https://gcc.gnu.org/bugzilla/show_bug.cgi?id=117214
--- Comment #2 from XU Kailiang <xu2k3l4 at outlook dot com> ---
Is this patch usable? Steps to setup struct tm are copied from other functions
in chrono_io.h. Hope I didn't get them wrong.
--- a/libstdc++-v3/include/bits/chrono_io.h
+++ b/libstdc++-v3/include/bits/chrono_io.h
@@ -787,27 +787,30 @@ namespace __format
template<typename _Tp, typename _FormatContext>
typename _FormatContext::iterator
- _M_c(const _Tp& __tt, typename _FormatContext::iterator __out,
+ _M_c(const _Tp& __t, typename _FormatContext::iterator __out,
_FormatContext& __ctx, bool __mod = false) const
{
// %c Locale's date and time representation.
// %Ec Locale's alternate date and time representation.
- basic_string<_CharT> __fmt;
- auto __t = _S_floor_seconds(__tt);
- locale __loc = _M_locale(__ctx);
- const auto& __tp = use_facet<__timepunct<_CharT>>(__loc);
- const _CharT* __formats[2];
- __tp._M_date_time_formats(__formats);
- if (*__formats[__mod]) [[likely]]
- {
- __fmt = _GLIBCXX_WIDEN("{:L}");
- __fmt.insert(3u, __formats[__mod]);
- }
- else
- __fmt = _GLIBCXX_WIDEN("{:L%a %b %e %T %Y}");
- return std::vformat_to(std::move(__out), __loc, __fmt,
- std::make_format_args<_FormatContext>(__t));
+ using namespace chrono;
+ auto __d = _S_days(__t);
+ using _TDays = decltype(__d);
+ const auto __ymd = _S_date(__d);
+ const auto __y = __ymd.year();
+ const auto __hms = _S_hms(__t);
+
+ struct tm __tm{};
+ __tm.tm_year = (int)__y - 1900;
+ __tm.tm_yday = (__d - _TDays(__y/January/1)).count();
+ __tm.tm_mon = (unsigned)_S_month(__t) - 1;
+ __tm.tm_mday = (unsigned)_S_day(__t);
+ __tm.tm_wday = _S_weekday(__t).c_encoding();
+ __tm.tm_hour = __hms.hours().count();
+ __tm.tm_min = __hms.minutes().count();
+ __tm.tm_sec = __hms.seconds().count();
+ return _M_locale_fmt(std::move(__out), _M_locale(__ctx), __tm, 'c',
+ __mod ? 'E' : '\0');
}
template<typename _Tp, typename _FormatContext>
