https://gcc.gnu.org/bugzilla/show_bug.cgi?id=62252
--- Comment #2 from klemen.jan.enova at gmail dot com --- TREE_CODE(type) returns an ERROR_MARK. So, (tree) event_data must not alias with a tree. This plugin is from https://github.com/gcc-mirror/gcc/blob/master/gcc/testsuite/g%2B%2B.dg/plugin/dumb_plugin.c. There are no checks there, it just assumes it is a type represented as a tree.
