Use golangci-lints's build-in modernize linter (#34341)

server/.golangci.yml

@@ -8,6 +8,7 @@ linters:
     - ineffassign
     - makezero
     - misspell
+    - modernize
     - revive
     - staticcheck
     - unconvert

server/Makefile

@@ -322,22 +322,13 @@ golang-versions: ## Install Golang versions used for compatibility testing (e.g.
 	export GO_COMPATIBILITY_TEST_VERSIONS="${GO_COMPATIBILITY_TEST_VERSIONS}"
 
 golangci-lint: ## Run golangci-lint on codebase
-	$(GO) install github.com/golangci/golangci-lint/v2/cmd/golangci-lint@v2.5.0
+	$(GO) install github.com/golangci/golangci-lint/v2/cmd/golangci-lint@v2.6.0
 ifeq ($(BUILD_ENTERPRISE_READY),true)
 	$(GOBIN)/golangci-lint run ./... ./public/... $(BUILD_ENTERPRISE_DIR)/...
 else
 	$(GOBIN)/golangci-lint run ./... ./public/...
 endif
 
-modernize: ## Run modernize linter on codebase
-## https://pkg.go.dev/golang.org/x/tools/gopls/internal/analysis/modernize is not support in golangci-lint.
-## We need to invoke it directly.
-ifeq ($(BUILD_ENTERPRISE_READY),true)
-	go run golang.org/x/tools/gopls/internal/analysis/modernize/cmd/modernize@v0.19.1 -test ./... ./public/... $(BUILD_ENTERPRISE_DIR)/...
-else
-	go run golang.org/x/tools/gopls/internal/analysis/modernize/cmd/modernize@v0.19.1 -test ./... ./public/...
-endif
-
 i18n-extract: ## Extract strings for translation from the source code
 	cd ../tools/mmgotool && $(GO) install .
 	$(GOBIN)/mmgotool i18n extract --portal-dir=""
@@ -431,7 +422,7 @@ ifeq ($(BUILD_ENTERPRISE_READY),true)
 endif
 endif
 
-check-style: plugin-checker vet modernize golangci-lint ## Runs style/lint checks
+check-style: plugin-checker vet golangci-lint ## Runs style/lint checks
 
 gotestsum:
 	$(GO) install gotest.tools/gotestsum@v1.11.0

server/channels/api4/user_test.go

@@ -3831,11 +3831,11 @@ func TestResetPassword(t *testing.T) {
 	resp, err = th.Client.ResetPassword(context.Background(), "junk", "newpwd")
 	require.Error(t, err)
 	CheckBadRequestStatus(t, resp)
-	code := ""
+	var code strings.Builder
 	for range model.TokenSize {
-		code += "a"
+		code.WriteString("a")
 	}
-	resp, err = th.Client.ResetPassword(context.Background(), code, "newpwd")
+	resp, err = th.Client.ResetPassword(context.Background(), code.String(), "newpwd")
 	require.Error(t, err)
 	CheckBadRequestStatus(t, resp)
 	_, err = th.Client.ResetPassword(context.Background(), recoveryToken.Token, "newpwd")

server/channels/api4/websocket_norace_test.go

@@ -2,7 +2,6 @@
 // See LICENSE.txt for license information.
 
 //go:build !race
-// +build !race
 
 package api4
 

server/channels/app/webhub_fuzz.go

@@ -1,5 +1,4 @@
 //go:build gofuzz
-// +build gofuzz
 
 // Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
 // See LICENSE.txt for license information.

server/channels/store/layer_generators/main.go

@@ -149,8 +149,7 @@ func extractStoreMetadata() (*storeMetadata, error) {
 						metadata.Methods[methodName] = extractMethodMetadata(method, src)
 					}
 				}
-			} else if strings.HasSuffix(x.Name.Name, "Store") {
-				subStoreName := strings.TrimSuffix(x.Name.Name, "Store")
+			} else if subStoreName, ok := strings.CutSuffix(x.Name.Name, "Store"); ok {
 				metadata.SubStores[subStoreName] = subStore{Methods: map[string]methodData{}}
 				for _, method := range x.Type.(*ast.InterfaceType).Methods.List {
 					methodName := method.Names[0].Name

server/channels/store/sqlstore/role_store.go

@@ -46,11 +46,11 @@ type channelRolesPermissions struct {
 
 func NewRoleFromModel(role *model.Role) *Role {
 	permissionsMap := make(map[string]bool)
-	permissions := ""
+	var permissions strings.Builder
 
 	for _, permission := range role.Permissions {
 		if !permissionsMap[permission] {
-			permissions += fmt.Sprintf(" %v", permission)
+			permissions.WriteString(fmt.Sprintf(" %v", permission))
 			permissionsMap[permission] = true
 		}
 	}
@@ -63,7 +63,7 @@ func NewRoleFromModel(role *model.Role) *Role {
 		CreateAt:      role.CreateAt,
 		UpdateAt:      role.UpdateAt,
 		DeleteAt:      role.DeleteAt,
-		Permissions:   permissions,
+		Permissions:   permissions.String(),
 		SchemeManaged: role.SchemeManaged,
 		BuiltIn:       role.BuiltIn,
 	}

server/channels/store/sqlstore/store.go

@@ -940,15 +940,15 @@ func (ss *SqlStore) hasLicense() bool {
 
 func convertMySQLFullTextColumnsToPostgres(columnNames string) string {
 	columns := strings.Split(columnNames, ", ")
-	concatenatedColumnNames := ""
+	var concatenatedColumnNames strings.Builder
 	for i, c := range columns {
-		concatenatedColumnNames += c
+		concatenatedColumnNames.WriteString(c)
 		if i < len(columns)-1 {
-			concatenatedColumnNames += " || ' ' || "
+			concatenatedColumnNames.WriteString(" || ' ' || ")
 		}
 	}
 
-	return concatenatedColumnNames
+	return concatenatedColumnNames.String()
 }
 
 // IsDuplicate checks whether an error is a duplicate key error, which comes when processes are competing on creating the same

server/cmd/mattermost/main_test.go

@@ -2,7 +2,6 @@
 // See LICENSE.txt for license information.
 
 //go:build maincoverage
-// +build maincoverage
 
 package main
 

server/cmd/mmctl/commands/enterprise.go

@@ -2,7 +2,6 @@
 // See LICENSE.txt for license information.
 
 //go:build enterprise
-// +build enterprise
 
 // This file is needed to ensure the enterprise code get complied
 // when running tests. See https://mattermost.atlassian.net/browse/MM-54929

server/cmd/mmctl/commands/main_test.go

@@ -2,7 +2,6 @@
 // See LICENSE.txt for license information.
 
 //go:build e2e
-// +build e2e
 
 package commands
 

server/cmd/mmctl/commands/mmctl_e2e_test.go

@@ -2,7 +2,6 @@
 // See LICENSE.txt for license information.
 
 //go:build e2e
-// +build e2e
 
 package commands
 

server/cmd/mmctl/commands/mmctl_unit_test.go

@@ -2,7 +2,6 @@
 // See LICENSE.txt for license information.
 
 //go:build unit
-// +build unit
 
 package commands
 

server/cmd/mmctl/commands/utils_unix.go

@@ -2,7 +2,6 @@
 // See LICENSE.txt for license information.
 
 //go:build linux || darwin || freebsd
-// +build linux darwin freebsd
 
 package commands
 

server/config/environment.go

@@ -73,7 +73,7 @@ func applyEnvKey(key, value string, rValueSubject reflect.Value) {
 			rFieldValue.Set(reflect.ValueOf(intVal))
 		}
 	case reflect.Slice:
-		if rFieldValue.Type() == reflect.TypeOf(json.RawMessage{}) {
+		if rFieldValue.Type() == reflect.TypeFor[json.RawMessage]() {
 			rFieldValue.Set(reflect.ValueOf([]byte(value)))
 			break
 		}
@@ -100,7 +100,7 @@ func applyEnvironmentMap(inputConfig *model.Config, env map[string]string) *mode
 // generateEnvironmentMap creates a map[string]any containing true at the leaves mirroring the
 // configuration structure so the client can know which env variables are overridden
 func generateEnvironmentMap(env map[string]string, filter func(reflect.StructField) bool) map[string]any {
-	rType := reflect.TypeOf(model.Config{})
+	rType := reflect.TypeFor[model.Config]()
 	return generateEnvironmentMapWithBaseKey(env, rType, "MM", filter)
 }
 

server/enterprise/elasticsearch/elasticsearch/elasticsearch.go

@@ -1350,7 +1350,8 @@ func (es *ElasticsearchInterfaceImpl) PurgeIndexes(rctx request.CTX) *model.AppE
 	}
 
 	indexPrefix := *es.Platform.Config().ElasticsearchSettings.IndexPrefix
-	indexesToDelete := indexPrefix + "*"
+	var indexesToDelete strings.Builder
+	indexesToDelete.WriteString(indexPrefix + "*")
 
 	if ignorePurgeIndexes := *es.Platform.Config().ElasticsearchSettings.IgnoredPurgeIndexes; ignorePurgeIndexes != "" {
 		// we are checking if provided indexes exist. If an index doesn't exist,
@@ -1365,14 +1366,14 @@ func (es *ElasticsearchInterfaceImpl) PurgeIndexes(rctx request.CTX) *model.AppE
 				rctx.Logger().Warn("Elasticsearch index get error", mlog.String("index", ignorePurgeIndex), mlog.Err(err))
 				continue
 			}
-			indexesToDelete += ",-" + strings.TrimSpace(ignorePurgeIndex)
+			indexesToDelete.WriteString(",-" + strings.TrimSpace(ignorePurgeIndex))
 		}
 	}
 
 	ctx, cancel := context.WithTimeout(context.Background(), time.Duration(*es.Platform.Config().ElasticsearchSettings.RequestTimeoutSeconds)*time.Second)
 	defer cancel()
 
-	_, err := es.client.Indices.Delete(indexesToDelete).Do(ctx)
+	_, err := es.client.Indices.Delete(indexesToDelete.String()).Do(ctx)
 	if err != nil {
 		rctx.Logger().Error("Elastic Search PurgeIndexes Error", mlog.Err(err))
 		return model.NewAppError("Elasticsearch.PurgeIndexes", "ent.elasticsearch.purge_index.delete_failed", nil, "", http.StatusInternalServerError).Wrap(err)

server/platform/services/upgrader/upgrader.go

@@ -2,7 +2,6 @@
 // See LICENSE.txt for license information.
 
 //go:build !linux
-// +build !linux
 
 package upgrader
 

server/public/model/access_policy_test.go

@@ -4,6 +4,7 @@
 package model
 
 import (
+	"strings"
 	"testing"
 
 	"github.com/stretchr/testify/require"
@@ -56,15 +57,15 @@ func TestAccessPolicyVersionV0_1(t *testing.T) {
 	})
 
 	t.Run("parent policy with too long name", func(t *testing.T) {
-		longName := ""
+		var longName strings.Builder
 		for i := 0; i <= MaxPolicyNameLength; i++ {
-			longName += "a"
+			longName.WriteString("a")
 		}
 
 		policy := &AccessControlPolicy{
 			ID:       NewId(),
 			Type:     AccessControlPolicyTypeParent,
-			Name:     longName,
+			Name:     longName.String(),
 			Revision: 1,
 			Version:  AccessControlPolicyVersionV0_1,
 			Rules:    []AccessControlPolicyRule{{Actions: []string{"read"}, Expression: "user.role == 'admin'"}},

server/public/model/channel_count.go

@@ -8,6 +8,7 @@ import (
 	"fmt"
 	"sort"
 	"strconv"
+	"strings"
 )
 
 type ChannelCounts struct {
@@ -24,12 +25,12 @@ func (o *ChannelCounts) Etag() string {
 	}
 	sort.Strings(ids)
 
-	str := ""
+	var str strings.Builder
 	for _, id := range ids {
-		str += id + strconv.FormatInt(o.Counts[id], 10)
+		str.WriteString(id + strconv.FormatInt(o.Counts[id], 10))
 	}
 
-	md5Counts := fmt.Sprintf("%x", md5.Sum([]byte(str)))
+	md5Counts := fmt.Sprintf("%x", md5.Sum([]byte(str.String())))
 
 	var update int64
 	for _, u := range o.UpdateTimes {

server/public/model/feature_flags.go

@@ -130,7 +130,7 @@ func (f *FeatureFlags) SetDefaults() {
 // Supports boolean and string feature flags.
 func (f *FeatureFlags) ToMap() map[string]string {
 	refStructVal := reflect.ValueOf(*f)
-	refStructType := reflect.TypeOf(*f)
+	refStructType := reflect.TypeFor[FeatureFlags]()
 	ret := make(map[string]string)
 	for i := 0; i < refStructVal.NumField(); i++ {
 		refFieldVal := refStructVal.Field(i)

server/public/model/permission.go

@@ -5,6 +5,7 @@ package model
 
 import (
 	"net/http"
+	"strings"
 )
 
 const (
@@ -2658,12 +2659,13 @@ func MakePermissionError(s *Session, permissions []*Permission) *AppError {
 }
 
 func MakePermissionErrorForUser(userId string, permissions []*Permission) *AppError {
-	permissionsStr := "permission="
+	var permissionsStr strings.Builder
+	permissionsStr.WriteString("permission=")
 	for i, permission := range permissions {
-		permissionsStr += permission.Id
+		permissionsStr.WriteString(permission.Id)
 		if i != len(permissions)-1 {
-			permissionsStr += ","
+			permissionsStr.WriteString(",")
 		}
 	}
-	return NewAppError("Permissions", "api.context.permissions.app_error", nil, "userId="+userId+", "+permissionsStr, http.StatusForbidden)
+	return NewAppError("Permissions", "api.context.permissions.app_error", nil, "userId="+userId+", "+permissionsStr.String(), http.StatusForbidden)
 }

server/public/model/utils.go

@@ -692,13 +692,14 @@ func IsValidAlphaNumHyphenUnderscorePlus(s string) bool {
 }
 
 func Etag(parts ...any) string {
-	etag := CurrentVersion
+	var etag strings.Builder
+	etag.WriteString(CurrentVersion)
 
 	for _, part := range parts {
-		etag += fmt.Sprintf(".%v", part)
+		etag.WriteString(fmt.Sprintf(".%v", part))
 	}
 
-	return etag
+	return etag.String()
 }
 
 var (
@@ -712,7 +713,7 @@ func ParseHashtags(text string) (string, string) {
 	words := strings.Fields(text)
 
 	hashtagString := ""
-	plainString := ""
+	var plainString strings.Builder
 	for _, word := range words {
 		// trim off surrounding punctuation
 		word = puncStart.ReplaceAllString(word, "")
@@ -724,7 +725,7 @@ func ParseHashtags(text string) (string, string) {
 		if validHashtag.MatchString(word) {
 			hashtagString += " " + word
 		} else {
-			plainString += " " + word
+			plainString.WriteString(" " + word)
 		}
 	}
 
@@ -738,7 +739,7 @@ func ParseHashtags(text string) (string, string) {
 		}
 	}
 
-	return strings.TrimSpace(hashtagString), strings.TrimSpace(plainString)
+	return strings.TrimSpace(hashtagString), strings.TrimSpace(plainString.String())
 }
 
 func ClearMentionTags(post string) string {

server/public/plugin/client_rpc.go

@@ -189,9 +189,9 @@ func (g *hooksRPCClient) Implemented() (impl []string, err error) {
 
 // Implemented replies with the names of the hooks that are implemented.
 func (s *hooksRPCServer) Implemented(args struct{}, reply *[]string) error {
-	ifaceType := reflect.TypeOf((*Hooks)(nil)).Elem()
+	ifaceType := reflect.TypeFor[Hooks]()
 	implType := reflect.TypeOf(s.impl)
-	selfType := reflect.TypeOf(s)
+	selfType := reflect.TypeFor[*hooksRPCServer]()
 	var methods []string
 	for i := 0; i < ifaceType.NumMethod(); i++ {
 		method := ifaceType.Method(i)

server/public/utils/json_test.go

@@ -52,7 +52,7 @@ func TestHumanizeJsonError(t *testing.T) {
 			[]byte("line 1\nline 2\nline 3"),
 			&json.UnmarshalTypeError{
 				Value:  "bool",
-				Type:   reflect.TypeOf(testType{}),
+				Type:   reflect.TypeFor[testType](),
 				Offset: 17,
 				Struct: "struct",
 				Field:  "field",