[Bug c++/84824] DCE fails to remove dead code of std::function constructor

[manjian2006 at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84824

--- Comment #3 from linzj <manjian2006 at gmail dot com> ---
From the function destructor
    ~_Function_base()
    {
      if (_M_manager)
        _M_manager(_M_functor, _M_functor, __destroy_functor);
    }