Function erlang_nif_sys::erlang_nif_sys_api::enif_get_atom_length

pub unsafe extern "C" fn enif_get_atom_length(
    arg1: *mut ErlNifEnv, 
    atom: ERL_NIF_TERM, 
    len: *mut c_uint, 
    arg2: ErlNifCharEncoding
) -> c_int

See enif_get_atom_length in the Erlang docs.