QQmlComponent: Check for existence of engine

Avoid a crash when setData or create are
called after a user mistakenly used the internal constructor of
QQmlComponent which does not take an engine.

Fixes: QTBUG-55407
Change-Id: Ia4295d1b044723efce1a95607349561d4f1640da
Reviewed-by: Ulf Hermann <ulf.hermann@qt.io>

1 files changed, 12 insertions, 0 deletions

diff --git a/src/qml/qml/qqmlcomponent.cpp b/src/qml/qml/qqmlcomponent.cpp
index a23a322df9..7ad9310160 100644
--- a/src/qml/qml/qqmlcomponent.cpp
+++ b/src/qml/qml/qqmlcomponent.cpp
@@ -571,6 +571,12 @@ void QQmlComponent::setData(const QByteArray &data, const QUrl &url)
 {
     Q_D(QQmlComponent);
 
+    if (!d->engine) {
+        // ###Qt6: In Qt 6, it should be impossible for users to create a QQmlComponent without an engine, and we can remove this check
+        qWarning("QQmlComponent: Must provide an engine before calling setData");
+        return;
+    }
+
     d->clear();
 
     d->url = url;
@@ -777,6 +783,12 @@ QObject *QQmlComponent::create(QQmlContext *context)
     Q_D(QQmlComponent);
     QML_MEMORY_SCOPE_URL(url());
 
+    if (!d->engine) {
+        // ###Qt6: In Qt 6, it should be impossible for users to create a QQmlComponent without an engine, and we can remove this check
+        qWarning("QQmlComponent: Must provide an engine before calling create");
+        return nullptr;
+    }
+
     if (!context)
         context = d->engine->rootContext();