On Wed, Sep 10, 2025 at 4:57 PM Tomasz Kamiński <tkami...@redhat.com> wrote:
> libstdc++-v3/ChangeLog:
>
> * testsuite/std/time/year_month_day/io.cc: Additional tests.
> ---
> Adding test coverate, before I touch the implementation.
>
Test test shows that %U/%W computest week count since start of specified
year,
so if you have a date with month outside of range, the weekday will be
outside of range.
This makes sense, as %Y will also input year.
The %V prints week count since ISO year, that is computed, so if your month
value
is out of range, both %G and %U will be updated, but they remain in sync.
> Testing on x86_64-linux locally.
> .../testsuite/std/time/year_month_day/io.cc | 48 +++++++++++--------
> 1 file changed, 28 insertions(+), 20 deletions(-)
>
> diff --git a/libstdc++-v3/testsuite/std/time/year_month_day/io.cc
> b/libstdc++-v3/testsuite/std/time/year_month_day/io.cc
> index 632b7a0fc2d..7c4876fbd01 100644
> --- a/libstdc++-v3/testsuite/std/time/year_month_day/io.cc
> +++ b/libstdc++-v3/testsuite/std/time/year_month_day/io.cc
> @@ -43,38 +43,46 @@ test_format()
> s = std::format("{:%G-W%V-%u}", 2022y/January/3);
> VERIFY( s == "2022-W01-1" );
>
> + std::chrono::month Quindecember(18);
> // %U: Week number for weeks starting on Sunday
> s = std::format("Day {:%w (%a) of Week %U of %Y}", 2022y/January/1);
> VERIFY( s == "Day 6 (Sat) of Week 00 of 2022" );
> s = std::format("Day {:%w (%a) of Week %U of %Y}", 2022y/January/2);
> VERIFY( s == "Day 0 (Sun) of Week 01 of 2022" );
> + s = std::format("Day {:%w (%a) of Week %U of %Y}",
> 2022y/Quindecember/20);
> + VERIFY( s == "Day 4 (Thu) of Week 77 of 2022" );
> // %W: Week number for weeks starting on Monday
> s = std::format("Day {:%u (%a) of Week %W of %Y}", 2022y/January/2);
> VERIFY( s == "Day 7 (Sun) of Week 00 of 2022" );
> s = std::format("Day {:%u (%a) of Week %W of %Y}", 2022y/January/3);
> VERIFY( s == "Day 1 (Mon) of Week 01 of 2022" );
> + s = std::format("Day {:%w (%a) of Week %U of %Y}",
> 2022y/Quindecember/20);
> + VERIFY( s == "Day 4 (Thu) of Week 77 of 2022" );
>
> + // %G: ISO week-calendar year (ISO 8601)
> // %V: ISO week number (ISO 8601).
> - s = std::format("W{:%V}", 1977y/1/1);
> - VERIFY( s == "W53" );
> - s = std::format("W{:%V}", 1977y/1/2);
> - VERIFY( s == "W53" );
> - s = std::format("W{:%V}", 1977y/12/31);
> - VERIFY( s == "W52" );
> - s = std::format("W{:%V}", 1978y/1/1);
> - VERIFY( s == "W52" );
> - s = std::format("W{:%V}", 1978y/1/2);
> - VERIFY( s == "W01" );
> - s = std::format("W{:%V}", 1978y/12/31);
> - VERIFY( s == "W52" );
> - s = std::format("W{:%V}", 1979y/1/1);
> - VERIFY( s == "W01" );
> - s = std::format("W{:%V}", 1979y/12/30);
> - VERIFY( s == "W52" );
> - s = std::format("W{:%V}", 1979y/12/31);
> - VERIFY( s == "W01" );
> - s = std::format("W{:%V}", 1980y/1/1);
> - VERIFY( s == "W01" );
> + s = std::format("{:%G-W%V}", 1977y/1/1);
> + VERIFY( s == "1976-W53" );
> + s = std::format("{:%G-W%V}", 1977y/1/2);
> + VERIFY( s == "1976-W53" );
> + s = std::format("{:%G-W%V}", 1977y/12/31);
> + VERIFY( s == "1977-W52" );
> + s = std::format("{:%G-W%V}", 1978y/1/1);
> + VERIFY( s == "1977-W52" );
> + s = std::format("{:%G-W%V}", 1978y/1/2);
> + VERIFY( s == "1978-W01" );
> + s = std::format("{:%G-W%V}", 1978y/12/31);
> + VERIFY( s == "1978-W52" );
> + s = std::format("{:%G-W%V}", 1979y/1/1);
> + VERIFY( s == "1979-W01" );
> + s = std::format("{:%G-W%V}", 1979y/12/30);
> + VERIFY( s == "1979-W52" );
> + s = std::format("{:%G-W%V}", 1979y/12/31);
> + VERIFY( s == "1980-W01" );
> + s = std::format("{:%G-W%V}", 1980y/1/1);
> + VERIFY( s == "1980-W01" );
> + s = std::format("{:%G-W%V}", 1980y/18/20);
> + VERIFY( s == "1981-W26" );
>
> s = std::format("{:%x}", 2022y/December/19);
> VERIFY( s == "12/19/22" );
> --
> 2.51.0
>
>
