Fix attached property propagation through ListView with Behavior

If the user had code like this:

    ApplicationWindow {
        // ...
        Material.theme: Material.Dark
        // ...
        ListView {
            // ...
            header: Text {
                Behavior on Material.elevation {}

The meta type that QQuickAttachedPropertyPropagator saw when looking
for the attached parent of the Text item was e.g.
QQuickMaterialStyle_QML_125. However,
QQmlMetaType::attachedPropertiesFunc only has attached property data
for QQuickMaterialStyle (i.e. attached property types created from
C++), and so it would never find the attached Material object on the
parent window and would fall back to the engine's.

Fix it by finding the first C++ meta object, which works even for
attached types created in QML.

Fixes: QTBUG-122783
Pick-to: 6.5 6.7
Change-Id: Ifd1b887b514ade4f320ace8a033d54cd16dbee1e
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>

1 files changed, 39 insertions, 0 deletions

diff --git a/tests/auto/quickcontrols/qquickmaterialstyle/data/tst_material.qml b/tests/auto/quickcontrols/qquickmaterialstyle/data/tst_material.qml
index c824ede3c3..cdd8fb41e6 100644
--- a/tests/auto/quickcontrols/qquickmaterialstyle/data/tst_material.qml
+++ b/tests/auto/quickcontrols/qquickmaterialstyle/data/tst_material.qml
@@ -1326,4 +1326,43 @@ TestCase {
         let childWindow = parentWindow.childWindow
         compare(childWindow.Material.theme, Material.Dark)
     }
+
+    Component {
+        id: themePropagationWithBehaviorComponent
+
+        ApplicationWindow {
+            width: 200
+            height: 200
+            visible: true
+
+            Material.theme: Material.Dark
+
+            property alias listView: listView
+
+            ListView {
+                id: listView
+                anchors.fill: parent
+                header: Text {
+                    text: `Material.theme for header is ${Material.theme} - should be 1`
+
+                    Rectangle {
+                        anchors.fill: parent
+                        z: -1
+                    }
+
+                    Material.elevation: 6
+                    // Having this would break the theme (QTBUG-122783)
+                    Behavior on Material.elevation {}
+                }
+            }
+        }
+    }
+
+    function test_themePropagationWithBehavior() {
+        let window = createTemporaryObject(themePropagationWithBehaviorComponent, testCase)
+        verify(window)
+
+        let headerItem = window.listView.headerItem
+        compare(headerItem.Material.theme, Material.Dark)
+    }
 }