{{#define pool_get_aligned_will_expand(P,YESNO,A) }}
{{do { }}
{{ pool_header_t * _pool_var (p) = pool_header (P); }}
{{ uword _pool_var (l); }}
{{ }}
{{ _pool_var (l) = 0; }}
{{ if (P) }}
{{ { }}
{{ if (_pool_var (p)->max_elts) }}
{{ return 0; }}
{{ _pool_var (l) = vec_len (_pool_var (p)->free_indices); }}
{{ } }}
{{ }}
{{ /* Free elements, certainly won't expand */ }}
{{ if (_pool_var (l) > 0) }}
{{ YESNO=0; }}
{{ else }}
{{ { }}
{{ /* Nothing on free list, make a new element and return it. */ }}
{{ YESNO = _vec_resize_will_expand }}
{{ (P, }}
{{ /* length_increment */ 1, }}
{{ /* new size */ (vec_len (P) + 1) * sizeof (P[0]), }}
{{ pool_aligned_header_bytes, }}
{{ /* align */ (A)); }}
{{ } }}
} while (0)

If I write

void foo()

{

 //pool_get_aligned_will_expand()

}

foo could return unexpectedly.