Add support for binding directly to QProperty instances

Avoid going through externally managed bindings and instead allocate a
more lightweight property binding. It's basically a
QQmlJavaScriptExpression and one pointer plus the overhead of
QPropertyBindingPrivate.

Change-Id: I1530330926d351b61f2b3bbad39301c628a8bef1
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>

4 files changed, 35 insertions, 0 deletions

diff --git a/tests/auto/qml/qqmlecmascript/data/bindingOnQProperty.qml b/tests/auto/qml/qqmlecmascript/data/bindingOnQProperty.qml
new file mode 100644
index 0000000000..1bd043d9df
--- /dev/null
+++ b/tests/auto/qml/qqmlecmascript/data/bindingOnQProperty.qml
@@ -0,0 +1,7 @@
+import Qt.test 1.0
+ClassWithQProperty {
+    property int externalValue
+    value: {
+        return externalValue
+    }
+}
diff --git a/tests/auto/qml/qqmlecmascript/testtypes.cpp b/tests/auto/qml/qqmlecmascript/testtypes.cpp
index 89887fe6c3..606860379e 100644
--- a/tests/auto/qml/qqmlecmascript/testtypes.cpp
+++ b/tests/auto/qml/qqmlecmascript/testtypes.cpp
@@ -548,6 +548,8 @@ void registerTypes()
     qmlRegisterType<FloatingQObject>("Qt.test", 1, 0, "FloatingQObject");
 
     qmlRegisterType<ClashingNames>("Qt.test", 1, 0, "ClashingNames");
+
+    qmlRegisterType<ClassWithQProperty>("Qt.test", 1, 0, "ClassWithQProperty");
 }
 
 #include "testtypes.moc"
diff --git a/tests/auto/qml/qqmlecmascript/testtypes.h b/tests/auto/qml/qqmlecmascript/testtypes.h
index 03e3262e7b..415e884eb8 100644
--- a/tests/auto/qml/qqmlecmascript/testtypes.h
+++ b/tests/auto/qml/qqmlecmascript/testtypes.h
@@ -44,6 +44,7 @@
 #include <QtCore/qjsonarray.h>
 #include <QtCore/qjsonobject.h>
 #include <QtCore/qjsonvalue.h>
+#include <QtCore/qproperty.h>
 #include <QtQml/qjsvalue.h>
 #include <QtQml/qqmlscriptstring.h>
 #include <QtQml/qqmlcomponent.h>
@@ -1726,6 +1727,14 @@ public:
     Q_INVOKABLE bool clashes() const { return true; }
 };
 
+struct ClassWithQProperty : public QObject
+{
+    Q_OBJECT
+    Q_PROPERTY(int value)
+public:
+    QProperty<int> value;
+};
+
 void registerTypes();
 
 #endif // TESTTYPES_H
diff --git a/tests/auto/qml/qqmlecmascript/tst_qqmlecmascript.cpp b/tests/auto/qml/qqmlecmascript/tst_qqmlecmascript.cpp
index b3e4296a13..fbb344f9a0 100644
--- a/tests/auto/qml/qqmlecmascript/tst_qqmlecmascript.cpp
+++ b/tests/auto/qml/qqmlecmascript/tst_qqmlecmascript.cpp
@@ -381,6 +381,7 @@ private slots:
     void getThisObject();
     void semicolonAfterProperty();
     void hugeStack();
+    void bindingOnQProperty();
 
     void gcCrashRegressionTest();
 
@@ -9281,6 +9282,22 @@ void tst_qqmlecmascript::gcCrashRegressionTest()
     QCOMPARE(process.exitCode(), 0);
 }
 
+void tst_qqmlecmascript::bindingOnQProperty()
+{
+    QQmlEngine engine;
+    QQmlComponent component(&engine, testFileUrl("bindingOnQProperty.qml"));
+    QVERIFY2(component.isReady(), qPrintable(component.errorString()));
+    QScopedPointer<QObject> test(component.create());
+    test->setProperty("externalValue", 42);
+    QCOMPARE(test->property("value").toInt(), 42);
+    test->setProperty("externalValue", 100);
+    QCOMPARE(test->property("value").toInt(), 100);
+
+    QVERIFY(qobject_cast<ClassWithQProperty*>(test.data()));
+    QProperty<int> &qprop = static_cast<ClassWithQProperty*>(test.data())->value;
+    QVERIFY(qprop.hasBinding());
+}
+
 QTEST_MAIN(tst_qqmlecmascript)
 
 #include "tst_qqmlecmascript.moc"