GH-48593: [C++] C++20: use standard calendar / timezone APIs

[rok]

Rationale for this change

Switch to std::chrono for MSVC to be able to use the system-provided timezone automatically on Windows.

What changes are included in this PR?

This adds chrono_internal.h that uses C++20 std::chrono timezone/calendar APIs on compilers with support (MSVC only for now) and falls back to vendored date.h otherwise.

Are these changes tested?

Partially tested locally and partially to be tested on CI.

Are there any user-facing changes?

Yes, Windows users will no longer need to install the IANA tzdb (see instructions here and here). We possibly have tzdb download set up in CI too and should update it appropriately.

• GitHub Issue: [C++] C++20: use standard calendar / timezone APIs #48593

[github-actions]

⚠️ GitHub issue #48593 has been automatically assigned in GitHub to PR creator.

[rok]

It seems that std::chrono on GCC (14.3.0, 15.2.0) potentially has a bug that triggers some of our tests. Meanwhile std::chrono on MSVC 19.44 ( 14.44) appears to be pass them and is correct or at least consistent with vendored date.h. I would therefore advise we only switch to std::chrono on MSVC for now as that gives us the most benefit anyway (users no longer have to deal with the tz db).

Below is the explanation and reproduction of the bug.

// GCC libstdc++ DST bug reproduction
//
// The AN to AS Transition Bug
// ---------------------------
// Source https://github.com/eggert/tz/blob/c37fbc3249c1a1334948b38f3bca47dee5c11dd1/australasia#L165-L192
// Australia/Broken_Hill used the AN (New South Wales) rules until 2000, then
// switched to AS (South Australia) rules. Under AN rules, DST started the last
// Sunday of October and ended the last Sunday of March. For the 1999-2000
// summer, DST started October 31, 1999 and would end March 26, 2000. February
// 29, 2000 falls squarely within this DST period, so the correct offset should
// be 9:30 base + 1:00 DST = 10:30 (630 minutes).
//
// Why GCC's Data is Wrong
// -----------------------
// When libstdc++ processes the zone transition from AN rules to AS rules (which
// happens in year 2000), it appears to lose or reset the DST state inherited
// from the AN rules. Instead of recognizing that DST is still active from the
// October 1999 transition, it reports offset=570 (just the 9:30 base) with
// save=0. The inconsistency is evident: it returns abbrev="ACDT" (daylight
// time) but the offset and save values indicate standard time. The AN rules
// clearly show DST should be active until the last Sunday of March 2000.
//
// Compile: g++ -std=c++20 -o gcc_dst_bug gcc_libstdcxx_dst_bug.cpp
// Expected: 630 (10:30 = 9:30 base + 1:00 DST)
// Actual:   570 (9:30 = base only, DST missing)

#include <chrono>
#include <iostream>

int main() {
  using namespace std::chrono;
  auto* tz = locate_zone("Australia/Broken_Hill");
  auto info = tz->get_info(sys_days{2000y / February / 29d} + 23h + 23min + 23s);
  std::cout << duration_cast<minutes>(info.offset).count() << "\n";
}

[rok]

@pitrou

[pitrou]

It seems that std::chrono on GCC (14.3.0, 15.2.0) potentially has a bug that triggers some of our tests.

Is the bug reported somewhere? If not, can you do that?

[pitrou]

We possibly have tzdb download set up in CI too and should update it appropriately.

Yes, I think we should do so. There are also a bunch of code snippets in the C++ and Python codebase that could be removed, IIRC.

[rok]

Is the bug reported somewhere? If not, can you do that?

It seems to be related to a known issue, I added comment explaining our case.

[github-actions]

Revision: ff58c12

Submitted crossbow builds: ursacomputing/crossbow @ actions-6e860e0ebf

Task	Status
test-r-macos-as-cran

[rok]

@github-actions crossbow submit test-r-macos-as-cran

[github-actions]

Revision: 58b86e1

Submitted crossbow builds: ursacomputing/crossbow @ actions-ec6d05eef3

Task	Status
test-r-macos-as-cran

[rok]

@github-actions crossbow submit test-r-macos-as-cran

[github-actions]

Revision: ff58c12

Submitted crossbow builds: ursacomputing/crossbow @ actions-73478be521

Task	Status
test-r-macos-as-cran

[jonkeane]

It looks like you're getting failures from #49371 / #49391 You could try and rebase from just before the commit that added that failure to see if that passes which would be enough to prove that this PR isn't making things worse vis a vis CRAN's partial C++20 compatibility.

[rok]

It looks like you're getting failures from #49371 / #49391 You could try and rebase from just before the commit that added that failure to see if that passes which would be enough to prove that this PR isn't making things worse vis a vis CRAN's partial C++20 compatibility.

Thanks for the idea @jonkeane, will attempt!

[rok]

@github-actions crossbow submit test-r-macos-as-cran

[github-actions]

Revision: 0313fa2

Submitted crossbow builds: ursacomputing/crossbow @ actions-1c56a26f57

Task	Status
test-r-macos-as-cran

[rok]

@github-actions crossbow submit test-r-macos-as-cran

[github-actions]

Revision: 4c5e112

Submitted crossbow builds: ursacomputing/crossbow @ actions-cb3021940b

Task	Status
test-r-macos-as-cran

[rok]

@github-actions crossbow submit test-r-macos-as-cran

[github-actions]

Revision: 9e87d57

Submitted crossbow builds: ursacomputing/crossbow @ actions-a1f6d9bce5

Task	Status
test-r-macos-as-cran

[rok]

I've tried a couple of eebases rebasing on commit before e37c516 succeeded. Trying rebase on 59e0ba6 now. I hope there's not too much to workaround.

[rok]

@github-actions crossbow submit test-r-macos-as-cran

[github-actions]

Revision: c6caa3c

Submitted crossbow builds: ursacomputing/crossbow @ actions-10e324e6df

Task	Status
test-r-macos-as-cran

[rok]

@jonkeane I rebased to the commit before #49298 and cherrypicked #49223 commit. CRAN CI is now passing. So this PR by itself is above board for CRAN I suppose?

[rok]

@pitrou since this won't cause issues with CRAN shall we proceed with review?

[rok]

@github-actions crossbow submit test-r-macos-as-cran

[github-actions]

Revision: a6660df

Submitted crossbow builds: ursacomputing/crossbow @ actions-608e1ed947

Task	Status
test-r-macos-as-cran