if errs != nil {
			scopes.Framework.Infof("=== FAILED: Building clusters ===")
		}
	}()

	allClusters := make(cluster.Map)
	var clusters cluster.Clusters
	for i, cfg := range configs {
		c, err := buildCluster(cfg, allClusters)
		if err != nil {
			errs = multierror.Append(errs, fmt.Errorf("failed building cluster from config %d: %v", i, err))
			continue
		}
		if _, ok := allClusters[c.Name()]; ok {

	if features.MetadataExchange {
		c.Filters = append(c.Filters, xdsfilters.TCPClusterMx)
	}
}

// buildCluster builds the default cluster and also applies global options.
// It is used for building both inbound and outbound cluster.
func (cb *ClusterBuilder) buildCluster(name string, discoveryType cluster.Cluster_DiscoveryType,
	localityLbEndpoints []*endpoint.LocalityLbEndpoints, direction model.TrafficDirection,

			proxy,
			cb.req.Push,
			clusterName,
			model.TrafficDirectionInboundVIP, subset, svc.Hostname, port.Port,
			svc, nil,
		).FromServiceEndpoints()
	}
	localCluster := cb.buildCluster(clusterName, discoveryType, lbEndpoints,
		model.TrafficDirectionInboundVIP, &port, svc, nil, subset)

	// Ensure VIP cluster has services metadata for stats filter usage

// BuildClusters returns the list of clusters for the given proxy. This is the CDS output
// For outbound: Cluster for each service/subset hostname or cidr with SNI set to service hostname
// Cluster type based on resolution
// For inbound (sidecar only): Cluster for each inbound endpoint port and for each service port

					servicePort,
				},
				Hostname:     "host",
				MeshExternal: false,
				Attributes:   model.ServiceAttributes{Name: "svc", Namespace: "default"},
			}
			defaultCluster := cb.buildCluster(tt.clusterName, tt.discovery, tt.endpoints, tt.direction, servicePort, service, nil, "")
			eb := endpoints.NewCDSEndpointBuilder(proxy, cb.req.Push, tt.clusterName,
				tt.direction, "", service.Hostname, servicePort.Port,

  llvm::StringMap<SmallVector<Cluster>> clusters = BuildAllClusters(
      main_func.front(), info, GetDevice, CanBeIgnoredInCluster);
  return clusters;
}

TEST(BuildClusters, TestSingleCluster) {
  static const char* const module_with_single_cluster =
      R"(module {
func.func @main(%arg0: tensor<?xi32>) -> tensor<?xi32> {
    %0 = "tf.A"(%arg0) : (tensor<?xi32>) -> tensor<?xi32>

    // the function body or if they are nested in individual
    // `tf_executor.island`.
    for (Block& block : func.getBody()) BuildClusters(block, builder, info);
    func.walk([&](tf_executor::IslandOp island) {
      BuildClusters(island.GetBody(), builder, info);
    });
  }
}

}  // namespace

std::unique_ptr<OperationPass<ModuleOp>> CreateClusterFormationPass() {

	// once and shared across multiple invocations of this function.
	BuildListeners(node *model.Proxy, push *model.PushContext) []*listener.Listener

	// BuildClusters returns the list of clusters for the given proxy. This is the CDS output
	BuildClusters(node *model.Proxy, req *model.PushRequest) ([]*discovery.Resource, model.XdsLogDetails)

	"istio.io/istio/pilot/pkg/util/protoconv"
	"istio.io/istio/pkg/config/host"
	"istio.io/istio/pkg/util/sets"
)

// BuildClusters handles a gRPC CDS request, used with the 'ApiListener' style of requests.
// The main difference is that the request includes Resources to filter.
func (g *GrpcConfigGenerator) BuildClusters(node *model.Proxy, push *model.PushContext, names []string) model.Resources {
	filter := newClusterFilter(names)

	switch w.TypeUrl {
	case v3.ListenerType:
		return g.BuildListeners(proxy, req.Push, w.ResourceNames), model.DefaultXdsLogDetails, nil
	case v3.ClusterType:
		return g.BuildClusters(proxy, req.Push, w.ResourceNames), model.DefaultXdsLogDetails, nil
	case v3.RouteType:
		return g.BuildHTTPRoutes(proxy, req.Push, w.ResourceNames), model.DefaultXdsLogDetails, nil
	}