The most worrying looking warnings are from Boost.Function IMO: ./boost/function/function_base.hpp:319: warning: dereferencing type-punned pointer will break strict-aliasing rules ./boost/function/function_base.hpp:323: warning: dereferencing type-punned pointer will break strict-aliasing rules Along with several other more verbose warnings to the same effect (included from program_options). Normally these warnings do genuinely indicate issues that will cause real bugs when optimisations are turned on, but in this case I don't see an obvious fix :-( This is with gcc-4.4.1 on Ubuntu BTW. This one looks like it could be easily fixed too: libs/program_options/src/options_description.cpp:74: warning: suggest explicit braces to avoid ambiguous 'else' as could: libs/program_options/src/value_semantic.cpp:175: warning: suggest parentheses around '&&' within '||' libs/program_options/src/value_semantic.cpp: In function 'void boost::program_options::validate(boost::any&, const std::vector<std::basic_string<wchar_t, std::char_traits<wchar_t>, std::allocator<wchar_t> >, std::allocator<std::basic_string<wchar_t, std::char_traits<wchar_t>, std::allocator<wchar_t> > > >&, std::string*, int)': libs/program_options/src/value_semantic.cpp:190: warning: suggest parentheses around '&&' within '||' Cheers, John.