fn adjust_for_rust_scalar<'tcx>(
    cx: LayoutCx<'tcx, TyCtxt<'tcx>>,
    attrs: &mut ArgAttributes,
    scalar: Scalar,
    layout: TyAndLayout<'tcx>,
    offset: Size,
    is_return: bool,
    drop_target_pointee: Option<Ty<'tcx>>
)