QmlCompiler: Allow primitive conversion if output is stored in var

We can always convertStored() if the contained type has been fixed.

Pick-to: 6.7
Fixes: QTBUG-120322
Change-Id: I7d834fa32a12503341c863c095d578ca6e838531
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>

src/qmlcompiler/qqmljscodegenerator.cpp

@@ -3723,22 +3723,31 @@ QString QQmlJSCodeGenerator::conversion(
 {
     const QQmlJSScope::ConstPtr contained = m_typeResolver->containedType(to);
 
-    // If both types are stored in QJSPrimitiveValue we coerce using QJSPrimitiveValue
+    // If from is QJSPrimitiveValue and to contains a primitive we coerce using QJSPrimitiveValue
     if (m_typeResolver->registerIsStoredIn(from, m_typeResolver->jsPrimitiveType())
-            && m_typeResolver->registerIsStoredIn(to, m_typeResolver->jsPrimitiveType())) {
-        if (m_typeResolver->equals(contained, m_typeResolver->jsPrimitiveType()))
-            return variable;
+            && m_typeResolver->isPrimitive(to)) {
 
-        const QString conversion = variable + u".to<QJSPrimitiveValue::%1>()"_s;
-        if (m_typeResolver->equals(contained, m_typeResolver->boolType()))
-            return conversion.arg(u"Boolean"_s);
-        if (m_typeResolver->isIntegral(to))
-            return conversion.arg(u"Integer"_s);
-        if (m_typeResolver->equals(contained, m_typeResolver->realType()))
-            return conversion.arg(u"Double"_s);
-        if (m_typeResolver->equals(contained, m_typeResolver->stringType()))
-            return conversion.arg(u"String"_s);
-        reject(u"Conversion of QJSPrimitiveValue to "_s + contained->internalName());
+        QString primitive = [&]() {
+            if (m_typeResolver->equals(contained, m_typeResolver->jsPrimitiveType()))
+                return variable;
+
+            const QString conversion = variable + u".to<QJSPrimitiveValue::%1>()"_s;
+            if (m_typeResolver->equals(contained, m_typeResolver->boolType()))
+                return conversion.arg(u"Boolean"_s);
+            if (m_typeResolver->isIntegral(to))
+                return conversion.arg(u"Integer"_s);
+            if (m_typeResolver->isNumeric(to))
+                return conversion.arg(u"Double"_s);
+            if (m_typeResolver->equals(contained, m_typeResolver->stringType()))
+                return conversion.arg(u"String"_s);
+            reject(u"Conversion of QJSPrimitiveValue to "_s + contained->internalName());
+            return QString();
+        }();
+
+        if (primitive.isEmpty())
+            return primitive;
+
+        return convertStored(m_typeResolver->jsPrimitiveType(), to.storedType(), primitive);
     }
 
     if (m_typeResolver->registerIsStoredIn(to, contained)

tests/auto/qml/qmlcppcodegen/data/CMakeLists.txt

@@ -103,6 +103,7 @@ set(qml_files
     conversionInDeadCode.qml
     conversions.qml
     conversions2.qml
+    convertPrimitiveToVar.qml
     convertQJSPrimitiveValueToIntegral.qml
     convertToOriginalReadAcumulatorForUnaryOperators.qml
     curlygrouped.qml

tests/auto/qml/qmlcppcodegen/data/convertPrimitiveToVar.qml

@@ -0,0 +1,18 @@
+pragma Strict
+import QtQml
+
+QtObject {
+    id: foo
+
+    property int offsetValue
+
+    function send(data : variant) {
+    }
+
+    Component.onCompleted: () => {
+        let deltaOffset = 42
+        deltaOffset -= 1
+        foo.offsetValue = deltaOffset
+        foo.send({offset: deltaOffset})
+    }
+}

tests/auto/qml/qmlcppcodegen/tst_qmlcppcodegen.cpp

@@ -71,6 +71,7 @@ private slots:
     void conversionDecrement();
     void conversionInDeadCode();
     void conversions();
+    void convertPrimitiveToVar();
     void convertQJSPrimitiveValueToIntegral();
     void convertToOriginalReadAcumulatorForUnaryOperators();
     void cppValueTypeList();
@@ -1307,6 +1308,19 @@ void tst_QmlCppCodegen::conversions()
     QVERIFY(!undef.isValid());
 }
 
+void tst_QmlCppCodegen::convertPrimitiveToVar()
+{
+    QQmlEngine engine;
+    QQmlComponent c(&engine, QUrl(u"qrc:/qt/qml/TestTypes/convertPrimitiveToVar.qml"_s));
+
+    QVERIFY2(c.isReady(), qPrintable(c.errorString()));
+
+    QScopedPointer<QObject> o(c.create());
+    QVERIFY(!o.isNull());
+
+    QCOMPARE(o->property("offsetValue").toInt(), 41);
+}
+
 void tst_QmlCppCodegen::convertQJSPrimitiveValueToIntegral()
 {
     QQmlEngine engine;