Prevent crash when destroying asynchronous Loader

Fixes: QTBUG-86255
Pick-to: 5.15
Change-Id: I30488b64d910a1409a43e2e98ee7ab084aec33d2
Reviewed-by: Ulf Hermann <ulf.hermann@qt.io>

2 files changed, 68 insertions, 0 deletions

diff --git a/tests/auto/quick/qquickgridview/data/qtbug86255.qml b/tests/auto/quick/qquickgridview/data/qtbug86255.qml
new file mode 100644
index 0000000000..20688b1967
--- /dev/null
+++ b/tests/auto/quick/qquickgridview/data/qtbug86255.qml
@@ -0,0 +1,55 @@
+import QtQuick 2.15
+
+Item {
+    width: 240
+    height: 320
+
+    GridView {
+        id: grid
+        objectName: "view"
+        anchors.fill: parent
+        cellWidth: 64
+        cellHeight: 64
+        model: ListModel {
+            id: listModel
+
+            Component.onCompleted: reload()
+
+            function reload() {
+                clear();
+                for (let i = 0; i < 1000; i++) {
+                    let magic = Math.random();
+                    append( { magic } );
+                }
+            }
+        }
+        clip: true
+        delegate: Item {
+            id: d
+            property string val: magic
+            Loader {
+                property alias value: d.val
+                asynchronous: true
+                sourceComponent: cmp
+            }
+        }
+    }
+
+    Timer {
+        running: true
+        interval: 1000
+        onTriggered: listModel.reload()
+    }
+    Timer {
+        running: true
+        interval: 500
+        onTriggered: grid.flick(0, -4000)
+    }
+
+    Component {
+        id: cmp
+        Text {
+            text: value
+        }
+    }
+}
diff --git a/tests/auto/quick/qquickgridview/tst_qquickgridview.cpp b/tests/auto/quick/qquickgridview/tst_qquickgridview.cpp
index 81b76cec25..323513400a 100644
--- a/tests/auto/quick/qquickgridview/tst_qquickgridview.cpp
+++ b/tests/auto/quick/qquickgridview/tst_qquickgridview.cpp
@@ -213,6 +213,7 @@ private slots:
     void QTBUG_45640();
     void QTBUG_49218();
     void QTBUG_48870_fastModelUpdates();
+    void QTBUG_86255();
 
     void keyNavigationEnabled();
     void releaseItems();
@@ -6795,6 +6796,18 @@ void tst_QQuickGridView::QTBUG_48870_fastModelUpdates()
     }
 }
 
+void tst_QQuickGridView::QTBUG_86255()
+{
+    QScopedPointer<QQuickView> window(createView());
+    window->setSource(testFileUrl("qtbug86255.qml"));
+    window->show();
+    QVERIFY(QTest::qWaitForWindowExposed(window.data()));
+    QQuickGridView *view = findItem<QQuickGridView>(window->rootObject(), "view");
+    QVERIFY(view != nullptr);
+    QTRY_COMPARE(view->isFlicking(), true);
+    QTRY_COMPARE(view->isFlicking(), false);
+}
+
 void tst_QQuickGridView::releaseItems()
 {
     QScopedPointer<QQuickView> view(createView());