用于进行gcc测试

				// { dg-do assemble  }				// GROUPS passed visibility				struct base				{				    protected:				        void base_func() {}// { dg-error "" } .*is protected.*				};								struct derived : public base				{				    protected:				        void derived_func(base *ptr) { ptr->base_func(); }// { dg-error "" }  within this context				};