QML engine: Fix binding setup

We set QProperty bindings up in the wrong way: Parent components would
overwrite their child component's binding. This patch reverses the
order, fixing the bug.

Task-number: QTBUG-87153
Pick-to: 6.0
Change-Id: I3e90d1d14a41a7c5c337745f1453484d360a3979
Reviewed-by: Ulf Hermann <ulf.hermann@qt.io>

4 files changed, 33 insertions, 0 deletions

diff --git a/tests/auto/qml/qqmlecmascript/data/QPropertyBase.qml b/tests/auto/qml/qqmlecmascript/data/QPropertyBase.qml
new file mode 100644
index 0000000000..40f29f589e
--- /dev/null
+++ b/tests/auto/qml/qqmlecmascript/data/QPropertyBase.qml
@@ -0,0 +1,5 @@
+import Qt.test 1
+ClassWithQProperty {
+    value2: 42
+    value: value2
+}
diff --git a/tests/auto/qml/qqmlecmascript/data/QPropertyOverwrite.qml b/tests/auto/qml/qqmlecmascript/data/QPropertyOverwrite.qml
new file mode 100644
index 0000000000..fd8b2c3dfd
--- /dev/null
+++ b/tests/auto/qml/qqmlecmascript/data/QPropertyOverwrite.qml
@@ -0,0 +1,11 @@
+import Qt.test 1
+
+ClassWithQProperty {
+    id: root
+    value: 13
+
+    property QPropertyBase prop: QPropertyBase {
+        objectName: "test"
+        value: root.value
+    }
+}
diff --git a/tests/auto/qml/qqmlecmascript/testtypes.h b/tests/auto/qml/qqmlecmascript/testtypes.h
index 159038f851..7074ffaa10 100644
--- a/tests/auto/qml/qqmlecmascript/testtypes.h
+++ b/tests/auto/qml/qqmlecmascript/testtypes.h
@@ -1732,9 +1732,12 @@ struct ClassWithQProperty : public QObject
 {
     Q_OBJECT
     Q_PROPERTY(float value MEMBER value BINDABLE bindableValue)
+    Q_PROPERTY(float value2 MEMBER value2 BINDABLE bindableValue2)
 public:
     QProperty<float> value;
+    QProperty<float> value2;
     QBindable<float> bindableValue() { return QBindable<float>(&value); }
+    QBindable<float> bindableValue2() { return QBindable<float>(&value2); }
 };
 
 class VariantConvertObject : public QObject
diff --git a/tests/auto/qml/qqmlecmascript/tst_qqmlecmascript.cpp b/tests/auto/qml/qqmlecmascript/tst_qqmlecmascript.cpp
index d7cb85a75d..37e3a33442 100644
--- a/tests/auto/qml/qqmlecmascript/tst_qqmlecmascript.cpp
+++ b/tests/auto/qml/qqmlecmascript/tst_qqmlecmascript.cpp
@@ -382,6 +382,7 @@ private slots:
     void semicolonAfterProperty();
     void hugeStack();
     void bindingOnQProperty();
+    void overwrittenBindingOnQProperty();
     void aliasOfQProperty();
     void bindingOnQPropertyContextProperty();
     void bindingContainingQProperty();
@@ -9182,6 +9183,19 @@ void tst_qqmlecmascript::bindingOnQProperty()
     QVERIFY(qprop.hasBinding());
 }
 
+void tst_qqmlecmascript::overwrittenBindingOnQProperty()
+{
+    QQmlEngine engine;
+    QQmlComponent component(&engine, testFileUrl("QPropertyOverwrite.qml"));
+    QVERIFY2(component.isReady(), qPrintable(component.errorString()));
+    QScopedPointer<QObject> root(component.create());
+    auto test = root->findChild<ClassWithQProperty *>("test");
+    QVERIFY(test);
+    QCOMPARE(test->value.value(), 13.f);
+    root->setProperty("value", 14.f);
+    QCOMPARE(test->value.value(), 14.0);
+}
+
 void tst_qqmlecmascript::aliasOfQProperty() {
     QQmlEngine engine;
     QQmlComponent component(&engine, testFileUrl("aliasOfQProperty.qml"));