Include guard names collision

[Enhex]

I'm getting this error when trying to use karma in boost 1.65.1: 'signbit': is not a member of 'boost::spirit::detail'

It seems that SPIRIT_SIGN_MAR_11_2009_0734PM is already defined in: boost\spirit\home\x3\support\numeric_utils\sign.hpp which triggers the include guard of: boost\spirit\home\support\detail\sign.hpp

I can work around it by using this code:

namespace boost {
    namespace spirit {
        namespace detail {
            using boost::spirit::x3::signbit;
        }
    }
}

[Kojoley]

https://svn.boost.org/trac10/ticket/12084 is linked issue