[gcc r16-1485] libstdc++: Format empty chrono-spec for the time points and hh_mm_ss directly.
Tomasz Kaminski
tkaminsk@gcc.gnu.org
Thu Jun 12 14:32:59 GMT 2025
https://gcc.gnu.org/g:8fa1e98493def5eb327397a587aa846f2145d634
commit r16-1485-g8fa1e98493def5eb327397a587aa846f2145d634
Author: Tomasz Kamiński <tkaminsk@redhat.com>
Date: Fri Jun 6 11:32:27 2025 +0200
libstdc++: Format empty chrono-spec for the time points and hh_mm_ss directly.
This patch change implementation of the formatters for time points and hh_mm_ss,
so they no longer delegate to operator<< for ostream in case of empty chrono-spec.
As in case of calendar types, the formatters for specific type now provide
__formatter_chrono with default _ChronoSpec that are used in case if empty
chrono-spec.
The configuration of __defSpec is straight forward, except for the sys_time,
and local_time that print time, if the duration is convertible to days,
which is equivalent to setting _M_chrono_specs "%F" instead of "%F %T".
Furthermore, certain sys_time<Dur> do not support ostream operator, and
should not be formattable with empty spec - in such case default
_M_chrono_spec, allowing the issue to still be detected in _M_parse.
Finally, _ChronoFormats are extended to cover required format strings.
libstdc++-v3/ChangeLog:
* include/bits/chrono_io.h (_ChronoFormats::_S_ftz)
(_ChronoFormats::_S_ft, _ChronoFormats::_S_t): Define.
(__formatter_chrono::_M_format_to_ostream): Remove handling for
time_points.
(std::formatter<chrono::hh_mm_ss<_Dur>, _CharT>)
(std::formatter<chrono::sys_time<_Dur>, _CharT>)
(std::formatter<chrono::utc_time<_Dur>, _CharT>)
(std::formatter<chrono::tai_time<_Dur>, _CharT>)
(std::formatter<chrono::gps_time<_Dur>, _CharT>)
(std::formatter<chrono::file_time<_Dur>, _CharT>)
(std::formatter<chrono::local_time<_Dur>, _CharT>)
(std::formatter<chrono::__detail::__local_time_fmt<_Dur>, _CharT>)
(std::formatter<chrono::zoned_time<_Dur>, _CharT>):
Define __defSpec, and pass it as argument to _M_prase and
constructor of __formatter_chrono.
Diff:
---
libstdc++-v3/include/bits/chrono_io.h | 220 +++++++++++++++++++++-------------
1 file changed, 135 insertions(+), 85 deletions(-)
diff --git a/libstdc++-v3/include/bits/chrono_io.h b/libstdc++-v3/include/bits/chrono_io.h
index 69cf2a6aa2b9..247d40c82d76 100644
--- a/libstdc++-v3/include/bits/chrono_io.h
+++ b/libstdc++-v3/include/bits/chrono_io.h
@@ -243,10 +243,25 @@ namespace __format
{
using _String_view = basic_string_view<_CharT>;
+ static consteval
+ _String_view
+ _S_ftz() noexcept
+ { return _GLIBCXX_WIDEN("%F %T %Z"); }
+
+ static consteval
+ _String_view
+ _S_ft() noexcept
+ { return _S_ftz().substr(0, 5); }
+
static consteval
_String_view
_S_f() noexcept
- { return _GLIBCXX_WIDEN("%F"); }
+ { return _S_ftz().substr(0, 2); }
+
+ static consteval
+ _String_view
+ _S_t() noexcept
+ { return _S_ftz().substr(3, 2); }
static consteval
_String_view
@@ -828,58 +843,17 @@ namespace __format
__os.imbue(_M_locale(__fc));
if constexpr (__is_specialization_of<_Tp, __local_time_fmt>)
- {
- // Format as "{:L%F %T}"
- auto __days = chrono::floor<chrono::days>(__t._M_time);
- __os << chrono::year_month_day(__days) << ' '
- << chrono::hh_mm_ss(__t._M_time - __days);
-
- // For __local_time_fmt the __is_neg flags says whether to
- // append " %Z" to the result.
- if (__is_neg)
- {
- if (!__t._M_abbrev) [[unlikely]]
- __format::__no_timezone_available();
- else if constexpr (is_same_v<_CharT, char>)
- __os << ' ' << *__t._M_abbrev;
- else
- {
- __os << L' ';
- for (char __c : *__t._M_abbrev)
- __os << __c;
- }
- }
- }
+ __builtin_trap();
+ else if constexpr (__is_specialization_of<_Tp, __utc_leap_second>)
+ __builtin_trap();
+ else if constexpr (chrono::__is_time_point_v<_Tp>)
+ __builtin_trap();
else
{
- if constexpr (__is_specialization_of<_Tp, __utc_leap_second>)
- __os << __t._M_date << ' ' << __t._M_time;
- else if constexpr (chrono::__is_time_point_v<_Tp>)
- {
- // Need to be careful here because not all specializations
- // of chrono::sys_time can be written to an ostream.
- // For the specializations of time_point that can be
- // formatted with an empty chrono-specs, either it's a
- // sys_time with period greater or equal to days:
- if constexpr (is_convertible_v<_Tp, chrono::sys_days>)
- __os << _S_date(__t);
- // Or a local_time with period greater or equal to days:
- else if constexpr (is_convertible_v<_Tp, chrono::local_days>)
- __os << _S_date(__t);
- else // Or it's formatted as "{:L%F %T}":
- {
- auto __days = chrono::floor<chrono::days>(__t);
- __os << chrono::year_month_day(__days) << ' '
- << chrono::hh_mm_ss(__t - __days);
- }
- }
- else
- {
- if constexpr (chrono::__is_duration_v<_Tp>)
- if (__is_neg) [[unlikely]]
- __os << _S_plus_minus[1];
- __os << __t;
- }
+ if constexpr (chrono::__is_duration_v<_Tp>)
+ if (__is_neg) [[unlikely]]
+ __os << _S_plus_minus[1];
+ __os << __t;
}
auto __str = std::move(__os).str();
@@ -2430,7 +2404,7 @@ namespace __format
{
constexpr typename basic_format_parse_context<_CharT>::iterator
parse(basic_format_parse_context<_CharT>& __pc)
- { return _M_f._M_parse(__pc, __format::_TimeOfDay); }
+ { return _M_f._M_parse(__pc, __format::_TimeOfDay, __defSpec); }
template<typename _Out>
typename basic_format_context<_Out, _CharT>::iterator
@@ -2439,7 +2413,15 @@ namespace __format
{ return _M_f._M_format(__t, __fc); }
private:
- __format::__formatter_chrono<_CharT> _M_f;
+ static constexpr __format::_ChronoSpec<_CharT> __defSpec = []
+ {
+ __format::_ChronoSpec<_CharT> __res{};
+ __res._M_localized = true;
+ __res._M_chrono_specs = __format::_ChronoFormats<_CharT>::_S_t();
+ return __res;
+ }();
+
+ __format::__formatter_chrono<_CharT> _M_f{__defSpec};
};
#if _GLIBCXX_USE_CXX11_ABI || ! _GLIBCXX_USE_DUAL_ABI
@@ -2484,7 +2466,7 @@ namespace __format
constexpr typename basic_format_parse_context<_CharT>::iterator
parse(basic_format_parse_context<_CharT>& __pc)
{
- auto __next = _M_f._M_parse(__pc, __format::_ZonedDateTime);
+ auto __next = _M_f._M_parse(__pc, __format::_ZonedDateTime, __defSpec);
if constexpr (!__stream_insertable)
if (_M_f._M_spec._M_chrono_specs.empty())
__format::__invalid_chrono_spec(); // chrono-specs can't be empty
@@ -2502,7 +2484,22 @@ namespace __format
= requires (basic_ostream<_CharT>& __os,
chrono::sys_time<_Duration> __t) { __os << __t; };
- __format::__formatter_chrono<_CharT> _M_f;
+ static constexpr __format::_ChronoSpec<_CharT> __defSpec = []
+ {
+ __format::_ChronoSpec<_CharT> __res{};
+ if constexpr (!__stream_insertable)
+ return __res;
+ else if constexpr (is_convertible_v<_Duration, chrono::days>)
+ __res._M_chrono_specs = __format::_ChronoFormats<_CharT>::_S_f();
+ else
+ {
+ __res._M_localized = true;
+ __res._M_chrono_specs = __format::_ChronoFormats<_CharT>::_S_ft();
+ }
+ return __res;
+ }();
+
+ __format::__formatter_chrono<_CharT> _M_f{__defSpec};
};
template<typename _Duration, __format::__char _CharT>
@@ -2511,11 +2508,11 @@ namespace __format
{
constexpr typename basic_format_parse_context<_CharT>::iterator
parse(basic_format_parse_context<_CharT>& __pc)
- { return _M_f._M_parse(__pc, __format::_ZonedDateTime); }
+ { return _M_f._M_parse(__pc, __format::_ZonedDateTime, __defSpec); }
template<typename _Out>
- typename basic_format_context<_Out, _CharT>::iterator
- format(const chrono::utc_time<_Duration>& __t,
+ typename basic_format_context<_Out, _CharT>::iterator
+ format(const chrono::utc_time<_Duration>& __t,
basic_format_context<_Out, _CharT>& __fc) const
{
// Adjust by removing leap seconds to get equivalent sys_time.
@@ -2536,7 +2533,15 @@ namespace __format
private:
friend formatter<chrono::__detail::__utc_leap_second<_Duration>, _CharT>;
- __format::__formatter_chrono<_CharT> _M_f;
+ static constexpr __format::_ChronoSpec<_CharT> __defSpec = []
+ {
+ __format::_ChronoSpec<_CharT> __res{};
+ __res._M_localized = true;
+ __res._M_chrono_specs = __format::_ChronoFormats<_CharT>::_S_ft();
+ return __res;
+ }();
+
+ __format::__formatter_chrono<_CharT> _M_f{__defSpec};
};
template<typename _Duration, __format::__char _CharT>
@@ -2545,11 +2550,11 @@ namespace __format
{
constexpr typename basic_format_parse_context<_CharT>::iterator
parse(basic_format_parse_context<_CharT>& __pc)
- { return _M_f._M_parse(__pc, __format::_ZonedDateTime); }
+ { return _M_f._M_parse(__pc, __format::_ZonedDateTime, __defSpec); }
template<typename _Out>
- typename basic_format_context<_Out, _CharT>::iterator
- format(const chrono::tai_time<_Duration>& __t,
+ typename basic_format_context<_Out, _CharT>::iterator
+ format(const chrono::tai_time<_Duration>& __t,
basic_format_context<_Out, _CharT>& __fc) const
{
// Convert to __local_time_fmt with abbrev "TAI" and offset 0s.
@@ -2567,7 +2572,15 @@ namespace __format
}
private:
- __format::__formatter_chrono<_CharT> _M_f;
+ static constexpr __format::_ChronoSpec<_CharT> __defSpec = []
+ {
+ __format::_ChronoSpec<_CharT> __res{};
+ __res._M_localized = true;
+ __res._M_chrono_specs = __format::_ChronoFormats<_CharT>::_S_ft();
+ return __res;
+ }();
+
+ __format::__formatter_chrono<_CharT> _M_f{__defSpec};
};
template<typename _Duration, __format::__char _CharT>
@@ -2576,11 +2589,11 @@ namespace __format
{
constexpr typename basic_format_parse_context<_CharT>::iterator
parse(basic_format_parse_context<_CharT>& __pc)
- { return _M_f._M_parse(__pc, __format::_ZonedDateTime); }
+ { return _M_f._M_parse(__pc, __format::_ZonedDateTime, __defSpec); }
template<typename _Out>
- typename basic_format_context<_Out, _CharT>::iterator
- format(const chrono::gps_time<_Duration>& __t,
+ typename basic_format_context<_Out, _CharT>::iterator
+ format(const chrono::gps_time<_Duration>& __t,
basic_format_context<_Out, _CharT>& __fc) const
{
// Convert to __local_time_fmt with abbrev "GPS" and offset 0s.
@@ -2598,7 +2611,15 @@ namespace __format
}
private:
- __format::__formatter_chrono<_CharT> _M_f;
+ static constexpr __format::_ChronoSpec<_CharT> __defSpec = []
+ {
+ __format::_ChronoSpec<_CharT> __res{};
+ __res._M_localized = true;
+ __res._M_chrono_specs = __format::_ChronoFormats<_CharT>::_S_ft();
+ return __res;
+ }();
+
+ __format::__formatter_chrono<_CharT> _M_f{__defSpec};
};
template<typename _Duration, __format::__char _CharT>
@@ -2606,11 +2627,11 @@ namespace __format
{
constexpr typename basic_format_parse_context<_CharT>::iterator
parse(basic_format_parse_context<_CharT>& __pc)
- { return _M_f._M_parse(__pc, __format::_ZonedDateTime); }
+ { return _M_f._M_parse(__pc, __format::_ZonedDateTime, __defSpec); }
template<typename _Out>
- typename basic_format_context<_Out, _CharT>::iterator
- format(const chrono::file_time<_Duration>& __t,
+ typename basic_format_context<_Out, _CharT>::iterator
+ format(const chrono::file_time<_Duration>& __t,
basic_format_context<_Out, _CharT>& __fc) const
{
using namespace chrono;
@@ -2618,24 +2639,45 @@ namespace __format
}
private:
- __format::__formatter_chrono<_CharT> _M_f;
- };
+ static constexpr __format::_ChronoSpec<_CharT> __defSpec = []
+ {
+ __format::_ChronoSpec<_CharT> __res{};
+ __res._M_localized = true;
+ __res._M_chrono_specs = __format::_ChronoFormats<_CharT>::_S_ft();
+ return __res;
+ }();
+
+ __format::__formatter_chrono<_CharT> _M_f{__defSpec};
+ };
template<typename _Duration, __format::__char _CharT>
struct formatter<chrono::local_time<_Duration>, _CharT>
{
constexpr typename basic_format_parse_context<_CharT>::iterator
parse(basic_format_parse_context<_CharT>& __pc)
- { return _M_f._M_parse(__pc, __format::_DateTime); }
+ { return _M_f._M_parse(__pc, __format::_DateTime, __defSpec); }
template<typename _Out>
- typename basic_format_context<_Out, _CharT>::iterator
- format(const chrono::local_time<_Duration>& __t,
+ typename basic_format_context<_Out, _CharT>::iterator
+ format(const chrono::local_time<_Duration>& __t,
basic_format_context<_Out, _CharT>& __fc) const
{ return _M_f._M_format(__t, __fc); }
private:
- __format::__formatter_chrono<_CharT> _M_f;
+ static constexpr __format::_ChronoSpec<_CharT> __defSpec = []
+ {
+ __format::_ChronoSpec<_CharT> __res{};
+ if constexpr (is_convertible_v<_Duration, chrono::days>)
+ __res._M_chrono_specs = __format::_ChronoFormats<_CharT>::_S_f();
+ else
+ {
+ __res._M_localized = true;
+ __res._M_chrono_specs = __format::_ChronoFormats<_CharT>::_S_ft();
+ }
+ return __res;
+ }();
+
+ __format::__formatter_chrono<_CharT> _M_f{__defSpec};
};
template<typename _Duration, __format::__char _CharT>
@@ -2643,16 +2685,24 @@ namespace __format
{
constexpr typename basic_format_parse_context<_CharT>::iterator
parse(basic_format_parse_context<_CharT>& __pc)
- { return _M_f._M_parse(__pc, __format::_ZonedDateTime); }
+ { return _M_f._M_parse(__pc, __format::_ZonedDateTime, __defSpec); }
template<typename _Out>
- typename basic_format_context<_Out, _CharT>::iterator
- format(const chrono::__detail::__local_time_fmt<_Duration>& __t,
+ typename basic_format_context<_Out, _CharT>::iterator
+ format(const chrono::__detail::__local_time_fmt<_Duration>& __t,
basic_format_context<_Out, _CharT>& __fc) const
- { return _M_f._M_format(__t, __fc, /* use %Z for {} */ true); }
+ { return _M_f._M_format(__t, __fc); }
private:
- __format::__formatter_chrono<_CharT> _M_f;
+ static constexpr __format::_ChronoSpec<_CharT> __defSpec = []
+ {
+ __format::_ChronoSpec<_CharT> __res{};
+ __res._M_localized = true;
+ __res._M_chrono_specs = __format::_ChronoFormats<_CharT>::_S_ftz();
+ return __res;
+ }();
+
+ __format::__formatter_chrono<_CharT> _M_f{__defSpec};
};
#if _GLIBCXX_USE_CXX11_ABI || ! _GLIBCXX_USE_DUAL_ABI
@@ -2661,8 +2711,8 @@ namespace __format
: formatter<chrono::__detail::__local_time_fmt_for<_Duration>, _CharT>
{
template<typename _Out>
- typename basic_format_context<_Out, _CharT>::iterator
- format(const chrono::zoned_time<_Duration, _TimeZonePtr>& __tp,
+ typename basic_format_context<_Out, _CharT>::iterator
+ format(const chrono::zoned_time<_Duration, _TimeZonePtr>& __tp,
basic_format_context<_Out, _CharT>& __fc) const
{
using _Ltf = chrono::__detail::__local_time_fmt_for<_Duration>;
@@ -2682,8 +2732,8 @@ namespace __format
: formatter<chrono::utc_time<_Duration>, _CharT>
{
template<typename _Out>
- typename basic_format_context<_Out, _CharT>::iterator
- format(const chrono::__detail::__utc_leap_second<_Duration>& __t,
+ typename basic_format_context<_Out, _CharT>::iterator
+ format(const chrono::__detail::__utc_leap_second<_Duration>& __t,
basic_format_context<_Out, _CharT>& __fc) const
{ return this->_M_f._M_format(__t, __fc); }
};
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