https://issues.dlang.org/show_bug.cgi?id=20558

          Issue ID: 20558
           Summary: __DATE__ and __TIMESTAMP__ use US-centric formats
           Product: D
           Version: D2
          Hardware: x86_64
                OS: Linux
            Status: NEW
          Severity: enhancement
          Priority: P1
         Component: dmd
          Assignee: nobody@puremagic.com
          Reporter: mark@qtrac.eu

I suggest adding __ISODATE__ and __ISOTIMESTAMP__ which should both use ISO8601
date formats.
See https://github.com/dlang/dlang.org/pull/2747#issuecomment-581239122

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