id	summary	reporter	owner	description	type	status	milestone	component	version	severity	resolution	keywords	cc
8162	lexical_cast is using math::changesign with long double regardless of whether BOOST_MATH_NO_LONG_DOUBLE_MATH_FUNCTIONS is defined or not.	Eric Niebler	Antony Polukhin	"Line 1399-1400 of `boost::lexical_cast` looks like this:

{{{
long double result = std::pow(10.0L, pow_of_10) * mantissa;
value = static_cast<T>( has_minus ? (boost::math::changesign)(result) : result);
}}}

It turns out that this causes problems in the guts of Boost.Math when `BOOST_MATH_NO_LONG_DOUBLE_MATH_FUNCTIONS` is defined. This is causing Boost.Test build failures. See for instance [http://tinyurl.com/af5453h], which at the time of writing shows:

{{{
    ""g++""  -ftemplate-depth-128 -O0 -fno-inline -Wall -g -ftemplate-depth-1024 -DBOOST_ALL_NO_LIB=1 -DBOOST_TEST_NO_AUTO_LINK=1  -I"".."" -c -o ""/usr/home/jim/boost_rt/trunk/results/boost/bin.v2/libs/xpressive/test/c_traits.test/gcc-4.2.1/debug/link-static/c_traits.o"" ""../libs/xpressive/test/c_traits.cpp""

In file included from ../libs/xpressive/test/./regress.ipp:19,
                 from ../libs/xpressive/test/c_traits.cpp:15:
../boost/math/tools/promotion.hpp: In instantiation of 'boost::math::tools::promote_args<long double, float, float, float, float, float>':
../boost/lexical_cast.hpp:1400:   instantiated from here
../boost/math/tools/promotion.hpp:141: error: invalid application of 'sizeof' to incomplete type 'boost::STATIC_ASSERTION_FAILURE<false>' }}}

Aside: there is no entry for lexical_cast in libs/maintainers.txt. There should be.
"	Bugs	closed	Boost 1.54.0	lexical_cast	Boost Development Trunk	Problem	fixed