Self-closing `/>` is invalid syntax on non-void HTML elements

[Marsel Shayhin]

Problem

The official Vue parser allows self-closing any HTML, but this is not valid by the spec. For example, this:

<template>
  <slot />
  <div class="bad" />
</template>

Using Nu HTML Checker by W3 results in a clear error:

The same happens when parsing with swc_html_parser. The error is being reported and the tag is not being closed:

InvalidHtml(NonVoidHtmlElementStartTagWithTrailingSolidus) <slot />

In addition, this also messes up the DOM Tree stack, which is the actual problem here.

Possible solution

All NonVoidHtmlElementStartTagWithTrailingSolidus should be considered a hard error.

Nice-to-have

It would also be nice to do RegEx search-replace as a utility in fervid.
Another option is to parse the HTML and only apply this fix to where the NonVoidHtmlElementStartTagWithTrailingSolidus problem is encountered.

[Marsel Shayhin]

Raised concerns with SWC project in hopes to get a configuration flag for it
swc-project/swc#8424

[Marsel Shayhin]

Closed in SWC via swc-project/swc#8460