dbt-labs/dbt-core · error · syn::Error

Failed to parse value of `{field}` as string.

Error message

Failed to parse value of `{field}` as string.

What it means

Raised by the `parse_string` helper in crates/dbt-runtime-macros/src/entry.rs when a string-valued attribute option — `name`, `flavor`, or `unhandled_panic` (per the setters `set_name`, `set_flavor`, `set_unhandled_panic`) — is given a literal that is neither a string literal nor a verbatim token, e.g. an integer or bool literal. The macro rejects it at expansion time naming the offending field.

Source

Thrown at crates/dbt-runtime-macros/src/entry.rs:286

        syn::Lit::Int(lit) => match lit.base10_parse::<usize>() {
            Ok(value) => Ok(value),
            Err(e) => Err(syn::Error::new(
                span,
                format!("Failed to parse value of `{field}` as integer: {e}"),
            )),
        },
        _ => Err(syn::Error::new(
            span,
            format!("Failed to parse value of `{field}` as integer."),
        )),
    }
}

fn parse_string(int: syn::Lit, span: Span, field: &str) -> Result<String, syn::Error> {
    match int {
        syn::Lit::Str(s) => Ok(s.value()),
        syn::Lit::Verbatim(s) => Ok(s.to_string()),
        _ => Err(syn::Error::new(
            span,
            format!("Failed to parse value of `{field}` as string."),
        )),
    }
}

fn parse_path(lit: syn::Lit, span: Span, field: &str) -> Result<Path, syn::Error> {
    match lit {
        syn::Lit::Str(s) => {
            let err = syn::Error::new(
                span,
                format!(
                    "Failed to parse value of `{}` as path: \"{}\"",
                    field,
                    s.value()
                ),
            );
            s.parse::<syn::Path>().map_err(|_| err.clone())

View on GitHub (pinned to 0267ce9170)

Solutions

1. Quote the value: `flavor = "multi_thread"`, `name = "my_task"`, `unhandled_panic = "abort_runtime"`.
2. For `unhandled_panic`, use the string literal form of the enum value, not a bare bool or identifier.
3. If a codegen tool emits the attribute, ensure string fields are emitted as quoted literals.

Example fix

// before
#[dbt_runtime::main(flavor = multi_thread)]
async fn main() { /* ... */ }

// after
#[dbt_runtime::main(flavor = "multi_thread")]
async fn main() { /* ... */ }

// String options (name, flavor, unhandled_panic) require quoted literals.
#[dbt_runtime::main(
    name = "svc",
    flavor = "multi_thread",
)]
async fn main() {}

When it happens

Trigger: Writing `name = 42`, `flavor = multi_thread` (unquoted identifier) or `unhandled_panic = true` in the attribute; anything that is not syn::Lit::Str or syn::Lit::Verbatim reaching `parse_string`.

Common situations: Forgetting quotes around enum-like values (`flavor = multi_thread` instead of `flavor = "multi_thread"`); passing a boolean to unhandled_panic instead of the string `"abort_runtime"`; templated attributes substituting unquoted values.

Understand the failure class

Background: Type mismatch errors: IllegalArgumentException, TypeError and type guards across 150 open-source libraries — this error's family across 150 libraries.

• Parsing and encoding errors: unexpected token, malformed input — why parsers reject input and how to find the real culprit.

Related errors

• Failed to parse value of `{field}` as integer.
• Failed to parse value of `{field}` as integer: {e}
• The `start_paused` option requires the `current_thread` runt
• The `unhandled_panic` option requires the `current_thread` r
• Failed to parse value of `{field}` as path.

AI-assisted analysis of dbt-labs/dbt-core@0267ce9170 (2026-09-07). Data as JSON: /api/errors/2ff47ffce0e69de1. Report an issue: GitHub.