QDateTime - Store Qt::TimeSpec, remove Daylight Status

Change storing the spec from QDateTimePrivate::Spec to Qt::TimeSpec.

Remove the storage and use of the Daylight Status as it is almost
never set or used, and would be inaccurate if the tz were to change.
It will be replaced later with proper daylight transition support.

This simplifies the code and makes the msecs storage change easier.

Change-Id: I78a70905025d7eddf1c2dc6001f6b490e5a2b3b8
Reviewed-by: Lars Knoll <lars.knoll@digia.com>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

2 files changed, 116 insertions, 102 deletions

diff --git a/src/corelib/tools/qdatetime.cpp b/src/corelib/tools/qdatetime.cpp
index 31e16f1702..cf8159245d 100644
--- a/src/corelib/tools/qdatetime.cpp
+++ b/src/corelib/tools/qdatetime.cpp
@@ -220,11 +220,11 @@ static int fromOffsetString(const QString &offsetString, bool *valid)
 
 #if !defined(Q_OS_WINCE)
 // Calls the platform variant of mktime for the given date and time,
-// and updates the date, time, spec and abbreviation with the returned values
+// and updates the date, time, daylightStatus and abbreviation with the returned values
 // If the date falls outside the 1970 to 2037 range supported by mktime / time_t
 // then null date/time will be returned, you should call adjustDate() first if
 // you need a guaranteed result.
-static time_t qt_mktime(QDate *date, QTime *time, QDateTimePrivate::Spec *spec,
+static time_t qt_mktime(QDate *date, QTime *time, QDateTimePrivate::DaylightStatus *daylightStatus,
                         QString *abbreviation, bool *ok)
 {
     if (ok)
@@ -251,18 +251,18 @@ static time_t qt_mktime(QDate *date, QTime *time, QDateTimePrivate::Spec *spec,
         *date = QDate(local.tm_year + 1900, local.tm_mon + 1, local.tm_mday);
         *time = QTime(local.tm_hour, local.tm_min, local.tm_sec, time->msec());
         if (local.tm_isdst == 1) {
-            if (spec)
-                *spec = QDateTimePrivate::LocalDST;
+            if (daylightStatus)
+                *daylightStatus = QDateTimePrivate::DaylightTime;
             if (abbreviation)
                 *abbreviation = QString::fromLocal8Bit(tzname[1]);
         } else if (local.tm_isdst == 0) {
-            if (spec)
-                *spec = QDateTimePrivate::LocalStandard;
+            if (daylightStatus)
+                *daylightStatus = QDateTimePrivate::StandardTime;
             if (abbreviation)
                 *abbreviation = QString::fromLocal8Bit(tzname[0]);
         } else {
-            if (spec)
-                *spec = QDateTimePrivate::LocalUnknown;
+            if (daylightStatus)
+                *daylightStatus = QDateTimePrivate::UnknownDaylightTime;
             if (abbreviation)
                 *abbreviation = QString::fromLocal8Bit(tzname[0]);
         }
@@ -271,8 +271,8 @@ static time_t qt_mktime(QDate *date, QTime *time, QDateTimePrivate::Spec *spec,
     } else {
         *date = QDate();
         *time = QTime();
-        if (spec)
-            *spec = QDateTimePrivate::LocalUnknown;
+        if (daylightStatus)
+            *daylightStatus = QDateTimePrivate::UnknownDaylightTime;
         if (abbreviation)
             *abbreviation = QString();
     }
@@ -2153,6 +2153,29 @@ int QTime::elapsed() const
     return n;
 }
 
+/*****************************************************************************
+  QDateTimePrivate member functions
+ *****************************************************************************/
+
+void QDateTimePrivate::setTimeSpec(Qt::TimeSpec spec, int offsetSeconds)
+{
+    switch (spec) {
+    case Qt::OffsetFromUTC:
+        if (offsetSeconds == 0) {
+            m_spec = Qt::UTC;
+            m_offsetFromUtc = 0;
+        } else {
+            m_spec = Qt::OffsetFromUTC;
+            m_offsetFromUtc = offsetSeconds;
+        }
+        break;
+    case Qt::UTC:
+    case Qt::LocalTime:
+        m_spec = spec;
+        m_offsetFromUtc = 0;
+        break;
+    }
+}
 
 /*****************************************************************************
   QDateTime member functions
@@ -2347,23 +2370,7 @@ QDateTimePrivate::QDateTimePrivate(const QDate &toDate, const QTime &toTime, Qt:
     else
         time = toTime;
 
-    m_offsetFromUtc = 0;
-
-    switch (toSpec) {
-    case Qt::UTC :
-        spec = QDateTimePrivate::UTC;
-        break;
-    case Qt::OffsetFromUTC :
-        if (offsetSeconds == 0) {
-            spec = QDateTimePrivate::UTC;
-        } else {
-            spec = QDateTimePrivate::OffsetFromUTC;
-            m_offsetFromUtc = offsetSeconds;
-        }
-        break;
-    case Qt::LocalTime :
-        spec = QDateTimePrivate::LocalUnknown;
-    }
+    setTimeSpec(toSpec, offsetSeconds);
 }
 
 /*!
@@ -2454,15 +2461,7 @@ QTime QDateTime::time() const
 
 Qt::TimeSpec QDateTime::timeSpec() const
 {
-    switch(d->spec)
-    {
-        case QDateTimePrivate::UTC:
-            return Qt::UTC;
-        case QDateTimePrivate::OffsetFromUTC:
-            return Qt::OffsetFromUTC;
-        default:
-            return Qt::LocalTime;
-    }
+    return d->m_spec;
 }
 
 /*!
@@ -2482,15 +2481,16 @@ Qt::TimeSpec QDateTime::timeSpec() const
 
 int QDateTime::offsetFromUtc() const
 {
-    switch (d->spec) {
-    case QDateTimePrivate::OffsetFromUTC:
+    switch (d->m_spec) {
+    case Qt::OffsetFromUTC:
         return d->m_offsetFromUtc;
-    case QDateTimePrivate::UTC:
+    case Qt::UTC:
         return 0;
-    default:  // Any Qt::LocalTime
+    case Qt::LocalTime:
         const QDateTime fakeDate(d->date, d->time, Qt::UTC);
         return (fakeDate.toMSecsSinceEpoch() - toMSecsSinceEpoch()) / 1000;
     }
+    return 0;
 }
 
 /*!
@@ -2516,12 +2516,12 @@ int QDateTime::offsetFromUtc() const
 
 QString QDateTime::timeZoneAbbreviation() const
 {
-    switch (d->spec) {
-    case QDateTimePrivate::UTC:
+    switch (d->m_spec) {
+    case Qt::UTC:
         return QStringLiteral("UTC");
-    case QDateTimePrivate::OffsetFromUTC:
+    case Qt::OffsetFromUTC:
         return QLatin1String("UTC") + toOffsetString(Qt::ISODate, d->m_offsetFromUtc);
-    default:  { // Any Qt::LocalTime
+    case Qt::LocalTime: {
 #if defined(Q_OS_WINCE)
         // TODO Stub to enable compilation on WinCE
         return QString();
@@ -2534,6 +2534,7 @@ QString QDateTime::timeZoneAbbreviation() const
 #endif // !Q_OS_WINCE
         }
     }
+    return QString();
 }
 
 /*!
@@ -2547,9 +2548,6 @@ void QDateTime::setDate(const QDate &date)
 {
     detach();
     d->date = date;
-    if (d->spec == QDateTimePrivate::LocalStandard
-        || d->spec == QDateTimePrivate::LocalDST)
-        d->spec = QDateTimePrivate::LocalUnknown;
     if (date.isValid() && !d->time.isValid())
         d->time = QTime(0, 0, 0);
 }
@@ -2563,9 +2561,6 @@ void QDateTime::setDate(const QDate &date)
 void QDateTime::setTime(const QTime &time)
 {
     detach();
-    if (d->spec == QDateTimePrivate::LocalStandard
-        || d->spec == QDateTimePrivate::LocalDST)
-        d->spec = QDateTimePrivate::LocalUnknown;
     d->time = time;
 }
 
@@ -2585,17 +2580,7 @@ void QDateTime::setTime(const QTime &time)
 void QDateTime::setTimeSpec(Qt::TimeSpec spec)
 {
     detach();
-
-    d->m_offsetFromUtc = 0;
-    switch (spec) {
-    case Qt::UTC:
-    case Qt::OffsetFromUTC:
-        d->spec = QDateTimePrivate::UTC;
-        break;
-    default:
-        d->spec = QDateTimePrivate::LocalUnknown;
-        break;
-    }
+    d->setTimeSpec(spec, 0);
 }
 
 /*!
@@ -2616,14 +2601,7 @@ void QDateTime::setTimeSpec(Qt::TimeSpec spec)
 void QDateTime::setOffsetFromUtc(int offsetSeconds)
 {
     detach();
-
-    if (offsetSeconds == 0) {
-        d->spec = QDateTimePrivate::UTC;
-        d->m_offsetFromUtc = 0;
-    } else {
-        d->spec = QDateTimePrivate::OffsetFromUTC;
-        d->m_offsetFromUtc = offsetSeconds;
-    }
+    d->setTimeSpec(Qt::OffsetFromUTC, offsetSeconds);
 }
 
 qint64 toMSecsSinceEpoch_helper(qint64 jd, int msecs)
@@ -2716,9 +2694,9 @@ void QDateTime::setMSecsSinceEpoch(qint64 msecs)
     d->date = QDate(1970, 1, 1).addDays(ddays);
     d->time = QTime::fromMSecsSinceStartOfDay(msecs);
 
-    if (d->spec == QDateTimePrivate::OffsetFromUTC)
+    if (d->m_spec == Qt::OffsetFromUTC)
         utcToOffset(&d->date, &d->time, d->m_offsetFromUtc);
-    else if (d->spec != QDateTimePrivate::UTC)
+    else if (d->m_spec != Qt::UTC)
         utcToLocal(d->date, d->time);
 }
 
@@ -2839,7 +2817,7 @@ QString QDateTime::toString(Qt::DateFormat format) const
                                                  .arg(d->date.year());
         if (timeSpec() != Qt::LocalTime) {
             buf += QStringLiteral(" GMT");
-            if (d->spec == QDateTimePrivate::OffsetFromUTC)
+            if (d->m_spec == Qt::OffsetFromUTC)
                 buf += toOffsetString(Qt::TextDate, d->m_offsetFromUtc);
         }
         return buf;
@@ -2850,11 +2828,11 @@ QString QDateTime::toString(Qt::DateFormat format) const
             return QString();   // failed to convert
         buf += QLatin1Char('T');
         buf += d->time.toString(Qt::ISODate);
-        switch (d->spec) {
-        case QDateTimePrivate::UTC:
+        switch (d->m_spec) {
+        case Qt::UTC:
             buf += QLatin1Char('Z');
             break;
-        case QDateTimePrivate::OffsetFromUTC:
+        case Qt::OffsetFromUTC:
             buf += toOffsetString(Qt::ISODate, d->m_offsetFromUtc);
             break;
         default:
@@ -3422,10 +3400,8 @@ QDateTime QDateTime::fromMSecsSinceEpoch(qint64 msecs)
 QDateTime QDateTime::fromMSecsSinceEpoch(qint64 msecs, Qt::TimeSpec spec, int offsetSeconds)
 {
     QDateTime dt;
-    if (spec == Qt::OffsetFromUTC)
-        dt.setOffsetFromUtc(offsetSeconds);
-    else
-        dt.setTimeSpec(spec);
+    dt.detach();
+    dt.d->setTimeSpec(spec, offsetSeconds);
     dt.setMSecsSinceEpoch(msecs);
     return dt;
 }
@@ -3934,10 +3910,21 @@ QDataStream &operator<<(QDataStream &out, const QDateTime &dateTime)
         out << (qint8)dateTime.timeSpec();
     } else {
         out << dateTime.d->date << dateTime.d->time;
-        if (out.version() >= QDataStream::Qt_4_0)
-            out << (qint8)dateTime.d->spec;
+        if (out.version() >= QDataStream::Qt_4_0) {
+            switch (dateTime.d->m_spec) {
+            case Qt::UTC:
+                out << (qint8)QDateTimePrivate::UTC;
+                break;
+            case Qt::OffsetFromUTC:
+                out << (qint8)QDateTimePrivate::OffsetFromUTC;
+                break;
+            case Qt::LocalTime:
+                out << (qint8)QDateTimePrivate::LocalUnknown;
+                break;
+            }
+        }
         if (out.version() >= QDataStream::Qt_5_2
-            && dateTime.d->spec == QDateTimePrivate::OffsetFromUTC) {
+            && dateTime.d->m_spec == Qt::OffsetFromUTC) {
             out << qint32(dateTime.offsetFromUtc());
         }
     }
@@ -3963,7 +3950,7 @@ QDataStream &operator>>(QDataStream &in, QDateTime &dateTime)
         in >> ts;
         if (dateTime.isValid()) {
             // We incorrectly stored the datetime as UTC in Qt_5_0.
-            dateTime.d->spec = QDateTimePrivate::UTC;
+            dateTime.d->m_spec = Qt::UTC;
             dateTime = dateTime.toTimeSpec(static_cast<Qt::TimeSpec>(ts));
         }
     } else {
@@ -3973,14 +3960,25 @@ QDataStream &operator>>(QDataStream &in, QDateTime &dateTime)
         qint32 offset = 0;
         if (in.version() >= QDataStream::Qt_5_2 && ts == qint8(QDateTimePrivate::OffsetFromUTC))
             in >> offset;
-        dateTime.d->spec = (QDateTimePrivate::Spec)ts;
+        switch ((QDateTimePrivate::Spec)ts) {
+        case QDateTimePrivate::UTC:
+            dateTime.d->m_spec = Qt::UTC;
+            break;
+        case QDateTimePrivate::OffsetFromUTC:
+            dateTime.d->m_spec = Qt::OffsetFromUTC;
+            break;
+        case QDateTimePrivate::LocalUnknown:
+        case QDateTimePrivate::LocalStandard:
+        case QDateTimePrivate::LocalDST:
+            dateTime.d->m_spec = Qt::LocalTime;
+            break;
+        }
         dateTime.d->m_offsetFromUtc = offset;
     }
     return in;
 }
 #endif // QT_NO_DATASTREAM
 
-
 /*****************************************************************************
   Some static function used by QDate, QTime and QDateTime
 *****************************************************************************/
@@ -4224,13 +4222,13 @@ QDateTimePrivate::Spec QDateTimePrivate::getLocal(QDate &outDate, QTime &outTime
 {
     outDate = date;
     outTime = time;
-    if (spec == QDateTimePrivate::UTC)
+    if (m_spec == Qt::UTC)
         return utcToLocal(outDate, outTime);
-    if (spec == QDateTimePrivate::OffsetFromUTC) {
+    if (m_spec == Qt::OffsetFromUTC) {
         offsetToUtc(&outDate, &outTime, m_offsetFromUtc);
         return utcToLocal(outDate, outTime);
     }
-    return spec;
+    return LocalUnknown;
 }
 
 // Get current date/time in UTC and put result in outDate and outTime
@@ -4239,10 +4237,10 @@ void QDateTimePrivate::getUTC(QDate &outDate, QTime &outTime) const
     outDate = date;
     outTime = time;
 
-    if (spec == QDateTimePrivate::OffsetFromUTC)
+    if (m_spec == Qt::OffsetFromUTC)
         offsetToUtc(&outDate, &outTime, m_offsetFromUtc);
-    else if (spec != QDateTimePrivate::UTC)
-        localToUtc(outDate, outTime, (int)spec);
+    else if (m_spec != Qt::UTC)
+        localToUtc(outDate, outTime, -1);
 }
 
 #if !defined(QT_NO_DEBUG_STREAM) && !defined(QT_NO_DATESTRING)
@@ -4261,18 +4259,16 @@ QDebug operator<<(QDebug dbg, const QTime &time)
 QDebug operator<<(QDebug dbg, const QDateTime &date)
 {
     QString spec;
-    switch (date.d->spec) {
-    case QDateTimePrivate::UTC :
+    switch (date.d->m_spec) {
+    case Qt::UTC:
         spec = QStringLiteral(" Qt::UTC");
         break;
-    case QDateTimePrivate::OffsetFromUTC :
+    case Qt::OffsetFromUTC:
         spec = QString::fromUtf8(" Qt::OffsetFromUTC %1s").arg(date.offsetFromUtc());
         break;
-    case QDateTimePrivate::LocalDST :
-    case QDateTimePrivate::LocalStandard :
-    case QDateTimePrivate::LocalUnknown :
-    default :
+    case Qt::LocalTime:
         spec = QStringLiteral(" Qt::LocalTime");
+        break;
     }
     QString output = date.toString(QStringLiteral("yyyy-MM-dd HH:mm:ss.zzz t")) + spec;
     dbg.nospace() << "QDateTime(" << output << ')';
diff --git a/src/corelib/tools/qdatetime_p.h b/src/corelib/tools/qdatetime_p.h
index f765403d37..e6cece141d 100644
--- a/src/corelib/tools/qdatetime_p.h
+++ b/src/corelib/tools/qdatetime_p.h
@@ -62,19 +62,35 @@ QT_BEGIN_NAMESPACE
 class QDateTimePrivate : public QSharedData
 {
 public:
-    enum Spec { LocalUnknown = -1, LocalStandard = 0, LocalDST = 1, UTC = 2, OffsetFromUTC = 3};
+    // Never change or delete this enum, it is required for backwards compatible
+    // serialization of QDateTime before 5.2, so is essentially public API
+    enum Spec {
+        LocalUnknown = -1,
+        LocalStandard = 0,
+        LocalDST = 1,
+        UTC = 2,
+        OffsetFromUTC = 3
+    };
 
-    QDateTimePrivate() : spec(LocalUnknown), m_offsetFromUtc(0) {}
+    // Daylight Time Status
+    enum DaylightStatus {
+        NoDaylightTime,
+        UnknownDaylightTime,
+        StandardTime,
+        DaylightTime
+    };
+
+    QDateTimePrivate() : m_spec(Qt::LocalTime), m_offsetFromUtc(0) {}
     QDateTimePrivate(const QDate &toDate, const QTime &toTime, Qt::TimeSpec toSpec,
                      int offsetSeconds);
     QDateTimePrivate(const QDateTimePrivate &other)
-        : QSharedData(other), date(other.date), time(other.time), spec(other.spec),
+        : QSharedData(other), date(other.date), time(other.time), m_spec(other.m_spec),
           m_offsetFromUtc(other.m_offsetFromUtc)
     {}
 
     QDate date;
     QTime time;
-    Spec spec;
+    Qt::TimeSpec m_spec;
     int m_offsetFromUtc;
 
     // Get current date/time in LocalTime and put result in outDate and outTime
@@ -85,6 +101,8 @@ public:
     // Add msecs to given datetime and put result in utcDate and utcTime
     static void addMSecs(QDate &utcDate, QTime &utcTime, qint64 msecs);
 
+    void setTimeSpec(Qt::TimeSpec spec, int offsetSeconds);
+
     static inline qint64 minJd() { return QDate::minJd(); }
     static inline qint64 maxJd() { return QDate::maxJd(); }
 };