Check that QStringView::split() w/rvalue QRegularExpression returns valid data

This test currently passes in Qt 6, but fails in Qt 5.15, thus the
QT_VERSION check.

Pick-to: 6.2 5.15
Task-number: QTBUG-98653
Change-Id: I3c7b9bc7ef74f605ff63768b38c473296274d0de
Reviewed-by: Giuseppe D'Angelo <giuseppe.dangelo@kdab.com>
Reviewed-by: Mårten Nordheim <marten.nordheim@qt.io>

tests/auto/corelib/text/qregularexpression/tst_qregularexpression.cpp

@@ -89,6 +89,7 @@ private slots:
     void threadSafety_data();
     void threadSafety();
 
+    void returnsViewsIntoOriginalString();
     void wildcard_data();
     void wildcard();
     void testInvalidWildcard_data();
@@ -2432,6 +2433,34 @@ void tst_QRegularExpression::threadSafety()
     }
 }
 
+void tst_QRegularExpression::returnsViewsIntoOriginalString()
+{
+    // https://bugreports.qt.io/browse/QTBUG-98653
+
+    auto to_void = [](const auto *p) -> const void* { return p; };
+
+    // GIVEN
+    //  a QString with dynamically-allocated data:
+    const QString string = QLatin1String("A\nA\nB\nB\n\nC\nC"); // NOT QStringLiteral!
+    const auto stringDataAddress = to_void(string.data());
+
+    //  and a view over said QString:
+    QStringView view(string);
+    const auto viewDataAddress = to_void(view.data());
+    QCOMPARE(stringDataAddress, viewDataAddress);
+
+    // WHEN
+    //  we call view.split() with a temporary QRegularExpression object
+    const auto split = view.split(QRegularExpression( "(\r\n|\n|\r)" ), Qt::KeepEmptyParts);
+
+    // THEN
+    //  the returned views should point into the underlying string:
+#if QT_VERSION < QT_VERSION_CHECK(6, 0, 0)
+    QEXPECT_FAIL("", "QTBUG-98653", Continue);
+#endif
+    QCOMPARE(to_void(split.front().data()), stringDataAddress);
+}
+
 void tst_QRegularExpression::wildcard_data()
 {
     QTest::addColumn<QString>("pattern");