Function lower_variant

fn lower_variant<'tcx>(
    tcx: TyCtxt<'tcx>,
    variant_did: Option<LocalDefId>,
    ident: Ident,
    discr: VariantDiscr,
    def: &VariantData<'tcx>,
    adt_kind: AdtKind,
    parent_did: LocalDefId,
) -> VariantDef