Empty p tags when adding multiple consecutive shortcodes in the editor.

[kmgalanakis]

Steps to reproduce

• Create a simple shortcode in your functions.php file.

  <?php
  function dummy_div_handler( $atts ){
      return "<div>Lorem ipsum dolor sit amet.</div>";
  }
  add_shortcode( 'dummy-div', 'dummy_div_handler' );
  

• Add the [dummy-div][dummy-div] shortcodes to a new page using either the Visual or the Text editor.

The markup that is outputted on the browser is

<p><div>Lorem ipsum dolor sit amet.</div><div>Lorem ipsum dolor sit amet.</div></p>

which clearly is invalid. The browser processes the page source and transforms those <p> and </p> tags to empty <p> tags by adding the missing opening or closing tag, so the resulting markup is something like

<p></p><div>Lorem ipsum dolor sit amet.</div><div>Lorem ipsum dolor sit amet.</div><p></p>

[noisysocks]

It looks like shortcode_unautop() is supposed to remove those <p> tags, but it only supports removing a single shortcode. To fix this, we could modify shortcode_unautop() to remove multiple shortcodes. Such a patch would have to include lots of unit tests because the combination of shortcodes and autop is very scary.

This is not a priority as the block editor makes both shortcodes and autop largely obsolete, but I'd be happy to see this ticket re-opened if someone wants to submit a patch.