date: support european dates and out-of-range years

[MuntasirSZN]

date accepts DAY.MONTH[.YEAR] dates (yearless forms use the current
year) and years beyond 9999 with any format. uutils/coreutils rejected both,
failing parts of tests/date/date.pl.

Rewrite european dates to ISO before parsing; accept extended years for
all output formats. Adds unit and integration tests.

tests/date/date.pl gnu test now passes.

Signed-off-by: MuntasirSZN muntasir.joypurhat@gmail.com

[codspeed-hq]

Merging this PR will degrade performance by 4.1%

⚠️ Different runtime environments detected

Some benchmarks with significant performance changes were compared across different runtime environments,
which may affect the accuracy of the results.

Open the report in CodSpeed to investigate

❌ 2 regressed benchmarks
✅ 345 untouched benchmarks
⏩ 46 skipped benchmarks¹

Warning

Please fix the performance issues or acknowledge them on CodSpeed.

Performance Changes

	Mode	Benchmark	BASE	HEAD	Efficiency
❌	Simulation	du_max_depth_balanced_tree[(6, 4, 10)]	62 ms	64.7 ms	-4.14%
❌	Simulation	du_summarize_balanced_tree[(5, 4, 10)]	16 ms	16.6 ms	-4.06%

Tip

Investigate this regression by commenting @codspeedbot fix this regression on this PR, or directly use the CodSpeed MCP with your agent.

---

_{Comparing MuntasirSZN:date-pl (5c25094) with main (2822878)}

Footnotes

1. 46 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩

[github-actions]

GNU testsuite comparison:

Skipping an intermittent issue tests/cut/bounded-memory (passes in this run but fails in the 'main' branch)
Skipping an intermittent issue tests/tail/tail-n0f (passes in this run but fails in the 'main' branch)
Congrats! The gnu test tests/date/date is no longer failing!

[collinfunk]

These tests are copied from GNU coreutils and should be licensed as such.

[MuntasirSZN]

These tests are copied from GNU coreutils and should be licensed as such.

Ok I gave attribution

[xtqqczze]

These tests are copied from GNU coreutils and should be licensed as such.

As per CONTRIBUTING.md, we cannot accept any changes based on the GNU source code. I recommend closing this PR and starting again from scratch.

[sylvestre]

yeah, you need to rewrite the tests

[MuntasirSZN]

yeah, you need to rewrite the tests

Ok doing it....

[github-actions]

Binary size comparison:

Individual binary size comparison VS main (threshold: >=5% AND >=4 KB).

Total size of compared binaries: 148.94 MB (+324 KB, +0.21%)

Significant per-binary changes:
  install     1.24 MB ->    1.32 MB  (+80 KB, +6.29%)
  mkdir       1.09 MB ->    1.17 MB  (+80 KB, +7.14%)
  mkfifo      1.09 MB ->    1.16 MB  (+76 KB, +6.83%)
  mknod       1.09 MB ->    1.17 MB  (+76 KB, +6.79%)

[MuntasirSZN]

@sylvestre @collinfunk @xtqqczze Sorry for ping, can you guys check now?

[xtqqczze]

@MuntasirSZN Could you please confirm that no code in this PR has been derived from GNU coreutils or any other GPL-licensed source, including small snippets, helper structures, test fixtures, or comments?

If you used an AI assistant during development, please also verify its output carefully, as AI-generated code may reproduce material from GPL-licensed sources, potentially without making the provenance apparent.

[MuntasirSZN]

@MuntasirSZN Could you please confirm that no code in this PR has been derived from GNU coreutils or any other GPL-licensed source, including small snippets, helper structures, test fixtures, or comments?

If you used an AI assistant during development, please also verify its output carefully, as AI-generated code may reproduce material from GPL-licensed sources, potentially without making the provenance apparent.

No, @xtqqczze. I verified myself.

[MuntasirSZN]

@sylvestre @cakebaker review pls? Sorry for ping.