QFontComboBox don't response qApp fontDatabaseChanged()

If QFontComboBox is instantiated in the form of new and call
QFontDatabase::addApplicationFont, QFontComboBoxPrivate::_q_updateModel()
will be called when the program exits, at this time qApp will crash.
Fix this by when program exiting, QFontComboBoxPrivate don't need
call _q_updateModel().

Fixes: QTBUG-98099
Done-With: Konstantin Ritt <ritt.ks@gmail.com>
Change-Id: I3df3d19c3d1971288d60f2eef386262befbf396b
Reviewed-by: Konstantin Ritt <ritt.ks@gmail.com>
Reviewed-by: Eskil Abrahamsen Blomfeldt <eskil.abrahamsen-blomfeldt@qt.io>
(cherry picked from commit 9a131b59ee561e300fb6078886a85dd7b3c53599)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

2 files changed, 12 insertions, 5 deletions

diff --git a/src/widgets/widgets/qfontcombobox.cpp b/src/widgets/widgets/qfontcombobox.cpp
index 59f499db8e..4eee66906d 100644
--- a/src/widgets/widgets/qfontcombobox.cpp
+++ b/src/widgets/widgets/qfontcombobox.cpp
@@ -313,6 +313,10 @@ public:
 void QFontComboBoxPrivate::_q_updateModel()
 {
     Q_Q(QFontComboBox);
+
+    if (QCoreApplication::closingDown())
+        return;
+
     const int scalableMask = (QFontComboBox::ScalableFonts | QFontComboBox::NonScalableFonts);
     const int spacingMask = (QFontComboBox::ProportionalFonts | QFontComboBox::MonospacedFonts);
 
diff --git a/tests/auto/widgets/widgets/qfontcombobox/tst_qfontcombobox.cpp b/tests/auto/widgets/widgets/qfontcombobox/tst_qfontcombobox.cpp
index bd3ea5686a..75f595e959 100644
--- a/tests/auto/widgets/widgets/qfontcombobox/tst_qfontcombobox.cpp
+++ b/tests/auto/widgets/widgets/qfontcombobox/tst_qfontcombobox.cpp
@@ -261,15 +261,18 @@ void tst_QFontComboBox::writingSystem()
 // protected void currentFontChanged(QFont const& f)
 void tst_QFontComboBox::currentFontChanged()
 {
-    SubQFontComboBox box;
-    QSignalSpy spy0(&box, SIGNAL(currentFontChanged(QFont)));
+    // The absence of this file does not affect the test results
+    QFontDatabase::addApplicationFont("ArianaVioleta-dz2K.ttf");
+
+    SubQFontComboBox *box = new SubQFontComboBox;
+    QSignalSpy spy0(box, SIGNAL(currentFontChanged(QFont)));
 
-    if (box.model()->rowCount() > 2) {
-        QTest::keyPress(&box, Qt::Key_Down);
+    if (box->model()->rowCount() > 2) {
+        QTest::keyPress(box, Qt::Key_Down);
         QCOMPARE(spy0.count(), 1);
 
         QFont f( "Sans Serif" );
-        box.setCurrentFont(f);
+        box->setCurrentFont(f);
         QCOMPARE(spy0.count(), 2);
     } else
         qWarning("Not enough fonts installed on test system. Consider adding some");