1 files changed, 33 insertions, 28 deletions

diff --git a/src/corelib/tools/qdatetime.cpp b/src/corelib/tools/qdatetime.cpp
index 56f715e5c8..6620c55a0f 100644
--- a/src/corelib/tools/qdatetime.cpp
+++ b/src/corelib/tools/qdatetime.cpp
@@ -894,7 +894,7 @@ QString QDate::toString(Qt::DateFormat format) const
     case Qt::DefaultLocaleLongDate:
         return QLocale().toString(*this, QLocale::LongFormat);
     case Qt::RFC2822Date:
-        return toString(QStringLiteral("dd MMM yyyy"));
+        return QLocale::c().toString(*this, QStringLiteral("dd MMM yyyy"));
     default:
 #ifndef QT_NO_TEXTDATE
     case Qt::TextDate:
@@ -1641,9 +1641,6 @@ QString QTime::toString(Qt::DateFormat format) const
     case Qt::DefaultLocaleLongDate:
         return QLocale().toString(*this, QLocale::LongFormat);
     case Qt::RFC2822Date:
-        return QString::fromLatin1("%1:%2:%3").arg(hour(), 2, 10, QLatin1Char('0'))
-                                              .arg(minute(), 2, 10, QLatin1Char('0'))
-                                              .arg(second(), 2, 10, QLatin1Char('0'));
     case Qt::ISODate:
     case Qt::TextDate:
     default:
@@ -3551,27 +3548,8 @@ QString QDateTime::toString(Qt::DateFormat format) const
     case Qt::DefaultLocaleLongDate:
         return QLocale().toString(*this, QLocale::LongFormat);
     case Qt::RFC2822Date: {
-        buf = toString(QStringLiteral("dd MMM yyyy hh:mm:ss "));
-
-        int utcOffset = d->m_offsetFromUtc;
-        if (timeSpec() == Qt::LocalTime) {
-            QDateTime utc = toUTC();
-            utc.setTimeSpec(timeSpec());
-            utcOffset = utc.secsTo(*this);
-        }
-
-        const int offset = qAbs(utcOffset);
-        buf += QLatin1Char((offset == utcOffset) ? '+' : '-');
-
-        const int hour = offset / 3600;
-        if (hour < 10)
-            buf += QLatin1Char('0');
-        buf += QString::number(hour);
-
-        const int min = (offset - (hour * 3600)) / 60;
-        if (min < 10)
-            buf += QLatin1Char('0');
-        buf += QString::number(min);
+        buf = QLocale::c().toString(*this, QStringLiteral("dd MMM yyyy hh:mm:ss "));
+        buf += toOffsetString(Qt::TextDate, d->m_offsetFromUtc);
         return buf;
     }
     default:
@@ -3924,7 +3902,16 @@ qint64 QDateTime::msecsTo(const QDateTime &other) const
 
 QDateTime QDateTime::toTimeSpec(Qt::TimeSpec spec) const
 {
-    return fromMSecsSinceEpoch(toMSecsSinceEpoch(), spec, 0);
+    if (d->m_spec == spec && (spec == Qt::UTC || spec == Qt::LocalTime))
+        return *this;
+
+    if (!isValid()) {
+        QDateTime ret = *this;
+        ret.setTimeSpec(spec);
+        return ret;
+    }
+
+    return fromMSecsSinceEpoch(d->toMSecsSinceEpoch(), spec, 0);
 }
 
 /*!
@@ -3942,7 +3929,16 @@ QDateTime QDateTime::toTimeSpec(Qt::TimeSpec spec) const
 
 QDateTime QDateTime::toOffsetFromUtc(int offsetSeconds) const
 {
-    return fromMSecsSinceEpoch(toMSecsSinceEpoch(), Qt::OffsetFromUTC, offsetSeconds);
+    if (d->m_spec == Qt::OffsetFromUTC && d->m_offsetFromUtc == offsetSeconds)
+        return *this;
+
+    if (!isValid()) {
+        QDateTime ret = *this;
+        ret.setOffsetFromUtc(offsetSeconds);
+        return ret;
+    }
+
+    return fromMSecsSinceEpoch(d->toMSecsSinceEpoch(), Qt::OffsetFromUTC, offsetSeconds);
 }
 
 #ifndef QT_BOOTSTRAPPED
@@ -3956,7 +3952,16 @@ QDateTime QDateTime::toOffsetFromUtc(int offsetSeconds) const
 
 QDateTime QDateTime::toTimeZone(const QTimeZone &timeZone) const
 {
-    return fromMSecsSinceEpoch(toMSecsSinceEpoch(), timeZone);
+    if (d->m_spec == Qt::TimeZone && d->m_timeZone == timeZone)
+        return *this;
+
+    if (!isValid()) {
+        QDateTime ret = *this;
+        ret.setTimeZone(timeZone);
+        return ret;
+    }
+
+    return fromMSecsSinceEpoch(d->toMSecsSinceEpoch(), timeZone);
 }
 #endif // QT_BOOTSTRAPPED