(rust) quotes around a char emoji are not colored properly

[tomsarry]

Describe the issue
In rust, single quotes around an emoji are not colored properly.
However, autodetect (on csharp) successfully colors it.

Which language seems to have the issue?
Rust

Are you using highlight or highlightAuto?
highlight

Sample Code to Reproduce
https://jsfiddle.net/cawyx173/

rust, coloring doesn't work

autodetect (csharp), works

Expected behavior
When using rust highlighting, single quotes around an emoji should have the same color as single quotes around any other character.

Additional context
Syntax highlighting works properly using double quotes around emojis.
Problem seen in rust book.

[joshgoebel]

 {
        className: 'string',
        variants: [
          { begin: /b?r(#*)"(.|\n)*?"\1(?!#)/ },
          { begin: /b?'\\?(x\w{2}|u\w{4}|U\w{8}|.)'/ }
        ]
      },

I'm guessing . doesn't cover Emoji... I'd have to play around with this one...

[tomsarry]

Would using |\p{Extended_Pictographic} be acceptable?
Quick checks seem to make it work.

https://regexr.com/7o2cc

[tomsarry]

I talked a bit too fast, the pattern above does not work either (I think ✨ is encoded using only one codepoint, the problem seems to be for characters encoded with 2 codepoints).
After looking at the char implementation, the following are also valid but not matched by the expression above:

• '\u{10ffff}'
• '\u{FFFD}'
• 🥰 (actually, most unicode emojis seem to fail)
• '𝕊'

I really am not a regex expert, but I found the following matches for emojis / unicode characters, this might be of some help:

• https://www.regextester.com/106421
• https://unicode.org/reports/tr51/#EBNF_and_Regex
• https://www.npmjs.com/package/emoji-regex

[joshgoebel]

Want to see if my fix works?