David, Not all of the warnings are benign. For example I get the following when compiling regex under vc8 with /analyze: h:\source code\boost\boost_1_33_1\libs\regex\src\wide_posix_api.cpp(159) : warning C6200: Index '20' is out of valid index range '0' to '15' for non-stack buffer 'wchar_t const * * boost::`anonymous namespace'::wnames' h:\source code\boost\boost_1_33_1\boost\regex\v4\basic_regex_creator.hpp(1183) : warning C6297: Arithmetic overflow: 32-bit value is shifted, then cast to 64-bit value. Results might not be an expected value h:\source code\boost\boost_1_33_1\boost\regex\v4\basic_regex_creator.hpp(1203) : warning C6297: Arithmetic overflow: 32-bit value is shifted, then cast to 64-bit value. Results might not be an expected value h:\source code\boost\boost_1_33_1\libs\regex\src\posix_api.cpp(146) : warning C6200: Index '20' is out of valid index range '0' to '15' for non-stack buffer 'char const * * boost::`anonymous namespace'::names' h:\source code\boost\boost_1_33_1\libs\regex\src\posix_api.cpp(132) : warning C6385: Invalid data: accessing 'char const * * boost::`anonymous namespace'::names', the readable size is '64' bytes, but '84' bytes might be read: Lines: 126, 127, 129, 130, 132 h:\source code\boost\boost_1_33_1\boost\regex\v4\w32_regex_traits.hpp(537) : warning C6385: Invalid data: accessing 'unsigned long const * const `private: unsigned long __thiscall boost::re_detail::w32_regex_traits_implementation<char>::lookup_classname_imp(char const *,char const *)const '::`2'::masks', the readable size is '80' bytes, but '84' bytes might be read: Lines: 505, 528, 530, 531, 532, 535, 536, 537 h:\source code\boost\boost_1_33_1\boost\regex\v4\basic_regex_creator.hpp(1203) : warning C6297: Arithmetic overflow: 32-bit value is shifted, then cast to 64-bit value. Results might not be an expected value h:\source code\boost\boost_1_33_1\boost\regex\v4\basic_regex_creator.hpp(576) : warning C6246: Local declaration of 'c3' hides declaration of the same name in outer scope. For additional information, see previous declaration at line '565' of 'h:\source code\boost\boost_1_33_1\boost\regex\v4\basic_regex_creator.hpp': Lines: 565 Generally I have found these warnings to be right on with my own code. :-) While some of the warnings represent MS design decisions (e.g. deprecating certain SL functions), code analysis as a whole is very helpful and boost might benefit from it. Regards, George.