Fixed leak of plugin instances

It seems that plugins were never explicitly unloaded, resulting in leaks
of the instance object. Added a static deleter to ensure deletion on
exit. The QPointer (previously in place) ensures we don't do a
double-free nor try to access an invalid pointer.

Task-number: 253013
Reviewed-by: mariusSO

1 files changed, 18 insertions, 1 deletions

diff --git a/src/corelib/plugin/qplugin.h b/src/corelib/plugin/qplugin.h
index 4d0e53c..121a875 100644
--- a/src/corelib/plugin/qplugin.h
+++ b/src/corelib/plugin/qplugin.h
@@ -63,6 +63,21 @@ typedef QObject *(*QtPluginInstanceFunction)();
 
 void Q_CORE_EXPORT qRegisterStaticPluginInstanceFunction(QtPluginInstanceFunction function);
 
+struct qt_plugin_instance_deleter
+{
+    qt_plugin_instance_deleter(QPointer<QObject> &instance)
+        : instance_(instance)
+    {
+    }
+
+    ~qt_plugin_instance_deleter()
+    {
+        delete instance_;
+    }
+
+    QPointer<QObject> &instance_;
+};
+
 #define Q_IMPORT_PLUGIN(PLUGIN) \
         extern QT_PREPEND_NAMESPACE(QObject) *qt_plugin_instance_##PLUGIN(); \
         class Static##PLUGIN##PluginInstance{ \
@@ -76,8 +91,10 @@ void Q_CORE_EXPORT qRegisterStaticPluginInstanceFunction(QtPluginInstanceFunctio
 #define Q_PLUGIN_INSTANCE(IMPLEMENTATION) \
         { \
             static QT_PREPEND_NAMESPACE(QPointer)<QT_PREPEND_NAMESPACE(QObject)> _instance; \
-            if (!_instance)      \
+            if (!_instance) { \
+                static QT_PREPEND_NAMESPACE(qt_plugin_instance_deleter) deleter(_instance); \
                 _instance = new IMPLEMENTATION; \
+            } \
             return _instance; \
         }