Function rmw_compare_gids_equal 

pub unsafe extern "C" fn rmw_compare_gids_equal(
    gid1: *const rmw_gid_t,
    gid2: *const rmw_gid_t,
    result: *mut bool,
) -> rmw_ret_t

Upstream rmw_compare_gids_equal. Exact parity.

Equal means the same implementation_identifier AND the same 24 bytes. Gids from different backends are never equal — which matters more here than upstream, because nros_rmw_cffi_register_named admits several backends in one image.

Comparison is over the WHOLE array, so a producer must zero-pad; see rmw_gid_t.