Gutenberg block admin add:
function test()
{
//
}
Database:
<!-- wp:syntaxhighlighter/code {"language":"php","lineNumbers":true} -->
<pre class="wp-block-syntaxhighlighter-code">function test()
{
//
}</pre>
<!-- /wp:syntaxhighlighter/code -->
Html front:
<div class="entry-content">
<p>Any blocks before</p>
<div><div id="highlighter_933185" class="syntaxhighlighter alignwide php"><div class="toolbar"><span><a href="#" class="toolbar_item command_help help">?</a></span></div><table border="0" cellpadding="0" cellspacing="0"><tbody></tbody></table></div></div>
<p></p>
<p>Any blocks after</p>
</div>
ALso check out syntaxhighlighter-html of any page by contributor Alex Mills:
https://alex.blog/wordpress-plugins/syntaxhighlighter/adding-a-new-brush-language/