./boost/boost/multiprecision/detail/functions/pow.hpp:89: error: invalid application of ‘sizeof’ to incomplete type ‘boost::STATIC_ASSERTION_FAILURE<false>’
That's a truly horrible error message: in my defence, compilers that implement static_assert give the rather better: 1>m:\data\boost\sandbox\big_number\boost\multiprecision\detail\functions\pow.hpp(89): error C2338: The pow function is only valid for floating point types. In other words I haven't implemented pow for integer types, I guess as other libraries like GMP do so I should follow suit, though I admit to being a bit conflicted on this as the results get real big real fast with exponentiation. If I get some time later I'll see if I can improve those error messages, and maybe extend pow to integers. Thanks for the report, John.