Show current PHP version in ClassicPress admin bar

functions.php

/**
 * Add PHP version to ClassicPress admin bar.
 *
 * For environments in which the PHP version is subject to change, this will add
 * the currently-running PHP version number to the admin bar to save some clicks
 * and keep it immediately discoverable.
 *
 * @author John Alarcon
 */
function codepotent_adminbar_php_version() {
	global $wp_admin_bar;
	$wp_admin_bar->add_menu([
		'parent' => false,
		'id'     => 'codepotent_adminbar_phpversion',
		'title'  => 'PHP '.phpversion()
	]);
}
add_action('wp_before_admin_bar_render', 'codepotent_adminbar_php_version', PHP_INT_MAX);