Enable even more frozen string in lib/gitlab

Enables frozen string for the following:

* lib/gitlab/fogbugz_import/**/*.rb
* lib/gitlab/gfm/**/*.rb
* lib/gitlab/git/**/*.rb
* lib/gitlab/gitaly_client/**/*.rb
* lib/gitlab/gitlab_import/**/*.rb
* lib/gitlab/google_code_import/**/*.rb
* lib/gitlab/gpg/**/*.rb
* lib/gitlab/grape_logging/**/*.rb
* lib/gitlab/graphql/**/*.rb
* lib/gitlab/graphs/**/*.rb
* lib/gitlab/hashed_storage/**/*.rb
* lib/gitlab/health_checks/**/*.rb

Partially address gitlab-org/gitlab-ce#47424.

changelogs/unreleased/frozen-string-lib-gitlab-even-more.yml

+---
+title: Enable even more frozen string in lib/gitlab/**/*.rb
+merge_request:
+author: gfyoung
+type: performance

lib/gitlab/fogbugz_import/client.rb

+# frozen_string_literal: true
+
 require 'fogbugz'
 
 module Gitlab

lib/gitlab/fogbugz_import/importer.rb

+# frozen_string_literal: true
+
 module Gitlab
   module FogbugzImport
     class Importer

lib/gitlab/fogbugz_import/project_creator.rb

+# frozen_string_literal: true
+
 module Gitlab
   module FogbugzImport
     class ProjectCreator

lib/gitlab/fogbugz_import/repository.rb

+# frozen_string_literal: true
+
 module Gitlab
   module FogbugzImport
     class Repository

lib/gitlab/gfm/reference_rewriter.rb

+# frozen_string_literal: true
+
 module Gitlab
   module Gfm
     ##

lib/gitlab/gfm/uploads_rewriter.rb

+# frozen_string_literal: true
+
 require 'fileutils'
 
 module Gitlab

lib/gitlab/git/attributes_at_ref_parser.rb

+# frozen_string_literal: true
+
 module Gitlab
   module Git
     # Parses root .gitattributes file at a given ref

lib/gitlab/git/attributes_parser.rb

+# frozen_string_literal: true
+
 module Gitlab
   module Git
     # Class for parsing Git attribute files and extracting the attributes for

lib/gitlab/git/blame.rb

+# frozen_string_literal: true
+
 module Gitlab
   module Git
     class Blame

lib/gitlab/git/blob.rb

+# frozen_string_literal: true
+
 # Gitaly note: JV: seems to be completely migrated (behind feature flags).
 
 module Gitlab

lib/gitlab/git/branch.rb

+# frozen_string_literal: true
+
 module Gitlab
   module Git
     class Branch < Ref

lib/gitlab/git/commit.rb

+# frozen_string_literal: true
+
 # Gitlab::Git::Commit is a wrapper around Gitaly::GitCommit
 module Gitlab
   module Git

lib/gitlab/git/commit_stats.rb

+# frozen_string_literal: true
+
 # Gitlab::Git::CommitStats counts the additions, deletions, and total changes
 # in a commit.
 module Gitlab

lib/gitlab/git/compare.rb

+# frozen_string_literal: true
+
 # Gitaly note: JV: no RPC's here.
 
 module Gitlab

lib/gitlab/git/conflict/file.rb

+# frozen_string_literal: true
+
 module Gitlab
   module Git
     module Conflict

lib/gitlab/git/conflict/parser.rb

+# frozen_string_literal: true
+
 module Gitlab
   module Git
     module Conflict

lib/gitlab/git/conflict/resolution.rb

+# frozen_string_literal: true
+
 module Gitlab
   module Git
     module Conflict

lib/gitlab/git/conflict/resolver.rb

+# frozen_string_literal: true
+
 module Gitlab
   module Git
     module Conflict

lib/gitlab/git/diff.rb

+# frozen_string_literal: true
+
 module Gitlab
   module Git
     class Diff

lib/gitlab/git/diff_collection.rb

+# frozen_string_literal: true
+
 # Gitaly note: JV: no RPC's here.
 
 module Gitlab

lib/gitlab/git/gitmodules_parser.rb

+# frozen_string_literal: true
+
 # Gitaly note: JV: no RPC's here.
 
 module Gitlab

lib/gitlab/git/hook_env.rb

+# frozen_string_literal: true
+
 # Gitaly note: JV: no RPC's here.
 
 module Gitlab

lib/gitlab/git/index.rb

+# frozen_string_literal: true
+
 module Gitlab
   module Git
     class Index

lib/gitlab/git/lfs_changes.rb

+# frozen_string_literal: true
+
 module Gitlab
   module Git
     class LfsChanges

lib/gitlab/git/lfs_pointer_file.rb

+# frozen_string_literal: true
+
 module Gitlab
   module Git
     class LfsPointerFile

lib/gitlab/git/operation_service.rb

+# frozen_string_literal: true
+
 module Gitlab
   module Git
     class OperationService

lib/gitlab/git/path_helper.rb

+# frozen_string_literal: true
+
 # Gitaly note: JV: no RPC's here.
 
 module Gitlab

lib/gitlab/git/pre_receive_error.rb

+# frozen_string_literal: true
+
 module Gitlab
   module Git
     #

lib/gitlab/git/raw_diff_change.rb

+# frozen_string_literal: true
+
 module Gitlab
   module Git
     # This class behaves like a struct with fields :blob_id, :blob_size, :operation, :old_path, :new_path

lib/gitlab/git/ref.rb

+# frozen_string_literal: true
+
 module Gitlab
   module Git
     class Ref

lib/gitlab/git/remote_mirror.rb

+# frozen_string_literal: true
+
 module Gitlab
   module Git
     class RemoteMirror

lib/gitlab/git/remote_repository.rb

+# frozen_string_literal: true
+
 module Gitlab
   module Git
     #

lib/gitlab/git/repository.rb

+# frozen_string_literal: true
+
 require 'tempfile'
 require 'forwardable'
 require "rubygems/package"

lib/gitlab/git/repository_mirroring.rb

+# frozen_string_literal: true
+
 module Gitlab
   module Git
     module RepositoryMirroring

lib/gitlab/git/tag.rb

+# frozen_string_literal: true
+
 module Gitlab
   module Git
     class Tag < Ref

lib/gitlab/git/tree.rb

+# frozen_string_literal: true
+
 module Gitlab
   module Git
     class Tree

lib/gitlab/git/user.rb

+# frozen_string_literal: true
+
 module Gitlab
   module Git
     class User

lib/gitlab/git/util.rb

+# frozen_string_literal: true
+
 # Gitaly note: JV: no RPC's here.
 
 module Gitlab

lib/gitlab/git/version.rb

+# frozen_string_literal: true
+
 module Gitlab
   module Git
     module Version

lib/gitlab/git/wiki.rb

+# frozen_string_literal: true
+
 module Gitlab
   module Git
     class Wiki

lib/gitlab/git/wiki_file.rb

+# frozen_string_literal: true
+
 module Gitlab
   module Git
     class WikiFile

lib/gitlab/git/wiki_page.rb

+# frozen_string_literal: true
+
 module Gitlab
   module Git
     class WikiPage

lib/gitlab/git/wiki_page_version.rb

+# frozen_string_literal: true
+
 module Gitlab
   module Git
     class WikiPageVersion

lib/gitlab/git/wraps_gitaly_errors.rb

+# frozen_string_literal: true
+
 module Gitlab
   module Git
     module WrapsGitalyErrors

lib/gitlab/gitaly_client/attributes_bag.rb

+# frozen_string_literal: true
+
 module Gitlab
   module GitalyClient
     # This module expects an `ATTRS` const to be defined on the subclass

lib/gitlab/gitaly_client/blob_service.rb

+# frozen_string_literal: true
+
 module Gitlab
   module GitalyClient
     class BlobService
@@ -15,7 +17,7 @@ module Gitlab
         )
         response = GitalyClient.call(@gitaly_repo.storage_name, :blob_service, :get_blob, request, timeout: GitalyClient.fast_timeout)
 
-        data = ''
+        data = []
         blob = nil
         response.each do |msg|
           if blob.nil?
@@ -27,6 +29,8 @@ module Gitlab
 
         return nil if blob.oid.blank?
 
+        data = data.join
+
         Gitlab::Git::Blob.new(
           id: blob.oid,
           size: blob.size,

lib/gitlab/gitaly_client/blobs_stitcher.rb

+# frozen_string_literal: true
+
 module Gitlab
   module GitalyClient
     class BlobsStitcher

lib/gitlab/gitaly_client/commit_service.rb

+# frozen_string_literal: true
+
 module Gitlab
   module GitalyClient
     class CommitService
@@ -93,7 +95,7 @@ module Gitlab
         response = GitalyClient.call(@repository.storage, :commit_service, :tree_entry, request, timeout: GitalyClient.medium_timeout)
 
         entry = nil
-        data = ''
+        data = []
         response.each do |msg|
           if entry.nil?
             entry = msg
@@ -103,7 +105,7 @@ module Gitlab
 
           data << msg.data
         end
-        entry.data = data
+        entry.data = data.join
 
         entry unless entry.oid.blank?
       end
@@ -254,7 +256,7 @@ module Gitlab
         )
 
         response = GitalyClient.call(@repository.storage, :commit_service, :raw_blame, request, timeout: GitalyClient.medium_timeout)
-        response.reduce("") { |memo, msg| memo << msg.data }
+        response.reduce([]) { |memo, msg| memo << msg.data }.join
       end
 
       def find_commit(revision)
@@ -345,8 +347,8 @@ module Gitlab
         request = Gitaly::ExtractCommitSignatureRequest.new(repository: @gitaly_repo, commit_id: commit_id)
         response = GitalyClient.call(@repository.storage, :commit_service, :extract_commit_signature, request)
 
-        signature = ''.b
-        signed_text = ''.b
+        signature = +''.b
+        signed_text = +''.b
 
         response.each do |message|
           signature << message.signature
@@ -364,7 +366,7 @@ module Gitlab
         request = Gitaly::GetCommitSignaturesRequest.new(repository: @gitaly_repo, commit_ids: commit_ids)
         response = GitalyClient.call(@repository.storage, :commit_service, :get_commit_signatures, request, timeout: GitalyClient.fast_timeout)
 
-        signatures = Hash.new { |h, k| h[k] = [''.b, ''.b] }
+        signatures = Hash.new { |h, k| h[k] = [+''.b, +''.b] }
         current_commit_id = nil
 
         response.each do |message|
@@ -383,7 +385,7 @@ module Gitlab
         request = Gitaly::GetCommitMessagesRequest.new(repository: @gitaly_repo, commit_ids: commit_ids)
         response = GitalyClient.call(@repository.storage, :commit_service, :get_commit_messages, request, timeout: GitalyClient.fast_timeout)
 
-        messages = Hash.new { |h, k| h[k] = ''.b }
+        messages = Hash.new { |h, k| h[k] = +''.b }
         current_commit_id = nil
 
         response.each do |rpc_message|

lib/gitlab/gitaly_client/conflict_files_stitcher.rb

+# frozen_string_literal: true
+
 module Gitlab
   module GitalyClient
     class ConflictFilesStitcher
@@ -17,7 +19,7 @@ module Gitlab
 
               current_file = file_from_gitaly_header(gitaly_file.header)
             else
-              current_file.raw_content << gitaly_file.content
+              current_file.raw_content = "#{current_file.raw_content}#{gitaly_file.content}"
             end
           end
         end

lib/gitlab/gitaly_client/conflicts_service.rb

+# frozen_string_literal: true
+
 module Gitlab
   module GitalyClient
     class ConflictsService

lib/gitlab/gitaly_client/diff.rb

+# frozen_string_literal: true
+
 module Gitlab
   module GitalyClient
     class Diff

lib/gitlab/gitaly_client/diff_stitcher.rb

+# frozen_string_literal: true
+
 module Gitlab
   module GitalyClient
     class DiffStitcher
@@ -20,7 +22,7 @@ module Gitlab
 
             current_diff = GitalyClient::Diff.new(diff_params)
           else
-            current_diff.patch += diff_msg.raw_patch_data
+            current_diff.patch = "#{current_diff.patch}#{diff_msg.raw_patch_data}"
           end
 
           if diff_msg.end_of_patch

lib/gitlab/gitaly_client/health_check_service.rb

+# frozen_string_literal: true
+
 module Gitlab
   module GitalyClient
     class HealthCheckService

lib/gitlab/gitaly_client/namespace_service.rb

+# frozen_string_literal: true
+
 module Gitlab
   module GitalyClient
     class NamespaceService

lib/gitlab/gitaly_client/notification_service.rb

+# frozen_string_literal: true
+
 module Gitlab
   module GitalyClient
     class NotificationService

lib/gitlab/gitaly_client/operation_service.rb

+# frozen_string_literal: true
+
 module Gitlab
   module GitalyClient
     class OperationService

lib/gitlab/gitaly_client/queue_enumerator.rb

+# frozen_string_literal: true
+
 module Gitlab
   module GitalyClient
     class QueueEnumerator

lib/gitlab/gitaly_client/ref_service.rb

+# frozen_string_literal: true
+
 module Gitlab
   module GitalyClient
     class RefService
@@ -218,7 +220,7 @@ module Gitlab
         request = Gitaly::GetTagMessagesRequest.new(repository: @gitaly_repo, tag_ids: tag_ids)
         response = GitalyClient.call(@repository.storage, :ref_service, :get_tag_messages, request, timeout: GitalyClient.fast_timeout)
 
-        messages = Hash.new { |h, k| h[k] = ''.b }
+        messages = Hash.new { |h, k| h[k] = +''.b }
         current_tag_id = nil
 
         response.each do |rpc_message|

lib/gitlab/gitaly_client/remote_service.rb

+# frozen_string_literal: true
+
 module Gitlab
   module GitalyClient
     class RemoteService

lib/gitlab/gitaly_client/repository_service.rb

+# frozen_string_literal: true
+
 module Gitlab
   module GitalyClient
     class RepositoryService
@@ -56,9 +58,9 @@ module Gitlab
         request = Gitaly::GetInfoAttributesRequest.new(repository: @gitaly_repo)
 
         response = GitalyClient.call(@storage, :repository_service, :get_info_attributes, request, timeout: GitalyClient.fast_timeout)
-        response.each_with_object("") do |message, attributes|
+        response.each_with_object([]) do |message, attributes|
           attributes << message.attributes
-        end
+        end.join
       end
 
       def fetch_remote(remote, ssh_auth:, forced:, no_tags:, timeout:, prune: true)

lib/gitlab/gitaly_client/server_service.rb

+# frozen_string_literal: true
+
 module Gitlab
   module GitalyClient
     # Meant for extraction of server data, and later maybe to perform misc task

lib/gitlab/gitaly_client/storage_service.rb

+# frozen_string_literal: true
+
 module Gitlab
   module GitalyClient
     class StorageService

lib/gitlab/gitaly_client/storage_settings.rb

+# frozen_string_literal: true
+
 module Gitlab
   module GitalyClient
     # This is a chokepoint that is meant to help us stop remove all places

lib/gitlab/gitaly_client/util.rb

+# frozen_string_literal: true
+
 module Gitlab
   module GitalyClient
     module Util

lib/gitlab/gitaly_client/wiki_file.rb

+# frozen_string_literal: true
+
 module Gitlab
   module GitalyClient
     class WikiFile

lib/gitlab/gitaly_client/wiki_page.rb

+# frozen_string_literal: true
+
 module Gitlab
   module GitalyClient
     class WikiPage

lib/gitlab/gitaly_client/wiki_service.rb

+# frozen_string_literal: true
+
 require 'stringio'
 
 module Gitlab
@@ -139,7 +141,7 @@ module Gitlab
           next unless message.name.present? || wiki_file
 
           if wiki_file
-            wiki_file.raw_data << message.raw_data
+            wiki_file.raw_data = "#{wiki_file.raw_data}#{message.raw_data}"
           else
             wiki_file = GitalyClient::WikiFile.new(message.to_h)
             # All gRPC strings in a response are frozen, so we get
@@ -160,7 +162,7 @@ module Gitlab
         )
 
         response = GitalyClient.call(@repository.storage, :wiki_service, :wiki_get_formatted_data, request)
-        response.reduce("") { |memo, msg| memo << msg.data }
+        response.reduce([]) { |memo, msg| memo << msg.data }.join
       end
 
       private

lib/gitlab/gitlab_import/client.rb

+# frozen_string_literal: true
+
 module Gitlab
   module GitlabImport
     class Client

lib/gitlab/gitlab_import/importer.rb

+# frozen_string_literal: true
+
 module Gitlab
   module GitlabImport
     class Importer
@@ -22,22 +24,22 @@ module Gitlab
           issues = client.issues(project_identifier)
 
           issues.each do |issue|
-            body = @formatter.author_line(issue["author"]["name"])
-            body += issue["description"]
+            body = [@formatter.author_line(issue["author"]["name"])]
+            body << issue["description"]
 
             comments = client.issue_comments(project_identifier, issue["iid"])
 
             if comments.any?
-              body += @formatter.comments_header
+              body << @formatter.comments_header
             end
 
             comments.each do |comment|
-              body += @formatter.comment(comment["author"]["name"], comment["created_at"], comment["body"])
+              body << @formatter.comment(comment["author"]["name"], comment["created_at"], comment["body"])
             end
 
             project.issues.create!(
               iid: issue["iid"],
-              description: body,
+              description: body.join,
               title: issue["title"],
               state: issue["state"],
               updated_at: issue["updated_at"],

lib/gitlab/gitlab_import/project_creator.rb

+# frozen_string_literal: true
+
 module Gitlab
   module GitlabImport
     class ProjectCreator

lib/gitlab/google_code_import/client.rb

+# frozen_string_literal: true
+
 module Gitlab
   module GoogleCodeImport
     class Client

lib/gitlab/google_code_import/importer.rb

+# frozen_string_literal: true
+
 module Gitlab
   module GoogleCodeImport
     class Importer

lib/gitlab/google_code_import/project_creator.rb

+# frozen_string_literal: true
+
 module Gitlab
   module GoogleCodeImport
     class ProjectCreator

lib/gitlab/google_code_import/repository.rb

+# frozen_string_literal: true
+
 module Gitlab
   module GoogleCodeImport
     class Repository

lib/gitlab/gpg/commit.rb

+# frozen_string_literal: true
+
 module Gitlab
   module Gpg
     class Commit

lib/gitlab/gpg/invalid_gpg_signature_updater.rb

+# frozen_string_literal: true
+
 module Gitlab
   module Gpg
     class InvalidGpgSignatureUpdater

lib/gitlab/grape_logging/formatters/lograge_with_timestamp.rb

+# frozen_string_literal: true
+
 module Gitlab
   module GrapeLogging
     module Formatters

lib/gitlab/grape_logging/loggers/queue_duration_logger.rb

+# frozen_string_literal: true
+
 # This grape_logging module (https://github.com/aserafin/grape_logging) makes it
 # possible to log how much time an API request was queued by Workhorse.
 module Gitlab

lib/gitlab/grape_logging/loggers/user_logger.rb

+# frozen_string_literal: true
+
 # This grape_logging module (https://github.com/aserafin/grape_logging) makes it
 # possible to log the user who performed the Grape API action by retrieving
 # the user context from the request environment.

lib/gitlab/graphql/authorize.rb

+# frozen_string_literal: true
+
 module Gitlab
   module Graphql
     # Allow fields to declare permissions their objects must have. The field

lib/gitlab/graphql/authorize/authorize_resource.rb

+# frozen_string_literal: true
+
 module Gitlab
   module Graphql
     module Authorize

lib/gitlab/graphql/authorize/instrumentation.rb

+# frozen_string_literal: true
+
 module Gitlab
   module Graphql
     module Authorize

lib/gitlab/graphql/connections.rb

+# frozen_string_literal: true
+
 module Gitlab
   module Graphql
     module Connections

lib/gitlab/graphql/connections/keyset_connection.rb

+# frozen_string_literal: true
+
 module Gitlab
   module Graphql
     module Connections

lib/gitlab/graphql/errors.rb

+# frozen_string_literal: true
+
 module Gitlab
   module Graphql
     module Errors

lib/gitlab/graphql/expose_permissions.rb

+# frozen_string_literal: true
+
 module Gitlab
   module Graphql
     module ExposePermissions

lib/gitlab/graphql/present.rb

+# frozen_string_literal: true
+
 module Gitlab
   module Graphql
     module Present

lib/gitlab/graphql/present/instrumentation.rb

+# frozen_string_literal: true
+
 module Gitlab
   module Graphql
     module Present

lib/gitlab/graphql/variables.rb

+# frozen_string_literal: true
+
 module Gitlab
   module Graphql
     class Variables

lib/gitlab/graphs/commits.rb

+# frozen_string_literal: true
+
 module Gitlab
   module Graphs
     class Commits

lib/gitlab/hashed_storage/migrator.rb

+# frozen_string_literal: true
+
 module Gitlab
   module HashedStorage
     # Hashed Storage Migrator

lib/gitlab/hashed_storage/rake_helper.rb

+# frozen_string_literal: true
+
 module Gitlab
   module HashedStorage
     module RakeHelper

lib/gitlab/health_checks/base_abstract_check.rb

+# frozen_string_literal: true
+
 module Gitlab
   module HealthChecks
     module BaseAbstractCheck

lib/gitlab/health_checks/db_check.rb

+# frozen_string_literal: true
+
 module Gitlab
   module HealthChecks
     class DbCheck

lib/gitlab/health_checks/gitaly_check.rb

+# frozen_string_literal: true
+
 module Gitlab
   module HealthChecks
     class GitalyCheck

lib/gitlab/health_checks/metric.rb

-module Gitlab::HealthChecks # rubocop:disable Naming/FileName
+# rubocop:disable Naming/FileName
+# frozen_string_literal: true
+
+module Gitlab::HealthChecks
   Metric = Struct.new(:name, :value, :labels)
 end

lib/gitlab/health_checks/prometheus_text_format.rb

+# frozen_string_literal: true
+
 module Gitlab
   module HealthChecks
     class PrometheusTextFormat

lib/gitlab/health_checks/redis/cache_check.rb

+# frozen_string_literal: true
+
 module Gitlab
   module HealthChecks
     module Redis

lib/gitlab/health_checks/redis/queues_check.rb

+# frozen_string_literal: true
+
 module Gitlab
   module HealthChecks
     module Redis