/span><span class="op">&gt;</span> <span class="ident">opt_help</span> <span class="comment">// &lt;-- optional attachments can have custom spans too</span>
);</pre></div>
<h3 id="proc_macro_error-attribute" class="section-header"><a href="#proc_macro_error-attribute"><code>#[proc_macro_error]</code> attribute</a></h3>
<p><strong>This attribute MUST be present on the top level of your macro.</strong></p>
<p>This attribute performs the setup and cleanup necessary to make things work.</p>
<h4 id="syntax-1" cl