QDateTime: ensure we always use the daylight status if known

Refactor the code so that the localMSecsToEpochMSecs function always
gets the daylight status as input. The calculation can be very wrong if
we forget to set it.

Change-Id: I39e2a3fa6dc7c4a417f23288f10b303e450b8b98
Reviewed-by: Frederik Gladhorn <frederik.gladhorn@theqtcompany.com>

1 files changed, 28 insertions, 19 deletions

diff --git a/src/corelib/tools/qdatetime.cpp b/src/corelib/tools/qdatetime.cpp
index 48cad022a1..505a6f863b 100644
--- a/src/corelib/tools/qdatetime.cpp
+++ b/src/corelib/tools/qdatetime.cpp
@@ -2440,11 +2440,12 @@ static bool epochMSecsToLocalTime(qint64 msecs, QDate *localDate, QTime *localTi
     }
 }
 
-// Convert a LocalTime expressed in local msecs encoding into a UTC epoch msecs
-// Optionally populate the returned values from mktime for the adjusted local
-// date and time and daylight status.  Uses daylightStatus in calculation if populated.
-static qint64 localMSecsToEpochMSecs(qint64 localMsecs, QDate *localDate = 0, QTime *localTime = 0,
-                                     QDateTimePrivate::DaylightStatus *daylightStatus = 0,
+// Convert a LocalTime expressed in local msecs encoding and the corresponding
+// daylight status into a UTC epoch msecs. Optionally populate the returned
+// values from mktime for the adjusted local date and time.
+static qint64 localMSecsToEpochMSecs(qint64 localMsecs,
+                                     QDateTimePrivate::DaylightStatus *daylightStatus,
+                                     QDate *localDate = 0, QTime *localTime = 0,
                                      QString *abbreviation = 0, bool *ok = 0)
 {
     QDate dt;
@@ -2680,9 +2681,11 @@ qint64 QDateTimePrivate::toMSecsSinceEpoch() const
     case Qt::UTC:
         return (m_msecs - (m_offsetFromUtc * 1000));
 
-    case Qt::LocalTime:
+    case Qt::LocalTime: {
         // recalculate the local timezone
-        return localMSecsToEpochMSecs(m_msecs);
+        DaylightStatus status = daylightStatus();
+        return localMSecsToEpochMSecs(m_msecs, &status);
+    }
 
     case Qt::TimeZone:
 #ifndef QT_BOOTSTRAPPED
@@ -2752,7 +2755,7 @@ void QDateTimePrivate::refreshDateTime()
     qint64 epochMSecs = 0;
     if (m_spec == Qt::LocalTime) {
         DaylightStatus status = daylightStatus();
-        epochMSecs = localMSecsToEpochMSecs(m_msecs, &testDate, &testTime, &status);
+        epochMSecs = localMSecsToEpochMSecs(m_msecs, &status, &testDate, &testTime);
 #ifndef QT_BOOTSTRAPPED
     } else {
         epochMSecs = zoneMSecsToEpochMSecs(m_msecs, m_timeZone, &testDate, &testTime);
@@ -3190,7 +3193,7 @@ QString QDateTime::timeZoneAbbreviation() const
     case Qt::LocalTime:  {
         QString abbrev;
         QDateTimePrivate::DaylightStatus status = d->daylightStatus();
-        localMSecsToEpochMSecs(d->m_msecs, 0, 0, &status, &abbrev);
+        localMSecsToEpochMSecs(d->m_msecs, &status, 0, 0, &abbrev);
         return abbrev;
         }
     }
@@ -3221,7 +3224,7 @@ bool QDateTime::isDaylightTime() const
     case Qt::LocalTime: {
         QDateTimePrivate::DaylightStatus status = d->daylightStatus();
         if (status == QDateTimePrivate::UnknownDaylightTime)
-            localMSecsToEpochMSecs(d->m_msecs, 0, 0, &status, 0);
+            localMSecsToEpochMSecs(d->m_msecs, &status);
         return (status == QDateTimePrivate::DaylightTime);
         }
     }
@@ -3676,12 +3679,14 @@ QDateTime QDateTime::addDays(qint64 ndays) const
     date = date.addDays(ndays);
     // Result might fall into "missing" DaylightTime transition hour,
     // so call conversion and use the adjusted returned time
-    if (d->m_spec == Qt::LocalTime)
-        localMSecsToEpochMSecs(timeToMSecs(date, time), &date, &time);
+    if (d->m_spec == Qt::LocalTime) {
+        QDateTimePrivate::DaylightStatus status = d->daylightStatus();
+        localMSecsToEpochMSecs(timeToMSecs(date, time), &status, &date, &time);
 #ifndef QT_BOOTSTRAPPED
-    else if (d->m_spec == Qt::TimeZone)
+    } else if (d->m_spec == Qt::TimeZone) {
         QDateTimePrivate::zoneMSecsToEpochMSecs(timeToMSecs(date, time), d->m_timeZone, &date, &time);
 #endif // QT_BOOTSTRAPPED
+    }
     dt.d->setDateTime(date, time);
     return dt;
 }
@@ -3710,12 +3715,14 @@ QDateTime QDateTime::addMonths(int nmonths) const
     date = date.addMonths(nmonths);
     // Result might fall into "missing" DaylightTime transition hour,
     // so call conversion and use the adjusted returned time
-    if (d->m_spec == Qt::LocalTime)
-        localMSecsToEpochMSecs(timeToMSecs(date, time), &date, &time);
+    if (d->m_spec == Qt::LocalTime) {
+        QDateTimePrivate::DaylightStatus status = d->daylightStatus();
+        localMSecsToEpochMSecs(timeToMSecs(date, time), &status, &date, &time);
 #ifndef QT_BOOTSTRAPPED
-    else if (d->m_spec == Qt::TimeZone)
+    } else if (d->m_spec == Qt::TimeZone) {
         QDateTimePrivate::zoneMSecsToEpochMSecs(timeToMSecs(date, time), d->m_timeZone, &date, &time);
 #endif // QT_BOOTSTRAPPED
+    }
     dt.d->setDateTime(date, time);
     return dt;
 }
@@ -3744,12 +3751,14 @@ QDateTime QDateTime::addYears(int nyears) const
     date = date.addYears(nyears);
     // Result might fall into "missing" DaylightTime transition hour,
     // so call conversion and use the adjusted returned time
-    if (d->m_spec == Qt::LocalTime)
-        localMSecsToEpochMSecs(timeToMSecs(date, time), &date, &time);
+    if (d->m_spec == Qt::LocalTime) {
+        QDateTimePrivate::DaylightStatus status = d->daylightStatus();
+        localMSecsToEpochMSecs(timeToMSecs(date, time), &status, &date, &time);
 #ifndef QT_BOOTSTRAPPED
-    else if (d->m_spec == Qt::TimeZone)
+    } else if (d->m_spec == Qt::TimeZone) {
         QDateTimePrivate::zoneMSecsToEpochMSecs(timeToMSecs(date, time), d->m_timeZone, &date, &time);
 #endif // QT_BOOTSTRAPPED
+    }
     dt.d->setDateTime(date, time);
     return dt;
 }