Fix end-of-parse fixup of two-digit year in QDateTimeParser

When a date string contains day of the week, day of the month, month
and two-digit year, it was still possible to get a conflicting result
in the default century instead of a consistent result in the next (in
fact present) century.

The actual logic needed to get the right year has to take into account
all date fields. This is all worked out already in actualDate(), so
delegate to it instead of trying to make do with just the year info.

Pick-to: 6.6 6.5
Fixes: QTBUG-123579
Change-Id: Id057128d8a0af9f3a7708d0ee173f854bb1a2a8e
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Reviewed-by: Dennis Oberst <dennis.oberst@qt.io>
(cherry picked from commit 3e426182e2e8122d96b208702faaf3177f3a3081)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

2 files changed, 7 insertions, 2 deletions

diff --git a/src/corelib/time/qdatetimeparser.cpp b/src/corelib/time/qdatetimeparser.cpp
index 7c6ec272fb..d6ff29cf7f 100644
--- a/src/corelib/time/qdatetimeparser.cpp
+++ b/src/corelib/time/qdatetimeparser.cpp
@@ -1360,13 +1360,15 @@ QDateTimeParser::scanString(const QDateTime &defaultValue, bool fixup) const
 
     if (parserType != QMetaType::QTime) {
         if (year % 100 != year2digits && (isSet & YearSection2Digits)) {
+            const QDate date = actualDate(isSet, calendar, defaultCenturyStart,
+                                          year, year2digits, month, day, dayofweek);
             if (!(isSet & YearSection)) {
-                year = yearInCenturyFrom(year2digits, defaultCenturyStart);
+                year = date.year();
             } else {
                 conflicts = true;
                 const SectionNode &sn = sectionNode(currentSectionIndex);
                 if (sn.type == YearSection2Digits)
-                    year = yearInCenturyFrom(year2digits, defaultCenturyStart);
+                    year = date.year();
             }
         }
 
diff --git a/tests/auto/corelib/time/qdatetime/tst_qdatetime.cpp b/tests/auto/corelib/time/qdatetime/tst_qdatetime.cpp
index 6c0733686d..f9c6afc795 100644
--- a/tests/auto/corelib/time/qdatetime/tst_qdatetime.cpp
+++ b/tests/auto/corelib/time/qdatetime/tst_qdatetime.cpp
@@ -3117,6 +3117,9 @@ void tst_QDateTime::fromStringStringFormat_data()
                 << u"Thu January 2004"_s << u"ddd MMMM yyyy"_s << 1900
                 << QDate(2004, 1, 1).startOfDay();
     }
+    QTest::newRow("yy=24/Mar/20") // QTBUG-123579
+            << u"Wed, 20 Mar 24 16:17:00"_s << u"ddd, dd MMM yy HH:mm:ss"_s << 1900
+            << QDateTime(QDate(2024, 3, 20), QTime(16, 17));
     QTest::newRow("secs-conflict") << u"1020"_s << u"sss"_s << 1900 << QDateTime();
     QTest::newRow("secs-split-conflict")
             << u"10hello20"_s << u"ss'hello'ss"_s << 1900 << QDateTime();