https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79814
--- Comment #2 from David Malcolm <dmalcolm at gcc dot gnu.org> --- The code in question is: do { ((void)(!( __null == pass_warn_unused_result_1) ? fancy_abort ("./pass-instances.def", 36, __FUNCTION__), 0 : 0)); if ((1) == 1) pass_warn_unused_result_1 = make_pass_warn_unused_result (m_ctxt); else { ((void)(!(pass_warn_unused_result_1) ? fancy_abort ("./pass-instances.def", 36, __FUNCTION__), 0 : 0)); pass_warn_unused_result_1 = pass_warn_unused_result_1->clone (); } p = next_pass_1 (p, pass_warn_unused_result_1, pass_warn_unused_result_1); } while (0); i.e. it's complaining about this assertion: gcc_assert (NULL == PASS ## _ ## NUM); \ within the definition of NEXT_PASS(PASS, NUM) supplied within the pass_manager ctor: it's asserting that a pointer field within the object is NULL. pass_manager::operator new ensures that the underlying memory of the pass manager is zero-initialized, but clearly the warning has no knowledge of this. Eliminating the assertion fixes the warning, FWIW.