5 files changed, 47 insertions, 25 deletions
diff --git a/src/corelib/time/qdatetime.cpp b/src/corelib/time/qdatetime.cpp
index e34ce71212..31206f779d 100644
--- a/src/corelib/time/qdatetime.cpp
+++ b/src/corelib/time/qdatetime.cpp
@@ -386,7 +386,7 @@ static constexpr int daysInUsualMonth(int month) // (February isn't usual.)
     for technical reasons limited to between -784350574879 and 784354017364,
     which means from before 2 billion BCE to after 2 billion CE.
 
-    \sa QTime, QDateTime, QDateEdit, QDateTimeEdit, QCalendarWidget
+    \sa QTime, QDateTime, QDateTime::YearRange, QDateEdit, QDateTimeEdit, QCalendarWidget
 */
 
 /*!
@@ -2464,7 +2464,7 @@ static int qt_timezone()
         // - It also takes DST into account, so we need to adjust it to always
         //   get the Standard Time offset.
         return -t.tm_gmtoff + (t.tm_isdst ? (long)SECS_PER_HOUR : 0L);
-#elif defined(Q_OS_INTEGRITY)
+#elif defined(Q_OS_INTEGRITY) || defined(Q_OS_RTEMS)
         return 0;
 #else
         return timezone;
@@ -3272,9 +3272,10 @@ inline qint64 QDateTimePrivate::zoneMSecsToEpochMSecs(qint64 zoneMSecs, const QT
     provides functions for comparing datetimes and for manipulating a
     datetime by adding a number of seconds, days, months, or years.
 
-    QDateTime can describe datetimes with respect to \l{Qt::LocalTime}{local
-    time}, to \l{Qt::UTC}{UTC}, to a specified \l{Qt::OffsetFromUTC}{offset
-    from UTC} or to a specified \l{{Qt::TimeZone}{time zone}, in conjunction
+    QDateTime can describe datetimes with respect to
+    \l{Qt::LocalTime}{local time}, to \l{Qt::UTC}{UTC}, to a specified
+    \l{Qt::OffsetFromUTC}{offset from UTC} or to a specified
+    \l{Qt::TimeZone}{time zone}, in conjunction
     with the QTimeZone class. For example, a time zone of "Europe/Berlin" will
     apply the daylight-saving rules as used in Germany since 1970. In contrast,
     an offset from UTC of +3600 seconds is one hour ahead of UTC (usually
@@ -3387,6 +3388,25 @@ inline qint64 QDateTimePrivate::zoneMSecsToEpochMSecs(qint64 zoneMSecs, const QT
 */
 
 /*!
+    \enum QDateTime::YearRange
+
+    This enumerated type describes the range of years (in the Gregorian
+    calendar) representable by QDateTime:
+
+    \value First The later parts of this year are representable
+    \value Last The earlier parts of this year are representable
+
+    All dates strictly between these two years are also representable.
+    Note, however, that the Gregorian Calendar has no year zero.
+
+    \note QDate can describe dates in a wider range of years.  For most
+    purposes, this makes little difference, as the range of years that QDateTime
+    can support reaches 292 million years either side of 1970.
+
+    \sa isValid(), QDate
+*/
+
+/*!
     Constructs a null datetime (i.e. null date and null time). A null
     datetime is invalid, since the date is invalid.
 
@@ -3534,7 +3554,7 @@ bool QDateTime::isNull() const
     hour, i.e. if the transition is at 2am and the clock goes forward to 3am
     then the time from 02:00:00 to 02:59:59.999 is considered to be invalid.
 
-    \sa QDate::isValid(), QTime::isValid()
+    \sa QDateTime::YearRange, QDate::isValid(), QTime::isValid()
 */
 
 bool QDateTime::isValid() const
diff --git a/src/corelib/time/qdatetime.h b/src/corelib/time/qdatetime.h
index 3e3b953b52..89ea4ee24a 100644
--- a/src/corelib/time/qdatetime.h
+++ b/src/corelib/time/qdatetime.h
@@ -384,6 +384,10 @@ public:
     NSDate *toNSDate() const Q_DECL_NS_RETURNS_AUTORELEASED;
 #endif
 
+    // (1<<63) ms is 292277024.6 (average Gregorian) years, counted from the start of 1970, so
+    // Last is floor(1970 + 292277024.6); no year 0, so First is floor(1970 - 1 - 292277024.6)
+    enum class YearRange : qint32 { First = -292275056,  Last = +292278994 };
+
 private:
     friend class QDateTimePrivate;
 
diff --git a/src/corelib/time/qdatetime_p.h b/src/corelib/time/qdatetime_p.h
index 6018f8f7b0..6e4120d762 100644
--- a/src/corelib/time/qdatetime_p.h
+++ b/src/corelib/time/qdatetime_p.h
@@ -140,10 +140,6 @@ public:
     // Inlined for its one caller in qdatetime.cpp
     inline void setUtcOffsetByTZ(qint64 atMSecsSinceEpoch);
 #endif // timezone
-
-    // ### Qt 5.14: expose publicly in QDateTime
-    // The first and last years of which QDateTime can represent some part:
-    enum class YearRange : qint32 { First = -292275056,  Last = +292278994 };
 };
 
 QT_END_NAMESPACE
diff --git a/src/corelib/time/qdatetimeparser.cpp b/src/corelib/time/qdatetimeparser.cpp
index 728b066db1..fc369bae75 100644
--- a/src/corelib/time/qdatetimeparser.cpp
+++ b/src/corelib/time/qdatetimeparser.cpp
@@ -621,11 +621,11 @@ int QDateTimeParser::sectionMaxSize(Section s, int count) const
     case LastSection: return 0;
 
     case AmPmSection: {
-        const int lowerMax = qMin(getAmPmText(AmText, LowerCase).size(),
+        const int lowerMax = qMax(getAmPmText(AmText, LowerCase).size(),
                                   getAmPmText(PmText, LowerCase).size());
-        const int upperMax = qMin(getAmPmText(AmText, UpperCase).size(),
+        const int upperMax = qMax(getAmPmText(AmText, UpperCase).size(),
                                   getAmPmText(PmText, UpperCase).size());
-        return qMin(4, qMin(lowerMax, upperMax));
+        return qMax(lowerMax, upperMax);
     }
 
     case Hour24Section:
@@ -1664,13 +1664,16 @@ QDateTimeParser::findTimeZone(QStringRef str, const QDateTime &when,
 /*!
   \internal
 
-  Returns
-  AM if str == tr("AM")
-  PM if str == tr("PM")
-  PossibleAM if str can become tr("AM")
-  PossiblePM if str can become tr("PM")
-  PossibleBoth if str can become tr("PM") and can become tr("AM")
-  Neither if str can't become anything sensible
+  Compares str to the am/pm texts returned by getAmPmText().
+  Returns AM or PM if str is one of those texts. Failing that, it looks to see
+  whether, ignoring spaces and case, each character of str appears in one of
+  the am/pm texts.
+  If neither text can be the result of the user typing more into str, returns
+  Neither. If both texts are possible results of further typing, returns
+  PossibleBoth. Otherwise, only one of them is a possible completion, so this
+  returns PossibleAM or PossiblePM to indicate which.
+
+  \sa getAmPmText()
 */
 QDateTimeParser::AmPmFinder QDateTimeParser::findAmPm(QString &str, int sectionIndex, int *used) const
 {
@@ -1699,10 +1702,10 @@ QDateTimeParser::AmPmFinder QDateTimeParser::findAmPm(QString &str, int sectionI
 
     QDTPDEBUG << "findAmPm" << str << ampm[0] << ampm[1];
 
-    if (str.indexOf(ampm[amindex], 0, Qt::CaseInsensitive) == 0) {
+    if (str.startsWith(ampm[amindex], Qt::CaseInsensitive)) {
         str = ampm[amindex];
         return AM;
-    } else if (str.indexOf(ampm[pmindex], 0, Qt::CaseInsensitive) == 0) {
+    } else if (str.startsWith(ampm[pmindex], Qt::CaseInsensitive)) {
         str = ampm[pmindex];
         return PM;
     } else if (context == FromString || (str.count(space) == 0 && str.size() >= size)) {
diff --git a/src/corelib/time/qtimezoneprivate_tz.cpp b/src/corelib/time/qtimezoneprivate_tz.cpp
index f62d7998c8..3c2695a789 100644
--- a/src/corelib/time/qtimezoneprivate_tz.cpp
+++ b/src/corelib/time/qtimezoneprivate_tz.cpp
@@ -39,7 +39,6 @@
 
 #include "qtimezone.h"
 #include "qtimezoneprivate_p.h"
-#include "qdatetime_p.h" // ### Qt 5.14: remove once YearRange is on QDateTime
 #include "private/qlocale_tools_p.h"
 
 #include <QtCore/QFile>
@@ -589,8 +588,8 @@ static QVector<QTimeZonePrivate::Data> calculatePosixTransitions(const QByteArra
         stdTime = QTime(2, 0, 0);
 
     // Limit year to the range QDateTime can represent:
-    const int minYear = int(QDateTimePrivate::YearRange::First);
-    const int maxYear = int(QDateTimePrivate::YearRange::Last);
+    const int minYear = int(QDateTime::YearRange::First);
+    const int maxYear = int(QDateTime::YearRange::Last);
     startYear = qBound(minYear, startYear, maxYear);
     endYear = qBound(minYear, endYear, maxYear);
     Q_ASSERT(startYear <= endYear);