ct types <code class="tmd-code-span">S1</code> and <code class="tmd-code-span">S2</code> can be converted to each other's types, if <code class="tmd-code-span">S1</code> and <code class="tmd-code-span">S2</code> share the identical underlying type (by ignoring field tags). In particular if either <code class="tmd-code-span">S1</code> or <code class="tmd-code-span">S2</code> is an <a href="type-system-overview.html#named-type">unnamed type</a> and their underlying types are identical (considering field tags)