QmlCompiler: Return early after reject()

Otherwise we can run into an infinite loop.

Fixes: QTBUG-120322
Change-Id: I81f9402beb48faf09b4fe148271d4347b84ddc5e
Reviewed-by: Olivier De Cannière <olivier.decanniere@qt.io>
Reviewed-by: Sami Shalayel <sami.shalayel@qt.io>
(cherry picked from commit 49ea766c8f)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

src/qmlcompiler/qqmljscodegenerator.cpp

@@ -4054,12 +4054,14 @@ QString QQmlJSCodeGenerator::convertContained(const QQmlJSRegisterContent &from,
     if (!m_typeResolver->registerIsStoredIn(to, m_typeResolver->varType()) &&
             !m_typeResolver->registerIsStoredIn(to, m_typeResolver->jsPrimitiveType())) {
         reject(u"internal conversion into unsupported wrapper type."_s);
+        return QString();
     }
 
     bool isExtension = false;
     if (m_typeResolver->canPopulate(containedTo, containedFrom, &isExtension)) {
         reject(u"populating "_s + containedTo->internalName()
                + u" from "_s + containedFrom->internalName());
+        return QString();
     } else if (const auto ctor = m_typeResolver->selectConstructor(
                 containedTo, containedFrom, &isExtension); ctor.isValid()) {
         const auto argumentTypes = ctor.parameters();

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

@@ -215,6 +215,7 @@ set(qml_files
     registerPropagation.qml
     registerelimination.qml
     renameAdjust.qml
+    returnAfterReject.qml
     revisions.qml
     scopeIdLookup.qml
     scopeVsObject.qml

tests/auto/qml/qmlcppcodegen/data/returnAfterReject.qml

@@ -0,0 +1,15 @@
+import QtQml
+
+QtObject {
+    id: remaining
+
+    property int bar: 0
+
+    Component.onCompleted: {
+        let remainingTime = 123
+        if (remainingTime < 0) {
+            remainingTime += 24 * 60 * 60
+        }
+        remaining.bar = isNaN(remainingTime) ? 0 : remainingTime
+    }
+}

tests/auto/qml/qmlcppcodegen/tst_qmlcppcodegen.cpp

@@ -183,6 +183,7 @@ private slots:
     void registerElimination();
     void registerPropagation();
     void renameAdjust();
+    void returnAfterReject();
     void revisions();
     void scopeIdLookup();
     void scopeObjectDestruction();
@@ -3802,6 +3803,16 @@ void tst_QmlCppCodegen::renameAdjust()
     QVERIFY(o);
 }
 
+void tst_QmlCppCodegen::returnAfterReject()
+{
+    QQmlEngine engine;
+    QQmlComponent c(&engine, QUrl(u"qrc:/qt/qml/TestTypes/returnAfterReject.qml"_s));
+    QVERIFY2(c.isReady(), qPrintable(c.errorString()));
+    QScopedPointer<QObject> o(c.create());
+    QVERIFY(o);
+    QCOMPARE(o->property("bar").toInt(), 123);
+}
+
 void tst_QmlCppCodegen::revisions()
 {
     QQmlEngine engine;