{"ast_node_type":"variable","tokens":[{"end":70,"kind":"keyword","start":0,"text":"let"}]}
    let mut type_folder = TransformTy::new(tcx, transform_ty_options);
        .unwrap_or_else(|| bug!("typeid_for_fnabi: invalid option(s) `{:?}`", options.bits()));
    let ty = fn_abi.ret.layout.ty.fold_with(&mut type_folder);