swc-project/swc · error · Error

Unexpected ']' in declaration value

Error message

Unexpected ']' in declaration value

What it means

Fired by the declaration-value validator: a preserved ']' token appears in a declaration value without a matching '[' block. This generic validation helper reports any unbalanced closing bracket as an invalid declaration value.

Source

Thrown at crates/swc_css_parser/src/parser/util.rs:386

        &mut self,
        component_value: &ComponentValue,
    ) -> PResult<()> {
        let ComponentValue::PreservedToken(preserved_token) = component_value else {
            return Ok(());
        };

        let kind = match preserved_token.token {
            Token::BadString { .. } => ErrorKind::Unexpected("bad string in declaration value"),
            Token::BadUrl { .. } => ErrorKind::Unexpected("bad url in declaration value"),
            Token::RParen => ErrorKind::Unexpected("')' in declaration value"),
            Token::RBracket => ErrorKind::Unexpected("']' in declaration value"),
            Token::RBrace => ErrorKind::Unexpected("'}' in declaration value"),
            Token::Semi => ErrorKind::Unexpected("';' in declaration value"),
            Token::Delim { value: '!' } => ErrorKind::Unexpected("'!' in declaration value"),
            _ => return Ok(()),
        };

        Err(Error::new(preserved_token.span, kind))
    }
}

pub(super) struct WithCtx<'w, I: 'w + ParserInput> {
    inner: &'w mut Parser<I>,
    orig_ctx: Ctx,
}

impl<I: ParserInput> Deref for WithCtx<'_, I> {
    type Target = Parser<I>;

    fn deref(&self) -> &Parser<I> {
        self.inner
    }
}
impl<I: ParserInput> DerefMut for WithCtx<'_, I> {
    fn deref_mut(&mut self) -> &mut Parser<I> {
        self.inner

View on GitHub (pinned to 5176682b65)

Solutions

1. Remove the stray ']' or add the matching '[' block
2. Rebalance square brackets inside the declaration value

When it happens

Trigger: Thrown at crates/swc_css_parser/src/parser/util.rs:386 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/349f460dee4aabb3. Report an issue: GitHub.