https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71166
--- Comment #3 from Nathan Sidwell <nathan at gcc dot gnu.org> --- Created attachment 38514 --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=38514&action=edit slightly more reduced test case We're invoking constexpr evaluation machinery after parsing is complete -- fini_constexpt has already been called. This occurs during the emission of BarContainer's constructor, after we've destructively gimplified MakeFoo. We end up in 0xa05bf2 maybe_constant_init(tree_node*, tree_node*) ../../../src/gcc/cp/constexpr.c:4457 0x929ce6 build_vec_init(tree_node*, tree_node*, tree_node*, bool, int, int) ../../../src/gcc/cp/init.c:4178 0x9db06b cp_gimplify_expr(tree_node**, gimple**, gimple**) ../../../src/gcc/cp/cp-gimplify.c:592 and from there we have const_expr_eval (Bar) -> const_expr_eval (MakeFoo) -> ICE The object we're gimplifying is a vec_init_expr
