g++ -std=c++11 -DHAVE_CONFIG_H -I. -I../src/config   -I. -I./obj -I/usr/include/db4/ -pthread -I/usr/include -DBOOST_NO_SCOPED_ENUMS -DBOOST_NO_CXX11_SCOPED_ENUMS -I./leveldb/include -I./leveldb/helpers/memenv   -I./secp256k1/include -I./univalue/include -DHAVE_BUILD_INFO -D__STDC_FORMAT_MACROS -D_FILE_OFFSET_BITS=64   -march=i586 -mtune=i686 -fmessage-length=0 -O2 -Wall -D_FORTIFY_SOURCE=2 -fstack-protector -funwind-tables -fasynchronous-unwind-tables -fPIE -fPIC -MT libbitcoin_util_a-util.o -MD -MP -MF .deps/libbitcoin_util_a-util.Tpo -c -o libbitcoin_util_a-util.o `test -f 'util.cpp' || echo './'`util.cpp
In file included from util.cpp:81:0:
/usr/include/boost/program_options/detail/config_file.hpp: In instantiation of 'bool boost::program_options::detail::basic_config_file_iterator<charT>::getline(std::string&) [with charT = char; std::string = std::basic_string<char>]':
util.cpp:812:1:   required from here
/usr/include/boost/program_options/detail/config_file.hpp:163:31: error: 'to_internal' was not declared in this scope, and no declarations were found by argument-dependent lookup at the point of instantiation [-fpermissive]
             s = to_internal(in);
                               ^
In file included from /usr/include/boost/program_options/detail/parsers.hpp:9:0,
                 from /usr/include/boost/program_options/parsers.hpp:265,
                 from util.cpp:82:
/usr/include/boost/program_options/detail/convert.hpp:75:34: note: 'template<class T> std::vector<std::basic_string<char> > boost::program_options::to_internal(const std::vector<_RealType>&)' declared here, later in the translation unit
         std::vector<std::string> to_internal(const std::vector<T>& s)
                                  ^