ndefined_expression : unit <span>&#45;&gt;</span> <a href="../IR/Exp/index.html#type-t">IR.Exp.t</a></code></dt><dt class="spec value" id="val-collect_controls"><a href="#val-collect_controls" class="anchor"></a><code><span class="keyword">val</span> collect_controls : <a href="../IR/Procdesc/index.html#type-t">IR.Procdesc.t</a> <span>&#45;&gt;</span> <span><a href="index.html#type-control">control</a> list</span> <span>&#45;&gt;</span> <a href="index.html#type-control">control</a></code></dt><dd><p>Collect