https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96381
--- Comment #2 from anlauf at gcc dot gnu.org --- The following patch fixes the invalid read: diff --git a/gcc/fortran/class.c b/gcc/fortran/class.c index 5677d920239..783e4c7354b 100644 --- a/gcc/fortran/class.c +++ b/gcc/fortran/class.c @@ -2906,7 +2906,9 @@ gfc_find_vtab (gfc_typespec *ts) case BT_DERIVED: return gfc_find_derived_vtab (ts->u.derived); case BT_CLASS: - if (ts->u.derived->components && ts->u.derived->components->ts.u.derived) + if (ts->u.derived->attr.is_class + && ts->u.derived->components + && ts->u.derived->components->ts.u.derived) return gfc_find_derived_vtab (ts->u.derived->components->ts.u.derived); else return NULL; Not regtested yet.