[Feature #19163] Marshal-loaded Data object also should be frozen

Author: nobu

struct.c

@@ -786,6 +786,7 @@ VALUE
 rb_struct_initialize(VALUE self, VALUE values)
 {
     rb_struct_initialize_m(RARRAY_LENINT(values), RARRAY_CONST_PTR(values), self);
+    if (rb_obj_is_kind_of(self, rb_cData)) OBJ_FREEZE_RAW(self);
     RB_GC_GUARD(values);
     return Qnil;
 }

test/ruby/test_data.rb

@@ -177,4 +177,14 @@ def test_dup
     assert_equal(klass.new(foo: 1, bar: 2), test.dup)
     assert_predicate(test.dup, :frozen?)
   end
+
+  Klass = Data.define(:foo, :bar)
+
+  def test_marshal
+    test = Klass.new(foo: 1, bar: 2)
+    loaded = Marshal.load(Marshal.dump(test))
+    assert_equal(test, loaded)
+    assert_not_same(test, loaded)
+    assert_predicate(loaded, :frozen?)
+  end
 end