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

2 files changed, 52 insertions, 5 deletions

diff --git a/i18npool/source/calendar/calendarImpl.cxx b/i18npool/source/calendar/calendarImpl.cxx
index 93ff9b16fa0b..f0962104a4b0 100644
--- a/i18npool/source/calendar/calendarImpl.cxx
+++ b/i18npool/source/calendar/calendarImpl.cxx
@@ -18,6 +18,7 @@
  */
 
 #include <calendarImpl.hxx>
+#include <calendar_gregorian.hxx>
 #include <localedata.hxx>
 #include <cppuhelper/supportsservice.hxx>
 
@@ -40,12 +41,12 @@ CalendarImpl::~CalendarImpl()
 }
 
 void SAL_CALL
-CalendarImpl::loadDefaultCalendar( const Locale& rLocale )
+CalendarImpl::loadDefaultCalendarTZ( const Locale& rLocale, const OUString& rTimeZone )
 {
     Sequence< Calendar2 > xC = LocaleDataImpl::get()->getAllCalendars2(rLocale);
     for (sal_Int32 i = 0; i < xC.getLength(); i++) {
         if (xC[i].Default) {
-            loadCalendar(xC[i].Name, rLocale);
+            loadCalendarTZ(xC[i].Name, rLocale, rTimeZone);
             return;
         }
     }
@@ -53,14 +54,16 @@ CalendarImpl::loadDefaultCalendar( const Locale& rLocale )
 }
 
 void SAL_CALL
-CalendarImpl::loadCalendar(const OUString& uniqueID, const Locale& rLocale )
+CalendarImpl::loadCalendarTZ( const OUString& uniqueID, const Locale& rLocale, const OUString& rTimeZone )
 {
     Reference < XCalendar4 > xOldCalendar( xCalendar );  // backup
+    const OUString aCacheID( uniqueID + "_" + rTimeZone);
+    bool bTimeZone = true;
     sal_Int32 i;
 
     for (i = 0; i < sal::static_int_cast<sal_Int32>(lookupTable.size()); i++) {
         lookupTableItem &listItem = lookupTable[i];
-        if (uniqueID == listItem.uniqueID) {
+        if (aCacheID == listItem.m_aCacheID) {
             xCalendar = listItem.xCalendar;
             break;
         }
@@ -85,7 +88,16 @@ CalendarImpl::loadCalendar(const OUString& uniqueID, const Locale& rLocale )
             throw ERROR;
         xCalendar.set(xI, UNO_QUERY);
 
-        lookupTable.emplace_back( uniqueID, xCalendar );
+        if (!rTimeZone.isEmpty())
+        {
+            /* XXX NOTE: currently (2019-06-19) calendar implementations derive
+             * from Calendar_gregorian, even Hijri and Jewish. If that should
+             * change in future this should be adapted. */
+            Calendar_gregorian* pCal = dynamic_cast<Calendar_gregorian*>(xCalendar.get());
+            bTimeZone = (pCal && pCal->setTimeZone(rTimeZone));
+        }
+
+        lookupTable.emplace_back( aCacheID, xCalendar );
     }
 
     if ( !xCalendar.is() )
@@ -103,6 +115,10 @@ CalendarImpl::loadCalendar(const OUString& uniqueID, const Locale& rLocale )
         xCalendar = xOldCalendar;
         throw;
     }
+
+    if (!bTimeZone)
+        // The calendar is usable but is not in the expected time zone.
+        throw ERROR;
 }
 
 Calendar2 SAL_CALL
@@ -164,6 +180,16 @@ CalendarImpl::getLocalDateTime()
     return xCalendar->getLocalDateTime();
 }
 
+void SAL_CALL CalendarImpl::loadDefaultCalendar( const css::lang::Locale& rLocale )
+{
+    loadDefaultCalendarTZ( rLocale, OUString());
+}
+
+void SAL_CALL CalendarImpl::loadCalendar( const OUString& uniqueID, const css::lang::Locale& rLocale )
+{
+    loadCalendarTZ( uniqueID, rLocale, OUString());
+}
+
 OUString SAL_CALL
 CalendarImpl::getUniqueID()
 {
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()