astral-sh/ruff · error · syn::Error

Can only derive CombineOptions from structs with named field

Error message

Can only derive CombineOptions from structs with named fields.

What it means

A syn compile error from the CombineOptions derive macro: the target is not a struct with named fields (tuple struct, unit struct, enum, or union). The generated combine logic assigns fields by name, so other shapes are rejected.

Source

Thrown at crates/ruff_macros/src/combine_options.rs:32

                .iter()
                .map(handle_field)
                .collect::<Result<Vec<_>, _>>()?;

            Ok(quote! {
                #[automatically_derived]
                impl crate::configuration::CombinePluginOptions for #ident {
                    fn combine(self, other: Self) -> Self {
                        #[expect(deprecated)]
                        Self {
                        #(
                            #output
                        ),*
                        }
                    }
                }
            })
        }
        _ => Err(syn::Error::new(
            ident.span(),
            "Can only derive CombineOptions from structs with named fields.",
        )),
    }
}

fn handle_field(field: &Field) -> syn::Result<proc_macro2::TokenStream> {
    let ident = field
        .ident
        .as_ref()
        .expect("Expected to handle named fields");

    match &field.ty {
        Type::Path(TypePath {
            path: Path { segments, .. },
            ..
        }) => match segments.first() {
            Some(PathSegment {

View on GitHub (pinned to 26f38c119c)

Solutions

1. Give the struct named fields
2. Implement CombineOptions manually for this shape

When it happens

Trigger: Thrown at crates/ruff_macros/src/combine_options.rs:32 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of astral-sh/ruff@26f38c119c (2026-09-05). Data as JSON: /api/errors/dd0345dacaf9ace6. Report an issue: GitHub.