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From: "redi at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug tree-optimization/101923] std::function's move ctor is slower
 than the copy one for empty source objects
Date: Tue, 17 Aug 2021 10:25:22 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D101923

--- Comment #7 from Jonathan Wakely <redi at gcc dot gnu.org> ---
We can do better than just making the swap conditional:

      function(function&& __x) noexcept
      : _Function_base(), _M_invoker(__x._M_invoker)
      {
        if (static_cast<bool>(__x))
          {
            _M_functor =3D __x._M_functor;
            _M_manager =3D __x._M_manager;
            __x._M_manager =3D nullptr;
            __x._M_invoker =3D nullptr;
          }
      }=