1 files changed, 125 insertions, 17 deletions
diff --git a/src/corelib/time/qtimezoneprivate.cpp b/src/corelib/time/qtimezoneprivate.cpp
index 2ad0d874b6..b18b7e8758 100644
--- a/src/corelib/time/qtimezoneprivate.cpp
+++ b/src/corelib/time/qtimezoneprivate.cpp
@@ -5,6 +5,9 @@
 
 #include "qtimezone.h"
 #include "qtimezoneprivate_p.h"
+#if QT_CONFIG(timezone_locale)
+#  include "qtimezonelocale_p.h"
+#endif
 #include "qtimezoneprivate_data_p.h"
 
 #include <qdatastream.h>
@@ -51,6 +54,11 @@ constexpr bool atLowerWindowsKey(const WindowsData &entry, qint16 winIdKey) noex
     return entry.windowsIdKey < winIdKey;
 }
 
+static bool earlierAliasId(const AliasData &entry, QByteArrayView aliasId) noexcept
+{
+    return entry.aliasId().compare(aliasId, Qt::CaseInsensitive) < 0;
+}
+
 static bool earlierWindowsId(const WindowsData &entry, QByteArrayView winId) noexcept
 {
     return entry.windowsId().compare(winId, Qt::CaseInsensitive) < 0;
@@ -172,22 +180,37 @@ QString QTimeZonePrivate::displayName(qint64 atMSecsSinceEpoch,
                                       QTimeZone::NameType nameType,
                                       const QLocale &locale) const
 {
-    if (nameType == QTimeZone::OffsetName)
-        return isoOffsetFormat(offsetFromUtc(atMSecsSinceEpoch));
-
-    if (isDaylightTime(atMSecsSinceEpoch))
-        return displayName(QTimeZone::DaylightTime, nameType, locale);
-    else
-        return displayName(QTimeZone::StandardTime, nameType, locale);
+    const Data tran = data(atMSecsSinceEpoch);
+    if (tran.atMSecsSinceEpoch != invalidMSecs()) {
+        if (nameType == QTimeZone::OffsetName && locale.language() == QLocale::C)
+            return isoOffsetFormat(tran.offsetFromUtc);
+        if (nameType == QTimeZone::ShortName && isDataLocale(locale))
+            return tran.abbreviation;
+
+        QTimeZone::TimeType timeType
+            = tran.daylightTimeOffset != 0 ? QTimeZone::DaylightTime : QTimeZone::StandardTime;
+#if QT_CONFIG(timezone_locale)
+        return localeName(atMSecsSinceEpoch, tran.offsetFromUtc, timeType, nameType, locale);
+#else
+        return displayName(timeType, nameType, locale);
+#endif
+    }
+    return QString();
 }
 
 QString QTimeZonePrivate::displayName(QTimeZone::TimeType timeType,
                                       QTimeZone::NameType nameType,
                                       const QLocale &locale) const
 {
-    Q_UNUSED(timeType);
-    Q_UNUSED(nameType);
-    Q_UNUSED(locale);
+    const Data tran = data(timeType);
+    if (tran.atMSecsSinceEpoch != invalidMSecs()) {
+        if (nameType == QTimeZone::OffsetName && isDataLocale(locale))
+            return isoOffsetFormat(tran.offsetFromUtc);
+
+#if QT_CONFIG(timezone_locale)
+        return localeName(tran.atMSecsSinceEpoch, tran.offsetFromUtc, timeType, nameType, locale);
+#endif
+    }
     return QString();
 }
 
@@ -227,6 +250,56 @@ bool QTimeZonePrivate::isDaylightTime(qint64 atMSecsSinceEpoch) const
     return false;
 }
 
+QTimeZonePrivate::Data QTimeZonePrivate::data(QTimeZone::TimeType timeType) const
+{
+    // True if tran is valid and has the DST-ness to match timeType:
+    const auto validMatch = [timeType](const QTimeZonePrivate::Data &tran) {
+        return tran.atMSecsSinceEpoch != invalidMSecs()
+            && ((timeType == QTimeZone::DaylightTime) != (tran.daylightTimeOffset == 0));
+    };
+
+    // Get current tran, use if suitable:
+    const qint64 currentMSecs = QDateTime::currentMSecsSinceEpoch();
+    QTimeZonePrivate::Data tran = data(currentMSecs);
+    if (validMatch(tran))
+        return tran;
+
+    if (hasTransitions()) {
+        // Otherwise, next tran probably flips DST-ness:
+        tran = nextTransition(currentMSecs);
+        if (validMatch(tran))
+            return tran;
+
+        // Failing that, prev (or present, if current MSecs is exactly a
+        // transition moment) tran defines what data() got us and the one before
+        // that probably flips DST-ness; failing that, keep marching backwards
+        // in search of a DST interval:
+        tran = previousTransition(currentMSecs + 1);
+        while (tran.atMSecsSinceEpoch != invalidMSecs()) {
+            tran = previousTransition(tran.atMSecsSinceEpoch);
+            if (validMatch(tran))
+                return tran;
+        }
+    }
+    return {};
+}
+
+/*!
+    \internal
+
+    Returns true if the abbreviation given in data()'s returns is appropriate
+    for use in the given \a locale.
+
+    Base implementation assumes data() corresponds to the system locale; derived
+    classes should override if their data() is something else (such as
+    C/English).
+*/
+bool QTimeZonePrivate::isDataLocale(const QLocale &locale) const
+{
+    // Guess data is for the system locale unless backend overrides that.
+    return locale == QLocale::system();
+}
+
 QTimeZonePrivate::Data QTimeZonePrivate::data(qint64 forMSecsSinceEpoch) const
 {
     Q_UNUSED(forMSecsSinceEpoch);
@@ -532,7 +605,8 @@ QList<QByteArray> QTimeZonePrivate::availableTimeZoneIds() const
     return QList<QByteArray>();
 }
 
-static QList<QByteArray> selectAvailable(QList<QByteArray>&& desired, const QList<QByteArray>& all)
+static QList<QByteArray> selectAvailable(QList<QByteArrayView> &&desired,
+                                         const QList<QByteArray> &all)
 {
     std::sort(desired.begin(), desired.end());
     const auto newEnd = std::unique(desired.begin(), desired.end());
@@ -547,13 +621,13 @@ static QList<QByteArray> selectAvailable(QList<QByteArray>&& desired, const QLis
 QList<QByteArray> QTimeZonePrivate::availableTimeZoneIds(QLocale::Territory territory) const
 {
     // Default fall-back mode, use the zoneTable to find Region of know Zones
-    QList<QByteArray> regions;
+    QList<QByteArrayView> regions;
 
     // First get all Zones in the Zones table belonging to the Region
     for (const ZoneData &data : zoneDataTable) {
         if (data.territory == territory) {
             for (auto l1 : data.ids())
-                regions << QByteArray(l1.data(), l1.size());
+                regions << QByteArrayView(l1.data(), l1.size());
         }
     }
     return selectAvailable(std::move(regions), availableTimeZoneIds());
@@ -561,16 +635,16 @@ QList<QByteArray> QTimeZonePrivate::availableTimeZoneIds(QLocale::Territory terr
 
 QList<QByteArray> QTimeZonePrivate::availableTimeZoneIds(int offsetFromUtc) const
 {
-    // Default fall-back mode, use the zoneTable to find Offset of know Zones
-    QList<QByteArray> offsets;
-    // First get all Zones in the table using the Offset
+    // Default fall-back mode: use the zoneTable to find offsets of know zones.
+    QList<QByteArrayView> offsets;
+    // First get all Zones in the table using the given offset:
     for (const WindowsData &winData : windowsDataTable) {
         if (winData.offsetFromUtc == offsetFromUtc) {
             for (auto data = zoneStartForWindowsId(winData.windowsIdKey);
                  data != std::end(zoneDataTable) && data->windowsIdKey == winData.windowsIdKey;
                  ++data) {
                 for (auto l1 : data->ids())
-                    offsets << QByteArray(l1.data(), l1.size());
+                    offsets << QByteArrayView(l1.data(), l1.size());
             }
         }
     }
@@ -701,6 +775,18 @@ QString QTimeZonePrivate::isoOffsetFormat(int offsetFromUtc, QTimeZone::NameType
     return result;
 }
 
+QByteArray QTimeZonePrivate::aliasToIana(QByteArrayView alias)
+{
+    const auto data = std::lower_bound(std::begin(aliasMappingTable), std::end(aliasMappingTable),
+                                       alias, earlierAliasId);
+    if (data != std::end(aliasMappingTable) && data->aliasId() == alias)
+        return data->ianaId().toByteArray();
+    // Note: empty return means not an alias, which is true of an ID that others
+    // are aliases to, as the table omits self-alias entries. Let caller sort
+    // that out, rather than allocating to return alias.toByteArray().
+    return {};
+}
+
 QByteArray QTimeZonePrivate::ianaIdToWindowsId(const QByteArray &id)
 {
     const auto idUtf8 = QUtf8StringView(id);
@@ -906,6 +992,19 @@ QTimeZonePrivate::Data QUtcTimeZonePrivate::data(qint64 forMSecsSinceEpoch) cons
     return d;
 }
 
+// Override to shortcut past base's complications:
+QTimeZonePrivate::Data QUtcTimeZonePrivate::data(QTimeZone::TimeType timeType) const
+{
+    Q_UNUSED(timeType);
+    return data(QDateTime::currentMSecsSinceEpoch());
+}
+
+bool QUtcTimeZonePrivate::isDataLocale(const QLocale &locale) const
+{
+    // Officially only supports C locale names; these are surely also viable for English.
+    return locale.language() == QLocale::C || locale.language() == QLocale::English;
+}
+
 void QUtcTimeZonePrivate::init(const QByteArray &zoneId)
 {
     m_id = zoneId;
@@ -933,6 +1032,15 @@ QString QUtcTimeZonePrivate::comment() const
     return m_comment;
 }
 
+// Override to bypass complications in base-class:
+QString QUtcTimeZonePrivate::displayName(qint64 atMSecsSinceEpoch,
+                                         QTimeZone::NameType nameType,
+                                         const QLocale &locale) const
+{
+    Q_UNUSED(atMSecsSinceEpoch);
+    return displayName(QTimeZone::StandardTime, nameType, locale);
+}
+
 QString QUtcTimeZonePrivate::displayName(QTimeZone::TimeType timeType,
                                          QTimeZone::NameType nameType,
                                          const QLocale &locale) const