From a14a1a5626a4d8e661a3e606f8f92b8c455b9a04 Mon Sep 17 00:00:00 2001
From: Nobuyoshi Nakada <nobu@ruby-lang.org>
Date: Thu, 1 Dec 2022 17:26:45 +0900
Subject: [PATCH] [Feature #19163] Data object should be frozen

---
 struct.c               | 12 +++++++++++-
 test/ruby/test_data.rb |  8 ++++++++
 2 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/struct.c b/struct.c
index 6f67984cf2..def15b0186 100644
--- a/struct.c
+++ b/struct.c
@@ -1818,9 +1818,19 @@ rb_data_initialize_m(int argc, const VALUE *argv, VALUE self)
     if (arg.unknown_keywords != Qnil) {
         rb_exc_raise(rb_keyword_error_new("unknown", arg.unknown_keywords));
     }
+    OBJ_FREEZE_RAW(self);
     return Qnil;
 }
 
+/* :nodoc: */
+static VALUE
+rb_data_init_copy(VALUE copy, VALUE s)
+{
+    copy = rb_struct_init_copy(copy, s);
+    RB_OBJ_FREEZE_RAW(copy);
+    return copy;
+}
+
 /*
  *  call-seq:
  *    inspect -> string
@@ -2180,7 +2190,7 @@ InitVM_Struct(void)
 #endif
 
     rb_define_method(rb_cData, "initialize", rb_data_initialize_m, -1);
-    rb_define_method(rb_cData, "initialize_copy", rb_struct_init_copy, 1);
+    rb_define_method(rb_cData, "initialize_copy", rb_data_init_copy, 1);
 
     rb_define_method(rb_cData, "==", rb_data_equal, 1);
     rb_define_method(rb_cData, "eql?", rb_data_eql, 1);
diff --git a/test/ruby/test_data.rb b/test/ruby/test_data.rb
index f63b0236fb..b8dc55815b 100644
--- a/test/ruby/test_data.rb
+++ b/test/ruby/test_data.rb
@@ -62,6 +62,7 @@ class TestData < Test::Unit::TestCase
     assert_equal(1, test.foo)
     assert_equal(2, test.bar)
     assert_equal(test, klass.new(1, 2))
+    assert_predicate(test, :frozen?)
 
     # Keywords
     test_kw = klass.new(foo: 1, bar: 2)
@@ -169,4 +170,11 @@ class TestData < Test::Unit::TestCase
     assert_equal([], test.members)
     assert_equal({}, test.to_h)
   end
+
+  def test_dup
+    klass = Data.define(:foo, :bar)
+    test = klass.new(foo: 1, bar: 2)
+    assert_equal(klass.new(foo: 1, bar: 2), test.dup)
+    assert_predicate(test.dup, :frozen?)
+  end
 end