Function clean_param_env

fn clean_param_env<'tcx>(
    cx: &mut DocContext<'tcx>,
    item_def_id: DefId,
    param_env: ParamEnv<'tcx>,
    region_data: RegionConstraintData<'tcx>,
    vid_to_region: FxIndexMap<RegionVid, Region<'tcx>>,
) -> Generics