From 3cd6323fbb2e054ee2cef28b2c1abef40db36354 Mon Sep 17 00:00:00 2001
From: Hiroshi SHIBATA <hsbt@ruby-lang.org>
Date: Tue, 24 Mar 2026 14:27:16 +0900
Subject: merge revision(s) d7a6ff8224519005d2deeb3f4e98689a8a0835ad: [Backport
 #21819]

	[Bug #21819] Data objects without members should also be frozen
---
 struct.c               | 1 +
 test/ruby/test_data.rb | 1 +
 version.h              | 2 +-
 3 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/struct.c b/struct.c
index 23420d5e8c..b751c08f6e 100644
--- a/struct.c
+++ b/struct.c
@@ -1785,6 +1785,7 @@ rb_data_initialize_m(int argc, const VALUE *argv, VALUE self)
         if (num_members > 0) {
             rb_exc_raise(rb_keyword_error_new("missing", members));
         }
+        OBJ_FREEZE(self);
         return Qnil;
     }
     if (argc > 1 || !RB_TYPE_P(argv[0], T_HASH)) {
diff --git a/test/ruby/test_data.rb b/test/ruby/test_data.rb
index dd698fdcc4..5ac4c6b84b 100644
--- a/test/ruby/test_data.rb
+++ b/test/ruby/test_data.rb
@@ -262,6 +262,7 @@ class TestData < Test::Unit::TestCase
     assert_equal('#<data >', test.inspect)
     assert_equal([], test.members)
     assert_equal({}, test.to_h)
+    assert_predicate(test, :frozen?)
   end
 
   def test_dup
diff --git a/version.h b/version.h
index 0fa74fde14..627e065c3b 100644
--- a/version.h
+++ b/version.h
@@ -11,7 +11,7 @@
 # define RUBY_VERSION_MINOR RUBY_API_VERSION_MINOR
 #define RUBY_VERSION_TEENY 10
 #define RUBY_RELEASE_DATE RUBY_RELEASE_YEAR_STR"-"RUBY_RELEASE_MONTH_STR"-"RUBY_RELEASE_DAY_STR
-#define RUBY_PATCHLEVEL 202
+#define RUBY_PATCHLEVEL 203
 
 #include "ruby/version.h"
 #include "ruby/internal/abi.h"
-- 
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