https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78338 --- Comment #1 from James Cowgill <james410 at cowgill dot org.uk> --- Seems to be fixed in r242522 2016-11-16 Jason Merrill <jason@redhat.com> * rtl.h: Declare gt_ggc_mx and gt_pch_nx.