QAccessibleComboBox: Cleanup comboBox() calls

Handle comboBox() returning nullptr.
Avoid repeated qobject_cast by calling comboBox() once per function.

Fixes: QTBUG-115161
Pick-to: 6.5 6.2
Change-Id: I3d102cebe807da379fa4d9ee2aee1e72b8fdf004
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>
(cherry picked from commit fc556e3571b7e2d7fe307778b17e6cf0ff9e1bfc)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

src/widgets/accessible/complexwidgets.cpp

@@ -283,17 +283,19 @@ QAccessibleComboBox::QAccessibleComboBox(QWidget *w)
 */
 QComboBox *QAccessibleComboBox::comboBox() const
 {
-    return qobject_cast<QComboBox*>(object());
+    return qobject_cast<QComboBox *>(object());
 }
 
 QAccessibleInterface *QAccessibleComboBox::child(int index) const
 {
+    if (QComboBox *cBox = comboBox()) {
         if (index == 0) {
-        QAbstractItemView *view = comboBox()->view();
+            QAbstractItemView *view = cBox->view();
             //QWidget *parent = view ? view->parentWidget() : 0;
             return QAccessible::queryAccessibleInterface(view);
-    } else if (index == 1 && comboBox()->isEditable()) {
+        } else if (index == 1 && cBox->isEditable()) {
-        return QAccessible::queryAccessibleInterface(comboBox()->lineEdit());
+            return QAccessible::queryAccessibleInterface(cBox->lineEdit());
+        }
     }
     return nullptr;
 }
@@ -301,22 +303,28 @@ QAccessibleInterface *QAccessibleComboBox::child(int index) const
 int QAccessibleComboBox::childCount() const
 {
     // list and text edit
-    return comboBox()->isEditable() ? 2 : 1;
+    if (QComboBox *cBox = comboBox())
+        return (cBox->isEditable()) ? 2 : 1;
+    return 0;
 }
 
 QAccessibleInterface *QAccessibleComboBox::childAt(int x, int y) const
 {
-    if (comboBox()->isEditable() && comboBox()->lineEdit()->rect().contains(x, y))
+    if (QComboBox *cBox = comboBox()) {
+        if (cBox->isEditable() && cBox->lineEdit()->rect().contains(x, y))
             return child(1);
+    }
     return nullptr;
 }
 
 int QAccessibleComboBox::indexOfChild(const QAccessibleInterface *child) const
 {
-    if (comboBox()->view() == child->object())
+    if (QComboBox *cBox = comboBox()) {
+        if (cBox->view() == child->object())
             return 0;
-    if (comboBox()->isEditable() && comboBox()->lineEdit() == child->object())
+        if (cBox->isEditable() && cBox->lineEdit() == child->object())
             return 1;
+    }
     return -1;
 }
 
@@ -325,8 +333,10 @@ QAccessibleInterface *QAccessibleComboBox::focusChild() const
     // The editable combobox is the focus proxy of its lineedit, so the
     // lineedit itself never gets focus. But it is the accessible focus
     // child of an editable combobox.
-    if (comboBox()->isEditable())
+    if (QComboBox *cBox = comboBox()) {
+        if (cBox->isEditable())
             return child(1);
+    }
     return nullptr;
 }
 
@@ -334,7 +344,7 @@ QAccessibleInterface *QAccessibleComboBox::focusChild() const
 QString QAccessibleComboBox::text(QAccessible::Text t) const
 {
     QString str;
-
+    if (QComboBox *cBox = comboBox()) {
         switch (t) {
         case QAccessible::Name:
 #ifndef Q_OS_UNIX // on Linux we use relations for this, name is text (fall through to Value)
@@ -342,10 +352,10 @@ QString QAccessibleComboBox::text(QAccessible::Text t) const
         break;
 #endif
         case QAccessible::Value:
-        if (comboBox()->isEditable())
+            if (cBox->isEditable())
-            str = comboBox()->lineEdit()->text();
+                str = cBox->lineEdit()->text();
             else
-            str = comboBox()->currentText();
+                str = cBox->currentText();
             break;
 #ifndef QT_NO_SHORTCUT
         case QAccessible::Accelerator:
@@ -357,6 +367,7 @@ QString QAccessibleComboBox::text(QAccessible::Text t) const
         }
         if (str.isEmpty())
             str = QAccessibleWidget::text(t);
+    }
     return str;
 }
 
@@ -364,10 +375,11 @@ QAccessible::State QAccessibleComboBox::state() const
 {
     QAccessible::State s = QAccessibleWidget::state();
 
+    if (QComboBox *cBox = comboBox()) {
         s.expandable = true;
-    s.expanded = isValid() && comboBox()->view()->isVisible();
+        s.expanded = isValid() && cBox->view()->isVisible();
-    s.editable = comboBox()->isEditable();
+        s.editable = cBox->isEditable();
-
+    }
     return s;
 }
 
@@ -385,18 +397,19 @@ QString QAccessibleComboBox::localizedActionDescription(const QString &actionNam
 
 void QAccessibleComboBox::doAction(const QString &actionName)
 {
+    if (QComboBox *cBox = comboBox()) {
         if (actionName == showMenuAction() || actionName == pressAction()) {
-        if (comboBox()->view()->isVisible()) {
+            if (cBox->view()->isVisible()) {
 #if defined(Q_OS_ANDROID)
                 const auto list = child(0)->tableInterface();
                 if (list && list->selectedRowCount() > 0) {
-                comboBox()->setCurrentIndex(list->selectedRows().at(0));
+                    cBox->setCurrentIndex(list->selectedRows().at(0));
                 }
-            comboBox()->setFocus();
+                cBox->setFocus();
 #endif
-            comboBox()->hidePopup();
+                cBox->hidePopup();
             } else {
-            comboBox()->showPopup();
+                cBox->showPopup();
 #if defined(Q_OS_ANDROID)
                 const auto list = child(0)->tableInterface();
                 if (list && list->selectedRowCount() > 0) {
@@ -407,6 +420,7 @@ void QAccessibleComboBox::doAction(const QString &actionName)
 #endif
             }
         }
+    }
 }
 
 QStringList QAccessibleComboBox::keyBindingsForAction(const QString &/*actionName*/) const