Add `lint-go-gopls` (#30729)

Uses `gopls check <files>` as a linter. Tested locally and brings up 149
errors currently for me. I don't think I want to fix them in this PR,
but I would like at least to get this analysis running on CI.

List of errors:
```
modules/indexer/code/indexer.go:181:11: impossible condition: nil != nil
routers/private/hook_post_receive.go:120:15: tautological condition: nil == nil
services/auth/source/oauth2/providers.go:185:9: tautological condition: nil == nil
services/convert/issue.go:216:11: tautological condition: non-nil != nil
tests/integration/git_test.go:332:9: impossible condition: nil != nil
services/migrations/migrate.go:179:24-43: unused parameter: ctx
services/repository/transfer.go:288:48-69: unused parameter: doer
tests/integration/api_repo_tags_test.go:75:41-61: unused parameter: session
tests/integration/git_test.go:696:64-74: unused parameter: baseBranch
tests/integration/gpg_git_test.go:265:27-39: unused parameter: t
tests/integration/gpg_git_test.go:284:23-29: unused parameter: tmpDir
tests/integration/gpg_git_test.go:284:31-35: unused parameter: name
tests/integration/gpg_git_test.go:284:37-42: unused parameter: email
```

(cherry picked from commit 816222243af523316041692622be6f48ef068693)

Conflicts:
	Makefile
	trivial context conflict and also ask renovate to watch over it
	do not include it in lint-backend because the errors are not fixed

Makefile

@@ -38,6 +38,7 @@ GO_LICENSES_PACKAGE ?= github.com/google/go-licenses@v1.6.0 # renovate: datasour
 GOVULNCHECK_PACKAGE ?= golang.org/x/vuln/cmd/govulncheck@v1 # renovate: datasource=go
 DEADCODE_PACKAGE ?= golang.org/x/tools/cmd/deadcode@v0.22.0 # renovate: datasource=go
 GOMOCK_PACKAGE ?= go.uber.org/mock/mockgen@v0.4.0 # renovate: datasource=go
+GOPLS_PACKAGE ?= golang.org/x/tools/gopls@v0.15.3 # renovate: datasource=go
 
 DOCKER_IMAGE ?= gitea/gitea
 DOCKER_TAG ?= latest
@@ -228,6 +229,7 @@ help:
 	@echo " - lint-go                          lint go files"
 	@echo " - lint-go-fix                      lint go files and fix issues"
 	@echo " - lint-go-vet                      lint go files with vet"
+	@echo " - lint-go-gopls                    lint go files with gopls"
 	@echo " - lint-js                          lint js files"
 	@echo " - lint-js-fix                      lint js files and fix issues"
 	@echo " - lint-css                         lint css files"
@@ -468,6 +470,11 @@ lint-go-vet:
 	@echo "Running go vet..."
 	@$(GO) vet ./...
 
+.PHONY: lint-go-gopls
+lint-go-gopls:
+	@echo "Running gopls check..."
+	@GO=$(GO) GOPLS_PACKAGE=$(GOPLS_PACKAGE) tools/lint-go-gopls.sh $(GO_SOURCES_NO_BINDATA)
+
 .PHONY: lint-editorconfig
 lint-editorconfig:
 	$(GO) run $(EDITORCONFIG_CHECKER_PACKAGE) templates .forgejo/workflows
@@ -879,6 +886,7 @@ deps-tools:
 	$(GO) install $(GO_LICENSES_PACKAGE)
 	$(GO) install $(GOVULNCHECK_PACKAGE)
 	$(GO) install $(GOMOCK_PACKAGE)
+	$(GO) install $(GOPLS_PACKAGE)
 
 node_modules: package-lock.json
 	npm install --no-save

services/migrations/migrate.go

@@ -183,7 +183,7 @@ func newDownloader(ctx context.Context, ownerName string, opts base.MigrateOptio
 // migrateRepository will download information and then upload it to Uploader, this is a simple
 // process for small repository. For a big repository, save all the data to disk
 // before upload is better
-func migrateRepository(ctx context.Context, doer *user_model.User, downloader base.Downloader, uploader base.Uploader, opts base.MigrateOptions, messenger base.Messenger) error {
+func migrateRepository(_ context.Context, doer *user_model.User, downloader base.Downloader, uploader base.Uploader, opts base.MigrateOptions, messenger base.Messenger) error {
 	if messenger == nil {
 		messenger = base.NilMessenger
 	}

services/repository/transfer.go

@@ -285,7 +285,7 @@ func transferOwnership(ctx context.Context, doer *user_model.User, newOwnerName
 }
 
 // changeRepositoryName changes all corresponding setting from old repository name to new one.
-func changeRepositoryName(ctx context.Context, doer *user_model.User, repo *repo_model.Repository, newRepoName string) (err error) {
+func changeRepositoryName(ctx context.Context, repo *repo_model.Repository, newRepoName string) (err error) {
 	oldRepoName := repo.Name
 	newRepoName = strings.ToLower(newRepoName)
 	if err = repo_model.IsUsableRepoName(newRepoName); err != nil {
@@ -347,7 +347,7 @@ func ChangeRepositoryName(ctx context.Context, doer *user_model.User, repo *repo
 	// local copy's origin accordingly.
 
 	repoWorkingPool.CheckIn(fmt.Sprint(repo.ID))
-	if err := changeRepositoryName(ctx, doer, repo, newRepoName); err != nil {
+	if err := changeRepositoryName(ctx, repo, newRepoName); err != nil {
 		repoWorkingPool.CheckOut(fmt.Sprint(repo.ID))
 		return err
 	}

tests/integration/api_repo_tags_test.go

@@ -42,7 +42,7 @@ func TestAPIRepoTags(t *testing.T) {
 	assert.Equal(t, setting.AppURL+"user2/repo1/archive/v1.1.zip", tags[0].ZipballURL)
 	assert.Equal(t, setting.AppURL+"user2/repo1/archive/v1.1.tar.gz", tags[0].TarballURL)
 
-	newTag := createNewTagUsingAPI(t, session, token, user.Name, repoName, "gitea/22", "", "nice!\nand some text")
+	newTag := createNewTagUsingAPI(t, token, user.Name, repoName, "gitea/22", "", "nice!\nand some text")
 	resp = MakeRequest(t, req, http.StatusOK)
 	DecodeJSON(t, resp, &tags)
 	assert.Len(t, tags, 2)
@@ -72,7 +72,7 @@ func TestAPIRepoTags(t *testing.T) {
 	MakeRequest(t, req, http.StatusNotFound)
 }
 
-func createNewTagUsingAPI(t *testing.T, session *TestSession, token, ownerName, repoName, name, target, msg string) *api.Tag {
+func createNewTagUsingAPI(t *testing.T, token, ownerName, repoName, name, target, msg string) *api.Tag {
 	urlStr := fmt.Sprintf("/api/v1/repos/%s/%s/tags", ownerName, repoName)
 	req := NewRequestWithJSON(t, "POST", urlStr, &api.CreateTagOption{
 		TagName: name,
@@ -96,7 +96,7 @@ func TestAPIGetTagArchiveDownloadCount(t *testing.T) {
 	repoName := "repo1"
 	tagName := "TagDownloadCount"
 
-	createNewTagUsingAPI(t, session, token, user.Name, repoName, tagName, "", "")
+	createNewTagUsingAPI(t, token, user.Name, repoName, tagName, "", "")
 
 	urlStr := fmt.Sprintf("/api/v1/repos/%s/%s/tags/%s?token=%s", user.Name, repoName, tagName, token)
 

tests/integration/dump_restore_test.go

@@ -237,7 +237,7 @@ func (c *compareDump) assertLoadFiles(beforeFilename, afterFilename string, t re
 		//
 		// Given []Something{} create afterPtr, beforePtr []*Something{}
 		//
-		sliceType := reflect.SliceOf(reflect.PtrTo(t.Elem()))
+		sliceType := reflect.SliceOf(reflect.PointerTo(t.Elem()))
 		beforeSlice := reflect.MakeSlice(sliceType, 0, 10)
 		beforePtr = reflect.New(beforeSlice.Type())
 		beforePtr.Elem().Set(beforeSlice)

tests/integration/gpg_git_test.go

@@ -36,7 +36,7 @@ func TestGPGGit(t *testing.T) {
 	defer os.Setenv("GNUPGHOME", oldGNUPGHome)
 
 	// Need to create a root key
-	rootKeyPair, err := importTestingKey(tmpDir, "gitea", "gitea@fake.local")
+	rootKeyPair, err := importTestingKey()
 	if !assert.NoError(t, err, "importTestingKey") {
 		return
 	}
@@ -263,7 +263,7 @@ func TestGPGGit(t *testing.T) {
 	})
 }
 
-func crudActionCreateFile(t *testing.T, ctx APITestContext, user *user_model.User, from, to, path string, callback ...func(*testing.T, api.FileResponse)) func(*testing.T) {
+func crudActionCreateFile(_ *testing.T, ctx APITestContext, user *user_model.User, from, to, path string, callback ...func(*testing.T, api.FileResponse)) func(*testing.T) {
 	return doAPICreateFile(ctx, path, &api.CreateFileOptions{
 		FileOptions: api.FileOptions{
 			BranchName:    from,
@@ -282,7 +282,7 @@ func crudActionCreateFile(t *testing.T, ctx APITestContext, user *user_model.Use
 	}, callback...)
 }
 
-func importTestingKey(tmpDir, name, email string) (*openpgp.Entity, error) {
+func importTestingKey() (*openpgp.Entity, error) {
 	if _, _, err := process.GetManager().Exec("gpg --import tests/integration/private-testing.key", "gpg", "--import", "tests/integration/private-testing.key"); err != nil {
 		return nil, err
 	}

tools/lint-go-gopls.sh

@@ -0,0 +1,23 @@
+#!/bin/bash
+set -uo pipefail
+
+cd "$(dirname -- "${BASH_SOURCE[0]}")" && cd ..
+
+IGNORE_PATTERNS=(
+  "is deprecated" # TODO: fix these
+)
+
+# lint all go files with 'gopls check' and look for lines starting with the
+# current absolute path, indicating a error was found. This is neccessary
+# because the tool does not set non-zero exit code when errors are found.
+# ref: https://github.com/golang/go/issues/67078
+ERROR_LINES=$("$GO" run "$GOPLS_PACKAGE" check "$@" 2>/dev/null | grep -E "^$PWD" | grep -vFf <(printf '%s\n' "${IGNORE_PATTERNS[@]}"));
+NUM_ERRORS=$(echo -n "$ERROR_LINES" | wc -l)
+
+if [ "$NUM_ERRORS" -eq "0" ]; then
+  exit 0;
+else
+  echo "$ERROR_LINES"
+  echo "Found $NUM_ERRORS 'gopls check' errors"
+  exit 1;
+fi