ing allocated, and let
     <code>_mpz_realloc</code> do the initial alloc.  Set
     <code>z-&gt;_mp_d</code> to a dummy that <code>mpz_get_ui</code> and
     similar can unconditionally fetch from.  Niels Möller has had a go at
     this.
     <br>
     The advantages of the lazy scheme would be:
     <ul>
     <li> Initial allocate would be the size required for the first value
          stored, rather than getting 1 limb in <code>mpz_init</code> and then
          more or less immediately reallocating.