fn fn_abi_adjust_for_abi<'tcx>(
    cx: &LayoutCx<'tcx, TyCtxt<'tcx>>,
    fn_abi: &mut FnAbi<'tcx, Ty<'tcx>>,
    abi: Abi,
    fn_def_id: Option<DefId>
) -> Result<(), &'tcx FnAbiError<'tcx>>