[Bug c++/78773] "Empty" const only class not optimized away

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78773

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Since you already use some c++11 features why don't use constexpr too. Note
there is a duplicate of this bug already.