Generalize role selection mechanism from QQuickComboBox

We can have QQmlDelegateModel pick specific roles from model items. That
can easily be done for variant maps, variant hashes, objects and
gadgets. We would like to do it for anything that has a
QMetaAssociation, but as we cannot get to the original type at that
place, it's currently not possible.

The special case about variant maps with exactly one item in variant
lists is clearly insane and therefore not included in the
generalization.

This requires some cleanup in the QQmlGadgetPointerWrapper. Passing the
wrapper itself to QMetaProperty::read() has always been a rather obscure
way of reading from the gadget.

Fixes: QTBUG-102983
Change-Id: I84ecef980783e7137aa4d77070ddce47b6ead260
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>
(cherry picked from commit d0c7c7234cb7629fbe7a04944cb5191414cc72b9)

1 files changed, 3 insertions, 4 deletions

diff --git a/tests/auto/qml/qqmlproperty/tst_qqmlproperty.cpp b/tests/auto/qml/qqmlproperty/tst_qqmlproperty.cpp
index 402a68afae..5d426cff4f 100644
--- a/tests/auto/qml/qqmlproperty/tst_qqmlproperty.cpp
+++ b/tests/auto/qml/qqmlproperty/tst_qqmlproperty.cpp
@@ -1943,8 +1943,8 @@ void tst_qqmlproperty::variantMapHandling()
 
 void tst_qqmlproperty::crashOnValueProperty()
 {
-    QQmlEngine *engine = new QQmlEngine;
-    QQmlComponent component(engine);
+    QScopedPointer<QQmlEngine> engine(new QQmlEngine);
+    QQmlComponent component(engine.data());
 
     component.setData("import Test 1.0\nPropertyObject { wrectProperty.x: 10 }", QUrl());
     QScopedPointer<QObject> object(component.create());
@@ -1957,8 +1957,7 @@ void tst_qqmlproperty::crashOnValueProperty()
     QCOMPARE(p.read(), QVariant(10));
 
     //don't crash once the engine is deleted
-    delete engine;
-    engine = nullptr;
+    engine.reset();
 
     QCOMPARE(p.propertyTypeName(), "int");
     QCOMPARE(p.read(), QVariant(10));