Fix dependency calculation for context and scope properties

We were incorrectly calculating writing to a context or scope property as a
dependency for an expression. We don't know whether a property is being written
only or also being read from at lookup time, but we can make that decision in
the isel then when generating the move instructions.

So initially context and scope properties end up in a candidate set first
and get promoted to real dependencies when they're being used in reading
moves.

Task-number: QTBUG-35210
Change-Id: Ia67057abafc2d611e1e6605327b4965ebe91cbed
Reviewed-by: Lars Knoll <lars.knoll@digia.com>

2 files changed, 23 insertions, 0 deletions

diff --git a/tests/auto/qml/qqmlecmascript/data/noCaptureWhenWritingProperty.qml b/tests/auto/qml/qqmlecmascript/data/noCaptureWhenWritingProperty.qml
new file mode 100644
index 0000000000..8b8601692d
--- /dev/null
+++ b/tests/auto/qml/qqmlecmascript/data/noCaptureWhenWritingProperty.qml
@@ -0,0 +1,14 @@
+import QtQml 2.0
+QtObject {
+    property bool somePropertyEvaluated: false;
+
+    property int someProperty: {
+        // It's sort of evil to set the property here, but that doesn't mean that
+        // this expression should get re-evaluated when unrelatedProperty changes later.
+        somePropertyEvaluated = true
+        return 20;
+    }
+    Component.onCompleted: {
+        somePropertyEvaluated = false
+    }
+}
diff --git a/tests/auto/qml/qqmlecmascript/tst_qqmlecmascript.cpp b/tests/auto/qml/qqmlecmascript/tst_qqmlecmascript.cpp
index 1e18e3c269..7b89709923 100644
--- a/tests/auto/qml/qqmlecmascript/tst_qqmlecmascript.cpp
+++ b/tests/auto/qml/qqmlecmascript/tst_qqmlecmascript.cpp
@@ -319,6 +319,7 @@ private slots:
     void stackLimits();
     void idsAsLValues();
     void qtbug_34792();
+    void noCaptureWhenWritingProperty();
 
 private:
 //    static void propertyVarWeakRefCallback(v8::Persistent<v8::Value> object, void* parameter);
@@ -7498,6 +7499,14 @@ void tst_qqmlecmascript::qtbug_34792()
     delete object;
 }
 
+void tst_qqmlecmascript::noCaptureWhenWritingProperty()
+{
+    QQmlComponent component(&engine, testFileUrl("noCaptureWhenWritingProperty.qml"));
+    QScopedPointer<QObject> obj(component.create());
+    QVERIFY(!obj.isNull());
+    QCOMPARE(obj->property("somePropertyEvaluated").toBool(), false);
+}
+
 QTEST_MAIN(tst_qqmlecmascript)
 
 #include "tst_qqmlecmascript.moc"