DioxusLabs/dioxus · error · syn::Error

Expected identifier pattern

Error message

Expected identifier pattern

What it means

Error "Expected identifier pattern" thrown in DioxusLabs/dioxus.

Source

Thrown at packages/manganis/manganis-macro/src/ffi.rs:207

    pub name: Ident,
    pub receiver: Option<Ident>, // The type name if first arg is `this: &TypeName`
    pub args: Vec<ForeignArg>,
    pub return_type: ForeignType,
}

impl ForeignFunctionDecl {
    fn from_foreign_fn(func: &ForeignItemFn) -> syn::Result<Self> {
        let name = func.sig.ident.clone();
        let mut receiver = None;
        let mut args = Vec::new();

        for (i, input) in func.sig.inputs.iter().enumerate() {
            match input {
                syn::FnArg::Typed(pat_type) => {
                    let arg_name = match &*pat_type.pat {
                        Pat::Ident(pat_ident) => pat_ident.ident.clone(),
                        _ => {
                            return Err(syn::Error::new(
                                pat_type.pat.span(),
                                "Expected identifier pattern",
                            ));
                        }
                    };

                    let arg_ty = ForeignType::from_type(&pat_type.ty)?;

                    // Check if first arg is `this: &SomeType`
                    if i == 0
                        && arg_name == "this"
                        && let ForeignType::OpaqueRef(type_name) = &arg_ty
                    {
                        receiver = Some(type_name.clone());
                        continue; // Don't add to args
                    }

                    args.push(ForeignArg {

View on GitHub (pinned to 393d190a80)

When it happens

Trigger: Thrown at packages/manganis/manganis-macro/src/ffi.rs:207 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of DioxusLabs/dioxus@393d190a80 (2026-08-16). Data as JSON: /api/errors/bca23e71ef3c2e02. Report an issue: GitHub.