https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105853
--- Comment #1 from David Binderman <dcb314 at hotmail dot com> --- Reduced C code seems to be: struct { struct { short e16[3]; } } const eth_addr_zero = {{}}; void compose_nd_na_ipv6_src() { packet_set_nd(eth_addr_zero); } Note no -march= setting is required.