PING
> On Jun 30, 2026, at 20:49, Anlai Lu <[email protected]> wrote:
>
> This is v3 of the patch series. Performance data: see v2 cover letter.
> Results are unchanged -- same stack-buffer + __ostream_insert approach.
>
> Patch 1 is unchanged from v2.
>
> Changes in Patch 2 from v2:
>
> - Dropped the format string parameter from __chrono_write.
> _S_empty_fs() is used directly, per Tomasz Kaminski's suggestion.
> All chrono types now share the same two call forms:
> __detail::__chrono_write(__os, __arg);
> __detail::__chrono_write(__os, __arg, __os.getloc());
>
> - Removed __detail::__empty_fmt: no longer needed.
>
> - All remaining operator<< that used basic_stringstream now use
> __chrono_write (month_day, month_day_last, month_weekday,
> month_weekday_last, year_month, year_month_day_last,
> year_month_weekday, year_month_weekday_last, sys_days, local_time).
>
> - The only types not converted: duration (must forward stream flags
> and precision) and local_info (uses __formatter_chrono_info).
>
> - Uses std::format_to_n (public API) instead of __do_vformat_to_n.
>
> Tested on x86_64-linux-gnu. libstdc++ testsuite (std/time/*) clean.
> All converted types verified byte-identical across C, en_US, de_DE,
> fr_FR, and zh_CN locales.
>
> Anlai Lu (2):
> libstdc++: Add stream state tests for chrono operator<<
> libstdc++: Use __chrono_write via _S_empty_fs for chrono ostream
> insertion
>
> libstdc++-v3/include/bits/chrono_io.h | 227 ++++--------------
> .../testsuite/std/time/ostream_insert.cc | 163 +++++++++++++
> 2 files changed, 212 insertions(+), 178 deletions(-)
> create mode 100644 libstdc++-v3/testsuite/std/time/ostream_insert.cc
>
> --
> 2.34.1
