Enable even more frozen string in lib/gitlab

Enables frozens string for the following:

* lib/gitlab/conflict/**/*.rb
* lib/gitlab/cross_project_access/**/*.rb
* lib/gitlab/cycle_analytics/**/*.rb
* lib/gitlab/data_builder/**/*.rb
* lib/gitlab/database/**/*.rb
* lib/gitlab/dependency_linker/**/*.rb
* lib/gitlab/diff/**/*.rb
* lib/gitlab/downtime_check/**/*.rb
* lib/gitlab/email/**/*.rb
* lib/gitlab/etag_caching/**/*.rb

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

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

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

lib/gitlab/conflict/file.rb

+# frozen_string_literal: true
+
 module Gitlab
   module Conflict
     class File

lib/gitlab/conflict/file_collection.rb

+# frozen_string_literal: true
+
 module Gitlab
   module Conflict
     class FileCollection

lib/gitlab/cross_project_access/check_collection.rb

+# frozen_string_literal: true
+
 module Gitlab
   class CrossProjectAccess
     class CheckCollection

lib/gitlab/cross_project_access/check_info.rb

+# frozen_string_literal: true
+
 module Gitlab
   class CrossProjectAccess
     class CheckInfo

lib/gitlab/cross_project_access/class_methods.rb

+# frozen_string_literal: true
+
 module Gitlab
   class CrossProjectAccess
     module ClassMethods

lib/gitlab/cycle_analytics/base_event_fetcher.rb

+# frozen_string_literal: true
+
 module Gitlab
   module CycleAnalytics
     class BaseEventFetcher

lib/gitlab/cycle_analytics/base_query.rb

+# frozen_string_literal: true
+
 module Gitlab
   module CycleAnalytics
     module BaseQuery

lib/gitlab/cycle_analytics/base_stage.rb

+# frozen_string_literal: true
+
 module Gitlab
   module CycleAnalytics
     class BaseStage

lib/gitlab/cycle_analytics/code_event_fetcher.rb

+# frozen_string_literal: true
+
 module Gitlab
   module CycleAnalytics
     class CodeEventFetcher < BaseEventFetcher

lib/gitlab/cycle_analytics/code_stage.rb

+# frozen_string_literal: true
+
 module Gitlab
   module CycleAnalytics
     class CodeStage < BaseStage

lib/gitlab/cycle_analytics/event_fetcher.rb

+# frozen_string_literal: true
+
 module Gitlab
   module CycleAnalytics
     module EventFetcher

lib/gitlab/cycle_analytics/issue_event_fetcher.rb

+# frozen_string_literal: true
+
 module Gitlab
   module CycleAnalytics
     class IssueEventFetcher < BaseEventFetcher

lib/gitlab/cycle_analytics/issue_stage.rb

+# frozen_string_literal: true
+
 module Gitlab
   module CycleAnalytics
     class IssueStage < BaseStage

lib/gitlab/cycle_analytics/metrics_tables.rb

+# frozen_string_literal: true
+
 module Gitlab
   module CycleAnalytics
     module MetricsTables

lib/gitlab/cycle_analytics/permissions.rb

+# frozen_string_literal: true
+
 module Gitlab
   module CycleAnalytics
     class Permissions

lib/gitlab/cycle_analytics/plan_event_fetcher.rb

+# frozen_string_literal: true
+
 module Gitlab
   module CycleAnalytics
     class PlanEventFetcher < BaseEventFetcher

lib/gitlab/cycle_analytics/plan_stage.rb

+# frozen_string_literal: true
+
 module Gitlab
   module CycleAnalytics
     class PlanStage < BaseStage

lib/gitlab/cycle_analytics/production_event_fetcher.rb

+# frozen_string_literal: true
+
 module Gitlab
   module CycleAnalytics
     class ProductionEventFetcher < IssueEventFetcher

lib/gitlab/cycle_analytics/production_helper.rb

+# frozen_string_literal: true
+
 module Gitlab
   module CycleAnalytics
     module ProductionHelper

lib/gitlab/cycle_analytics/production_stage.rb

+# frozen_string_literal: true
+
 module Gitlab
   module CycleAnalytics
     class ProductionStage < BaseStage

lib/gitlab/cycle_analytics/review_event_fetcher.rb

+# frozen_string_literal: true
+
 module Gitlab
   module CycleAnalytics
     class ReviewEventFetcher < BaseEventFetcher

lib/gitlab/cycle_analytics/review_stage.rb

+# frozen_string_literal: true
+
 module Gitlab
   module CycleAnalytics
     class ReviewStage < BaseStage

lib/gitlab/cycle_analytics/stage.rb

+# frozen_string_literal: true
+
 module Gitlab
   module CycleAnalytics
     module Stage

lib/gitlab/cycle_analytics/stage_summary.rb

+# frozen_string_literal: true
+
 module Gitlab
   module CycleAnalytics
     class StageSummary

lib/gitlab/cycle_analytics/staging_event_fetcher.rb

+# frozen_string_literal: true
+
 module Gitlab
   module CycleAnalytics
     class StagingEventFetcher < BaseEventFetcher

lib/gitlab/cycle_analytics/staging_stage.rb

+# frozen_string_literal: true
+
 module Gitlab
   module CycleAnalytics
     class StagingStage < BaseStage

lib/gitlab/cycle_analytics/summary/base.rb

+# frozen_string_literal: true
+
 module Gitlab
   module CycleAnalytics
     module Summary

lib/gitlab/cycle_analytics/summary/commit.rb

+# frozen_string_literal: true
+
 module Gitlab
   module CycleAnalytics
     module Summary

lib/gitlab/cycle_analytics/summary/deploy.rb

+# frozen_string_literal: true
+
 module Gitlab
   module CycleAnalytics
     module Summary

lib/gitlab/cycle_analytics/summary/issue.rb

+# frozen_string_literal: true
+
 module Gitlab
   module CycleAnalytics
     module Summary

lib/gitlab/cycle_analytics/test_event_fetcher.rb

+# frozen_string_literal: true
+
 module Gitlab
   module CycleAnalytics
     class TestEventFetcher < StagingEventFetcher

lib/gitlab/cycle_analytics/test_stage.rb

+# frozen_string_literal: true
+
 module Gitlab
   module CycleAnalytics
     class TestStage < BaseStage

lib/gitlab/cycle_analytics/updater.rb

+# frozen_string_literal: true
+
 module Gitlab
   module CycleAnalytics
     class Updater

lib/gitlab/cycle_analytics/usage_data.rb

+# frozen_string_literal: true
+
 module Gitlab
   module CycleAnalytics
     class UsageData

lib/gitlab/data_builder/build.rb

+# frozen_string_literal: true
+
 module Gitlab
   module DataBuilder
     module Build

lib/gitlab/data_builder/note.rb

+# frozen_string_literal: true
+
 module Gitlab
   module DataBuilder
     module Note

lib/gitlab/data_builder/pipeline.rb

+# frozen_string_literal: true
+
 module Gitlab
   module DataBuilder
     module Pipeline

lib/gitlab/data_builder/push.rb

+# frozen_string_literal: true
+
 module Gitlab
   module DataBuilder
     module Push

lib/gitlab/data_builder/repository.rb

+# frozen_string_literal: true
+
 module Gitlab
   module DataBuilder
     module Repository

lib/gitlab/data_builder/wiki_page.rb

+# frozen_string_literal: true
+
 module Gitlab
   module DataBuilder
     module WikiPage

lib/gitlab/database/arel_methods.rb

+# frozen_string_literal: true
+
 module Gitlab
   module Database
     module ArelMethods

lib/gitlab/database/count.rb

+# frozen_string_literal: true
+
 # For large tables, PostgreSQL can take a long time to count rows due to MVCC.
 # We can optimize this by using the reltuples count as described in https://wiki.postgresql.org/wiki/Slow_Counting.
 module Gitlab

lib/gitlab/database/date_time.rb

+# frozen_string_literal: true
+
 module Gitlab
   module Database
     module DateTime

lib/gitlab/database/grant.rb

+# frozen_string_literal: true
+
 module Gitlab
   module Database
     # Model that can be used for querying permissions of a SQL user.

lib/gitlab/database/median.rb

+# frozen_string_literal: true
+
 # https://www.periscopedata.com/blog/medians-in-sql.html
 module Gitlab
   module Database

lib/gitlab/database/migration_helpers.rb

+# frozen_string_literal: true
+
 module Gitlab
   module Database
     module MigrationHelpers

lib/gitlab/database/multi_threaded_migration.rb

+# frozen_string_literal: true
+
 module Gitlab
   module Database
     module MultiThreadedMigration

lib/gitlab/database/read_only_relation.rb

+# frozen_string_literal: true
+
 module Gitlab
   module Database
     # Module that can be injected into a ActiveRecord::Relation to make it

lib/gitlab/database/rename_reserved_paths_migration/v1.rb

+# frozen_string_literal: true
+
 # This module can be included in migrations to make it easier to rename paths
 # of `Namespace` & `Project` models certain paths would become `reserved`.
 #

lib/gitlab/database/rename_reserved_paths_migration/v1/migration_classes.rb

+# frozen_string_literal: true
+
 module Gitlab
   module Database
     module RenameReservedPathsMigration

lib/gitlab/database/rename_reserved_paths_migration/v1/rename_base.rb

+# frozen_string_literal: true
+
 module Gitlab
   module Database
     module RenameReservedPathsMigration

lib/gitlab/database/rename_reserved_paths_migration/v1/rename_namespaces.rb

+# frozen_string_literal: true
+
 module Gitlab
   module Database
     module RenameReservedPathsMigration

lib/gitlab/database/rename_reserved_paths_migration/v1/rename_projects.rb

+# frozen_string_literal: true
+
 module Gitlab
   module Database
     module RenameReservedPathsMigration

lib/gitlab/database/sha_attribute.rb

+# frozen_string_literal: true
+
 module Gitlab
   module Database
     BINARY_TYPE =

lib/gitlab/dependency_linker/base_linker.rb

+# frozen_string_literal: true
+
 module Gitlab
   module DependencyLinker
     class BaseLinker

lib/gitlab/dependency_linker/cartfile_linker.rb

+# frozen_string_literal: true
+
 module Gitlab
   module DependencyLinker
     class CartfileLinker < MethodLinker

lib/gitlab/dependency_linker/cocoapods.rb

+# frozen_string_literal: true
+
 module Gitlab
   module DependencyLinker
     module Cocoapods

lib/gitlab/dependency_linker/composer_json_linker.rb

+# frozen_string_literal: true
+
 module Gitlab
   module DependencyLinker
     class ComposerJsonLinker < PackageJsonLinker

lib/gitlab/dependency_linker/gemfile_linker.rb

+# frozen_string_literal: true
+
 module Gitlab
   module DependencyLinker
     class GemfileLinker < MethodLinker

lib/gitlab/dependency_linker/gemspec_linker.rb

+# frozen_string_literal: true
+
 module Gitlab
   module DependencyLinker
     class GemspecLinker < MethodLinker

lib/gitlab/dependency_linker/godeps_json_linker.rb

+# frozen_string_literal: true
+
 module Gitlab
   module DependencyLinker
     class GodepsJsonLinker < JsonLinker

lib/gitlab/dependency_linker/json_linker.rb

+# frozen_string_literal: true
+
 module Gitlab
   module DependencyLinker
     class JsonLinker < BaseLinker

lib/gitlab/dependency_linker/method_linker.rb

+# frozen_string_literal: true
+
 module Gitlab
   module DependencyLinker
     class MethodLinker < BaseLinker

lib/gitlab/dependency_linker/package_json_linker.rb

+# frozen_string_literal: true
+
 module Gitlab
   module DependencyLinker
     class PackageJsonLinker < JsonLinker

lib/gitlab/dependency_linker/podfile_linker.rb

+# frozen_string_literal: true
+
 module Gitlab
   module DependencyLinker
     class PodfileLinker < GemfileLinker

lib/gitlab/dependency_linker/podspec_json_linker.rb

+# frozen_string_literal: true
+
 module Gitlab
   module DependencyLinker
     class PodspecJsonLinker < JsonLinker

lib/gitlab/dependency_linker/podspec_linker.rb

+# frozen_string_literal: true
+
 module Gitlab
   module DependencyLinker
     class PodspecLinker < MethodLinker

lib/gitlab/dependency_linker/requirements_txt_linker.rb

+# frozen_string_literal: true
+
 module Gitlab
   module DependencyLinker
     class RequirementsTxtLinker < BaseLinker

lib/gitlab/diff/diff_refs.rb

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

lib/gitlab/diff/file.rb

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

lib/gitlab/diff/file_collection/base.rb

+# frozen_string_literal: true
+
 module Gitlab
   module Diff
     module FileCollection

lib/gitlab/diff/file_collection/commit.rb

+# frozen_string_literal: true
+
 module Gitlab
   module Diff
     module FileCollection

lib/gitlab/diff/file_collection/compare.rb

+# frozen_string_literal: true
+
 module Gitlab
   module Diff
     module FileCollection

lib/gitlab/diff/file_collection/merge_request_diff.rb

+# frozen_string_literal: true
+
 module Gitlab
   module Diff
     module FileCollection

lib/gitlab/diff/formatters/base_formatter.rb

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

lib/gitlab/diff/formatters/image_formatter.rb

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

lib/gitlab/diff/formatters/text_formatter.rb

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

lib/gitlab/diff/highlight.rb

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

lib/gitlab/diff/image_point.rb

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

lib/gitlab/diff/inline_diff.rb

+# frozen_string_literal: true
+
 module Gitlab
   module Diff
     class InlineDiff
@@ -71,7 +73,7 @@ module Gitlab
         def find_changed_line_pairs(lines)
           # Prefixes of all diff lines, indicating their types
           # For example: `" - +  -+  ---+++ --+  -++"`
-          line_prefixes = lines.each_with_object("") { |line, s| s << (line[0] || ' ') }.gsub(/[^ +-]/, ' ')
+          line_prefixes = lines.each_with_object(+"") { |line, s| s << (line[0] || ' ') }.gsub(/[^ +-]/, ' ')
 
           changed_line_pairs = []
           line_prefixes.scan(LINE_PAIRS_PATTERN) do

lib/gitlab/diff/inline_diff_markdown_marker.rb

+# frozen_string_literal: true
+
 module Gitlab
   module Diff
     class InlineDiffMarkdownMarker < Gitlab::StringRangeMarker

lib/gitlab/diff/inline_diff_marker.rb

+# frozen_string_literal: true
+
 module Gitlab
   module Diff
     class InlineDiffMarker < Gitlab::StringRangeMarker

lib/gitlab/diff/line.rb

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

lib/gitlab/diff/line_mapper.rb

+# frozen_string_literal: true
+
 # When provided a diff for a specific file, maps old line numbers to new line
 # numbers and back, to find out where a specific line in a file was moved by the
 # changes.

lib/gitlab/diff/parallel_diff.rb

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

lib/gitlab/diff/parser.rb

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

lib/gitlab/diff/position.rb

+# frozen_string_literal: true
+
 # Defines a specific location, identified by paths line numbers and image coordinates,
 # within a specific diff, identified by start, head and base commit ids.
 module Gitlab

lib/gitlab/diff/position_tracer.rb

+# frozen_string_literal: true
+
 # Finds the diff position in the new diff that corresponds to the same location
 # specified by the provided position in the old diff.
 module Gitlab

lib/gitlab/downtime_check/message.rb

+# frozen_string_literal: true
+
 module Gitlab
   class DowntimeCheck
     class Message
@@ -18,13 +20,13 @@ module Gitlab
       def to_s
         label = offline ? OFFLINE : ONLINE
 
-        message = "[#{label}]: #{path}"
+        message = ["[#{label}]: #{path}"]
 
         if reason?
-          message += ":\n\n#{reason}\n\n"
+          message << ":\n\n#{reason}\n\n"
         end
 
-        message
+        message.join
       end
 
       def reason?

lib/gitlab/email/attachment_uploader.rb

+# frozen_string_literal: true
+
 module Gitlab
   module Email
     class AttachmentUploader

lib/gitlab/email/hook/additional_headers_interceptor.rb

+# frozen_string_literal: true
+
 module Gitlab
   module Email
     module Hook

lib/gitlab/email/hook/delivery_metrics_observer.rb

+# frozen_string_literal: true
+
 module Gitlab
   module Email
     module Hook

lib/gitlab/email/hook/disable_email_interceptor.rb

+# frozen_string_literal: true
+
 module Gitlab
   module Email
     module Hook

lib/gitlab/email/hook/email_template_interceptor.rb

+# frozen_string_literal: true
+
 module Gitlab
   module Email
     module Hook

lib/gitlab/email/html_parser.rb

+# frozen_string_literal: true
+
 module Gitlab
   module Email
     class HTMLParser

lib/gitlab/email/message/repository_push.rb

+# frozen_string_literal: true
+
 module Gitlab
   module Email
     module Message
@@ -116,7 +118,7 @@ module Gitlab
         end
 
         def subject
-          subject_text = '[Git]'
+          subject_text = ['[Git]']
           subject_text << "[#{project.full_path}]"
           subject_text << "[#{ref_name}]" if @action == :push
           subject_text << ' '
@@ -134,6 +136,8 @@ module Gitlab
             subject_action[0] = subject_action[0].capitalize
             subject_text << "#{subject_action} #{ref_type} #{ref_name}"
           end
+
+          subject_text.join
         end
       end
     end

lib/gitlab/email/receiver.rb

+# frozen_string_literal: true
+
 require_dependency 'gitlab/email/handler'
 
 # Inspired in great part by Discourse's Email::Receiver

lib/gitlab/email/reply_parser.rb

+# frozen_string_literal: true
+
 # Inspired in great part by Discourse's Email::Receiver
 module Gitlab
   module Email

lib/gitlab/etag_caching/middleware.rb

+# frozen_string_literal: true
+
 module Gitlab
   module EtagCaching
     class Middleware