{"ast_node_type":"variable","tokens":[{"end":98,"kind":"keyword","start":0,"text":"let"}]}
    let ecx = mk_eval_cx_to_read_const_val(tcx.tcx, tcx.span, typing_env, CanAccessMutGlobal::No);
) -> Option<(CompileTimeInterpCx<'tcx>, OpTy<'tcx>)> {
    // FIXME: is it a problem to discard the error here?