https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106223
Andrew Pinski <pinskia at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Resolution|--- |INVALID Status|UNCONFIRMED |RESOLVED --- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> --- You missed this part: "meets the standard library requirements for the original template." std::forward cannot do anything except for the forwarding part so yes it is undefined.