swc-project/swc · error · syn::Error

unknown ast_node option

Error message

unknown ast_node option

What it means

The #[ast_node] attribute macro's Args parser accepts only the `no_partial_eq` option after the type; any other identifier makes the proc macro return this syn::Error at the option's span, failing compilation of the annotated item.

Source

Thrown at crates/ast_node/src/ast_node_macro.rs:24

#[derive(Clone)]
pub struct Args {
    pub ty: Literal,
    pub no_partial_eq: bool,
}

impl Parse for Args {
    fn parse(i: ParseStream<'_>) -> syn::Result<Self> {
        let ty = i.parse()?;
        let mut no_partial_eq = false;

        if i.parse::<Option<Token![,]>>()?.is_some() {
            let option: Ident = i.parse()?;

            if option == "no_partial_eq" {
                no_partial_eq = true;
            } else {
                return Err(Error::new(option.span(), "unknown ast_node option"));
            }
        }

        if !i.is_empty() {
            return Err(i.error("unexpected ast_node arguments"));
        }

        Ok(Args { ty, no_partial_eq })
    }
}

pub fn expand_struct(args: Args, i: DeriveInput) -> Vec<ItemImpl> {
    let mut items = Vec::new();
    let generics = i.generics.clone();
    // let item_ident = Ident::new("Item", i.ident.span());

    {
        let ty = &i.ident;

View on GitHub (pinned to 5176682b65)

Solutions

1. Use only the supported `no_partial_eq` option in the #[ast_node] invocation
2. Fix the typo in the attribute name
3. Extend Args::parse if a genuinely new option is required

When it happens

Trigger: Thrown at crates/ast_node/src/ast_node_macro.rs:24 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/d325cbb2fd43d65d. Report an issue: GitHub.