swc-project/swc · error · Error

Expected dimension token

Error message

Expected dimension token

What it means

Fired while parsing a Dimension: the current token was not a Dimension token (a number with a unit, e.g. 10px), which is required to build a Dimension node. This `if !is!(self, Dimension)` check is a validation guard; input at fault is a length/angle/etc. position in input that receives a bare number, string, or other token.

Source

Thrown at crates/swc_css_parser/src/parser/values_and_units/mod.rs:1963

                value,
                raw: Some(raw),
            }),
            _ => {
                unreachable!()
            }
        }
    }
}

impl<I> Parse<Dimension> for Parser<I>
where
    I: ParserInput,
{
    fn parse(&mut self) -> PResult<Dimension> {
        let span = self.input.cur_span();

        if !is!(self, Dimension) {
            return Err(Error::new(span, ErrorKind::Expected("dimension token")));
        }

        match cur!(self) {
            Token::Dimension {
                dimension: dimension_token,
            } => {
                match &dimension_token.unit {
                    // <length>
                    unit if is_length_unit(unit)
                        || (self.ctx.in_container_at_rule && is_container_lengths_unit(unit)) =>
                    {
                        Ok(Dimension::Length(self.parse()?))
                    }
                    // <angle>
                    unit if is_angle_unit(unit) => Ok(Dimension::Angle(self.parse()?)),
                    // <time>
                    unit if is_time_unit(unit) => Ok(Dimension::Time(self.parse()?)),
                    // <frequency>

View on GitHub (pinned to 5176682b65)

Solutions

1. Provide a number with a unit (e.g. '10px', '2em')
2. Use a plain number or percentage type if no unit was intended

When it happens

Trigger: Thrown at crates/swc_css_parser/src/parser/values_and_units/mod.rs:1963 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/af3e5c76bd9dd3af. Report an issue: GitHub.