https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89285
--- Comment #8 from Jakub Jelinek <jakub at gcc dot gnu.org> --- I'll try to copy & adjust (mostly kill almost everything) copy_tree_body_r and use that in register_constexpr_fundef. As we don't need to remap decls or types, I think we just need copy_statement_list for STATEMENT_LIST, remap_save_expr for SAVE_EXPR/TARGET_EXPR, copy_tree_r for the rest?
