wpautop() formatting function generate invalid HTML if the text end with an empty <p> tag

[gillesdoge]

It's probably my first ticket (hi there 👋 !).

When preparing a migration of an old WordPress, I was facing the following issue:

<?php

$text = "<p>test</p>
<p></p>";

var_dump(wpautop($text);
// Output: string(16) "<p>test</p></p>
// "

You may ask, but why do you need to apply wpautop() on an already formatted text?
Because some of the content needed it (paragraphs only separated by newlines) and some was already formatted with HTML and Classic Editor.

My current countermeasure is to test if the content already have <p> and don't apply wpautop().

Is this a know issue (I found nothing when searching) ?

[SirLouen]

Reproduction Report

Description

This report validates that the issue can be reproduced.

Environment

• WordPress: 6.8-beta3-60042-src
• PHP: 8.2.28
• Server: nginx/1.27.4
• Database: mysqli (Server: 8.4.4 / Client: mysqlnd 8.2.28)
• Browser: Chrome 134.0.0.0
• OS: Windows 10/11
• Theme: Twenty Nineteen 3.0
• MU Plugins: None activated
• Plugins:
  • Hello Dolly 1.7.2
  • Test Reports 1.2.0

Actual Results

1. ✅ Error condition occurs (reproduced).

Supplemental Artifacts

Trac ticket: https://core.trac.wordpress.org/ticket/63148

[wildworks]

I'm reviewing this ticket in preparation for a 6.9 dry run.

I'm removing the version field, since at least this issue isn't an issue that occurred in an unreleased development branch.

Additionally, unit tests are needed to move this ticket forward.

[gillesdoge]

I will try write some PHPUnit tests to reproduce the issue.

[gillesdoge]

Is this another duplicate of #27350 ?