build: modernize Go usage

This commit modernizes Go usage. This was done with:

go run golang.org/x/tools/gopls/internal/analysis/modernize/cmd/modernize@latest -fix -test ./...

Then files needed to be `go fmt`ed and a few comments needed to be
restored.

The modernizations include replacing

- if/else conditional assignment by a call to the built-in min or max functions added in go1.21
- sort.Slice(x, func(i, j int) bool) { return s[i] < s[j] } by a call to slices.Sort(s), added in go1.21
- interface{} by the 'any' type added in go1.18
- append([]T(nil), s...) by slices.Clone(s) or slices.Concat(s), added in go1.21
- loop around an m[k]=v map update by a call to one of the Collect, Copy, Clone, or Insert functions from the maps package, added in go1.21
- []byte(fmt.Sprintf...) by fmt.Appendf(nil, ...), added in go1.19
- append(s[:i], s[i+1]...) by slices.Delete(s, i, i+1), added in go1.21
- a 3-clause for i := 0; i < n; i++ {} loop by for i := range n {}, added in go1.22

backend/b2/api/types.go

@@ -130,10 +130,10 @@ type AuthorizeAccountResponse struct {
 	AbsoluteMinimumPartSize int      `json:"absoluteMinimumPartSize"` // The smallest possible size of a part of a large file.
 	AccountID               string   `json:"accountId"`               // The identifier for the account.
 	Allowed                 struct { // An object (see below) containing the capabilities of this auth token, and any restrictions on using it.
-		BucketID     string      `json:"bucketId"`     // When present, access is restricted to one bucket.
-		BucketName   string      `json:"bucketName"`   // When present, name of bucket - may be empty
-		Capabilities []string    `json:"capabilities"` // A list of strings, each one naming a capability the key has.
-		NamePrefix   interface{} `json:"namePrefix"`   // When present, access is restricted to files whose names start with the prefix
+		BucketID     string   `json:"bucketId"`     // When present, access is restricted to one bucket.
+		BucketName   string   `json:"bucketName"`   // When present, name of bucket - may be empty
+		Capabilities []string `json:"capabilities"` // A list of strings, each one naming a capability the key has.
+		NamePrefix   any      `json:"namePrefix"`   // When present, access is restricted to files whose names start with the prefix
 	} `json:"allowed"`
 	APIURL              string `json:"apiUrl"`              // The base URL to use for all API calls except for uploading and downloading files.
 	AuthorizationToken  string `json:"authorizationToken"`  // An authorization token to use with all calls, other than b2_authorize_account, that need an Authorization header.

backend/b2/b2.go

@@ -16,6 +16,7 @@ import (
 	"io"
 	"net/http"
 	"path"
+	"slices"
 	"strconv"
 	"strings"
 	"sync"
@@ -589,12 +590,7 @@ func (f *Fs) authorizeAccount(ctx context.Context) error {
 
 // hasPermission returns if the current AuthorizationToken has the selected permission
 func (f *Fs) hasPermission(permission string) bool {
-	for _, capability := range f.info.Allowed.Capabilities {
-		if capability == permission {
-			return true
-		}
-	}
-	return false
+	return slices.Contains(f.info.Allowed.Capabilities, permission)
 }
 
 // getUploadURL returns the upload info with the UploadURL and the AuthorizationToken
@@ -1275,7 +1271,7 @@ func (f *Fs) purge(ctx context.Context, dir string, oldOnly bool, deleteHidden b
 	toBeDeleted := make(chan *api.File, f.ci.Transfers)
 	var wg sync.WaitGroup
 	wg.Add(f.ci.Transfers)
-	for i := 0; i < f.ci.Transfers; i++ {
+	for range f.ci.Transfers {
 		go func() {
 			defer wg.Done()
 			for object := range toBeDeleted {
@@ -1939,7 +1935,7 @@ func init() {
 // urlEncode encodes in with % encoding
 func urlEncode(in string) string {
 	var out bytes.Buffer
-	for i := 0; i < len(in); i++ {
+	for i := range len(in) {
 		c := in[i]
 		if noNeedToEncode[c] {
 			_ = out.WriteByte(c)
@@ -2260,7 +2256,7 @@ See: https://www.backblaze.com/docs/cloud-storage-lifecycle-rules
 	},
 }
 
-func (f *Fs) lifecycleCommand(ctx context.Context, name string, arg []string, opt map[string]string) (out interface{}, err error) {
+func (f *Fs) lifecycleCommand(ctx context.Context, name string, arg []string, opt map[string]string) (out any, err error) {
 	var newRule api.LifecycleRule
 	if daysStr := opt["daysFromHidingToDeleting"]; daysStr != "" {
 		days, err := strconv.Atoi(daysStr)
@@ -2349,7 +2345,7 @@ Durations are parsed as per the rest of rclone, 2h, 7d, 7w etc.
 	},
 }
 
-func (f *Fs) cleanupCommand(ctx context.Context, name string, arg []string, opt map[string]string) (out interface{}, err error) {
+func (f *Fs) cleanupCommand(ctx context.Context, name string, arg []string, opt map[string]string) (out any, err error) {
 	maxAge := defaultMaxAge
 	if opt["max-age"] != "" {
 		maxAge, err = fs.ParseDuration(opt["max-age"])
@@ -2372,7 +2368,7 @@ it would do.
 `,
 }
 
-func (f *Fs) cleanupHiddenCommand(ctx context.Context, name string, arg []string, opt map[string]string) (out interface{}, err error) {
+func (f *Fs) cleanupHiddenCommand(ctx context.Context, name string, arg []string, opt map[string]string) (out any, err error) {
 	return nil, f.cleanUp(ctx, true, false, 0)
 }
 
@@ -2391,7 +2387,7 @@ var commandHelp = []fs.CommandHelp{
 // The result should be capable of being JSON encoded
 // If it is a string or a []string it will be shown to the user
 // otherwise it will be JSON encoded and shown to the user like that
-func (f *Fs) Command(ctx context.Context, name string, arg []string, opt map[string]string) (out interface{}, err error) {
+func (f *Fs) Command(ctx context.Context, name string, arg []string, opt map[string]string) (out any, err error) {
 	switch name {
 	case "lifecycle":
 		return f.lifecycleCommand(ctx, name, arg, opt)

backend/b2/upload.go

@@ -478,17 +478,14 @@ func (up *largeUpload) Copy(ctx context.Context) (err error) {
 		remaining = up.size
 	)
 	g.SetLimit(up.f.opt.UploadConcurrency)
-	for part := 0; part < up.parts; part++ {
+	for part := range up.parts {
 		// Fail fast, in case an errgroup managed function returns an error
 		// gCtx is cancelled. There is no point in copying all the other parts.
 		if gCtx.Err() != nil {
 			break
 		}
 
-		reqSize := remaining
-		if reqSize >= up.chunkSize {
-			reqSize = up.chunkSize
-		}
+		reqSize := min(remaining, up.chunkSize)
 
 		part := part // for the closure
 		g.Go(func() (err error) {