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[C++] Remove the vendored datetime fallback when toolchain support permits #51267
Description
Describe the enhancement requested
#51216 makes std::chrono the default datetime backend and removes vendored datetime dependencies from standard-backend binaries. However most builds still default to vendored date.h library. The vendored fallback must remain for unsupported standard libraries.
This requires:
- Raising the minimum Linux libstdc++ version to GCC 16.2 or newer.
- Apple libc++ providing working C++20 timezone and formatting APIs.
- Migrating Rtools40 and MSYS2 Clang64 builds.
- Validating Emscripten, and other supported targets.
- Retiring the ARROW_USE_STD_CHRONO=0 override.
Once all supported toolchains use std::chrono, remove the vendored sources and build plumbing (e.g. reload_tzdb). The Windows text-tzdb configuration APIs, including the deprecated Python API and R initialization, can also be removed once no supported Windows build uses the fallback.
Component(s)
C++
Activity
Adarsh-Me commentedon Sep 10, 2026
take
Adarsh-Me commentedon Sep 12, 2026
Opened #51315 as a first step: it adds
ARROW_USE_STD_CHRONO(CMake) /use_std_chrono(Meson) options with toolchain feature detection (__cpp_lib_chrono >= 201907L).AUTOpreserves the current platform default (vendored fallback everywhere except Windows toolchains with timezone support) until the minimum-toolchain prerequisites above are met; explicit opt-in fails fast at configure time on unsupported toolchains, and standard-backend binaries no longer bundlevendored/datetime.cpp. Full removal of the vendored sources still waits on the toolchain upgrades listed in this issue.apacheGH-51267: [C++] address review findings on the std::chrono opt-in
apacheGH-51267: [C++] fix option description line continuation in Def…
apacheGH-51267: [C++] apply clang-format, cmake-format and meson-fmt
apacheGH-51267: [C++] stop the chrono probe from carrying a second /s…
apacheGH-51267: [C++] Add std::chrono opt-in with toolchain feature d…
apacheGH-51267: [C++] address review findings on the std::chrono opt-in
apacheGH-51267: [C++] fix option description line continuation in Def…
apacheGH-51267: [C++] apply clang-format, cmake-format and meson-fmt
apacheGH-51267: [C++] stop the chrono probe from carrying a second /s…
apacheGH-51267: [C++] address remaining review findings on the std::c…
apacheGH-51267: [C++] address remaining review findings on the std::c…
apacheGH-51267: [C++] bind the probe time point before make_format_args
apacheGH-51267: [C++] include chrono_internal.h outside namespace arr…
rok commentedon Sep 17, 2026
The point of this issue is to remove the vendored sources. Conditions for this are that Arrow uses only new enough libstdc++ libraries. This issue should likely wait until such time.
apacheGH-51267: [C++] enable MSVC exception unwinding in chrono probe
Adarsh-Me commentedon Oct 3, 2026
Update on this claim: still no PR from me. Removing the vendored datetime fallback means building and testing the C++ libraries, and this machine has no CMake or usable C++ toolchain, so anything I posted would be unverified. Freeing this issue up for a contributor who can actually run the arrow-cpp suite.
Adarsh-Me commentedon Oct 10, 2026
@rok this one is unassigned but #51315 already implements it - the std::chrono opt-in, with the toolchain gate you flagged. Could you assign #51267 to me so nobody duplicates the work? The PR has a merge conflict and one MATLAB check red that I have shown is repo-wide; I will rebase once the assignment lands.