Fix QQuickControlPrivate::getContentItem() overrides

When no content item is explicitly assigned, container type of controls
(Page, Pane, Popup...) create a default content item on demand. Notice
that the content item is created from within the contentItem() getter,
so it must not emit contentItemChanged() to avoid binding loops.

QQuickControl::setContentItem_helper() was introduced in 1eaebd0 to
mitigate basically the same problem with QQuickScrollView, which has
its own special lazy creation of a Flickable content item.

Now, the problem is that the other container controls are not executing
setContentItem_helper(), because they have already assigned contentItem
and therefore it returns right away. Fix the issue by returning the new
content item without assigning it to let setContentItem_helper() do its
job. The issue was spotted while debugging QTBUG-61434.

Change-Id: Id6f84748ec08bbdfd3bd934dda627e2619af7d2a
Reviewed-by: Mitch Curtis <mitch.curtis@qt.io>

4 files changed, 8 insertions, 12 deletions

diff --git a/src/quicktemplates2/qquickpage.cpp b/src/quicktemplates2/qquickpage.cpp
index 40d47cda..ecc5a9c9 100644
--- a/src/quicktemplates2/qquickpage.cpp
+++ b/src/quicktemplates2/qquickpage.cpp
@@ -107,7 +107,7 @@ QQuickItem *QQuickPagePrivate::getContentItem()
 {
     Q_Q(QQuickPage);
     if (!contentItem)
-        contentItem = new QQuickItem(q);
+        return new QQuickItem(q);
     return contentItem;
 }
 
@@ -298,8 +298,7 @@ void QQuickPage::setContentHeight(qreal height)
 */
 QQmlListProperty<QObject> QQuickPage::contentData()
 {
-    Q_D(QQuickPage);
-    return QQmlListProperty<QObject>(d->getContentItem(), nullptr,
+    return QQmlListProperty<QObject>(contentItem(), nullptr,
                                      QQuickItemPrivate::data_append,
                                      QQuickItemPrivate::data_count,
                                      QQuickItemPrivate::data_at,
@@ -321,8 +320,7 @@ QQmlListProperty<QObject> QQuickPage::contentData()
 */
 QQmlListProperty<QQuickItem> QQuickPage::contentChildren()
 {
-    Q_D(QQuickPage);
-    return QQmlListProperty<QQuickItem>(d->getContentItem(), nullptr,
+    return QQmlListProperty<QQuickItem>(contentItem(), nullptr,
                                         QQuickItemPrivate::children_append,
                                         QQuickItemPrivate::children_count,
                                         QQuickItemPrivate::children_at,
diff --git a/src/quicktemplates2/qquickpane.cpp b/src/quicktemplates2/qquickpane.cpp
index efa85e0c..b89131c4 100644
--- a/src/quicktemplates2/qquickpane.cpp
+++ b/src/quicktemplates2/qquickpane.cpp
@@ -114,7 +114,7 @@ QQuickItem *QQuickPanePrivate::getContentItem()
 {
     Q_Q(QQuickPane);
     if (!contentItem)
-        contentItem = new QQuickItem(q);
+        return new QQuickItem(q);
     return contentItem;
 }
 
@@ -206,8 +206,7 @@ void QQuickPane::setContentHeight(qreal height)
 */
 QQmlListProperty<QObject> QQuickPane::contentData()
 {
-    Q_D(QQuickPane);
-    return QQmlListProperty<QObject>(d->getContentItem(), nullptr,
+    return QQmlListProperty<QObject>(contentItem(), nullptr,
                                      QQuickItemPrivate::data_append,
                                      QQuickItemPrivate::data_count,
                                      QQuickItemPrivate::data_at,
@@ -229,8 +228,7 @@ QQmlListProperty<QObject> QQuickPane::contentData()
 */
 QQmlListProperty<QQuickItem> QQuickPane::contentChildren()
 {
-    Q_D(QQuickPane);
-    return QQmlListProperty<QQuickItem>(d->getContentItem(), nullptr,
+    return QQmlListProperty<QQuickItem>(contentItem(), nullptr,
                                         QQuickItemPrivate::children_append,
                                         QQuickItemPrivate::children_count,
                                         QQuickItemPrivate::children_at,
diff --git a/src/quicktemplates2/qquickpopup.cpp b/src/quicktemplates2/qquickpopup.cpp
index c457b347..ce4072e5 100644
--- a/src/quicktemplates2/qquickpopup.cpp
+++ b/src/quicktemplates2/qquickpopup.cpp
@@ -261,6 +261,7 @@ void QQuickPopupPrivate::init()
     popupItem->setVisible(false);
     q->setParentItem(qobject_cast<QQuickItem *>(parent));
     QObject::connect(popupItem, &QQuickControl::paddingChanged, q, &QQuickPopup::paddingChanged);
+    QObject::connect(popupItem, &QQuickControl::contentItemChanged, q, &QQuickPopup::contentItemChanged);
     positioner = new QQuickPopupPositioner(q);
 }
 
@@ -2027,7 +2028,6 @@ void QQuickPopup::contentItemChange(QQuickItem *newItem, QQuickItem *oldItem)
 {
     Q_UNUSED(newItem);
     Q_UNUSED(oldItem);
-    emit contentItemChanged();
 }
 
 void QQuickPopup::fontChange(const QFont &newFont, const QFont &oldFont)
diff --git a/src/quicktemplates2/qquickpopupitem.cpp b/src/quicktemplates2/qquickpopupitem.cpp
index 952c2db6..6f9d7697 100644
--- a/src/quicktemplates2/qquickpopupitem.cpp
+++ b/src/quicktemplates2/qquickpopupitem.cpp
@@ -96,7 +96,7 @@ QQuickItem *QQuickPopupItemPrivate::getContentItem()
 {
     Q_Q(QQuickPopupItem);
     if (!contentItem)
-        contentItem = new QQuickItem(q);
+        return new QQuickItem(q);
     return contentItem;
 }