1 files changed, 38 insertions, 25 deletions

diff --git a/src/corelib/time/qtimezoneprivate.cpp b/src/corelib/time/qtimezoneprivate.cpp
index facdf6661d..244ebbb07c 100644
--- a/src/corelib/time/qtimezoneprivate.cpp
+++ b/src/corelib/time/qtimezoneprivate.cpp
@@ -356,26 +356,33 @@ QTimeZonePrivate::Data QTimeZonePrivate::dataForLocalTime(qint64 forLocalMSecs,
 
         // Check we do *really* have transitions for this zone:
         if (tran.atMSecsSinceEpoch != invalidMSecs()) {
-
-            /*
-              So now tran is definitely before and nextTran is either after or only
-              slightly before.  One is standard time; we interpret the other as DST
-              (although the transition might in fact by a change in standard offset).  Our
-              hint tells us which of those to use (defaulting to standard if no hint): try
-              it first; if that fails, try the other; if both fail, life's tricky.
-            */
+            /* So now tran is definitely before ... */
             Q_ASSERT(forLocalMSecs < 0
                      || forLocalMSecs - tran.offsetFromUtc * 1000 > tran.atMSecsSinceEpoch);
+            // Work out the UTC value it would make sense to return if using tran:
+            tran.atMSecsSinceEpoch = forLocalMSecs - tran.offsetFromUtc * 1000;
+            // If we know of no transition after it, the answer is easy:
             const qint64 nextStart = nextTran.atMSecsSinceEpoch;
-            // Work out the UTC values it might make sense to return:
+            if (nextStart == invalidMSecs())
+                return tran;
+
+            /*
+              ... and nextTran is either after or only slightly before. We're
+              going to interpret one as standard time, the other as DST
+              (although the transition might in fact be a change in standard
+              offset, or a change in DST offset, e.g. to/from double-DST). Our
+              hint tells us which of those to use (defaulting to standard if no
+              hint): try it first; if that fails, try the other; if both fail,
+              life's tricky.
+            */
+            // Work out the UTC value it would make sense to return if using nextTran:
             nextTran.atMSecsSinceEpoch = forLocalMSecs - nextTran.offsetFromUtc * 1000;
-            tran.atMSecsSinceEpoch = forLocalMSecs - tran.offsetFromUtc * 1000;
 
             // If both or neither have zero DST, treat the one with lower offset as standard:
             const bool nextIsDst = !nextTran.daylightTimeOffset == !tran.daylightTimeOffset
                 ? tran.offsetFromUtc < nextTran.offsetFromUtc : nextTran.daylightTimeOffset;
             // If that agrees with hint > 0, our first guess is to use nextTran; else tran.
-            const bool nextFirst = nextIsDst == (hint > 0) && nextStart != invalidMSecs();
+            const bool nextFirst = nextIsDst == (hint > 0);
             for (int i = 0; i < 2; i++) {
                 /*
                   On the first pass, the case we consider is what hint told us to expect
@@ -384,12 +391,11 @@ QTimeZonePrivate::Data QTimeZonePrivate::dataForLocalTime(qint64 forLocalMSecs,
                   by which time the second case, that we're trying, is likely right.
                 */
                 if (nextFirst ? i == 0 : i) {
-                    Q_ASSERT(nextStart != invalidMSecs());
                     if (nextStart <= nextTran.atMSecsSinceEpoch)
                         return nextTran;
                 } else {
                     // If next is invalid, nextFirst is false, to route us here first:
-                    if (nextStart == invalidMSecs() || nextStart > tran.atMSecsSinceEpoch)
+                    if (nextStart > tran.atMSecsSinceEpoch)
                         return tran;
                 }
             }
@@ -663,12 +669,25 @@ bool QTimeZonePrivate::isValidId(const QByteArray &ianaId)
     return true;
 }
 
-QString QTimeZonePrivate::isoOffsetFormat(int offsetFromUtc)
+QString QTimeZonePrivate::isoOffsetFormat(int offsetFromUtc, QTimeZone::NameType mode)
 {
-    const int mins = offsetFromUtc / 60;
-    return QString::fromUtf8("UTC%1%2:%3").arg(mins >= 0 ? QLatin1Char('+') : QLatin1Char('-'))
-                                          .arg(qAbs(mins) / 60, 2, 10, QLatin1Char('0'))
-                                          .arg(qAbs(mins) % 60, 2, 10, QLatin1Char('0'));
+    if (mode == QTimeZone::ShortName && !offsetFromUtc)
+        return utcQString();
+
+    char sign = '+';
+    if (offsetFromUtc < 0) {
+        sign = '-';
+        offsetFromUtc = -offsetFromUtc;
+    }
+    const int secs = offsetFromUtc % 60;
+    const int mins = (offsetFromUtc / 60) % 60;
+    const int hour = offsetFromUtc / 3600;
+    QString result = QString::asprintf("UTC%c%02d", sign, hour);
+    if (mode != QTimeZone::ShortName || secs || mins)
+        result += QString::asprintf(":%02d", mins);
+    if (mode == QTimeZone::LongName || secs)
+        result += QString::asprintf(":%02d", secs);
+    return result;
 }
 
 QByteArray QTimeZonePrivate::ianaIdToWindowsId(const QByteArray &id)
@@ -801,13 +820,7 @@ qint64 QUtcTimeZonePrivate::offsetFromUtcString(const QByteArray &id)
 // Create offset from UTC
 QUtcTimeZonePrivate::QUtcTimeZonePrivate(qint32 offsetSeconds)
 {
-    QString utcId;
-
-    if (offsetSeconds == 0)
-        utcId = utcQString();
-    else
-        utcId = isoOffsetFormat(offsetSeconds);
-
+    QString utcId = isoOffsetFormat(offsetSeconds, QTimeZone::ShortName);
     init(utcId.toUtf8(), offsetSeconds, utcId, utcId, QLocale::AnyCountry, utcId);
 }