{"ast_node_type":"function","tokens":[{"end":91,"kind":"keyword","start":0,"text":"fn"}]}
    fn find_builder_fn(&self, err: &mut Diag<'_>, rcvr_ty: Ty<'tcx>, expr_id: hir::HirId) {
    /// to look for builders that return `Self`, `Option<Self>` or `Result<Self, _>`.
        let ty::Adt(adt_def, _) = rcvr_ty.kind() else {