swc-project/swc · error

ToCode for {}

Error message

ToCode for {}

What it means

A todo!() stub generated by the fail_todo! macro in swc_ecma_quote_macros (ast/mod.rs:11). For AST node types the quote-strings-to-code machinery has not implemented yet, the macro installs a ToCode impl that panics with 'ToCode for <Type>' when that node is quoted. It fires whenever a quoted expression contains an AST node kind lacking a real ToCode implementation; the node type named in the message is the gap.

Source

Thrown at crates/swc_ecma_quote_macros/src/ast/mod.rs:11

use swc_common::{Span, SyntaxContext};
use swc_ecma_ast::*;
use syn::{parse_quote, ExprBlock};

use crate::ctxt::Ctx;

macro_rules! fail_todo {
    ($T:ty) => {
        impl crate::ast::ToCode for $T {
            fn to_code(&self, _: &crate::ctxt::Ctx) -> syn::Expr {
                todo!("ToCode for {}", stringify!($T))
            }
        }
    };
}

macro_rules! impl_enum_body {
    ($E:ident, $s:expr, $cx:expr,[ $($v:ident),* ]) => {
        match $s {
            $(
                $E::$v(inner) => {
                    let val = crate::ast::ToCode::to_code(inner, $cx);
                    syn::parse_quote!(
                        swc_core::ecma::ast::$E::$v(#val)
                    )
                },
            )*
            #[cfg(swc_ast_unknown)]
            _ => panic!("unable to access unknown nodes"),

View on GitHub (pinned to 5176682b65)

Solutions

1. Implement ToCode for the node type named in the panic message and contribute it upstream
2. Avoid quoting that node kind inside the quote macros until support exists
3. Check swc release notes — the missing ToCode impl may have been added in a newer version

When it happens

Trigger: Thrown at crates/swc_ecma_quote_macros/src/ast/mod.rs:11 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/3ec767715c6761d5. Report an issue: GitHub.