Aggregation: Fix crash when components are in parent-child relationship

and the child is deleted first.

Change-Id: Idea3b4a3410bda99a8727551e2cbeab3a7b95d85
Reviewed-by: Christian Stenger <christian.stenger@qt.io>
Reviewed-by: <github-actions-qt-creator@cristianadam.eu>

src/libs/aggregation/aggregate.cpp

@@ -193,6 +193,9 @@ void Aggregate::deleteSelf(QObject *obj)
         QWriteLocker locker(&lock());
         aggregateMap().remove(obj);
         m_components.removeAll(obj);
+        // Avoid issues if obj was child of another component of the aggregate.
+        // The parent is deleted in ~Aggregate and might still have a reference on obj
+        obj->setParent({});
     }
     delete this;
 }

tests/auto/aggregation/tst_aggregate.cpp

@@ -78,6 +78,24 @@ void tst_Aggregate::deleteAggregation()
     component1 = new Interface1;
     delete component1;
     QVERIFY(component1 == 0);
+
+    // do not crash if components are in a child/parent relationship
+    //    parent deleted first
+    aggregation = new Aggregation::Aggregate;
+    component1 = new Interface1;
+    component2 = new Interface2;
+    component2->setParent(component1);
+    aggregation->add(component1);
+    aggregation->add(component2);
+    delete component1;
+    //    child deleted first
+    aggregation = new Aggregation::Aggregate;
+    component1 = new Interface1;
+    component2 = new Interface2;
+    component2->setParent(component1);
+    aggregation->add(component1);
+    aggregation->add(component2);
+    delete component2;
 }
 
 void tst_Aggregate::queryAggregation()