<a href="#Interface_types">interface type</a>, but not a
<a href="#Type_parameter_declarations">type parameter</a>, and each non-interface type
<code>T</code> listed in a case must implement the type of <code>x</code>.
The types listed in the cases of a type switch must all be
<a href="#Type_identity">different</a>.
</p>

<pre class="ebnf">