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  1. Qt
  2. QTBUG-68812

A new back-end for QTimeZone based on C++20 std::chrono::tzdb

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Details

    • Task
    • Resolution: Fixed
    • P3: Somewhat important
    • 6.9
    • None
    • Core: Date/Time
    • None

    • All, C++20

    • 8
    • 678f6d472 (dev), dea91dbb5 (dev), 755733f59 (dev), 152cb77f8 (dev)
    • Foundation Sprint 109, Foundation Sprint 110, Foundation Sprint 111, Foundation Sprint 112, Foundation Sprint 113, Foundation Sprint 114, Foundation Sprint 115, Foundation Sprint 116

    Description

      In C++20, <tz.h> std::chrono::tzdb will provide access to the Olson database.
      This should be sufficient to implement a back-end for QTimeZone; ultimately (some time in the late 2020s) we can hope for it to make all others redundant.
      As discussed at QtCS2018 it's worth getting it implemented early,

      • so that we'll have all the bugs out of it by that time; and
      • so that we notice (and address) any limitations in the <tz.h> API that we want fixed before it gets fossilized by standardization – too late for that.

      Once we have this backend, the intent is to use it whenever it is supported, making the other backends redundant. This makes QTBUG-101730's call to include conversion from std::chrono::time_zone to QTimeZone trivial, provided we include a constructor from time_zone when using this backend.

      Attachments

        Issue Links

          is blocked by

          Task - A task that needs to be done. QTBUG-107201 Spike: Look into std::chrono::tzdb's APIs, work out how much work QTBUG-68812 will take

          • P2: Important - Urgent, should be fixed, but will not stop the release.
          • Closed
          relates to

          Bug - A problem which impairs or prevents the functions of the product. QTBUG-115158 Time zone names and abbreviations are not localised

          • P2: Important - Urgent, should be fixed, but will not stop the release.
          • Closed

          Task - A task that needs to be done. QTBUG-88858 VxWorks 7 does not support any of the existing QTimeZone backends

          • P3: Somewhat important - Should be fixed, but doesn't affect the release in any way.
          • Reported

          Task - A task that needs to be done. QTBUG-102042 Look into using libicu on Android (>= 12) for date/time support

          • P3: Somewhat important - Should be fixed, but doesn't affect the release in any way.
          • Reported

          Technical task - A technical task. QTBUG-112909 Support all CLDR's various ways of naming time-zones

          • P3: Somewhat important - Should be fixed, but doesn't affect the release in any way.
          • Open

          Epic - Created by Jira Software - do not edit or delete. Issue type for a big user story that needs to be broken down. QTBUG-71036 Qt Core Changes in Qt 6

          • P2: Important - Urgent, should be fixed, but will not stop the release.
          • Closed

          Task - A task that needs to be done. QTBUG-91441 Support timezones on WASM

          • P2: Important - Urgent, should be fixed, but will not stop the release.
          • Reported

          Task - A task that needs to be done. QTBUG-102047 Windows SDK ships a subset of ICU and does not get picked up by CMake because of it

          • P3: Somewhat important - Should be fixed, but doesn't affect the release in any way.
          • Reported

          Task - A task that needs to be done. QTBUG-112006 Separate out POSIX zone descriptors in QTimeZone backends

          • P3: Somewhat important - Should be fixed, but doesn't affect the release in any way.
          • Reported

          Task - A task that needs to be done. QTBUG-101730 Research and implement QDateTime/etc. <=> C++20 calendaring integration

          • P3: Somewhat important - Should be fixed, but doesn't affect the release in any way.
          • Open

          Task - A task that needs to be done. QTBUG-130085 Create an overview of C++20 features available in Qt

          • P2: Important - Urgent, should be fixed, but will not stop the release.
          • In Progress
          replaces

          Task - A task that needs to be done. QTBUG-102187 QTimeZone on Windows (w/o ICU) does not recognize some time zones reported by C++20

          • P4: Low - Would be nice to fix, but it's not very important.
          • Closed
          resulted in

          Bug - A problem which impairs or prevents the functions of the product. QTBUG-127598 GCC's libstdc++ supplies QTimeZone's tzdb backend with bad data

          • P4: Low - Would be nice to fix, but it's not very important.
          • Open
          mentioned in

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              magdalenas Magdalena Stojek
              Eddy Edward Welbourne
              Vladimir Minenko Vladimir Minenko
              Alex Blasche Alex Blasche
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