[DEADCODE] Add deadcode linter

- Add the experimental
[deacode](https://pkg.go.dev/golang.org/x/tools/internal/cmd/deadcode)
linter to Forgejo.
- To deal with false positives that can happen due to build tags or with code
that's currently only referenced by test code, the output of the tool is
compared against a known-good output.
- This commit doesn't make any attempt to remove any deadcode.

(cherry picked from commit ac462279e9)
(cherry picked from commit b5ea6e85ac)
(cherry picked from commit 5915f3643c)

[CLEANUP] Remove deadcode

- This is deadcode since https://codeberg.org/forgejo/forgejo/pulls/1802
removed the usage of it.

(cherry picked from commit d840b9923e)
(cherry picked from commit 9442bab626)
(cherry picked from commit 0de9d18863)
(cherry picked from commit 26abf78374)
(cherry picked from commit 05d3a143c3)
(cherry picked from commit 4b3d38d5e1)
(cherry picked from commit a726e71986)
(cherry picked from commit cb62ae5b98)
(cherry picked from commit 8195ba06d5)

.deadcode-out

@@ -0,0 +1,366 @@
+package "code.gitea.io/gitea/cmd"
+	func NoMainListener
+
+package "code.gitea.io/gitea/cmd/forgejo"
+	func ContextSetNoInit
+	func ContextSetNoExit
+	func ContextSetStderr
+	func ContextGetStderr
+	func ContextSetStdout
+	func ContextSetStdin
+
+package "code.gitea.io/gitea/models"
+	func IsErrUpdateTaskNotExist
+	func (ErrUpdateTaskNotExist).Error
+	func (ErrUpdateTaskNotExist).Unwrap
+	func IsErrSHANotFound
+	func GetYamlFixturesAccess
+
+package "code.gitea.io/gitea/models/actions"
+	func ListUploadedArtifactsByRunID
+	func CountRunJobs
+	func (ScheduleList).GetUserIDs
+	func (ScheduleList).GetRepoIDs
+	func (ScheduleList).LoadTriggerUser
+	func (ScheduleList).LoadRepos
+	func FindSchedules
+	func CountSpecs
+	func GetVariableByID
+
+package "code.gitea.io/gitea/models/asymkey"
+	func HasDeployKey
+
+package "code.gitea.io/gitea/models/auth"
+	func DeleteAuthTokenByID
+	func GetSourceByName
+	func GetWebAuthnCredentialByID
+	func WebAuthnCredentials
+
+package "code.gitea.io/gitea/models/db"
+	func TruncateBeans
+	func InTransaction
+	func DumpTables
+	func Count
+	func FindAndCount
+
+package "code.gitea.io/gitea/models/dbfs"
+	func (*file).renameTo
+	func Create
+	func Rename
+
+package "code.gitea.io/gitea/models/forgejo/semver"
+	func GetVersion
+	func SetVersionString
+	func SetVersion
+
+package "code.gitea.io/gitea/models/forgejo_migrations"
+	func GetCurrentDBVersion
+	func EnsureUpToDate
+
+package "code.gitea.io/gitea/models/git"
+	func RemoveDeletedBranchByID
+
+package "code.gitea.io/gitea/models/issues"
+	func IsErrUnknownDependencyType
+	func (ErrNewIssueInsert).Error
+	func IsErrIssueWasClosed
+	func GetIssueWithAttrsByID
+	func GetRepoIDsForIssuesOptions
+	func GetLabelIDsInOrgByNames
+	func ChangeMilestoneStatus
+	func GetMilestonesByRepoIDs
+	func CountMilestonesByRepoCond
+	func GetMilestonesStatsByRepoCond
+	func IsErrErrPullRequestHeadRepoMissing
+	func (ErrPullRequestHeadRepoMissing).Error
+	func GetPullRequestsByHeadBranch
+	func (ErrIssueStopwatchAlreadyExist).Error
+	func (ErrIssueStopwatchAlreadyExist).Unwrap
+
+package "code.gitea.io/gitea/models/migrations/base"
+	func removeAllWithRetry
+	func newXORMEngine
+	func deleteDB
+	func PrepareTestEnv
+	func MainTest
+
+package "code.gitea.io/gitea/models/organization"
+	func UpdateTeamUnits
+	func (SearchMembersOptions).ToConds
+	func UsersInTeamsCount
+
+package "code.gitea.io/gitea/models/packages/alpine"
+	func GetBranches
+	func GetRepositories
+	func GetArchitectures
+
+package "code.gitea.io/gitea/models/perm/access"
+	func GetRepoWriters
+
+package "code.gitea.io/gitea/models/project"
+	func UpdateBoardSorting
+	func ChangeProjectStatus
+
+package "code.gitea.io/gitea/models/repo"
+	func DeleteAttachmentsByIssue
+	func (*releaseSorter).Len
+	func (*releaseSorter).Less
+	func (*releaseSorter).Swap
+	func SortReleases
+	func (SearchOrderBy).String
+	func IsErrTopicNotExist
+	func (ErrTopicNotExist).Error
+	func (ErrTopicNotExist).Unwrap
+	func GetTopicByName
+	func WatchRepoMode
+
+package "code.gitea.io/gitea/models/system"
+	func DeleteNotice
+
+package "code.gitea.io/gitea/models/unittest"
+	func CheckConsistencyFor
+	func checkForConsistency
+	func GetXORMEngine
+	func OverrideFixtures
+	func InitFixtures
+	func LoadFixtures
+	func Copy
+	func CopyDir
+	func FixturesDir
+	func fatalTestError
+	func InitSettings
+	func MainTest
+	func CreateTestEngine
+	func PrepareTestDatabase
+	func PrepareTestEnv
+	func Cond
+	func OrderBy
+	func LoadBeanIfExists
+	func BeanExists
+	func AssertExistsAndLoadBean
+	func GetCount
+	func AssertNotExistsBean
+	func AssertExistsIf
+	func AssertSuccessfulInsert
+	func AssertCount
+	func AssertInt64InRange
+
+package "code.gitea.io/gitea/models/user"
+	func IsErrPrimaryEmailCannotDelete
+	func (ErrUserInactive).Error
+	func (ErrUserInactive).Unwrap
+	func IsErrExternalLoginUserAlreadyExist
+	func IsErrExternalLoginUserNotExist
+	func IsErrUserSettingIsNotExist
+	func GetUserAllSettings
+	func DeleteUserSetting
+	func GetUserEmailsByNames
+
+package "code.gitea.io/gitea/modules/activitypub"
+	func CurrentTime
+	func containsRequiredHTTPHeaders
+	func NewClient
+	func (*Client).NewRequest
+	func (*Client).Post
+	func GetPrivateKey
+
+package "code.gitea.io/gitea/modules/assetfs"
+	func Bindata
+
+package "code.gitea.io/gitea/modules/auth/password/hash"
+	func (*DummyHasher).HashWithSaltBytes
+	func NewDummyHasher
+
+package "code.gitea.io/gitea/modules/auth/password/pwn"
+	func WithHTTP
+
+package "code.gitea.io/gitea/modules/base"
+	func BasicAuthEncode
+	func IsLetter
+	func SetupGiteaRoot
+
+package "code.gitea.io/gitea/modules/cache"
+	func GetInt
+	func WithNoCacheContext
+	func RemoveContextData
+
+package "code.gitea.io/gitea/modules/charset"
+	func (*BreakWriter).Write
+	func ToUTF8
+	func EscapeControlString
+
+package "code.gitea.io/gitea/modules/context"
+	func GetPrivateContext
+
+package "code.gitea.io/gitea/modules/emoji"
+	func ReplaceCodes
+
+package "code.gitea.io/gitea/modules/eventsource"
+	func (*Event).String
+
+package "code.gitea.io/gitea/modules/git"
+	func AllowLFSFiltersArgs
+	func AddChanges
+	func AddChangesWithArgs
+	func CommitChanges
+	func CommitChangesWithArgs
+	func IsErrExecTimeout
+	func (ErrExecTimeout).Error
+	func (ErrUnsupportedVersion).Error
+	func SetUpdateHook
+	func openRepositoryWithDefaultContext
+	func GetBranchCommitID
+	func IsTagExist
+	func ToEntryMode
+	func (*LimitedReaderCloser).Read
+	func (*LimitedReaderCloser).Close
+
+package "code.gitea.io/gitea/modules/gitgraph"
+	func (*Parser).Reset
+
+package "code.gitea.io/gitea/modules/graceful"
+	func (*Manager).TerminateContext
+	func (*Manager).IsTerminate
+	func (*Manager).Err
+	func (*Manager).Value
+	func (*Manager).Deadline
+
+package "code.gitea.io/gitea/modules/hcaptcha"
+	func WithHTTP
+
+package "code.gitea.io/gitea/modules/json"
+	func (StdJSON).Marshal
+	func (StdJSON).Unmarshal
+	func (StdJSON).NewEncoder
+	func (StdJSON).NewDecoder
+	func (StdJSON).Indent
+
+package "code.gitea.io/gitea/modules/markup"
+	func GetRendererByType
+	func RenderString
+	func IsMarkupFile
+
+package "code.gitea.io/gitea/modules/markup/console"
+	func Render
+	func RenderString
+
+package "code.gitea.io/gitea/modules/markup/markdown"
+	func IsDetails
+	func IsSummary
+	func IsTaskCheckBoxListItem
+	func IsIcon
+	func IsColorPreview
+	func RenderRawString
+
+package "code.gitea.io/gitea/modules/markup/markdown/math"
+	func WithInlineDollarParser
+	func WithBlockDollarParser
+
+package "code.gitea.io/gitea/modules/markup/mdstripper"
+	func StripMarkdown
+
+package "code.gitea.io/gitea/modules/markup/orgmode"
+	func RenderString
+
+package "code.gitea.io/gitea/modules/private"
+	func ActionsRunnerRegister
+
+package "code.gitea.io/gitea/modules/process"
+	func (*Manager).ExecTimeout
+
+package "code.gitea.io/gitea/modules/queue"
+	func newBaseChannelSimple
+	func newBaseChannelUnique
+	func newBaseRedisSimple
+	func newBaseRedisUnique
+	func newWorkerPoolQueueForTest
+
+package "code.gitea.io/gitea/modules/queue/lqinternal"
+	func QueueItemIDBytes
+	func QueueItemKeyBytes
+	func ListLevelQueueKeys
+
+package "code.gitea.io/gitea/modules/setting"
+	func NewConfigProviderFromData
+	func (*GitConfigType).GetOption
+	func InitLoggersForTest
+
+package "code.gitea.io/gitea/modules/storage"
+	func (ErrInvalidConfiguration).Error
+	func IsErrInvalidConfiguration
+
+package "code.gitea.io/gitea/modules/structs"
+	func ParseCreateHook
+	func ParsePushHook
+
+package "code.gitea.io/gitea/modules/sync"
+	func (*StatusTable).Start
+	func (*StatusTable).IsRunning
+
+package "code.gitea.io/gitea/modules/testlogger"
+	func (*testLoggerWriterCloser).pushT
+	func (*testLoggerWriterCloser).Write
+	func (*testLoggerWriterCloser).popT
+	func (*testLoggerWriterCloser).Close
+	func (*testLoggerWriterCloser).Reset
+	func PrintCurrentTest
+	func Printf
+	func NewTestLoggerWriter
+
+package "code.gitea.io/gitea/modules/timeutil"
+	func GetExecutableModTime
+	func Set
+	func Unset
+
+package "code.gitea.io/gitea/modules/translation"
+	func (MockLocale).Language
+	func (MockLocale).Tr
+	func (MockLocale).TrN
+	func (MockLocale).PrettyNumber
+
+package "code.gitea.io/gitea/modules/util/filebuffer"
+	func CreateFromReader
+
+package "code.gitea.io/gitea/modules/web"
+	func RouteMock
+	func RouteMockReset
+
+package "code.gitea.io/gitea/modules/web/middleware"
+	func DeleteLocaleCookie
+
+package "code.gitea.io/gitea/routers/web"
+	func NotFound
+
+package "code.gitea.io/gitea/routers/web/org"
+	func MustEnableProjects
+	func getActionIssues
+	func UpdateIssueProject
+
+package "code.gitea.io/gitea/services/convert"
+	func ToSecret
+
+package "code.gitea.io/gitea/services/forms"
+	func (*DeadlineForm).Validate
+
+package "code.gitea.io/gitea/services/packages/alpine"
+	func BuildAllRepositoryFiles
+
+package "code.gitea.io/gitea/services/pull"
+	func IsCommitStatusContextSuccess
+
+package "code.gitea.io/gitea/services/repository"
+	func GetBranchCommitID
+	func IsErrForkAlreadyExist
+
+package "code.gitea.io/gitea/services/repository/archiver"
+	func ArchiveRepository
+
+package "code.gitea.io/gitea/services/repository/files"
+	func (*ContentType).String
+	func GetFileResponseFromCommit
+	func (*TemporaryUploadRepository).GetLastCommit
+	func (*TemporaryUploadRepository).GetLastCommitByRef
+
+package "code.gitea.io/gitea/services/webhook"
+	func NewNotifier
+

.gitignore

@@ -97,6 +97,7 @@ cpu.out
 /VERSION
 /.air
 /.go-licenses
+/.cur-deadcode-out
 
 # Snapcraft
 /gitea_a*.txt

Makefile

@@ -22,6 +22,7 @@ GO ?= go
 SHASUM ?= shasum -a 256
 HAS_GO := $(shell hash $(GO) > /dev/null 2>&1 && echo yes)
 COMMA := ,
+DIFF ?= diff --unified
 
 XGO_VERSION := go-1.21.x
 
@@ -36,6 +37,7 @@ XGO_PACKAGE ?= src.techknowlogick.com/xgo@latest
 GO_LICENSES_PACKAGE ?= github.com/google/go-licenses@v1.6.0
 GOVULNCHECK_PACKAGE ?= golang.org/x/vuln/cmd/govulncheck@v1.0.1
 ACTIONLINT_PACKAGE ?= github.com/rhysd/actionlint/cmd/actionlint@v1.6.25
+DEADCODE_PACKAGE ?= golang.org/x/tools/internal/cmd/deadcode@v0.14.0
 
 DOCKER_IMAGE ?= gitea/gitea
 DOCKER_TAG ?= latest
@@ -409,10 +411,17 @@ lint-md: node_modules
 .PHONY: lint-go
 lint-go:
 	$(GO) run $(GOLANGCI_LINT_PACKAGE) run $(GOLANGCI_LINT_ARGS)
+	$(GO) run $(DEADCODE_PACKAGE) -generated=false -test code.gitea.io/gitea > .cur-deadcode-out
+	@$(DIFF) .deadcode-out .cur-deadcode-out; \
+	if [ $$? -eq 1 ]; then \
+		echo "Please run 'make lint-go-fix' and commit the result"; \
+		exit 1; \
+	fi
 
 .PHONY: lint-go-fix
 lint-go-fix:
 	$(GO) run $(GOLANGCI_LINT_PACKAGE) run $(GOLANGCI_LINT_ARGS) --fix
+	$(GO) run $(DEADCODE_PACKAGE) -generated=false -test code.gitea.io/gitea > .deadcode-out
 
 # workaround step for the lint-go-windows CI task because 'go run' can not
 # have distinct GOOS/GOARCH for its build and run steps

modules/util/legacy.go

@@ -4,10 +4,6 @@
 package util
 
 import (
-	"crypto/aes"
-	"crypto/cipher"
-	"crypto/rand"
-	"errors"
 	"io"
 	"os"
 )
@@ -40,52 +36,3 @@ func CopyFile(src, dest string) error {
 	}
 	return os.Chmod(dest, si.Mode())
 }
-
-// AESGCMEncrypt (from legacy package): encrypts plaintext with the given key using AES in GCM mode. should be replaced.
-func AESGCMEncrypt(key, plaintext []byte) ([]byte, error) {
-	block, err := aes.NewCipher(key)
-	if err != nil {
-		return nil, err
-	}
-
-	gcm, err := cipher.NewGCM(block)
-	if err != nil {
-		return nil, err
-	}
-
-	nonce := make([]byte, gcm.NonceSize())
-	if _, err := rand.Read(nonce); err != nil {
-		return nil, err
-	}
-
-	ciphertext := gcm.Seal(nil, nonce, plaintext, nil)
-	return append(nonce, ciphertext...), nil
-}
-
-// AESGCMDecrypt (from legacy package): decrypts ciphertext with the given key using AES in GCM mode. should be replaced.
-func AESGCMDecrypt(key, ciphertext []byte) ([]byte, error) {
-	block, err := aes.NewCipher(key)
-	if err != nil {
-		return nil, err
-	}
-
-	gcm, err := cipher.NewGCM(block)
-	if err != nil {
-		return nil, err
-	}
-
-	size := gcm.NonceSize()
-	if len(ciphertext)-size <= 0 {
-		return nil, errors.New("ciphertext is empty")
-	}
-
-	nonce := ciphertext[:size]
-	ciphertext = ciphertext[size:]
-
-	plainText, err := gcm.Open(nil, nonce, ciphertext, nil)
-	if err != nil {
-		return nil, err
-	}
-
-	return plainText, nil
-}

modules/util/legacy_test.go

@@ -4,8 +4,6 @@
 package util
 
 import (
-	"crypto/aes"
-	"crypto/rand"
 	"fmt"
 	"os"
 	"testing"
@@ -37,21 +35,3 @@ func TestCopyFile(t *testing.T) {
 	assert.NoError(t, err)
 	assert.Equal(t, testContent, dstContent)
 }
-
-func TestAESGCM(t *testing.T) {
-	t.Parallel()
-
-	key := make([]byte, aes.BlockSize)
-	_, err := rand.Read(key)
-	assert.NoError(t, err)
-
-	plaintext := []byte("this will be encrypted")
-
-	ciphertext, err := AESGCMEncrypt(key, plaintext)
-	assert.NoError(t, err)
-
-	decrypted, err := AESGCMDecrypt(key, ciphertext)
-	assert.NoError(t, err)
-
-	assert.Equal(t, plaintext, decrypted)
-}