Compilation error with Boost log library when using date_time_formatter

Question

I'm trying to use the Boost log library, and I want to add a timestamp to the output. I started out from this example, but I ran into compilation error. I copied the code exactly as in the example, and changed the init() function to the second one (example_tutorial_formatters_stream_date_time). Now I have the following compilation error:

$ g++ -Wall -Wextra -O0 -g -isystem /proj/cudbdm/tools/external/boost/inst_1_54_0_cxx11/include -c main.cpp -o main.o
In file included from /proj/cudbdm/tools/external/boost/inst_1_54_0_cxx11/include/boost/log/expressions/formatters.hpp:23:0,
                 from /proj/cudbdm/tools/external/boost/inst_1_54_0_cxx11/include/boost/log/expressions.hpp:26,
                 from main.cpp:109:
/proj/cudbdm/tools/external/boost/inst_1_54_0_cxx11/include/boost/log/expressions/formatters/date_time.hpp: In instantiation of 'boost::log::v2s_mt_posix::expressions::format_date_time_terminal<T, FallbackPolicyT, CharT>::format_date_time_terminal(const boost::log::v2s_mt_posix::attribute_name&, const fallback_policy&, const string_type&) [with T = boost::posix_time::ptime; FallbackPolicyT = boost::log::v2s_mt_posix::fallback_to_none; CharT = char; boost::log::v2s_mt_posix::expressions::format_date_time_terminal<T, FallbackPolicyT, CharT>::fallback_policy = boost::log::v2s_mt_posix::fallback_to_none; boost::log::v2s_mt_posix::expressions::format_date_time_terminal<T, FallbackPolicyT, CharT>::string_type = std::basic_string<char>]':
/proj/cudbdm/tools/external/boost/inst_1_54_0_cxx11/include/boost/log/expressions/formatters/date_time.hpp:229:94:   required from 'boost::log::v2s_mt_posix::expressions::format_date_time_actor<AttributeValueT, boost::log::v2s_mt_posix::fallback_to_none, CharT> boost::log::v2s_mt_posix::expressions::format_date_time(const boost::log::v2s_mt_posix::attribute_name&, const CharT*) [with AttributeValueT = boost::posix_time::ptime; CharT = char]'
main.cpp:156:103:   required from here
/proj/cudbdm/tools/external/boost/inst_1_54_0_cxx11/include/boost/log/expressions/formatters/date_time.hpp:94:68: error: incomplete type 'boost::log::v2s_mt_posix::expressions::format_date_time_terminal<boost::posix_time::ptime, boost::log::v2s_mt_posix::fallback_to_none, char>::formatter_generator {aka boost::log::v2s_mt_posix::expressions::aux::date_time_formatter_generator_traits<boost::posix_time::ptime, char, void>}' used in nested name specifier
         m_name(name), m_formatter(formatter_generator::parse(format)), m_visitor_invoker(fallback)
                                                                    ^

I tried using gcc 4.7.2 and 4.8.1 with and without the -std=c++11 flag, but I got the same result every time. It seems that the error is in the Boost library, which is strange to me as even the official example doesn't compile.

Answer 1

The problem is that <boost/log/support/date_time.hpp> needs to be included. It is also stated in the documentation at the proper place, but is somehow left out of the example.