id	summary	reporter	owner	description	type	status	milestone	component	version	severity	resolution	keywords	cc
4798	date_time: valgrind warnings via strings_from_facet.hpp	Lars Immisch <lars.immisch@…>	az_sw_dude	"On Ubuntu, with GNU libc6 (2.7-10ubuntu7), and a program that uses `boost::date_time::time_input_facet< boost::posix_time::ptime,char>` valgrind generates a warning:

{{{
==11026== Conditional jump or move depends on uninitialised value(s)
==11026==    at 0x467C04B: __strftime_internal (strftime_l.c:574)
==11026==    by 0x467DD4F: strftime_l (strftime_l.c:490)
==11026==    by 0x456B420: std::__timepunct<char>::_M_put(char*, unsigned int, char const*, tm const*) const (in /usr/lib/libstdc++.so.6.0.13)
==11026==    by 0x452BB4C: std::time_put<char, std::ostreambuf_iterator<char, std::char_traits<char> > >::do_put(std::ostreambuf_iterator<char, std::char_traits<char> >, std::ios_base&, char, tm const*, char, char) const (in /usr/lib/libstdc++.so.6.0.13)
==11026==    by 0x452B0CF: std::time_put<char, std::ostreambuf_iterator<char, std::char_traits<char> > >::put(std::ostreambuf_iterator<char, std::char_traits<char> >, std::ios_base&, char, tm const*, char const*, char const*) const (in /usr/lib/libstdc++.so.6.0.13)
==11026==    by 0x8430C83: std::vector<std::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::allocator<std::basic_string<char, std::char_traits<char>, std::allocator<char> > > > boost::date_time::gather_month_strings<char>(std::locale const&, bool) (strings_from_facet.hpp:58)
==11026==    by 0x84310D9: boost::date_time::format_date_parser<boost::gregorian::date, char>::format_date_parser(std::string const&, std::locale const&) (format_date_parser.hpp:188)
==11026==    by 0x8431435: boost::date_time::date_input_facet<boost::gregorian::date, char, std::istreambuf_iterator<char, std::char_traits<char> > >::date_input_facet(std::string const&, unsigned int) (date_facet.hpp:462)
==11026==    by 0x84315E0: boost::date_time::time_input_facet<boost::posix_time::ptime, char, std::istreambuf_iterator<char, std::char_traits<char> > >::time_input_facet(std::string const&, unsigned int) (time_facet.hpp:696)
}}}

The actual problem is in GNU libc6, ''strftime_l.c:574'', which computes a 12 hour clock in `__strftime_internal` regardless of the format string:
{{{
  if (hour12 > 12)
    hour12 -= 12;
  else
    if (hour12 == 0)
      hour12 = 12;
}}}

The attached patch works around the warning by using an initialised struct tm in two places:
{{{
tm tm_value = { 0, 0, 0, 0, 0, 0, 0, 0, 0 };
}}}

We'd very much appreciate if the attached patch was accepted, even if it is only cosmetic."	Patches	closed	To Be Determined	date_time	Boost Development Trunk	Cosmetic	fixed	valgrind