constexpr decltype()

in src/libraries/math/include/m/math/integer_functor_macros.h [49:52]


    constexpr decltype(auto) operator*(TLEFT l, TRIGHT r)                                          \
    {                                                                                              \
        return m::multiplication_functor(l, r);                                                    \
    };                                                                                             \