Add a means to unregister custom qml types

In cases where Qt is used in a plugin it is possible that a plugin will
be unloaded while Qt itself is still loaded and as a result there is a
chance that there will be conflicting types registered.

Therefore, to ensure that plugins correctly clean up after themselves
cleanly, we need to add a means to unregister qml types. This is
intended to only be used when the user knows what they are doing.

Task-number: QTBUG-56521
Task-number: QTBUG-56532
Change-Id: Ie396e522385004e6e9f3841e04f8072ff29cb15b
Reviewed-by: Simon Hausmann <simon.hausmann@qt.io>

1 files changed, 21 insertions, 0 deletions

diff --git a/src/qml/qml/qqmlmetatype.cpp b/src/qml/qml/qqmlmetatype.cpp
index ac670bdabb..3a0d5c3daf 100644
--- a/src/qml/qml/qqmlmetatype.cpp
+++ b/src/qml/qml/qqmlmetatype.cpp
@@ -2238,6 +2238,27 @@ QQmlPropertyCache *QQmlMetaType::propertyCache(const QQmlType &type, int minorVe
     return data->propertyCache(type, minorVersion);
 }
 
+void qmlUnregisterType(int typeIndex)
+{
+    QMutexLocker lock(metaTypeDataLock());
+    QQmlMetaTypeData *data = metaTypeData();
+    {
+        const QQmlTypePrivate *d = data->types.value(typeIndex).priv();
+        if (d) {
+            removeQQmlTypePrivate(data->idToType, d);
+            removeQQmlTypePrivate(data->nameToType, d);
+            removeQQmlTypePrivate(data->urlToType, d);
+            removeQQmlTypePrivate(data->urlToNonFileImportType, d);
+            removeQQmlTypePrivate(data->metaObjectToType, d);
+            for (QQmlMetaTypeData::TypeModules::Iterator module = data->uriToModule.begin(); module != data->uriToModule.end(); ++module) {
+                 QQmlTypeModulePrivate *modulePrivate = (*module)->priv();
+                 modulePrivate->remove(d);
+            }
+            data->types[typeIndex] = QQmlType();
+        }
+    }
+}
+
 void QQmlMetaType::freeUnusedTypesAndCaches()
 {
     QMutexLocker lock(metaTypeDataLock());