add_shortcode('test1', 'test1');
function test1($atts) {
//extract(shortcode_atts(array('src' => NULL), $atts));
return do_shortcode($atts[0]);
}
add_shortcode('test2', 'test2');
function test2() {
return 'Привет!';
}[test1 src="[test2]"]
[test1 [test2]]
[test2]src="[test2"]
[test2]
Привет!The shortcode parser does not accept square brackets within attributes