You can't mismatch the export macros. The QT_MOC_EXPORT_PLUGIN_V2 macro
defines these functions as Q_DECL_EXPORT so they can be found by
QPluginLoader. We must match the macro here, otherwise GCC 12 complains
(tst_moc.cpp is compiled with -fvisibility=hidden):
tst_moc.cpp.o: non-canonical reference to canonical protected function `qt_plugin_instance' in moc_plugin_metadata.cpp.o
Pick-to: 6.4
Change-Id: Id0fb9ab0089845ee8843fffd16f99893d5730da5
Reviewed-by: Marc Mutz <marc.mutz@qt.io>