Handle specified time-spec in date-time parsing

When a date-time was parsed from a string, the result was equal (as a
date-time) to the correct value, but had (at least in some cases) the
wrong spec, where it should have had a spec reflecting the zone
specifier parsed.

The time-spec imposed for the benefit of QDateTimeEdit is now moved
from QDateTimeParser to QDateTimeEditPrivate, which takes over
responsibility for imposing it. QDateTimeParser assumes Qt::LocalTime
in member functions (where applicable) and uses the time-spec parsed
from the string when constructing the date-time.

QDateTime::fromString() and QLocale::toDateTime() are updated to
use the full QDateTime returned by QDateTimeParser.

Fixes: QTBUG-83075
Done-With: Edward Welbourne <edward.welbourne@qt.io>
Change-Id: I8b79add2c7fc13a200e1252d48dbfa70b36757bf
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>

6 files changed, 68 insertions, 39 deletions

diff --git a/src/corelib/text/qlocale.cpp b/src/corelib/text/qlocale.cpp
index 6e33e27276..60bfac62ab 100644
--- a/src/corelib/text/qlocale.cpp
+++ b/src/corelib/text/qlocale.cpp
@@ -2559,19 +2559,18 @@ QDateTime QLocale::toDateTime(const QString &string, const QString &format) cons
 QDateTime QLocale::toDateTime(const QString &string, const QString &format, QCalendar cal) const
 {
 #if QT_CONFIG(datetimeparser)
-    QTime time;
-    QDate date;
+    QDateTime datetime;
 
     QDateTimeParser dt(QMetaType::QDateTime, QDateTimeParser::FromString, cal);
     dt.setDefaultLocale(*this);
-    if (dt.parseFormat(format) && dt.fromString(string, &date, &time))
-        return QDateTime(date, time);
+    if (dt.parseFormat(format) && dt.fromString(string, &datetime))
+        return datetime;
 #else
     Q_UNUSED(string);
     Q_UNUSED(format);
     Q_UNUSED(cal);
 #endif
-    return QDateTime(QDate(), QTime(-1, -1, -1));
+    return QDateTime();
 }
 #endif // datestring
 
diff --git a/src/corelib/time/qdatetime.cpp b/src/corelib/time/qdatetime.cpp
index 9d95f6eb1c..36942bf68e 100644
--- a/src/corelib/time/qdatetime.cpp
+++ b/src/corelib/time/qdatetime.cpp
@@ -5537,13 +5537,12 @@ QT_WARNING_POP
 QDateTime QDateTime::fromString(const QString &string, const QString &format, QCalendar cal)
 {
 #if QT_CONFIG(datetimeparser)
-    QTime time;
-    QDate date;
+    QDateTime datetime;
 
     QDateTimeParser dt(QMetaType::QDateTime, QDateTimeParser::FromString, cal);
     // dt.setDefaultLocale(QLocale::c()); ### Qt 6
-    if (dt.parseFormat(format) && dt.fromString(string, &date, &time))
-        return QDateTime(date, time);
+    if (dt.parseFormat(format) && dt.fromString(string, &datetime))
+        return datetime;
 #else
     Q_UNUSED(string);
     Q_UNUSED(format);
diff --git a/src/corelib/time/qdatetimeparser.cpp b/src/corelib/time/qdatetimeparser.cpp
index 2a19611493..3374b28b69 100644
--- a/src/corelib/time/qdatetimeparser.cpp
+++ b/src/corelib/time/qdatetimeparser.cpp
@@ -1207,12 +1207,16 @@ QDateTimeParser::scanString(const QDateTime &defaultValue,
                 Q_ASSERT(!zoneName.isEmpty()); // sect.used > 0
                 const QByteArray latinZone(zoneName == QLatin1String("Z")
                                            ? QByteArray("UTC") : zoneName.toLatin1());
-                timeZone = QTimeZone(latinZone);
-                tspec = timeZone.isValid()
-                    ? (QTimeZone::isTimeZoneIdAvailable(latinZone)
-                       ? Qt::TimeZone
-                       : Qt::OffsetFromUTC)
-                    : (Q_ASSERT(startsWithLocalTimeZone(zoneName)), Qt::LocalTime);
+                if (latinZone.startsWith("UTC") &&
+                    (latinZone.size() == 3 || latinZone.at(3) == '+' || latinZone.at(3) == '-' )) {
+                    timeZone = QTimeZone(sect.value);
+                    tspec = sect.value ? Qt::OffsetFromUTC : Qt::UTC;
+                } else {
+                    timeZone = QTimeZone(latinZone);
+                    tspec = timeZone.isValid()
+                        ? Qt::TimeZone
+                        : (Q_ASSERT(startsWithLocalTimeZone(zoneName)), Qt::LocalTime);
+                }
 #else
                 tspec = Qt::LocalTime;
 #endif
@@ -1537,12 +1541,10 @@ QDateTimeParser::parse(QString input, int position, const QDateTime &defaultValu
         }
     }
     text = scan.input = input;
-    // Set spec *after* all checking, so validity is a property of the string:
-    scan.value = scan.value.toTimeSpec(spec);
 
     /*
-        However, even with a valid string we might have ended up with an invalid datetime:
-        the non-existent hour during dst changes, for instance.
+        We might have ended up with an invalid datetime: the non-existent hour
+        during dst changes, for instance.
     */
     if (!scan.value.isValid() && scan.state == Acceptable)
         scan.state = Intermediate;
@@ -2018,13 +2020,12 @@ QString QDateTimeParser::stateName(State s) const
 #if QT_CONFIG(datestring)
 bool QDateTimeParser::fromString(const QString &t, QDate *date, QTime *time) const
 {
-    QDateTime val(QDate(1900, 1, 1).startOfDay());
-    const StateNode tmp = parse(t, -1, val, false);
-    if (tmp.state != Acceptable || tmp.conflicts) {
+    QDateTime datetime;
+    if (!fromString(t, &datetime))
         return false;
-    }
+
     if (time) {
-        const QTime t = tmp.value.time();
+        const QTime t = datetime.time();
         if (!t.isValid()) {
             return false;
         }
@@ -2032,7 +2033,7 @@ bool QDateTimeParser::fromString(const QString &t, QDate *date, QTime *time) con
     }
 
     if (date) {
-        const QDate d = tmp.value.date();
+        const QDate d = datetime.date();
         if (!d.isValid()) {
             return false;
         }
@@ -2040,26 +2041,43 @@ bool QDateTimeParser::fromString(const QString &t, QDate *date, QTime *time) con
     }
     return true;
 }
+
+bool QDateTimeParser::fromString(const QString &t, QDateTime* datetime) const
+{
+    QDateTime val(QDate(1900, 1, 1).startOfDay());
+    const StateNode tmp = parse(t, -1, val, false);
+    if (tmp.state != Acceptable || tmp.conflicts)
+        return false;
+    if (datetime) {
+        if (!tmp.value.isValid())
+            return false;
+        *datetime = tmp.value;
+    }
+
+    return true;
+}
 #endif // datestring
 
 QDateTime QDateTimeParser::getMinimum() const
 {
-    // Cache the most common case
-    if (spec == Qt::LocalTime) {
-        static const QDateTime localTimeMin(QDATETIMEEDIT_DATE_MIN.startOfDay(Qt::LocalTime));
-        return localTimeMin;
-    }
-    return QDateTime(QDATETIMEEDIT_DATE_MIN.startOfDay(spec));
+    // NB: QDateTimeParser always uses Qt::LocalTime time spec by default. If
+    //     any subclass needs a changing time spec, it must override this
+    //     method. At the time of writing, this is done by QDateTimeEditPrivate.
+
+    // Cache the only case
+    static const QDateTime localTimeMin(QDATETIMEEDIT_DATE_MIN.startOfDay(Qt::LocalTime));
+    return localTimeMin;
 }
 
 QDateTime QDateTimeParser::getMaximum() const
 {
-    // Cache the most common case
-    if (spec == Qt::LocalTime) {
-        static const QDateTime localTimeMax(QDATETIMEEDIT_DATE_MAX.endOfDay(Qt::LocalTime));
-        return localTimeMax;
-    }
-    return QDateTime(QDATETIMEEDIT_DATE_MAX.endOfDay(spec));
+    // NB: QDateTimeParser always uses Qt::LocalTime time spec by default. If
+    //     any subclass needs a changing time spec, it must override this
+    //     method. At the time of writing, this is done by QDateTimeEditPrivate.
+
+    // Cache the only case
+    static const QDateTime localTimeMax(QDATETIMEEDIT_DATE_MAX.endOfDay(Qt::LocalTime));
+    return localTimeMax;
 }
 
 QString QDateTimeParser::getAmPmText(AmPm ap, Case cs) const
diff --git a/src/corelib/time/qdatetimeparser_p.h b/src/corelib/time/qdatetimeparser_p.h
index 5c612ef6a4..f2795c31f0 100644
--- a/src/corelib/time/qdatetimeparser_p.h
+++ b/src/corelib/time/qdatetimeparser_p.h
@@ -85,7 +85,7 @@ public:
     };
     QDateTimeParser(QMetaType::Type t, Context ctx, const QCalendar &cal = QCalendar())
         : currentSectionIndex(-1), cachedDay(-1), parserType(t),
-        fixday(false), spec(Qt::LocalTime), context(ctx), calendar(cal)
+        fixday(false), context(ctx), calendar(cal)
     {
         defaultLocale = QLocale::system();
         first.type = FirstSection;
@@ -181,6 +181,7 @@ public:
 #if QT_CONFIG(datestring)
     StateNode parse(QString input, int position, const QDateTime &defaultValue, bool fixup) const;
     bool fromString(const QString &text, QDate *date, QTime *time) const;
+    bool fromString(const QString &text, QDateTime* datetime) const;
 #endif
     bool parseFormat(const QString &format);
 
@@ -297,7 +298,6 @@ protected: // for the benefit of QDateTimeEditPrivate
     QLocale defaultLocale;
     QMetaType::Type parserType;
     bool fixday;
-    Qt::TimeSpec spec; // spec if used by QDateTimeEdit
     Context context;
     QCalendar calendar;
 };
diff --git a/src/widgets/widgets/qdatetimeedit.cpp b/src/widgets/widgets/qdatetimeedit.cpp
index d145985c1d..deb4dc36ba 100644
--- a/src/widgets/widgets/qdatetimeedit.cpp
+++ b/src/widgets/widgets/qdatetimeedit.cpp
@@ -1976,7 +1976,14 @@ QDateTime QDateTimeEditPrivate::validateAndInterpret(QString &input, int &positi
             return minimum.toDateTime();
         }
     }
+
     StateNode tmp = parse(input, position, value.toDateTime(), fixup);
+    // Impose this widget's spec:
+    tmp.value = tmp.value.toTimeSpec(spec);
+    // ... but that might turn a valid datetime into an invalid one:
+    if (!tmp.value.isValid() && tmp.state == Acceptable)
+        tmp.state = Intermediate;
+
     input = tmp.input;
     position += tmp.padded;
     state = QValidator::State(int(tmp.state));
diff --git a/src/widgets/widgets/qdatetimeedit_p.h b/src/widgets/widgets/qdatetimeedit_p.h
index 323246a87b..7df2b59710 100644
--- a/src/widgets/widgets/qdatetimeedit_p.h
+++ b/src/widgets/widgets/qdatetimeedit_p.h
@@ -98,12 +98,16 @@ public:
     {
         if (keyboardTracking)
             return minimum.toDateTime();
+        if (spec != Qt::LocalTime)
+            return QDateTime(QDATETIMEEDIT_DATE_MIN.startOfDay(spec));
         return QDateTimeParser::getMinimum();
     }
     QDateTime getMaximum() const override
     {
         if (keyboardTracking)
             return maximum.toDateTime();
+        if (spec != Qt::LocalTime)
+            return QDateTime(QDATETIMEEDIT_DATE_MIN.startOfDay(spec));
         return QDateTimeParser::getMaximum();
     }
     QLocale locale() const override { return q_func()->locale(); }
@@ -148,6 +152,8 @@ public:
 #ifdef QT_KEYPAD_NAVIGATION
     bool focusOnButton;
 #endif
+
+    Qt::TimeSpec spec = Qt::LocalTime;
 };