{"ast_node_type":"variable","tokens":[{"end":19,"kind":"keyword","start":0,"text":"let"}]}
    let trait_ref =
    let (infcx, param_env) = tcx.infer_ctxt().build_with_typing_env(typing_env);
        ty::TraitRef::new(tcx, tcx.require_lang_item(hir::LangItem::Copy, DUMMY_SP), [ty]);