{"ast_node_type":"function","tokens":[{"end":79,"kind":"keyword","start":0,"text":"fn"}]}
    fn is_diag_message<'cx>(cx: &LateContext<'cx>, ty: MiddleTy<'cx>) -> bool {
    // Is the type `{D,Subd}iagMessage`?
        if let Some(adt_def) = ty.ty_adt_def()