Remove signal index mismatch in aot-compiled code

There are multiple types of signal indexes, one of them
belongs to QMetaMethod::signalIndex and another one to
QObjectPrivate::signalIndex.

Stop mixing them up in aot-compiled code when capturing
properties as this leads to weird and hard to debug bugs.

Add a smaller version of the drag and drop example as test
to make sure that the bug does not appear again, without any
visual elements.

Fixes: QTBUG-104047
Fixes: QTBUG-104716
Pick-to: 6.4 6.2
Change-Id: I4f64ba237e824ff0ba1624c29ddcf5371d03d69e
Reviewed-by: Ulf Hermann <ulf.hermann@qt.io>
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>

1 files changed, 2 insertions, 1 deletions

diff --git a/src/qml/qml/qqml.cpp b/src/qml/qml/qqml.cpp
index d5e98f1805..5e99f92bc7 100644
--- a/src/qml/qml/qqml.cpp
+++ b/src/qml/qml/qqml.cpp
@@ -1022,7 +1022,8 @@ static ObjectLookupResult initObjectLookup(
         // & 1 to tell the gc that this is not heap allocated; see markObjects in qv4lookup_p.h
         l->qobjectFallbackLookup.metaObject = quintptr(metaObject) + 1;
         l->qobjectFallbackLookup.coreIndex = coreIndex;
-        l->qobjectFallbackLookup.notifyIndex = property.notifySignalIndex();
+        l->qobjectFallbackLookup.notifyIndex =
+                QMetaObjectPrivate::signalIndex(property.notifySignal());
         l->qobjectFallbackLookup.isConstant = property.isConstant() ? 1 : 0;
         return ObjectLookupResult::Fallback;
     }