Merge pull request #1894 from mtrmac/go1.18

Update to Go 1.18

cmd/skopeo/inspect.go

@@ -74,7 +74,7 @@ func (opts *inspectOptions) run(args []string, stdout io.Writer) (retErr error)
 		rawManifest []byte
 		src         types.ImageSource
 		imgInspect  *types.ImageInspectInfo
-		data        []interface{}
+		data        []any
 	)
 	ctx, cancel := opts.global.commandTimeoutContext()
 	defer cancel()
@@ -240,7 +240,7 @@ func (opts *inspectOptions) run(args []string, stdout io.Writer) (retErr error)
 	return printTmpl(stdout, row, data)
 }
 
-func printTmpl(stdout io.Writer, row string, data []interface{}) error {
+func printTmpl(stdout io.Writer, row string, data []any) error {
 	t, err := template.New("skopeo inspect").Parse(row)
 	if err != nil {
 		return err

cmd/skopeo/list_tags.go

@@ -16,6 +16,7 @@ import (
 	"github.com/containers/image/v5/transports/alltransports"
 	"github.com/containers/image/v5/types"
 	"github.com/spf13/cobra"
+	"golang.org/x/exp/maps"
 )
 
 // tagListOutput is the output format of (skopeo list-tags), primarily so that we can format it with a simple json.MarshalIndent.
@@ -37,10 +38,7 @@ var transportHandlers = map[string]func(ctx context.Context, sys *types.SystemCo
 
 // supportedTransports returns all the supported transports
 func supportedTransports(joinStr string) string {
-	res := make([]string, 0, len(transportHandlers))
+	res := maps.Keys(transportHandlers)
-	for handlerName := range transportHandlers {
-		res = append(res, handlerName)
-	}
 	sort.Strings(res)
 	return strings.Join(res, joinStr)
 }
@@ -84,12 +82,12 @@ func parseDockerRepositoryReference(refString string) (types.ImageReference, err
 		return nil, fmt.Errorf("docker: image reference %s does not start with %s://", refString, docker.Transport.Name())
 	}
 
-	parts := strings.SplitN(refString, ":", 2)
+	_, dockerImageName, hasColon := strings.Cut(refString, ":")
-	if len(parts) != 2 {
+	if !hasColon {
 		return nil, fmt.Errorf(`Invalid image name "%s", expected colon-separated transport:reference`, refString)
 	}
 
-	ref, err := reference.ParseNormalizedNamed(strings.TrimPrefix(parts[1], "//"))
+	ref, err := reference.ParseNormalizedNamed(strings.TrimPrefix(dockerImageName, "//"))
 	if err != nil {
 		return nil, err
 	}

cmd/skopeo/proxy.go

@@ -115,7 +115,7 @@ type request struct {
 	// Method is the name of the function
 	Method string `json:"method"`
 	// Args is the arguments (parsed inside the function)
-	Args []interface{} `json:"args"`
+	Args []any `json:"args"`
 }
 
 // reply is serialized to JSON as the return value from a function call.
@@ -123,7 +123,7 @@ type reply struct {
 	// Success is true if and only if the call succeeded.
 	Success bool `json:"success"`
 	// Value is an arbitrary value (or values, as array/map) returned from the call.
-	Value interface{} `json:"value"`
+	Value any `json:"value"`
 	// PipeID is an index into open pipes, and should be passed to FinishPipe
 	PipeID uint32 `json:"pipeid"`
 	// Error should be non-empty if Success == false
@@ -133,7 +133,7 @@ type reply struct {
 // replyBuf is our internal deserialization of reply plus optional fd
 type replyBuf struct {
 	// value will be converted to a reply Value
-	value interface{}
+	value any
 	// fd is the read half of a pipe, passed back to the client
 	fd *os.File
 	// pipeid will be provided to the client as PipeID, an index into our open pipes
@@ -185,7 +185,7 @@ type convertedLayerInfo struct {
 }
 
 // Initialize performs one-time initialization, and returns the protocol version
-func (h *proxyHandler) Initialize(args []interface{}) (replyBuf, error) {
+func (h *proxyHandler) Initialize(args []any) (replyBuf, error) {
 	h.lock.Lock()
 	defer h.lock.Unlock()
 
@@ -214,7 +214,7 @@ func (h *proxyHandler) Initialize(args []interface{}) (replyBuf, error) {
 
 // OpenImage accepts a string image reference i.e. TRANSPORT:REF - like `skopeo copy`.
 // The return value is an opaque integer handle.
-func (h *proxyHandler) OpenImage(args []interface{}) (replyBuf, error) {
+func (h *proxyHandler) OpenImage(args []any) (replyBuf, error) {
 	return h.openImageImpl(args, false)
 }
 
@@ -237,7 +237,7 @@ func isNotFoundImageError(err error) bool {
 		errors.Is(err, ocilayout.ImageNotFoundError{})
 }
 
-func (h *proxyHandler) openImageImpl(args []interface{}, allowNotFound bool) (replyBuf, error) {
+func (h *proxyHandler) openImageImpl(args []any, allowNotFound bool) (replyBuf, error) {
 	h.lock.Lock()
 	defer h.lock.Unlock()
 	var ret replyBuf
@@ -282,11 +282,11 @@ func (h *proxyHandler) openImageImpl(args []interface{}, allowNotFound bool) (re
 // OpenImage accepts a string image reference i.e. TRANSPORT:REF - like `skopeo copy`.
 // The return value is an opaque integer handle.  If the image does not exist, zero
 // is returned.
-func (h *proxyHandler) OpenImageOptional(args []interface{}) (replyBuf, error) {
+func (h *proxyHandler) OpenImageOptional(args []any) (replyBuf, error) {
 	return h.openImageImpl(args, true)
 }
 
-func (h *proxyHandler) CloseImage(args []interface{}) (replyBuf, error) {
+func (h *proxyHandler) CloseImage(args []any) (replyBuf, error) {
 	h.lock.Lock()
 	defer h.lock.Unlock()
 	var ret replyBuf
@@ -307,7 +307,7 @@ func (h *proxyHandler) CloseImage(args []interface{}) (replyBuf, error) {
 	return ret, nil
 }
 
-func parseImageID(v interface{}) (uint32, error) {
+func parseImageID(v any) (uint32, error) {
 	imgidf, ok := v.(float64)
 	if !ok {
 		return 0, fmt.Errorf("expecting integer imageid, not %T", v)
@@ -316,7 +316,7 @@ func parseImageID(v interface{}) (uint32, error) {
 }
 
 // parseUint64 validates that a number fits inside a JavaScript safe integer
-func parseUint64(v interface{}) (uint64, error) {
+func parseUint64(v any) (uint64, error) {
 	f, ok := v.(float64)
 	if !ok {
 		return 0, fmt.Errorf("expecting numeric, not %T", v)
@@ -327,7 +327,7 @@ func parseUint64(v interface{}) (uint64, error) {
 	return uint64(f), nil
 }
 
-func (h *proxyHandler) parseImageFromID(v interface{}) (*openImage, error) {
+func (h *proxyHandler) parseImageFromID(v any) (*openImage, error) {
 	imgid, err := parseImageID(v)
 	if err != nil {
 		return nil, err
@@ -357,7 +357,7 @@ func (h *proxyHandler) allocPipe() (*os.File, *activePipe, error) {
 
 // returnBytes generates a return pipe() from a byte array
 // In the future it might be nicer to return this via memfd_create()
-func (h *proxyHandler) returnBytes(retval interface{}, buf []byte) (replyBuf, error) {
+func (h *proxyHandler) returnBytes(retval any, buf []byte) (replyBuf, error) {
 	var ret replyBuf
 	piper, f, err := h.allocPipe()
 	if err != nil {
@@ -419,7 +419,7 @@ func (h *proxyHandler) cacheTargetManifest(img *openImage) error {
 
 // GetManifest returns a copy of the manifest, converted to OCI format, along with the original digest.
 // Manifest lists are resolved to the current operating system and architecture.
-func (h *proxyHandler) GetManifest(args []interface{}) (replyBuf, error) {
+func (h *proxyHandler) GetManifest(args []any) (replyBuf, error) {
 	h.lock.Lock()
 	defer h.lock.Unlock()
 
@@ -490,7 +490,7 @@ func (h *proxyHandler) GetManifest(args []interface{}) (replyBuf, error) {
 
 // GetFullConfig returns a copy of the image configuration, converted to OCI format.
 // https://github.com/opencontainers/image-spec/blob/main/config.md
-func (h *proxyHandler) GetFullConfig(args []interface{}) (replyBuf, error) {
+func (h *proxyHandler) GetFullConfig(args []any) (replyBuf, error) {
 	h.lock.Lock()
 	defer h.lock.Unlock()
 
@@ -527,7 +527,7 @@ func (h *proxyHandler) GetFullConfig(args []interface{}) (replyBuf, error) {
 // GetConfig returns a copy of the container runtime configuration, converted to OCI format.
 // Note that due to a historical mistake, this returns not the full image configuration,
 // but just the container runtime configuration.  You should use GetFullConfig instead.
-func (h *proxyHandler) GetConfig(args []interface{}) (replyBuf, error) {
+func (h *proxyHandler) GetConfig(args []any) (replyBuf, error) {
 	h.lock.Lock()
 	defer h.lock.Unlock()
 
@@ -562,7 +562,7 @@ func (h *proxyHandler) GetConfig(args []interface{}) (replyBuf, error) {
 }
 
 // GetBlob fetches a blob, performing digest verification.
-func (h *proxyHandler) GetBlob(args []interface{}) (replyBuf, error) {
+func (h *proxyHandler) GetBlob(args []any) (replyBuf, error) {
 	h.lock.Lock()
 	defer h.lock.Unlock()
 
@@ -632,7 +632,7 @@ func (h *proxyHandler) GetBlob(args []interface{}) (replyBuf, error) {
 // This needs to be called since the data returned by GetManifest() does not allow to correctly
 // calling GetBlob() for the containers-storage: transport (which doesn’t store the original compressed
 // representations referenced in the manifest).
-func (h *proxyHandler) GetLayerInfo(args []interface{}) (replyBuf, error) {
+func (h *proxyHandler) GetLayerInfo(args []any) (replyBuf, error) {
 	h.lock.Lock()
 	defer h.lock.Unlock()
 
@@ -678,7 +678,7 @@ func (h *proxyHandler) GetLayerInfo(args []interface{}) (replyBuf, error) {
 }
 
 // FinishPipe waits for the worker goroutine to finish, and closes the write side of the pipe.
-func (h *proxyHandler) FinishPipe(args []interface{}) (replyBuf, error) {
+func (h *proxyHandler) FinishPipe(args []any) (replyBuf, error) {
 	h.lock.Lock()
 	defer h.lock.Unlock()
 

cmd/skopeo/sync.go

@@ -26,6 +26,7 @@ import (
 	"github.com/opencontainers/go-digest"
 	"github.com/sirupsen/logrus"
 	"github.com/spf13/cobra"
+	"golang.org/x/exp/slices"
 	"gopkg.in/yaml.v3"
 )
 
@@ -523,26 +524,17 @@ func (opts *syncOptions) run(args []string, stdout io.Writer) (retErr error) {
 	}()
 
 	// validate source and destination options
-	contains := func(val string, list []string) (_ bool) {
-		for _, l := range list {
-			if l == val {
-				return true
-			}
-		}
-		return
-	}
-
 	if len(opts.source) == 0 {
 		return errors.New("A source transport must be specified")
 	}
-	if !contains(opts.source, []string{docker.Transport.Name(), directory.Transport.Name(), "yaml"}) {
+	if !slices.Contains([]string{docker.Transport.Name(), directory.Transport.Name(), "yaml"}, opts.source) {
 		return fmt.Errorf("%q is not a valid source transport", opts.source)
 	}
 
 	if len(opts.destination) == 0 {
 		return errors.New("A destination transport must be specified")
 	}
-	if !contains(opts.destination, []string{docker.Transport.Name(), directory.Transport.Name()}) {
+	if !slices.Contains([]string{docker.Transport.Name(), directory.Transport.Name()}, opts.destination) {
 		return fmt.Errorf("%q is not a valid destination transport", opts.destination)
 	}
 

cmd/skopeo/unshare_linux.go

@@ -6,6 +6,7 @@ import (
 	"github.com/containers/image/v5/transports/alltransports"
 	"github.com/containers/storage/pkg/unshare"
 	"github.com/syndtr/gocapability/capability"
+	"golang.org/x/exp/slices"
 )
 
 var neededCapabilities = []capability.Cap{
@@ -25,25 +26,25 @@ func maybeReexec() error {
 	if err != nil {
 		return fmt.Errorf("error reading the current capabilities sets: %w", err)
 	}
-	for _, cap := range neededCapabilities {
+	if slices.ContainsFunc(neededCapabilities, func(cap capability.Cap) bool {
-		if !capabilities.Get(capability.EFFECTIVE, cap) {
+		return !capabilities.Get(capability.EFFECTIVE, cap)
-			// We miss a capability we need, create a user namespaces
+	}) {
-			unshare.MaybeReexecUsingUserNamespace(true)
+		// We miss a capability we need, create a user namespaces
-			return nil
+		unshare.MaybeReexecUsingUserNamespace(true)
-		}
+		return nil
 	}
 	return nil
 }
 
 func reexecIfNecessaryForImages(imageNames ...string) error {
 	// Check if container-storage is used before doing unshare
-	for _, imageName := range imageNames {
+	if slices.ContainsFunc(imageNames, func(imageName string) bool {
 		transport := alltransports.TransportFromImageName(imageName)
 		// Hard-code the storage name to avoid a reference on c/image/storage.
 		// See https://github.com/containers/skopeo/issues/771#issuecomment-563125006.
-		if transport != nil && transport.Name() == "containers-storage" {
+		return transport != nil && transport.Name() == "containers-storage"
-			return maybeReexec()
+	}) {
-		}
+		return maybeReexec()
 	}
 	return nil
 }

cmd/skopeo/utils.go

@@ -315,14 +315,11 @@ func parseCreds(creds string) (string, string, error) {
 	if creds == "" {
 		return "", "", errors.New("credentials can't be empty")
 	}
-	up := strings.SplitN(creds, ":", 2)
+	username, password, _ := strings.Cut(creds, ":") // Sets password to "" if there is no ":"
-	if len(up) == 1 {
+	if username == "" {
-		return up[0], "", nil
-	}
-	if up[0] == "" {
 		return "", "", errors.New("username can't be empty")
 	}
-	return up[0], up[1], nil
+	return username, password, nil
 }
 
 func getDockerAuth(creds string) (*types.DockerAuthConfig, error) {

go.mod

@@ -1,6 +1,6 @@
 module github.com/containers/skopeo
 
-go 1.17
+go 1.18
 
 require (
 	github.com/containers/common v0.51.0
@@ -16,6 +16,7 @@ require (
 	github.com/spf13/pflag v1.0.5
 	github.com/stretchr/testify v1.8.1
 	github.com/syndtr/gocapability v0.0.0-20200815063812-42c35b437635
+	golang.org/x/exp v0.0.0-20230202163644-54bba9f4231b
 	golang.org/x/term v0.4.0
 	gopkg.in/check.v1 v1.0.0-20201130134442-10cb98267c6c
 	gopkg.in/yaml.v3 v3.0.1

integration/copy_test.go

@@ -607,12 +607,12 @@ func assertDirImagesAreEqual(c *check.C, dir1, dir2 string) {
 // Check whether schema1 dir: images in dir1 and dir2 are equal, ignoring schema1 signatures and the embedded path/tag values, which should have the expected values.
 func assertSchema1DirImagesAreEqualExceptNames(c *check.C, dir1, ref1, dir2, ref2 string) {
 	// The manifests may have different JWS signatures and names; so, unmarshal and delete these elements.
-	manifests := []map[string]interface{}{}
+	manifests := []map[string]any{}
 	for dir, ref := range map[string]string{dir1: ref1, dir2: ref2} {
 		manifestPath := filepath.Join(dir, "manifest.json")
 		m, err := os.ReadFile(manifestPath)
 		c.Assert(err, check.IsNil)
-		data := map[string]interface{}{}
+		data := map[string]any{}
 		err = json.Unmarshal(m, &data)
 		c.Assert(err, check.IsNil)
 		c.Assert(data["schemaVersion"], check.Equals, float64(1))

integration/openshift.go

@@ -154,7 +154,7 @@ func (cluster *openshiftCluster) prepareRegistryConfig(c *check.C) {
 }
 
 // startRegistry starts the OpenShift registry with configPart on port, waits for it to be ready, and returns the process object, or terminates on failure.
-func (cluster *openshiftCluster) startRegistryProcess(c *check.C, port int, configPath string) *exec.Cmd {
+func (cluster *openshiftCluster) startRegistryProcess(c *check.C, port uint16, configPath string) *exec.Cmd {
 	cmd := cluster.clusterCmd(map[string]string{
 		"KUBECONFIG":          "openshift.local.registry/openshift-registry.kubeconfig",
 		"DOCKER_REGISTRY_URL": fmt.Sprintf("127.0.0.1:%d", port),

integration/proxy_test.go

@@ -32,7 +32,7 @@ type request struct {
 	// Method is the name of the function
 	Method string `json:"method"`
 	// Args is the arguments (parsed inside the function)
-	Args []interface{} `json:"args"`
+	Args []any `json:"args"`
 }
 
 // reply is copied from proxy.go
@@ -40,7 +40,7 @@ type reply struct {
 	// Success is true if and only if the call succeeded.
 	Success bool `json:"success"`
 	// Value is an arbitrary value (or values, as array/map) returned from the call.
-	Value interface{} `json:"value"`
+	Value any `json:"value"`
 	// PipeID is an index into open pipes, and should be passed to FinishPipe
 	PipeID uint32 `json:"pipeid"`
 	// Error should be non-empty if Success == false
@@ -60,7 +60,7 @@ type pipefd struct {
 	fd *os.File
 }
 
-func (p *proxy) call(method string, args []interface{}) (rval interface{}, fd *pipefd, err error) {
+func (p *proxy) call(method string, args []any) (rval any, fd *pipefd, err error) {
 	req := request{
 		Method: method,
 		Args:   args,
@@ -122,7 +122,7 @@ func (p *proxy) call(method string, args []interface{}) (rval interface{}, fd *p
 	return
 }
 
-func (p *proxy) callNoFd(method string, args []interface{}) (rval interface{}, err error) {
+func (p *proxy) callNoFd(method string, args []any) (rval any, err error) {
 	var fd *pipefd
 	rval, fd, err = p.call(method, args)
 	if err != nil {
@@ -135,7 +135,7 @@ func (p *proxy) callNoFd(method string, args []interface{}) (rval interface{}, e
 	return rval, nil
 }
 
-func (p *proxy) callReadAllBytes(method string, args []interface{}) (rval interface{}, buf []byte, err error) {
+func (p *proxy) callReadAllBytes(method string, args []any) (rval any, buf []byte, err error) {
 	var fd *pipefd
 	rval, fd, err = p.call(method, args)
 	if err != nil {
@@ -153,7 +153,7 @@ func (p *proxy) callReadAllBytes(method string, args []interface{}) (rval interf
 			err:     err,
 		}
 	}()
-	_, err = p.callNoFd("FinishPipe", []interface{}{fd.id})
+	_, err = p.callNoFd("FinishPipe", []any{fd.id})
 	if err != nil {
 		return
 	}
@@ -233,7 +233,7 @@ type byteFetch struct {
 }
 
 func runTestGetManifestAndConfig(p *proxy, img string) error {
-	v, err := p.callNoFd("OpenImage", []interface{}{knownNotManifestListedImage_x8664})
+	v, err := p.callNoFd("OpenImage", []any{knownNotManifestListedImage_x8664})
 	if err != nil {
 		return err
 	}
@@ -248,7 +248,7 @@ func runTestGetManifestAndConfig(p *proxy, img string) error {
 	}
 
 	// Also verify the optional path
-	v, err = p.callNoFd("OpenImageOptional", []interface{}{knownNotManifestListedImage_x8664})
+	v, err = p.callNoFd("OpenImageOptional", []any{knownNotManifestListedImage_x8664})
 	if err != nil {
 		return err
 	}
@@ -262,12 +262,12 @@ func runTestGetManifestAndConfig(p *proxy, img string) error {
 		return fmt.Errorf("got zero from expected image")
 	}
 
-	_, err = p.callNoFd("CloseImage", []interface{}{imgid2})
+	_, err = p.callNoFd("CloseImage", []any{imgid2})
 	if err != nil {
 		return err
 	}
 
-	_, manifestBytes, err := p.callReadAllBytes("GetManifest", []interface{}{imgid})
+	_, manifestBytes, err := p.callReadAllBytes("GetManifest", []any{imgid})
 	if err != nil {
 		return err
 	}
@@ -276,7 +276,7 @@ func runTestGetManifestAndConfig(p *proxy, img string) error {
 		return err
 	}
 
-	_, configBytes, err := p.callReadAllBytes("GetFullConfig", []interface{}{imgid})
+	_, configBytes, err := p.callReadAllBytes("GetFullConfig", []any{imgid})
 	if err != nil {
 		return err
 	}
@@ -295,7 +295,7 @@ func runTestGetManifestAndConfig(p *proxy, img string) error {
 	}
 
 	// Also test this legacy interface
-	_, ctrconfigBytes, err := p.callReadAllBytes("GetConfig", []interface{}{imgid})
+	_, ctrconfigBytes, err := p.callReadAllBytes("GetConfig", []any{imgid})
 	if err != nil {
 		return err
 	}
@@ -310,7 +310,7 @@ func runTestGetManifestAndConfig(p *proxy, img string) error {
 		return fmt.Errorf("No CMD or ENTRYPOINT set")
 	}
 
-	_, err = p.callNoFd("CloseImage", []interface{}{imgid})
+	_, err = p.callNoFd("CloseImage", []any{imgid})
 	if err != nil {
 		return err
 	}
@@ -319,7 +319,7 @@ func runTestGetManifestAndConfig(p *proxy, img string) error {
 }
 
 func runTestOpenImageOptionalNotFound(p *proxy, img string) error {
-	v, err := p.callNoFd("OpenImageOptional", []interface{}{img})
+	v, err := p.callNoFd("OpenImageOptional", []any{img})
 	if err != nil {
 		return err
 	}

integration/utils.go

@@ -4,6 +4,7 @@ import (
 	"bytes"
 	"io"
 	"net"
+	"net/netip"
 	"os"
 	"os/exec"
 	"path/filepath"
@@ -105,8 +106,9 @@ func runExecCmdWithInput(c *check.C, cmd *exec.Cmd, input string) {
 }
 
 // isPortOpen returns true iff the specified port on localhost is open.
-func isPortOpen(port int) bool {
+func isPortOpen(port uint16) bool {
-	conn, err := net.DialTCP("tcp", nil, &net.TCPAddr{IP: net.IPv4(127, 0, 0, 1), Port: port})
+	ap := netip.AddrPortFrom(netip.AddrFrom4([4]byte{127, 0, 0, 1}), port)
+	conn, err := net.DialTCP("tcp", nil, net.TCPAddrFromAddrPort(ap))
 	if err != nil {
 		return false
 	}
@@ -118,7 +120,7 @@ func isPortOpen(port int) bool {
 // The checking can be aborted by sending a value to the terminate channel, which the caller should
 // always do using
 // defer func() {terminate <- true}()
-func newPortChecker(c *check.C, port int) (portOpen <-chan bool, terminate chan<- bool) {
+func newPortChecker(c *check.C, port uint16) (portOpen <-chan bool, terminate chan<- bool) {
 	portOpenBidi := make(chan bool)
 	// Buffered, so that sending a terminate request after the goroutine has exited does not block.
 	terminateBidi := make(chan bool, 1)

vendor/golang.org/x/exp/LICENSE

@@ -0,0 +1,27 @@
+Copyright (c) 2009 The Go Authors. All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are
+met:
+
+   * Redistributions of source code must retain the above copyright
+notice, this list of conditions and the following disclaimer.
+   * Redistributions in binary form must reproduce the above
+copyright notice, this list of conditions and the following disclaimer
+in the documentation and/or other materials provided with the
+distribution.
+   * Neither the name of Google Inc. nor the names of its
+contributors may be used to endorse or promote products derived from
+this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

vendor/golang.org/x/exp/PATENTS

@@ -0,0 +1,22 @@
+Additional IP Rights Grant (Patents)
+
+"This implementation" means the copyrightable works distributed by
+Google as part of the Go project.
+
+Google hereby grants to You a perpetual, worldwide, non-exclusive,
+no-charge, royalty-free, irrevocable (except as stated in this section)
+patent license to make, have made, use, offer to sell, sell, import,
+transfer and otherwise run, modify and propagate the contents of this
+implementation of Go, where such license applies only to those patent
+claims, both currently owned or controlled by Google and acquired in
+the future, licensable by Google that are necessarily infringed by this
+implementation of Go.  This grant does not include claims that would be
+infringed only as a consequence of further modification of this
+implementation.  If you or your agent or exclusive licensee institute or
+order or agree to the institution of patent litigation against any
+entity (including a cross-claim or counterclaim in a lawsuit) alleging
+that this implementation of Go or any code incorporated within this
+implementation of Go constitutes direct or contributory patent
+infringement, or inducement of patent infringement, then any patent
+rights granted to you under this License for this implementation of Go
+shall terminate as of the date such litigation is filed.

vendor/golang.org/x/exp/constraints/constraints.go

@@ -0,0 +1,50 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package constraints defines a set of useful constraints to be used
+// with type parameters.
+package constraints
+
+// Signed is a constraint that permits any signed integer type.
+// If future releases of Go add new predeclared signed integer types,
+// this constraint will be modified to include them.
+type Signed interface {
+	~int | ~int8 | ~int16 | ~int32 | ~int64
+}
+
+// Unsigned is a constraint that permits any unsigned integer type.
+// If future releases of Go add new predeclared unsigned integer types,
+// this constraint will be modified to include them.
+type Unsigned interface {
+	~uint | ~uint8 | ~uint16 | ~uint32 | ~uint64 | ~uintptr
+}
+
+// Integer is a constraint that permits any integer type.
+// If future releases of Go add new predeclared integer types,
+// this constraint will be modified to include them.
+type Integer interface {
+	Signed | Unsigned
+}
+
+// Float is a constraint that permits any floating-point type.
+// If future releases of Go add new predeclared floating-point types,
+// this constraint will be modified to include them.
+type Float interface {
+	~float32 | ~float64
+}
+
+// Complex is a constraint that permits any complex numeric type.
+// If future releases of Go add new predeclared complex numeric types,
+// this constraint will be modified to include them.
+type Complex interface {
+	~complex64 | ~complex128
+}
+
+// Ordered is a constraint that permits any ordered type: any type
+// that supports the operators < <= >= >.
+// If future releases of Go add new ordered types,
+// this constraint will be modified to include them.
+type Ordered interface {
+	Integer | Float | ~string
+}

vendor/golang.org/x/exp/maps/maps.go

@@ -0,0 +1,94 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package maps defines various functions useful with maps of any type.
+package maps
+
+// Keys returns the keys of the map m.
+// The keys will be in an indeterminate order.
+func Keys[M ~map[K]V, K comparable, V any](m M) []K {
+	r := make([]K, 0, len(m))
+	for k := range m {
+		r = append(r, k)
+	}
+	return r
+}
+
+// Values returns the values of the map m.
+// The values will be in an indeterminate order.
+func Values[M ~map[K]V, K comparable, V any](m M) []V {
+	r := make([]V, 0, len(m))
+	for _, v := range m {
+		r = append(r, v)
+	}
+	return r
+}
+
+// Equal reports whether two maps contain the same key/value pairs.
+// Values are compared using ==.
+func Equal[M1, M2 ~map[K]V, K, V comparable](m1 M1, m2 M2) bool {
+	if len(m1) != len(m2) {
+		return false
+	}
+	for k, v1 := range m1 {
+		if v2, ok := m2[k]; !ok || v1 != v2 {
+			return false
+		}
+	}
+	return true
+}
+
+// EqualFunc is like Equal, but compares values using eq.
+// Keys are still compared with ==.
+func EqualFunc[M1 ~map[K]V1, M2 ~map[K]V2, K comparable, V1, V2 any](m1 M1, m2 M2, eq func(V1, V2) bool) bool {
+	if len(m1) != len(m2) {
+		return false
+	}
+	for k, v1 := range m1 {
+		if v2, ok := m2[k]; !ok || !eq(v1, v2) {
+			return false
+		}
+	}
+	return true
+}
+
+// Clear removes all entries from m, leaving it empty.
+func Clear[M ~map[K]V, K comparable, V any](m M) {
+	for k := range m {
+		delete(m, k)
+	}
+}
+
+// Clone returns a copy of m.  This is a shallow clone:
+// the new keys and values are set using ordinary assignment.
+func Clone[M ~map[K]V, K comparable, V any](m M) M {
+	// Preserve nil in case it matters.
+	if m == nil {
+		return nil
+	}
+	r := make(M, len(m))
+	for k, v := range m {
+		r[k] = v
+	}
+	return r
+}
+
+// Copy copies all key/value pairs in src adding them to dst.
+// When a key in src is already present in dst,
+// the value in dst will be overwritten by the value associated
+// with the key in src.
+func Copy[M1 ~map[K]V, M2 ~map[K]V, K comparable, V any](dst M1, src M2) {
+	for k, v := range src {
+		dst[k] = v
+	}
+}
+
+// DeleteFunc deletes any key/value pairs from m for which del returns true.
+func DeleteFunc[M ~map[K]V, K comparable, V any](m M, del func(K, V) bool) {
+	for k, v := range m {
+		if del(k, v) {
+			delete(m, k)
+		}
+	}
+}

vendor/golang.org/x/exp/slices/slices.go

@@ -0,0 +1,258 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package slices defines various functions useful with slices of any type.
+// Unless otherwise specified, these functions all apply to the elements
+// of a slice at index 0 <= i < len(s).
+//
+// Note that the less function in IsSortedFunc, SortFunc, SortStableFunc requires a
+// strict weak ordering (https://en.wikipedia.org/wiki/Weak_ordering#Strict_weak_orderings),
+// or the sorting may fail to sort correctly. A common case is when sorting slices of
+// floating-point numbers containing NaN values.
+package slices
+
+import "golang.org/x/exp/constraints"
+
+// Equal reports whether two slices are equal: the same length and all
+// elements equal. If the lengths are different, Equal returns false.
+// Otherwise, the elements are compared in increasing index order, and the
+// comparison stops at the first unequal pair.
+// Floating point NaNs are not considered equal.
+func Equal[E comparable](s1, s2 []E) bool {
+	if len(s1) != len(s2) {
+		return false
+	}
+	for i := range s1 {
+		if s1[i] != s2[i] {
+			return false
+		}
+	}
+	return true
+}
+
+// EqualFunc reports whether two slices are equal using a comparison
+// function on each pair of elements. If the lengths are different,
+// EqualFunc returns false. Otherwise, the elements are compared in
+// increasing index order, and the comparison stops at the first index
+// for which eq returns false.
+func EqualFunc[E1, E2 any](s1 []E1, s2 []E2, eq func(E1, E2) bool) bool {
+	if len(s1) != len(s2) {
+		return false
+	}
+	for i, v1 := range s1 {
+		v2 := s2[i]
+		if !eq(v1, v2) {
+			return false
+		}
+	}
+	return true
+}
+
+// Compare compares the elements of s1 and s2.
+// The elements are compared sequentially, starting at index 0,
+// until one element is not equal to the other.
+// The result of comparing the first non-matching elements is returned.
+// If both slices are equal until one of them ends, the shorter slice is
+// considered less than the longer one.
+// The result is 0 if s1 == s2, -1 if s1 < s2, and +1 if s1 > s2.
+// Comparisons involving floating point NaNs are ignored.
+func Compare[E constraints.Ordered](s1, s2 []E) int {
+	s2len := len(s2)
+	for i, v1 := range s1 {
+		if i >= s2len {
+			return +1
+		}
+		v2 := s2[i]
+		switch {
+		case v1 < v2:
+			return -1
+		case v1 > v2:
+			return +1
+		}
+	}
+	if len(s1) < s2len {
+		return -1
+	}
+	return 0
+}
+
+// CompareFunc is like Compare but uses a comparison function
+// on each pair of elements. The elements are compared in increasing
+// index order, and the comparisons stop after the first time cmp
+// returns non-zero.
+// The result is the first non-zero result of cmp; if cmp always
+// returns 0 the result is 0 if len(s1) == len(s2), -1 if len(s1) < len(s2),
+// and +1 if len(s1) > len(s2).
+func CompareFunc[E1, E2 any](s1 []E1, s2 []E2, cmp func(E1, E2) int) int {
+	s2len := len(s2)
+	for i, v1 := range s1 {
+		if i >= s2len {
+			return +1
+		}
+		v2 := s2[i]
+		if c := cmp(v1, v2); c != 0 {
+			return c
+		}
+	}
+	if len(s1) < s2len {
+		return -1
+	}
+	return 0
+}
+
+// Index returns the index of the first occurrence of v in s,
+// or -1 if not present.
+func Index[E comparable](s []E, v E) int {
+	for i, vs := range s {
+		if v == vs {
+			return i
+		}
+	}
+	return -1
+}
+
+// IndexFunc returns the first index i satisfying f(s[i]),
+// or -1 if none do.
+func IndexFunc[E any](s []E, f func(E) bool) int {
+	for i, v := range s {
+		if f(v) {
+			return i
+		}
+	}
+	return -1
+}
+
+// Contains reports whether v is present in s.
+func Contains[E comparable](s []E, v E) bool {
+	return Index(s, v) >= 0
+}
+
+// ContainsFunc reports whether at least one
+// element e of s satisfies f(e).
+func ContainsFunc[E any](s []E, f func(E) bool) bool {
+	return IndexFunc(s, f) >= 0
+}
+
+// Insert inserts the values v... into s at index i,
+// returning the modified slice.
+// In the returned slice r, r[i] == v[0].
+// Insert panics if i is out of range.
+// This function is O(len(s) + len(v)).
+func Insert[S ~[]E, E any](s S, i int, v ...E) S {
+	tot := len(s) + len(v)
+	if tot <= cap(s) {
+		s2 := s[:tot]
+		copy(s2[i+len(v):], s[i:])
+		copy(s2[i:], v)
+		return s2
+	}
+	s2 := make(S, tot)
+	copy(s2, s[:i])
+	copy(s2[i:], v)
+	copy(s2[i+len(v):], s[i:])
+	return s2
+}
+
+// Delete removes the elements s[i:j] from s, returning the modified slice.
+// Delete panics if s[i:j] is not a valid slice of s.
+// Delete modifies the contents of the slice s; it does not create a new slice.
+// Delete is O(len(s)-j), so if many items must be deleted, it is better to
+// make a single call deleting them all together than to delete one at a time.
+// Delete might not modify the elements s[len(s)-(j-i):len(s)]. If those
+// elements contain pointers you might consider zeroing those elements so that
+// objects they reference can be garbage collected.
+func Delete[S ~[]E, E any](s S, i, j int) S {
+	_ = s[i:j] // bounds check
+
+	return append(s[:i], s[j:]...)
+}
+
+// Replace replaces the elements s[i:j] by the given v, and returns the
+// modified slice. Replace panics if s[i:j] is not a valid slice of s.
+func Replace[S ~[]E, E any](s S, i, j int, v ...E) S {
+	_ = s[i:j] // verify that i:j is a valid subslice
+	tot := len(s[:i]) + len(v) + len(s[j:])
+	if tot <= cap(s) {
+		s2 := s[:tot]
+		copy(s2[i+len(v):], s[j:])
+		copy(s2[i:], v)
+		return s2
+	}
+	s2 := make(S, tot)
+	copy(s2, s[:i])
+	copy(s2[i:], v)
+	copy(s2[i+len(v):], s[j:])
+	return s2
+}
+
+// Clone returns a copy of the slice.
+// The elements are copied using assignment, so this is a shallow clone.
+func Clone[S ~[]E, E any](s S) S {
+	// Preserve nil in case it matters.
+	if s == nil {
+		return nil
+	}
+	return append(S([]E{}), s...)
+}
+
+// Compact replaces consecutive runs of equal elements with a single copy.
+// This is like the uniq command found on Unix.
+// Compact modifies the contents of the slice s; it does not create a new slice.
+// When Compact discards m elements in total, it might not modify the elements
+// s[len(s)-m:len(s)]. If those elements contain pointers you might consider
+// zeroing those elements so that objects they reference can be garbage collected.
+func Compact[S ~[]E, E comparable](s S) S {
+	if len(s) < 2 {
+		return s
+	}
+	i := 1
+	last := s[0]
+	for _, v := range s[1:] {
+		if v != last {
+			s[i] = v
+			i++
+			last = v
+		}
+	}
+	return s[:i]
+}
+
+// CompactFunc is like Compact but uses a comparison function.
+func CompactFunc[S ~[]E, E any](s S, eq func(E, E) bool) S {
+	if len(s) < 2 {
+		return s
+	}
+	i := 1
+	last := s[0]
+	for _, v := range s[1:] {
+		if !eq(v, last) {
+			s[i] = v
+			i++
+			last = v
+		}
+	}
+	return s[:i]
+}
+
+// Grow increases the slice's capacity, if necessary, to guarantee space for
+// another n elements. After Grow(n), at least n elements can be appended
+// to the slice without another allocation. If n is negative or too large to
+// allocate the memory, Grow panics.
+func Grow[S ~[]E, E any](s S, n int) S {
+	if n < 0 {
+		panic("cannot be negative")
+	}
+	if n -= cap(s) - len(s); n > 0 {
+		// TODO(https://go.dev/issue/53888): Make using []E instead of S
+		// to workaround a compiler bug where the runtime.growslice optimization
+		// does not take effect. Revert when the compiler is fixed.
+		s = append([]E(s)[:cap(s)], make([]E, n)...)[:len(s)]
+	}
+	return s
+}
+
+// Clip removes unused capacity from the slice, returning s[:len(s):len(s)].
+func Clip[S ~[]E, E any](s S) S {
+	return s[:len(s):len(s)]
+}

vendor/golang.org/x/exp/slices/sort.go

@@ -0,0 +1,126 @@
+// Copyright 2022 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package slices
+
+import (
+	"math/bits"
+
+	"golang.org/x/exp/constraints"
+)
+
+// Sort sorts a slice of any ordered type in ascending order.
+// Sort may fail to sort correctly when sorting slices of floating-point
+// numbers containing Not-a-number (NaN) values.
+// Use slices.SortFunc(x, func(a, b float64) bool {return a < b || (math.IsNaN(a) && !math.IsNaN(b))})
+// instead if the input may contain NaNs.
+func Sort[E constraints.Ordered](x []E) {
+	n := len(x)
+	pdqsortOrdered(x, 0, n, bits.Len(uint(n)))
+}
+
+// SortFunc sorts the slice x in ascending order as determined by the less function.
+// This sort is not guaranteed to be stable.
+//
+// SortFunc requires that less is a strict weak ordering.
+// See https://en.wikipedia.org/wiki/Weak_ordering#Strict_weak_orderings.
+func SortFunc[E any](x []E, less func(a, b E) bool) {
+	n := len(x)
+	pdqsortLessFunc(x, 0, n, bits.Len(uint(n)), less)
+}
+
+// SortStableFunc sorts the slice x while keeping the original order of equal
+// elements, using less to compare elements.
+func SortStableFunc[E any](x []E, less func(a, b E) bool) {
+	stableLessFunc(x, len(x), less)
+}
+
+// IsSorted reports whether x is sorted in ascending order.
+func IsSorted[E constraints.Ordered](x []E) bool {
+	for i := len(x) - 1; i > 0; i-- {
+		if x[i] < x[i-1] {
+			return false
+		}
+	}
+	return true
+}
+
+// IsSortedFunc reports whether x is sorted in ascending order, with less as the
+// comparison function.
+func IsSortedFunc[E any](x []E, less func(a, b E) bool) bool {
+	for i := len(x) - 1; i > 0; i-- {
+		if less(x[i], x[i-1]) {
+			return false
+		}
+	}
+	return true
+}
+
+// BinarySearch searches for target in a sorted slice and returns the position
+// where target is found, or the position where target would appear in the
+// sort order; it also returns a bool saying whether the target is really found
+// in the slice. The slice must be sorted in increasing order.
+func BinarySearch[E constraints.Ordered](x []E, target E) (int, bool) {
+	// Inlining is faster than calling BinarySearchFunc with a lambda.
+	n := len(x)
+	// Define x[-1] < target and x[n] >= target.
+	// Invariant: x[i-1] < target, x[j] >= target.
+	i, j := 0, n
+	for i < j {
+		h := int(uint(i+j) >> 1) // avoid overflow when computing h
+		// i ≤ h < j
+		if x[h] < target {
+			i = h + 1 // preserves x[i-1] < target
+		} else {
+			j = h // preserves x[j] >= target
+		}
+	}
+	// i == j, x[i-1] < target, and x[j] (= x[i]) >= target  =>  answer is i.
+	return i, i < n && x[i] == target
+}
+
+// BinarySearchFunc works like BinarySearch, but uses a custom comparison
+// function. The slice must be sorted in increasing order, where "increasing" is
+// defined by cmp. cmp(a, b) is expected to return an integer comparing the two
+// parameters: 0 if a == b, a negative number if a < b and a positive number if
+// a > b.
+func BinarySearchFunc[E any](x []E, target E, cmp func(E, E) int) (int, bool) {
+	n := len(x)
+	// Define cmp(x[-1], target) < 0 and cmp(x[n], target) >= 0 .
+	// Invariant: cmp(x[i - 1], target) < 0, cmp(x[j], target) >= 0.
+	i, j := 0, n
+	for i < j {
+		h := int(uint(i+j) >> 1) // avoid overflow when computing h
+		// i ≤ h < j
+		if cmp(x[h], target) < 0 {
+			i = h + 1 // preserves cmp(x[i - 1], target) < 0
+		} else {
+			j = h // preserves cmp(x[j], target) >= 0
+		}
+	}
+	// i == j, cmp(x[i-1], target) < 0, and cmp(x[j], target) (= cmp(x[i], target)) >= 0  =>  answer is i.
+	return i, i < n && cmp(x[i], target) == 0
+}
+
+type sortedHint int // hint for pdqsort when choosing the pivot
+
+const (
+	unknownHint sortedHint = iota
+	increasingHint
+	decreasingHint
+)
+
+// xorshift paper: https://www.jstatsoft.org/article/view/v008i14/xorshift.pdf
+type xorshift uint64
+
+func (r *xorshift) Next() uint64 {
+	*r ^= *r << 13
+	*r ^= *r >> 17
+	*r ^= *r << 5
+	return uint64(*r)
+}
+
+func nextPowerOfTwo(length int) uint {
+	return 1 << bits.Len(uint(length))
+}

vendor/golang.org/x/exp/slices/zsortfunc.go

@@ -0,0 +1,479 @@
+// Code generated by gen_sort_variants.go; DO NOT EDIT.
+
+// Copyright 2022 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package slices
+
+// insertionSortLessFunc sorts data[a:b] using insertion sort.
+func insertionSortLessFunc[E any](data []E, a, b int, less func(a, b E) bool) {
+	for i := a + 1; i < b; i++ {
+		for j := i; j > a && less(data[j], data[j-1]); j-- {
+			data[j], data[j-1] = data[j-1], data[j]
+		}
+	}
+}
+
+// siftDownLessFunc implements the heap property on data[lo:hi].
+// first is an offset into the array where the root of the heap lies.
+func siftDownLessFunc[E any](data []E, lo, hi, first int, less func(a, b E) bool) {
+	root := lo
+	for {
+		child := 2*root + 1
+		if child >= hi {
+			break
+		}
+		if child+1 < hi && less(data[first+child], data[first+child+1]) {
+			child++
+		}
+		if !less(data[first+root], data[first+child]) {
+			return
+		}
+		data[first+root], data[first+child] = data[first+child], data[first+root]
+		root = child
+	}
+}
+
+func heapSortLessFunc[E any](data []E, a, b int, less func(a, b E) bool) {
+	first := a
+	lo := 0
+	hi := b - a
+
+	// Build heap with greatest element at top.
+	for i := (hi - 1) / 2; i >= 0; i-- {
+		siftDownLessFunc(data, i, hi, first, less)
+	}
+
+	// Pop elements, largest first, into end of data.
+	for i := hi - 1; i >= 0; i-- {
+		data[first], data[first+i] = data[first+i], data[first]
+		siftDownLessFunc(data, lo, i, first, less)
+	}
+}
+
+// pdqsortLessFunc sorts data[a:b].
+// The algorithm based on pattern-defeating quicksort(pdqsort), but without the optimizations from BlockQuicksort.
+// pdqsort paper: https://arxiv.org/pdf/2106.05123.pdf
+// C++ implementation: https://github.com/orlp/pdqsort
+// Rust implementation: https://docs.rs/pdqsort/latest/pdqsort/
+// limit is the number of allowed bad (very unbalanced) pivots before falling back to heapsort.
+func pdqsortLessFunc[E any](data []E, a, b, limit int, less func(a, b E) bool) {
+	const maxInsertion = 12
+
+	var (
+		wasBalanced    = true // whether the last partitioning was reasonably balanced
+		wasPartitioned = true // whether the slice was already partitioned
+	)
+
+	for {
+		length := b - a
+
+		if length <= maxInsertion {
+			insertionSortLessFunc(data, a, b, less)
+			return
+		}
+
+		// Fall back to heapsort if too many bad choices were made.
+		if limit == 0 {
+			heapSortLessFunc(data, a, b, less)
+			return
+		}
+
+		// If the last partitioning was imbalanced, we need to breaking patterns.
+		if !wasBalanced {
+			breakPatternsLessFunc(data, a, b, less)
+			limit--
+		}
+
+		pivot, hint := choosePivotLessFunc(data, a, b, less)
+		if hint == decreasingHint {
+			reverseRangeLessFunc(data, a, b, less)
+			// The chosen pivot was pivot-a elements after the start of the array.
+			// After reversing it is pivot-a elements before the end of the array.
+			// The idea came from Rust's implementation.
+			pivot = (b - 1) - (pivot - a)
+			hint = increasingHint
+		}
+
+		// The slice is likely already sorted.
+		if wasBalanced && wasPartitioned && hint == increasingHint {
+			if partialInsertionSortLessFunc(data, a, b, less) {
+				return
+			}
+		}
+
+		// Probably the slice contains many duplicate elements, partition the slice into
+		// elements equal to and elements greater than the pivot.
+		if a > 0 && !less(data[a-1], data[pivot]) {
+			mid := partitionEqualLessFunc(data, a, b, pivot, less)
+			a = mid
+			continue
+		}
+
+		mid, alreadyPartitioned := partitionLessFunc(data, a, b, pivot, less)
+		wasPartitioned = alreadyPartitioned
+
+		leftLen, rightLen := mid-a, b-mid
+		balanceThreshold := length / 8
+		if leftLen < rightLen {
+			wasBalanced = leftLen >= balanceThreshold
+			pdqsortLessFunc(data, a, mid, limit, less)
+			a = mid + 1
+		} else {
+			wasBalanced = rightLen >= balanceThreshold
+			pdqsortLessFunc(data, mid+1, b, limit, less)
+			b = mid
+		}
+	}
+}
+
+// partitionLessFunc does one quicksort partition.
+// Let p = data[pivot]
+// Moves elements in data[a:b] around, so that data[i]<p and data[j]>=p for i<newpivot and j>newpivot.
+// On return, data[newpivot] = p
+func partitionLessFunc[E any](data []E, a, b, pivot int, less func(a, b E) bool) (newpivot int, alreadyPartitioned bool) {
+	data[a], data[pivot] = data[pivot], data[a]
+	i, j := a+1, b-1 // i and j are inclusive of the elements remaining to be partitioned
+
+	for i <= j && less(data[i], data[a]) {
+		i++
+	}
+	for i <= j && !less(data[j], data[a]) {
+		j--
+	}
+	if i > j {
+		data[j], data[a] = data[a], data[j]
+		return j, true
+	}
+	data[i], data[j] = data[j], data[i]
+	i++
+	j--
+
+	for {
+		for i <= j && less(data[i], data[a]) {
+			i++
+		}
+		for i <= j && !less(data[j], data[a]) {
+			j--
+		}
+		if i > j {
+			break
+		}
+		data[i], data[j] = data[j], data[i]
+		i++
+		j--
+	}
+	data[j], data[a] = data[a], data[j]
+	return j, false
+}
+
+// partitionEqualLessFunc partitions data[a:b] into elements equal to data[pivot] followed by elements greater than data[pivot].
+// It assumed that data[a:b] does not contain elements smaller than the data[pivot].
+func partitionEqualLessFunc[E any](data []E, a, b, pivot int, less func(a, b E) bool) (newpivot int) {
+	data[a], data[pivot] = data[pivot], data[a]
+	i, j := a+1, b-1 // i and j are inclusive of the elements remaining to be partitioned
+
+	for {
+		for i <= j && !less(data[a], data[i]) {
+			i++
+		}
+		for i <= j && less(data[a], data[j]) {
+			j--
+		}
+		if i > j {
+			break
+		}
+		data[i], data[j] = data[j], data[i]
+		i++
+		j--
+	}
+	return i
+}
+
+// partialInsertionSortLessFunc partially sorts a slice, returns true if the slice is sorted at the end.
+func partialInsertionSortLessFunc[E any](data []E, a, b int, less func(a, b E) bool) bool {
+	const (
+		maxSteps         = 5  // maximum number of adjacent out-of-order pairs that will get shifted
+		shortestShifting = 50 // don't shift any elements on short arrays
+	)
+	i := a + 1
+	for j := 0; j < maxSteps; j++ {
+		for i < b && !less(data[i], data[i-1]) {
+			i++
+		}
+
+		if i == b {
+			return true
+		}
+
+		if b-a < shortestShifting {
+			return false
+		}
+
+		data[i], data[i-1] = data[i-1], data[i]
+
+		// Shift the smaller one to the left.
+		if i-a >= 2 {
+			for j := i - 1; j >= 1; j-- {
+				if !less(data[j], data[j-1]) {
+					break
+				}
+				data[j], data[j-1] = data[j-1], data[j]
+			}
+		}
+		// Shift the greater one to the right.
+		if b-i >= 2 {
+			for j := i + 1; j < b; j++ {
+				if !less(data[j], data[j-1]) {
+					break
+				}
+				data[j], data[j-1] = data[j-1], data[j]
+			}
+		}
+	}
+	return false
+}
+
+// breakPatternsLessFunc scatters some elements around in an attempt to break some patterns
+// that might cause imbalanced partitions in quicksort.
+func breakPatternsLessFunc[E any](data []E, a, b int, less func(a, b E) bool) {
+	length := b - a
+	if length >= 8 {
+		random := xorshift(length)
+		modulus := nextPowerOfTwo(length)
+
+		for idx := a + (length/4)*2 - 1; idx <= a+(length/4)*2+1; idx++ {
+			other := int(uint(random.Next()) & (modulus - 1))
+			if other >= length {
+				other -= length
+			}
+			data[idx], data[a+other] = data[a+other], data[idx]
+		}
+	}
+}
+
+// choosePivotLessFunc chooses a pivot in data[a:b].
+//
+// [0,8): chooses a static pivot.
+// [8,shortestNinther): uses the simple median-of-three method.
+// [shortestNinther,∞): uses the Tukey ninther method.
+func choosePivotLessFunc[E any](data []E, a, b int, less func(a, b E) bool) (pivot int, hint sortedHint) {
+	const (
+		shortestNinther = 50
+		maxSwaps        = 4 * 3
+	)
+
+	l := b - a
+
+	var (
+		swaps int
+		i     = a + l/4*1
+		j     = a + l/4*2
+		k     = a + l/4*3
+	)
+
+	if l >= 8 {
+		if l >= shortestNinther {
+			// Tukey ninther method, the idea came from Rust's implementation.
+			i = medianAdjacentLessFunc(data, i, &swaps, less)
+			j = medianAdjacentLessFunc(data, j, &swaps, less)
+			k = medianAdjacentLessFunc(data, k, &swaps, less)
+		}
+		// Find the median among i, j, k and stores it into j.
+		j = medianLessFunc(data, i, j, k, &swaps, less)
+	}
+
+	switch swaps {
+	case 0:
+		return j, increasingHint
+	case maxSwaps:
+		return j, decreasingHint
+	default:
+		return j, unknownHint
+	}
+}
+
+// order2LessFunc returns x,y where data[x] <= data[y], where x,y=a,b or x,y=b,a.
+func order2LessFunc[E any](data []E, a, b int, swaps *int, less func(a, b E) bool) (int, int) {
+	if less(data[b], data[a]) {
+		*swaps++
+		return b, a
+	}
+	return a, b
+}
+
+// medianLessFunc returns x where data[x] is the median of data[a],data[b],data[c], where x is a, b, or c.
+func medianLessFunc[E any](data []E, a, b, c int, swaps *int, less func(a, b E) bool) int {
+	a, b = order2LessFunc(data, a, b, swaps, less)
+	b, c = order2LessFunc(data, b, c, swaps, less)
+	a, b = order2LessFunc(data, a, b, swaps, less)
+	return b
+}
+
+// medianAdjacentLessFunc finds the median of data[a - 1], data[a], data[a + 1] and stores the index into a.
+func medianAdjacentLessFunc[E any](data []E, a int, swaps *int, less func(a, b E) bool) int {
+	return medianLessFunc(data, a-1, a, a+1, swaps, less)
+}
+
+func reverseRangeLessFunc[E any](data []E, a, b int, less func(a, b E) bool) {
+	i := a
+	j := b - 1
+	for i < j {
+		data[i], data[j] = data[j], data[i]
+		i++
+		j--
+	}
+}
+
+func swapRangeLessFunc[E any](data []E, a, b, n int, less func(a, b E) bool) {
+	for i := 0; i < n; i++ {
+		data[a+i], data[b+i] = data[b+i], data[a+i]
+	}
+}
+
+func stableLessFunc[E any](data []E, n int, less func(a, b E) bool) {
+	blockSize := 20 // must be > 0
+	a, b := 0, blockSize
+	for b <= n {
+		insertionSortLessFunc(data, a, b, less)
+		a = b
+		b += blockSize
+	}
+	insertionSortLessFunc(data, a, n, less)
+
+	for blockSize < n {
+		a, b = 0, 2*blockSize
+		for b <= n {
+			symMergeLessFunc(data, a, a+blockSize, b, less)
+			a = b
+			b += 2 * blockSize
+		}
+		if m := a + blockSize; m < n {
+			symMergeLessFunc(data, a, m, n, less)
+		}
+		blockSize *= 2
+	}
+}
+
+// symMergeLessFunc merges the two sorted subsequences data[a:m] and data[m:b] using
+// the SymMerge algorithm from Pok-Son Kim and Arne Kutzner, "Stable Minimum
+// Storage Merging by Symmetric Comparisons", in Susanne Albers and Tomasz
+// Radzik, editors, Algorithms - ESA 2004, volume 3221 of Lecture Notes in
+// Computer Science, pages 714-723. Springer, 2004.
+//
+// Let M = m-a and N = b-n. Wolog M < N.
+// The recursion depth is bound by ceil(log(N+M)).
+// The algorithm needs O(M*log(N/M + 1)) calls to data.Less.
+// The algorithm needs O((M+N)*log(M)) calls to data.Swap.
+//
+// The paper gives O((M+N)*log(M)) as the number of assignments assuming a
+// rotation algorithm which uses O(M+N+gcd(M+N)) assignments. The argumentation
+// in the paper carries through for Swap operations, especially as the block
+// swapping rotate uses only O(M+N) Swaps.
+//
+// symMerge assumes non-degenerate arguments: a < m && m < b.
+// Having the caller check this condition eliminates many leaf recursion calls,
+// which improves performance.
+func symMergeLessFunc[E any](data []E, a, m, b int, less func(a, b E) bool) {
+	// Avoid unnecessary recursions of symMerge
+	// by direct insertion of data[a] into data[m:b]
+	// if data[a:m] only contains one element.
+	if m-a == 1 {
+		// Use binary search to find the lowest index i
+		// such that data[i] >= data[a] for m <= i < b.
+		// Exit the search loop with i == b in case no such index exists.
+		i := m
+		j := b
+		for i < j {
+			h := int(uint(i+j) >> 1)
+			if less(data[h], data[a]) {
+				i = h + 1
+			} else {
+				j = h
+			}
+		}
+		// Swap values until data[a] reaches the position before i.
+		for k := a; k < i-1; k++ {
+			data[k], data[k+1] = data[k+1], data[k]
+		}
+		return
+	}
+
+	// Avoid unnecessary recursions of symMerge
+	// by direct insertion of data[m] into data[a:m]
+	// if data[m:b] only contains one element.
+	if b-m == 1 {
+		// Use binary search to find the lowest index i
+		// such that data[i] > data[m] for a <= i < m.
+		// Exit the search loop with i == m in case no such index exists.
+		i := a
+		j := m
+		for i < j {
+			h := int(uint(i+j) >> 1)
+			if !less(data[m], data[h]) {
+				i = h + 1
+			} else {
+				j = h
+			}
+		}
+		// Swap values until data[m] reaches the position i.
+		for k := m; k > i; k-- {
+			data[k], data[k-1] = data[k-1], data[k]
+		}
+		return
+	}
+
+	mid := int(uint(a+b) >> 1)
+	n := mid + m
+	var start, r int
+	if m > mid {
+		start = n - b
+		r = mid
+	} else {
+		start = a
+		r = m
+	}
+	p := n - 1
+
+	for start < r {
+		c := int(uint(start+r) >> 1)
+		if !less(data[p-c], data[c]) {
+			start = c + 1
+		} else {
+			r = c
+		}
+	}
+
+	end := n - start
+	if start < m && m < end {
+		rotateLessFunc(data, start, m, end, less)
+	}
+	if a < start && start < mid {
+		symMergeLessFunc(data, a, start, mid, less)
+	}
+	if mid < end && end < b {
+		symMergeLessFunc(data, mid, end, b, less)
+	}
+}
+
+// rotateLessFunc rotates two consecutive blocks u = data[a:m] and v = data[m:b] in data:
+// Data of the form 'x u v y' is changed to 'x v u y'.
+// rotate performs at most b-a many calls to data.Swap,
+// and it assumes non-degenerate arguments: a < m && m < b.
+func rotateLessFunc[E any](data []E, a, m, b int, less func(a, b E) bool) {
+	i := m - a
+	j := b - m
+
+	for i != j {
+		if i > j {
+			swapRangeLessFunc(data, m-i, m, j, less)
+			i -= j
+		} else {
+			swapRangeLessFunc(data, m-i, m+j-i, i, less)
+			j -= i
+		}
+	}
+	// i == j
+	swapRangeLessFunc(data, m-i, m, i, less)
+}

vendor/golang.org/x/exp/slices/zsortordered.go

@@ -0,0 +1,481 @@
+// Code generated by gen_sort_variants.go; DO NOT EDIT.
+
+// Copyright 2022 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package slices
+
+import "golang.org/x/exp/constraints"
+
+// insertionSortOrdered sorts data[a:b] using insertion sort.
+func insertionSortOrdered[E constraints.Ordered](data []E, a, b int) {
+	for i := a + 1; i < b; i++ {
+		for j := i; j > a && (data[j] < data[j-1]); j-- {
+			data[j], data[j-1] = data[j-1], data[j]
+		}
+	}
+}
+
+// siftDownOrdered implements the heap property on data[lo:hi].
+// first is an offset into the array where the root of the heap lies.
+func siftDownOrdered[E constraints.Ordered](data []E, lo, hi, first int) {
+	root := lo
+	for {
+		child := 2*root + 1
+		if child >= hi {
+			break
+		}
+		if child+1 < hi && (data[first+child] < data[first+child+1]) {
+			child++
+		}
+		if !(data[first+root] < data[first+child]) {
+			return
+		}
+		data[first+root], data[first+child] = data[first+child], data[first+root]
+		root = child
+	}
+}
+
+func heapSortOrdered[E constraints.Ordered](data []E, a, b int) {
+	first := a
+	lo := 0
+	hi := b - a
+
+	// Build heap with greatest element at top.
+	for i := (hi - 1) / 2; i >= 0; i-- {
+		siftDownOrdered(data, i, hi, first)
+	}
+
+	// Pop elements, largest first, into end of data.
+	for i := hi - 1; i >= 0; i-- {
+		data[first], data[first+i] = data[first+i], data[first]
+		siftDownOrdered(data, lo, i, first)
+	}
+}
+
+// pdqsortOrdered sorts data[a:b].
+// The algorithm based on pattern-defeating quicksort(pdqsort), but without the optimizations from BlockQuicksort.
+// pdqsort paper: https://arxiv.org/pdf/2106.05123.pdf
+// C++ implementation: https://github.com/orlp/pdqsort
+// Rust implementation: https://docs.rs/pdqsort/latest/pdqsort/
+// limit is the number of allowed bad (very unbalanced) pivots before falling back to heapsort.
+func pdqsortOrdered[E constraints.Ordered](data []E, a, b, limit int) {
+	const maxInsertion = 12
+
+	var (
+		wasBalanced    = true // whether the last partitioning was reasonably balanced
+		wasPartitioned = true // whether the slice was already partitioned
+	)
+
+	for {
+		length := b - a
+
+		if length <= maxInsertion {
+			insertionSortOrdered(data, a, b)
+			return
+		}
+
+		// Fall back to heapsort if too many bad choices were made.
+		if limit == 0 {
+			heapSortOrdered(data, a, b)
+			return
+		}
+
+		// If the last partitioning was imbalanced, we need to breaking patterns.
+		if !wasBalanced {
+			breakPatternsOrdered(data, a, b)
+			limit--
+		}
+
+		pivot, hint := choosePivotOrdered(data, a, b)
+		if hint == decreasingHint {
+			reverseRangeOrdered(data, a, b)
+			// The chosen pivot was pivot-a elements after the start of the array.
+			// After reversing it is pivot-a elements before the end of the array.
+			// The idea came from Rust's implementation.
+			pivot = (b - 1) - (pivot - a)
+			hint = increasingHint
+		}
+
+		// The slice is likely already sorted.
+		if wasBalanced && wasPartitioned && hint == increasingHint {
+			if partialInsertionSortOrdered(data, a, b) {
+				return
+			}
+		}
+
+		// Probably the slice contains many duplicate elements, partition the slice into
+		// elements equal to and elements greater than the pivot.
+		if a > 0 && !(data[a-1] < data[pivot]) {
+			mid := partitionEqualOrdered(data, a, b, pivot)
+			a = mid
+			continue
+		}
+
+		mid, alreadyPartitioned := partitionOrdered(data, a, b, pivot)
+		wasPartitioned = alreadyPartitioned
+
+		leftLen, rightLen := mid-a, b-mid
+		balanceThreshold := length / 8
+		if leftLen < rightLen {
+			wasBalanced = leftLen >= balanceThreshold
+			pdqsortOrdered(data, a, mid, limit)
+			a = mid + 1
+		} else {
+			wasBalanced = rightLen >= balanceThreshold
+			pdqsortOrdered(data, mid+1, b, limit)
+			b = mid
+		}
+	}
+}
+
+// partitionOrdered does one quicksort partition.
+// Let p = data[pivot]
+// Moves elements in data[a:b] around, so that data[i]<p and data[j]>=p for i<newpivot and j>newpivot.
+// On return, data[newpivot] = p
+func partitionOrdered[E constraints.Ordered](data []E, a, b, pivot int) (newpivot int, alreadyPartitioned bool) {
+	data[a], data[pivot] = data[pivot], data[a]
+	i, j := a+1, b-1 // i and j are inclusive of the elements remaining to be partitioned
+
+	for i <= j && (data[i] < data[a]) {
+		i++
+	}
+	for i <= j && !(data[j] < data[a]) {
+		j--
+	}
+	if i > j {
+		data[j], data[a] = data[a], data[j]
+		return j, true
+	}
+	data[i], data[j] = data[j], data[i]
+	i++
+	j--
+
+	for {
+		for i <= j && (data[i] < data[a]) {
+			i++
+		}
+		for i <= j && !(data[j] < data[a]) {
+			j--
+		}
+		if i > j {
+			break
+		}
+		data[i], data[j] = data[j], data[i]
+		i++
+		j--
+	}
+	data[j], data[a] = data[a], data[j]
+	return j, false
+}
+
+// partitionEqualOrdered partitions data[a:b] into elements equal to data[pivot] followed by elements greater than data[pivot].
+// It assumed that data[a:b] does not contain elements smaller than the data[pivot].
+func partitionEqualOrdered[E constraints.Ordered](data []E, a, b, pivot int) (newpivot int) {
+	data[a], data[pivot] = data[pivot], data[a]
+	i, j := a+1, b-1 // i and j are inclusive of the elements remaining to be partitioned
+
+	for {
+		for i <= j && !(data[a] < data[i]) {
+			i++
+		}
+		for i <= j && (data[a] < data[j]) {
+			j--
+		}
+		if i > j {
+			break
+		}
+		data[i], data[j] = data[j], data[i]
+		i++
+		j--
+	}
+	return i
+}
+
+// partialInsertionSortOrdered partially sorts a slice, returns true if the slice is sorted at the end.
+func partialInsertionSortOrdered[E constraints.Ordered](data []E, a, b int) bool {
+	const (
+		maxSteps         = 5  // maximum number of adjacent out-of-order pairs that will get shifted
+		shortestShifting = 50 // don't shift any elements on short arrays
+	)
+	i := a + 1
+	for j := 0; j < maxSteps; j++ {
+		for i < b && !(data[i] < data[i-1]) {
+			i++
+		}
+
+		if i == b {
+			return true
+		}
+
+		if b-a < shortestShifting {
+			return false
+		}
+
+		data[i], data[i-1] = data[i-1], data[i]
+
+		// Shift the smaller one to the left.
+		if i-a >= 2 {
+			for j := i - 1; j >= 1; j-- {
+				if !(data[j] < data[j-1]) {
+					break
+				}
+				data[j], data[j-1] = data[j-1], data[j]
+			}
+		}
+		// Shift the greater one to the right.
+		if b-i >= 2 {
+			for j := i + 1; j < b; j++ {
+				if !(data[j] < data[j-1]) {
+					break
+				}
+				data[j], data[j-1] = data[j-1], data[j]
+			}
+		}
+	}
+	return false
+}
+
+// breakPatternsOrdered scatters some elements around in an attempt to break some patterns
+// that might cause imbalanced partitions in quicksort.
+func breakPatternsOrdered[E constraints.Ordered](data []E, a, b int) {
+	length := b - a
+	if length >= 8 {
+		random := xorshift(length)
+		modulus := nextPowerOfTwo(length)
+
+		for idx := a + (length/4)*2 - 1; idx <= a+(length/4)*2+1; idx++ {
+			other := int(uint(random.Next()) & (modulus - 1))
+			if other >= length {
+				other -= length
+			}
+			data[idx], data[a+other] = data[a+other], data[idx]
+		}
+	}
+}
+
+// choosePivotOrdered chooses a pivot in data[a:b].
+//
+// [0,8): chooses a static pivot.
+// [8,shortestNinther): uses the simple median-of-three method.
+// [shortestNinther,∞): uses the Tukey ninther method.
+func choosePivotOrdered[E constraints.Ordered](data []E, a, b int) (pivot int, hint sortedHint) {
+	const (
+		shortestNinther = 50
+		maxSwaps        = 4 * 3
+	)
+
+	l := b - a
+
+	var (
+		swaps int
+		i     = a + l/4*1
+		j     = a + l/4*2
+		k     = a + l/4*3
+	)
+
+	if l >= 8 {
+		if l >= shortestNinther {
+			// Tukey ninther method, the idea came from Rust's implementation.
+			i = medianAdjacentOrdered(data, i, &swaps)
+			j = medianAdjacentOrdered(data, j, &swaps)
+			k = medianAdjacentOrdered(data, k, &swaps)
+		}
+		// Find the median among i, j, k and stores it into j.
+		j = medianOrdered(data, i, j, k, &swaps)
+	}
+
+	switch swaps {
+	case 0:
+		return j, increasingHint
+	case maxSwaps:
+		return j, decreasingHint
+	default:
+		return j, unknownHint
+	}
+}
+
+// order2Ordered returns x,y where data[x] <= data[y], where x,y=a,b or x,y=b,a.
+func order2Ordered[E constraints.Ordered](data []E, a, b int, swaps *int) (int, int) {
+	if data[b] < data[a] {
+		*swaps++
+		return b, a
+	}
+	return a, b
+}
+
+// medianOrdered returns x where data[x] is the median of data[a],data[b],data[c], where x is a, b, or c.
+func medianOrdered[E constraints.Ordered](data []E, a, b, c int, swaps *int) int {
+	a, b = order2Ordered(data, a, b, swaps)
+	b, c = order2Ordered(data, b, c, swaps)
+	a, b = order2Ordered(data, a, b, swaps)
+	return b
+}
+
+// medianAdjacentOrdered finds the median of data[a - 1], data[a], data[a + 1] and stores the index into a.
+func medianAdjacentOrdered[E constraints.Ordered](data []E, a int, swaps *int) int {
+	return medianOrdered(data, a-1, a, a+1, swaps)
+}
+
+func reverseRangeOrdered[E constraints.Ordered](data []E, a, b int) {
+	i := a
+	j := b - 1
+	for i < j {
+		data[i], data[j] = data[j], data[i]
+		i++
+		j--
+	}
+}
+
+func swapRangeOrdered[E constraints.Ordered](data []E, a, b, n int) {
+	for i := 0; i < n; i++ {
+		data[a+i], data[b+i] = data[b+i], data[a+i]
+	}
+}
+
+func stableOrdered[E constraints.Ordered](data []E, n int) {
+	blockSize := 20 // must be > 0
+	a, b := 0, blockSize
+	for b <= n {
+		insertionSortOrdered(data, a, b)
+		a = b
+		b += blockSize
+	}
+	insertionSortOrdered(data, a, n)
+
+	for blockSize < n {
+		a, b = 0, 2*blockSize
+		for b <= n {
+			symMergeOrdered(data, a, a+blockSize, b)
+			a = b
+			b += 2 * blockSize
+		}
+		if m := a + blockSize; m < n {
+			symMergeOrdered(data, a, m, n)
+		}
+		blockSize *= 2
+	}
+}
+
+// symMergeOrdered merges the two sorted subsequences data[a:m] and data[m:b] using
+// the SymMerge algorithm from Pok-Son Kim and Arne Kutzner, "Stable Minimum
+// Storage Merging by Symmetric Comparisons", in Susanne Albers and Tomasz
+// Radzik, editors, Algorithms - ESA 2004, volume 3221 of Lecture Notes in
+// Computer Science, pages 714-723. Springer, 2004.
+//
+// Let M = m-a and N = b-n. Wolog M < N.
+// The recursion depth is bound by ceil(log(N+M)).
+// The algorithm needs O(M*log(N/M + 1)) calls to data.Less.
+// The algorithm needs O((M+N)*log(M)) calls to data.Swap.
+//
+// The paper gives O((M+N)*log(M)) as the number of assignments assuming a
+// rotation algorithm which uses O(M+N+gcd(M+N)) assignments. The argumentation
+// in the paper carries through for Swap operations, especially as the block
+// swapping rotate uses only O(M+N) Swaps.
+//
+// symMerge assumes non-degenerate arguments: a < m && m < b.
+// Having the caller check this condition eliminates many leaf recursion calls,
+// which improves performance.
+func symMergeOrdered[E constraints.Ordered](data []E, a, m, b int) {
+	// Avoid unnecessary recursions of symMerge
+	// by direct insertion of data[a] into data[m:b]
+	// if data[a:m] only contains one element.
+	if m-a == 1 {
+		// Use binary search to find the lowest index i
+		// such that data[i] >= data[a] for m <= i < b.
+		// Exit the search loop with i == b in case no such index exists.
+		i := m
+		j := b
+		for i < j {
+			h := int(uint(i+j) >> 1)
+			if data[h] < data[a] {
+				i = h + 1
+			} else {
+				j = h
+			}
+		}
+		// Swap values until data[a] reaches the position before i.
+		for k := a; k < i-1; k++ {
+			data[k], data[k+1] = data[k+1], data[k]
+		}
+		return
+	}
+
+	// Avoid unnecessary recursions of symMerge
+	// by direct insertion of data[m] into data[a:m]
+	// if data[m:b] only contains one element.
+	if b-m == 1 {
+		// Use binary search to find the lowest index i
+		// such that data[i] > data[m] for a <= i < m.
+		// Exit the search loop with i == m in case no such index exists.
+		i := a
+		j := m
+		for i < j {
+			h := int(uint(i+j) >> 1)
+			if !(data[m] < data[h]) {
+				i = h + 1
+			} else {
+				j = h
+			}
+		}
+		// Swap values until data[m] reaches the position i.
+		for k := m; k > i; k-- {
+			data[k], data[k-1] = data[k-1], data[k]
+		}
+		return
+	}
+
+	mid := int(uint(a+b) >> 1)
+	n := mid + m
+	var start, r int
+	if m > mid {
+		start = n - b
+		r = mid
+	} else {
+		start = a
+		r = m
+	}
+	p := n - 1
+
+	for start < r {
+		c := int(uint(start+r) >> 1)
+		if !(data[p-c] < data[c]) {
+			start = c + 1
+		} else {
+			r = c
+		}
+	}
+
+	end := n - start
+	if start < m && m < end {
+		rotateOrdered(data, start, m, end)
+	}
+	if a < start && start < mid {
+		symMergeOrdered(data, a, start, mid)
+	}
+	if mid < end && end < b {
+		symMergeOrdered(data, mid, end, b)
+	}
+}
+
+// rotateOrdered rotates two consecutive blocks u = data[a:m] and v = data[m:b] in data:
+// Data of the form 'x u v y' is changed to 'x v u y'.
+// rotate performs at most b-a many calls to data.Swap,
+// and it assumes non-degenerate arguments: a < m && m < b.
+func rotateOrdered[E constraints.Ordered](data []E, a, m, b int) {
+	i := m - a
+	j := b - m
+
+	for i != j {
+		if i > j {
+			swapRangeOrdered(data, m-i, m, j)
+			i -= j
+		} else {
+			swapRangeOrdered(data, m-i, m+j-i, i)
+			j -= i
+		}
+	}
+	// i == j
+	swapRangeOrdered(data, m-i, m, i)
+}

vendor/modules.txt

@@ -610,6 +610,11 @@ golang.org/x/crypto/pbkdf2
 golang.org/x/crypto/salsa20/salsa
 golang.org/x/crypto/scrypt
 golang.org/x/crypto/sha3
+# golang.org/x/exp v0.0.0-20230202163644-54bba9f4231b
+## explicit; go 1.18
+golang.org/x/exp/constraints
+golang.org/x/exp/maps
+golang.org/x/exp/slices
 # golang.org/x/mod v0.7.0
 ## explicit; go 1.17
 golang.org/x/mod/semver