Bug in wp_html_split with unclosed PHP tag

Hi, I have already asked similar question, but I had no time to dive deeper in this problem couple weeks ago.

https://wordpress.org/support/topic/wordpress-php-code-in-post-content-bug/

But today I have stacktraced the flow in search of the problem, and I’ve finally found it.

The problem is in the shortcodes.php file, but exact problem is function wp_html_split in formatting.php

This function doesn’t splits parts correctly thats why I am missing output.

Lets start from the beginning. Consider following post code.

Some amount of useless text <!--more-->

[code-highlight line-numbers="table" linenostart="53" highlight-lines="1,3,8" style="native" lang="html+php" pyg-id="1" ]
<?php
//This callback registers our plug-in
function wpse72394_register_tinymce_plugin($plugin_array) {
    $plugin_array['wpse72394_button'] = 'path/to/shortcode.js';
    return $plugin_array;
}

//This callback adds our button to the toolbar
function wpse72394_add_tinymce_button($buttons) {
            //Add the button ID to the $button array
    $buttons[] = "wpse72394_button";
    return $buttons;
}
?
[/code-highlight]

Some amount of useless text <strong>checkstyle</strong>

[code-highlight style="native" lang="perl" pyg-id="2" ]
(?:s+)(?:(/*([^*]|[rn]|(*+([^*/]|[rn])))**+/)|(//(?!.*(CHECKSTYLE)).*))
[/code-highlight]

Here is result for user

Lets find out why

Because of incorrect regex

Here dump after this line

$textarr = wp_html_split( $content );
    var_dump($textarr);
    exit;

                array(25) {
  [0]=>
  string(0) ""
  [1]=>
  string(3) "<p>"
  [2]=>
  string(28) "Some amount of useless text "
  [3]=>
  string(11) "<!--more-->"
  [4]=>
  string(0) ""
  [5]=>
  string(4) "</p>"
  [6]=>
  string(1) "
"
  [7]=>
  string(3) "<p>"
  [8]=>
  string(121) "[code-highlight line-numbers="table" linenostart="53" highlight-lines="1,3,8" style="native" lang="html+php" pyg-id="1" ]"
  [9]=>
  string(6) "<br />"
  [10]=>
  string(1) "
"
  [11]=>
  string(464) "<?php
//This callback registers our plug-in
function wpse72394_register_tinymce_plugin($plugin_array) {
    $plugin_array['wpse72394_button'] = 'path/to/shortcode.js';
    return $plugin_array;
}

//This callback adds our button to the toolbar
function wpse72394_add_tinymce_button($buttons) {
            //Add the button ID to the $button array
    $buttons[] = "wpse72394_button";
    return $buttons;
}
?
[/code-highlight]

Some amount of useless text <strong>"
  [12]=>
  string(10) "checkstyle"
  [13]=>
  string(9) "</strong>"
  [14]=>
  string(0) ""
  [15]=>
  string(4) "</p>"
  [16]=>
  string(56) "
[code-highlight style="native" lang="perl" pyg-id="2" ]"
  [17]=>
  string(6) "<br />"
  [18]=>
  string(72) "
(?:s+)(?:(/*([^*]|[rn]|(*+([^*/]|[rn])))**+/)|(//(?!.*(CHECKSTYLE)).*))"
  [19]=>
  string(6) "<br />"
  [20]=>
  string(19) "
[/code-highlight]
"
  [21]=>
  string(3) "<p>"
  [22]=>
  string(15) "Some Text Again"
  [23]=>
  string(4) "</p>"
  [24]=>
  string(1) "
"
}

As you can see one shortcode was not splitted, and here the problem.
Problematic regex provider

function get_html_split_regex() {
	static $regex;

	if ( ! isset( $regex ) ) {
		$comments =
			  '!'           // Start of comment, after the <.
			. '(?:'         // Unroll the loop: Consume everything until --> is found.
			.     '-(?!->)' // Dash not followed by end of comment.
			.     '[^\-]*+' // Consume non-dashes.
			. ')*+'         // Loop possessively.
			. '(?:-->)?';   // End of comment. If not found, match all input.

		$cdata =
			  '!\[CDATA\['  // Start of comment, after the <.
			. '[^\]]*+'     // Consume non-].
			. '(?:'         // Unroll the loop: Consume everything until ]]> is found.
			.     '](?!]>)' // One ] not followed by end of comment.
			.     '[^\]]*+' // Consume non-].
			. ')*+'         // Loop possessively.
			. '(?:]]>)?';   // End of comment. If not found, match all input.

		$escaped =
			  '(?='           // Is the element escaped?
			.    '!--'
			. '|'
			.    '!\[CDATA\['
			. ')'
			. '(?(?=!-)'      // If yes, which type?
			.     $comments
			. '|'
			.     $cdata
			. ')';

		$regex =
			  '/('              // Capture the entire match.
			.     '<'           // Find start of element.
			.     '(?'          // Conditional expression follows.
			.         $escaped  // Find end of escaped element.
			.     '|'           // ... else ...
			.         '[^>]*>?' // Find end of normal element.
			.     ')'
			. ')/';
	}

	return $regex;
}

So I am asking for help to fix this bug, I have some skills in regex and will try to fix it myself, but it would better to discuss this problem with community.

Hope for your help.