The `clone` method should copy object status (e.g. frozen) too; #4030

src/kernel.c

@@ -348,6 +348,7 @@ mrb_obj_clone(mrb_state *mrb, mrb_value self)
   mrb_field_write_barrier(mrb, (struct RBasic*)p, (struct RBasic*)p->c);
   clone = mrb_obj_value(p);
   init_copy(mrb, clone, self);
+  p->flags = mrb_obj_ptr(self)->flags;
 
   return clone;
 }

test/t/kernel.rb

@@ -171,6 +171,10 @@ assert('Kernel#clone', '15.3.1.3.8') do
   assert_true a.respond_to?(:test)
   assert_false b.respond_to?(:test)
   assert_true c.respond_to?(:test)
+  
+  a.freeze
+  d = a.clone
+  assert_true d.frozen?
 end
 
 assert('Kernel#dup', '15.3.1.3.9') do