSpace.define_finalizer(OBJ, fin)
+      OBJ.freeze
+
+      10.times do
+        OBJ.clone
+      end
+
+      p :ok
+    RUBY
+  end
+
   def test_finalizer_with_super
     assert_in_out_err(["-e", <<-END], "", %w(:ok), [])
       class A