http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59415
--- Comment #1 from Tobias Burnus <burnus at gcc dot gnu.org> --- It fails in 575 verify_bb_vtables (basic_block bb) ... 589 if (gimple_code (stmt) == GIMPLE_CALL) 590 { 591 tree fncall = gimple_call_fn (stmt); 592 if (TREE_CODE (fncall) == OBJ_TYPE_REF) There, one has: (gdb) p debug_bb(bb) <bb 2>: UBSAN_NULL (this_1(D), 3); _2 = this_1(D)->_M_dataplus._M_p;