swc-project/swc · error

Expected 'u' ident token

Error message

Expected 'u' ident token

What it means

Fired while parsing a UnicodeRange: the range must begin with the ident `u`/`U` (as in U+0-7F), but the current token was not that ident. This match-with-fallback is a validation guard; input at fault is a @unicode-range value that does not start with `u`/`U`, e.g. a bare number or hex digits.

Source

Thrown at crates/swc_css_parser/src/parser/values_and_units/mod.rs:2715

{
    fn parse(&mut self) -> PResult<UnicodeRange> {
        let span = self.input.cur_span();
        let mut unicode_range = String::new();

        // should start with `u` or `U`
        match cur!(self) {
            Token::Ident { value, .. } if matches_eq_ignore_ascii_case!(value, "u") => {
                let u = match bump!(self) {
                    Token::Ident { value, .. } => value,
                    _ => {
                        unreachable!();
                    }
                };

                unicode_range.push_str(&u);
            }
            _ => {
                return Err(Error::new(span, ErrorKind::Expected("'u' ident token")));
            }
        };

        match cur!(self) {
            // u '+' <ident-token> '?'*
            // u '+' '?'+
            Token::Delim { value } if *value == '+' => {
                let plus = match bump!(self) {
                    Token::Delim { value } => value,
                    _ => {
                        unreachable!();
                    }
                };

                unicode_range.push(plus);

                if is!(self, Ident) {
                    let ident = match bump!(self) {

View on GitHub (pinned to 5176682b65)

Solutions

1. Start the range with 'U' or 'u', e.g. 'U+0-7F'
2. Check for typos in the unicode-range descriptor value

When it happens

Trigger: Thrown at crates/swc_css_parser/src/parser/values_and_units/mod.rs:2715 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of swc-project/swc@5176682b65 (2026-08-17). Data as JSON: /api/errors/0d4ed3dd1fe7911e. Report an issue: GitHub.