Smart quotes / wptexturize alternative

[ellatrix]

Writing this down before I forget about it, though it's currently low priority for me. I'm curious to see if there's interest in this.

Currently we have smart quotes (and more) in WP through a PHP display filter. With the introduction of RichText a while ago, this feature could be improved.

• RichText splits formatting from text, so it's easier and less error prone to automatically convert quotes. There are quite a few wptexturize bugs around converting quotes next to HTML tags. It's really hard to get right in HTML without parsing the HTML.
• Auto conversion happens when you type instead of forcing it on the whole content, unlike the PHP filter which forces the replacement. We could of course run it on pasted content and maybe allow the user to convert a whole document.
• Quotes can be converted back through the current Backspace and Esc mechanism. With the PHP filter, you cannot even remove a badly converted quote.
• Since quotes are converted in the editor, it's a closer WYSIWYG experience.
• When quotes are converted, wptexturize will skip it, which means less load on the server and faster loading times.
• Of course, localisation is possible.

[jasmussen]

I'm seeing some issues with beautificiation (specifically single quotes rewritten as quotes) in the HTML block (reported here). Is that in any way related/addressed by this?

Edit: Ticketed the issue https://github.com/WordPress/gutenberg/issues/33813