Re: [boost] [config][mpl][type_traits][integer] BOOST_STATIC_CONSTANT should use constexpr

Even if most of the uses of integral_constant is to use its member ::value integral constant defines also the operator(), so it is a nullary functor.

OK, but we can add that now without changing BOOST_STATIC_CONSTANT.

The last sentence will not compile if the operator() is not a constexpr and it can not be a constexpr if ::value is not a consexpr, or can it?

Sure it can, the member value is an interal-constant-expression however we define it so it can be used in all constexpr functions. John.