Cancel incubation recursively

It turns out that cancelling the incubation of eg. a combobox popup
alone is not enough when its children might be incubating and would
be left incorrectly guarded. Cancel recursively the whole object
tree of a replaced/destroyed delegate to avoid that.

Task-number: QTBUG-50992
Change-Id: Ia06931c4c7af3ed8bb56af6c29eb51081c4fccbb
Reviewed-by: J-P Nurmi <jpnurmi@qt.io>

1 files changed, 15 insertions, 3 deletions

diff --git a/src/quicktemplates2/qquickcontrol.cpp b/src/quicktemplates2/qquickcontrol.cpp
index b673a424..eb66f313 100644
--- a/src/quicktemplates2/qquickcontrol.cpp
+++ b/src/quicktemplates2/qquickcontrol.cpp
@@ -866,12 +866,24 @@ QLocale QQuickControlPrivate::calcLocale(const QQuickItem *item)
 }
 
 /*
-    Cancels incubation to avoid "Object destroyed during incubation" (QTBUG-50992)
+    Cancels incubation recursively to avoid "Object destroyed during incubation" (QTBUG-50992)
 */
+static void cancelIncubation(QObject *object, QQmlContext *context)
+{
+    const auto children = object->children();
+    for (QObject *child : children)
+        cancelIncubation(child, context);
+    QQmlIncubatorPrivate::cancel(object, context);
+}
+
 void QQuickControlPrivate::destroyDelegate(QObject *delegate, QObject *parent)
 {
-    if (delegate && parent)
-        QQmlIncubatorPrivate::cancel(delegate, qmlContext(parent));
+    if (!delegate)
+        return;
+
+    QQmlContext *context = parent ? qmlContext(parent) : nullptr;
+    if (context)
+        cancelIncubation(delegate, context);
     delete delegate;
 }