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

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

Error message

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

What it means

Raised by the `parse_int` helper in crates/dbt-runtime-macros/src/entry.rs when an integer-valued attribute option (e.g. `worker_threads`) is given a literal that is not an integer at all — anything other than syn::Lit::Int, such as a string or bool literal. The macro rejects it at expansion time with a plain message naming the field.

Source

Thrown at crates/dbt-runtime-macros/src/entry.rs:275

            crate_name: self.crate_name.clone(),
            flavor,
            worker_threads,
            start_paused,
            unhandled_panic,
        })
    }
}

fn parse_int(int: syn::Lit, span: Span, field: &str) -> Result<usize, syn::Error> {
    match int {
        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> {

View on GitHub (pinned to 0267ce9170)

Solutions

1. Remove the quotes: use an unquoted integer literal, e.g. `worker_threads = 4`.
2. Ensure the field you set is one that expects an integer; string-valued options (name, flavor, unhandled_panic) should not use parse_int fields.
3. Check codegen/config templating so numeric values are emitted unquoted.

Example fix

// before
#[dbt_runtime::main(worker_threads = "4")]
async fn main() { /* ... */ }

// after
#[dbt_runtime::main(flavor = "multi_thread", worker_threads = 4)]
async fn main() { /* ... */ }

// Integer options must be unquoted integer literals in the attribute.
// WRONG: #[dbt_runtime::main(worker_threads = "4")]
// RIGHT:
#[dbt_runtime::main(flavor = "multi_thread", worker_threads = 4)]
async fn main() {}

When it happens

Trigger: Writing `worker_threads = "8"` (string instead of integer literal) or `worker_threads = true` in the attribute; passing any non-Int literal to a field parsed by `parse_int` via `set_worker_threads`.

Common situations: Quoting numeric attribute values out of habit; generating attributes from config where the value was serialized as a string; editing an attribute and accidentally adding quotes.

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 string.
• 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/e7ad0a9c84cb6a1b. Report an issue: GitHub.