qmllint: Warn about assigning values to read-only properties

Fixes: QTBUG-92844
Change-Id: Iff893296784043d86ba00fd9f08d28d85873d9b2
Reviewed-by: Andrei Golubev <andrei.golubev@qt.io>
Reviewed-by: Ulf Hermann <ulf.hermann@qt.io>

src/qmlcompiler/qqmljstypepropagator.cpp

@@ -487,6 +487,15 @@ void QQmlJSTypePropagator::generate_StoreNameSloppy(int nameIndex)
         return;
     }
 
+    if (!type.isWritable()) {
+        setError(u"Can't assign to read-only property %1"_qs.arg(name));
+
+        m_logger->logWarning(u"Cannot assign to read-only property %1"_qs.arg(name), Log_Property,
+                             getCurrentSourceLocation());
+
+        return;
+    }
+
     if (!canConvertFromTo(m_state.accumulatorIn, type)) {
         setError(u"cannot convert from %1 to %2"_qs
                          .arg(m_state.accumulatorIn.descriptiveName(), type.descriptiveName()));
@@ -640,6 +649,10 @@ void QQmlJSTypePropagator::generate_StoreProperty(int nameIndex, int base)
 
     if (!property.isWritable()) {
         setError(u"Can't assign to read-only property %1"_qs.arg(propertyName));
+
+        m_logger->logWarning(u"Cannot assign to read-only property %1"_qs.arg(propertyName),
+                             Log_Property, getCurrentSourceLocation());
+
         return;
     }
 

tests/auto/qml/qmllint/data/assignToReadOnlyProperty.qml

@@ -0,0 +1,6 @@
+import QtQuick 2.0
+
+Item {
+    activeFocus: true
+    Component.onCompleted: activeFocus = false
+}

tests/auto/qml/qmllint/data/assignToReadOnlyProperty2.qml

@@ -0,0 +1,7 @@
+import QtQuick 2.0
+
+Item {
+    id: item
+    activeFocus: true
+    Component.onCompleted: item.activeFocus = false
+}

tests/auto/qml/qmllint/tst_qmllint.cpp

@@ -656,6 +656,14 @@ void TestQmllint::dirtyQmlCode_data()
             << QStringLiteral("Cannot use non-reference type QRectF as base "
                               "of namespaced attached type")
             << QString() << false;
+    QTest::newRow("AssignToReadOnlyProperty")
+            << QStringLiteral("assignToReadOnlyProperty.qml")
+            << QStringLiteral("Cannot assign to read-only property activeFocus") << QString()
+            << false;
+    QTest::newRow("AssignToReadOnlyProperty")
+            << QStringLiteral("assignToReadOnlyProperty2.qml")
+            << QStringLiteral("Cannot assign to read-only property activeFocus") << QString()
+            << false;
 }
 
 void TestQmllint::dirtyQmlCode()