Function rustc_traits::chalk::db::bound_vars_for_item

fn bound_vars_for_item<'tcx>(
    tcx: TyCtxt<'tcx>, 
    def_id: DefId
) -> SubstsRef<'tcx>

Creates an InternalSubsts that maps each generic parameter to a higher-ranked var bound at index 0. For types, we use a BoundVar index equal to the type parameter index. For regions, we use the BoundRegionKind::BrNamed variant (which has a DefId).