Function layout_of 

pub(crate) fn layout_of<'tcx>(
    tcx: TyCtxt<'tcx>,
    _key: PseudoCanonicalInput<'tcx, Ty<'tcx>>,
    cycle: Cycle<'tcx>,
    err: Diag<'_>,
) -> Result<TyAndLayout<'tcx>, &'tcx LayoutError<'tcx>>