Checking at compile time if specified value is in a range of a type

Question

Is it possible to check this:

template
struct X{};

What I mean by this is, is it possible to check that va

Answer 1

Now that you've changed X's signature from the way it was in the original unedited question, it's easily implemented using Boost.Integer:

#include 
#include 
#include 

template<
    typename IntType,
    boost::uint64_t Value,
    bool IsSigned = boost::integer_traits::is_signed
>
struct validate_range;

template
struct validate_range
{
    typedef boost::integer_traits traits_t;
    static bool const value =
        static_cast(Value) >= traits_t::const_min &&
        static_cast(Value) <= traits_t::const_max;
};

template
struct validate_range
{
    typedef boost::integer_traits traits_t;
    static bool const value =
        Value >= traits_t::const_min &&
        Value <= traits_t::const_max;
};

template
struct X
{
    BOOST_STATIC_ASSERT_MSG(
        (validate_range::value),
        "Value constant is out of range"
    );
};

int main()
{
    X x1;             // fails iif char is unsigned by default
    X x2;              // fine
    X x3;            // fails iif char is signed by default
    X x4;    // fails
    X x5;   // fine
    X x6;   // fails
}