karma.hpp を含めるだけで、この STATIC_ASSERT エラーが発生します。
In file included from /apps/boost/include/boost/math/special_functions/detail/round_fwd.hpp:12:0,
from /apps/boost/include/boost/math/special_functions/math_fwd.hpp:26,
from /apps/boost/include/boost/math/special_functions/fpclassify.hpp:19,
from /apps/boost/include/boost/spirit/home/support/detail/sign.hpp:22,
from /apps/boost/include/boost/spirit/home/karma/numeric/detail/numeric_utils.hpp:22,
from /apps/boost/include/boost/spirit/home/karma/numeric/bool_policies.hpp:16,
from /apps/boost/include/boost/spirit/home/karma/numeric/bool.hpp:29,
from /apps/boost/include/boost/spirit/home/karma/numeric.hpp:13,
from /apps/boost/include/boost/spirit/home/karma.hpp:15,
from /apps/boost/include/boost/spirit/include/karma.hpp:16,
from /home/<my header file that includes boost/spirit/include/karma.hpp>
from /home/<my other header file that includes the above>
/apps/boost/include/boost/math/tools/promotion.hpp: In instantiation of `struct boost::math::tools::promote_args<long double, float, float, float, float, float>':
/apps/boost/include/boost/math/special_functions/sign.hpp:114:50: required from `int boost::math::signbit(T) [with T = long double]'
/apps/boost/include/boost/spirit/home/support/detail/sign.hpp:47:51: required from `bool boost::spirit::detail::signbit(T) [with T = long double]'
/apps/boost/include/boost/spirit/home/karma/numeric/detail/numeric_utils.hpp:130:47: required from here
/apps/boost/include/boost/math/tools/promotion.hpp:141:10: error: invalid application of `sizeof' to incomplete type `boost::STATIC_ASSERTION_FAILURE<false>'
何を与える？私が把握できる最善の方法は、サポートされていない場所での long double の使用を static assert がガードしていることです。でも、ロングダブルは他で使ってますが大丈夫です。
**編集: Boost の最新の開発リリースは、修正っぽいものを提供します。SVN から取得します。