macro_rules repeater syntax highlight error

[A4-Tacks]

file src/main.rs

fn main() {
    macro_rules! foo {
        ( a $(b)?) => { };
    }
    macro_rules! bar {
        ($(:)hello*) => {};
        ($(:)r#const*) => {};
        ($(:)<-*) => {};
        ($(:)impl*) => {};
        ($(:)$*) => {};
        ($(:)-*) => {};
        ($(:)...*) => {};
        ($(:)*=*) => {};
        ($(:)#*) => {};
        ($(:)||*) => {};
    }

    foo!(a);
    foo!(a b);

    bar!(: hello : hello :);
    bar!(: r#const : r#const :);
    bar!(: $ : $ :);
    bar!(: *= : *= :);
    bar!(: ... : ... :);
    bar!(: # : # :);
    bar!(: || : || :);
}

syntax/rust.vim.patch

70c70
< syn region rustMacroRepeat matchgroup=rustMacroRepeatDelimiters start="$(" end="),\=[*+]" contains=TOP
---
> syn region rustMacroRepeat matchgroup=rustMacroRepeatDelimiters start="$(" end=")\%(?\|\%(&\|&&\|&=\|@\|\^\|\^=\|:\|,\|\$\|\.\|\.\.\|\.\.\.\|\.\.=\|=\|==\|=>\|>=\|>\|<[-=]\=\|-\|-=\|!=\|!\||\||=\|||\|::\|%\|%=\|+=\|#\|->\|;\|<<\|<<=\|>>\|>>=\|/\|/=\|\*=\|\~\|_\|\%(r#\)\=\w\+\)\=[*+]\)\=" contains=TOP

?, optional group
+ or *, use any token separate, token list from syn crate

char str and other tokens are not commonly used and have more complex rules, so ignore them

[A4-Tacks]

I don't seem to have found a good way to both omit trailing duplicates and pair parentheses, while ensuring performance when inputting parentheses in large text

The solution I am currently using will slow down when entering parentheses when there is a lot of text

syn region rustParen start="(" end=")" transparent