Resolves: tdf#92503 introduce TimeZone to calendar loading and default to UTC

Without that, the system's time zone was used which on DST
transition dates leads to non-existent times when switching
to/from DST. As the calendar use and number parser/formatter nor
conversions or calculations are time zone aware, using not DST
afflicted UTC is the better choice.

Change-Id: I3303c6620d8c4b9d081555c8293954fb1bd67895
Reviewed-on: https://gerrit.libreoffice.org/74386
Reviewed-by: Eike Rathke <erack@redhat.com>
Tested-by: Jenkins
(cherry picked from commit 942de6a01ba990e5f3bc55ce4ab3737a03f67f39)
Reviewed-on: https://gerrit.libreoffice.org/74399

1 files changed, 21 insertions, 0 deletions

diff --git a/i18npool/source/calendar/calendar_gregorian.cxx b/i18npool/source/calendar/calendar_gregorian.cxx
index 18676361027a..f3b228efc04e 100644
--- a/i18npool/source/calendar/calendar_gregorian.cxx
+++ b/i18npool/source/calendar/calendar_gregorian.cxx
@@ -167,6 +167,11 @@ Calendar_gregorian::init(const Era *_eraArray)
      * */
     icu::Locale aIcuLocale( "", nullptr, nullptr, "calendar=gregorian");
 
+    /* XXX: not specifying a timezone when creating a calendar assigns the
+     * system's timezone with all DST quirks, invalid times when switching
+     * to/from DST and so on. The XCalendar* interfaces are defined to support
+     * local time and UTC time so we can not override that here.
+     */
     UErrorCode status = U_ZERO_ERROR;
     body.reset( icu::Calendar::createInstance( aIcuLocale, status) );
     if (!body || !U_SUCCESS(status)) throw ERROR;
@@ -369,6 +374,22 @@ Calendar_gregorian::getLocalDateTime()
     return (fTime + (nZoneOffset + nDSTOffset)) / U_MILLIS_PER_DAY;
 }
 
+bool Calendar_gregorian::setTimeZone( const OUString& rTimeZone )
+{
+    if (fieldSet)
+    {
+        setValue();
+        getValue();
+    }
+    const icu::UnicodeString aID( reinterpret_cast<const UChar*>(rTimeZone.getStr()), rTimeZone.getLength());
+    const std::unique_ptr<const icu::TimeZone> pTZ( icu::TimeZone::createTimeZone(aID));
+    if (!pTZ)
+        return false;
+
+    body->setTimeZone(*pTZ);
+    return true;
+}
+
 // map field value from gregorian calendar to other calendar, it can be overwritten by derived class.
 // By using eraArray, it can take care Japanese and Taiwan ROC calendar.
 void Calendar_gregorian::mapFromGregorian()