Merge #7100

7100: Prefer `require_relative` for internal requires r=deivid-rodriguez a=deivid-rodriguez

### What was the end-user problem that led to this PR?

The problem was that `bundler` seems to, in some very rare cases, leak to the copy of itself installed as a default gem. I have been able to reproduce this only for stuff that we have already fixed. For example: https://github.com/bundler/bundler/pull/6502. However, I have the gut feeling that this can still happen under some conditions, because sometimes we still get reports from people using bundler 2, and getting the error "You must user Bundler 2 or greater with this Gemfile". 

### What was your diagnosis of the problem?

My diagnosis was that somehow, due to the complicated LOAD_PATH manipulation bundler does, we may endup requiring bundler files in another copy of bundler.

### What is your fix for the problem, implemented in this PR?

My fix is not really a fix, although it _might_ prevent the potential issue from happening. As @colby-swandale would say, we should fix the real culprit instead. However, I think using `require_relative` is a better practice anyways, because it makes it clear that you are requiring "internal" files and not files from some dependencies. And it should also be faster because it does not search the LOAD_PATH. And it skips the rubygems monkeypatches to `require`, which seems also good.

### Why did you choose this fix out of the possible options?

I chose this fix because I think it's a good practice.

Co-authored-by: David Rodríguez <deivid.rodriguez@riseup.net>

50 files changed, 138 insertions, 131 deletions

diff --git a/lib/bundler.rb b/lib/bundler.rb
index f792a3bc98..0c24a21d7a 100644
--- a/lib/bundler.rb
+++ b/lib/bundler.rb
@@ -1,20 +1,20 @@
 # frozen_string_literal: true
 
-require "bundler/compatibility_guard"
+require_relative "bundler/compatibility_guard"
 
-require "bundler/vendored_fileutils"
+require_relative "bundler/vendored_fileutils"
 require "pathname"
 require "rbconfig"
 
-require "bundler/errors"
-require "bundler/environment_preserver"
-require "bundler/plugin"
-require "bundler/rubygems_ext"
-require "bundler/rubygems_integration"
-require "bundler/version"
-require "bundler/constants"
-require "bundler/current_ruby"
-require "bundler/build_metadata"
+require_relative "bundler/errors"
+require_relative "bundler/environment_preserver"
+require_relative "bundler/plugin"
+require_relative "bundler/rubygems_ext"
+require_relative "bundler/rubygems_integration"
+require_relative "bundler/version"
+require_relative "bundler/constants"
+require_relative "bundler/current_ruby"
+require_relative "bundler/build_metadata"
 
 module Bundler
   environment_preserver = EnvironmentPreserver.new(ENV, EnvironmentPreserver::BUNDLER_KEYS)
diff --git a/lib/bundler/capistrano.rb b/lib/bundler/capistrano.rb
index 1b7145b72b..573df95043 100644
--- a/lib/bundler/capistrano.rb
+++ b/lib/bundler/capistrano.rb
@@ -1,6 +1,6 @@
 # frozen_string_literal: true
 
-require "bundler/shared_helpers"
+require_relative "shared_helpers"
 Bundler::SharedHelpers.major_deprecation 2,
   "The Bundler task for Capistrano. Please use http://github.com/capistrano/bundler"
 
@@ -8,7 +8,7 @@ Bundler::SharedHelpers.major_deprecation 2,
 #
 # Add "require 'bundler/capistrano'" in your Capistrano deploy.rb, and
 # Bundler will be activated after each new deployment.
-require "bundler/deployment"
+require_relative "deployment"
 require "capistrano/version"
 
 if defined?(Capistrano::Version) && Gem::Version.new(Capistrano::Version).release >= Gem::Version.new("3.0")
diff --git a/lib/bundler/cli.rb b/lib/bundler/cli.rb
index 4e3735847e..5d5363aee8 100644
--- a/lib/bundler/cli.rb
+++ b/lib/bundler/cli.rb
@@ -1,11 +1,10 @@
 # frozen_string_literal: true
 
-require "bundler"
-require "bundler/vendored_thor"
+require_relative "vendored_thor"
 
 module Bundler
   class CLI < Thor
-    require "bundler/cli/common"
+    require_relative "cli/common"
 
     package_name "Bundler"
 
@@ -139,7 +138,7 @@ module Bundler
     D
     method_option "gemspec", :type => :string, :banner => "Use the specified .gemspec to create the Gemfile"
     def init
-      require "bundler/cli/init"
+      require_relative "cli/init"
       Init.new(options.dup).run
     end
 
@@ -157,7 +156,7 @@ module Bundler
       "Specify a different path than the system default ($BUNDLE_PATH or $GEM_HOME).#{" Bundler will remember this value for future installs on this machine" unless Bundler.feature_flag.forget_cli_options?}"
     map "c" => "check"
     def check
-      require "bundler/cli/check"
+      require_relative "cli/check"
       Check.new(options).run
     end
 
@@ -168,7 +167,7 @@ module Bundler
     method_option "install", :type => :boolean, :banner =>
       "Runs 'bundle install' after removing the gems from the Gemfile"
     def remove(*gems)
-      require "bundler/cli/remove"
+      require_relative "cli/remove"
       Remove.new(gems, options).run
     end
 
@@ -230,7 +229,7 @@ module Bundler
         remembered_flag_deprecation(option)
       end
 
-      require "bundler/cli/install"
+      require_relative "cli/install"
       Bundler.settings.temporary(:no_install => false) do
         Install.new(options.dup).run
       end
@@ -276,7 +275,7 @@ module Bundler
       "Update everything."
     def update(*gems)
       SharedHelpers.major_deprecation(2, "The `--force` option has been renamed to `--redownload`") if ARGV.include?("--force")
-      require "bundler/cli/update"
+      require_relative "cli/update"
       Bundler.settings.temporary(:no_install => false) do
         Update.new(options, gems).run
       end
@@ -312,7 +311,7 @@ module Bundler
             Bundler::SharedHelpers.major_deprecation(2, "use `bundle #{new_argv}` instead of `bundle #{old_argv}`")
           end
         end
-        require "bundler/cli/show"
+        require_relative "cli/show"
         Show.new(options, gem_name).run
       end
     end
@@ -323,7 +322,7 @@ module Bundler
     method_option "without-group", :type => :string, :banner => "print all gems except from a group"
     method_option "paths", :type => :boolean, :banner => "print the path to each gem in the bundle"
     def list
-      require "bundler/cli/list"
+      require_relative "cli/list"
       List.new(options).run
     end
 
@@ -332,7 +331,7 @@ module Bundler
     desc "info GEM [OPTIONS]", "Show information for the given gem"
     method_option "path", :type => :boolean, :banner => "Print full path to gem"
     def info(gem_name)
-      require "bundler/cli/info"
+      require_relative "cli/info"
       Info.new(options, gem_name).run
     end
 
@@ -353,7 +352,7 @@ module Bundler
     method_option "all", :type => :boolean, :banner =>
       "Install binstubs for all gems"
     def binstubs(*gems)
-      require "bundler/cli/binstubs"
+      require_relative "cli/binstubs"
       Binstubs.new(options, gems).run
     end
 
@@ -369,7 +368,7 @@ module Bundler
     method_option "optimistic", :type => :boolean, :banner => "Adds optimistic declaration of version to gem"
     method_option "strict", :type => :boolean, :banner => "Adds strict declaration of version to gem"
     def add(*gems)
-      require "bundler/cli/add"
+      require_relative "cli/add"
       Add.new(options.dup, gems).run
     end
 
@@ -405,7 +404,7 @@ module Bundler
     method_option "only-explicit", :type => :boolean, :banner =>
       "Only list gems specified in your Gemfile, not their dependencies"
     def outdated(*gems)
-      require "bundler/cli/outdated"
+      require_relative "cli/outdated"
       Outdated.new(options, gems).run
     end
 
@@ -420,7 +419,7 @@ module Bundler
       method_option "all-platforms", :type => :boolean, :banner => "Include gems for all platforms present in the lockfile, not only the current one"
       method_option "no-prune", :type => :boolean, :banner => "Don't remove stale gems from the cache."
       def cache
-        require "bundler/cli/cache"
+        require_relative "cli/cache"
         Cache.new(options).run
       end
     end
@@ -448,7 +447,7 @@ module Bundler
       bundle without having to download any additional gems.
     D
     def package
-      require "bundler/cli/package"
+      require_relative "cli/package"
       Package.new(options).run
     end
     map %w[pack] => :package
@@ -463,7 +462,7 @@ module Bundler
     D
     map "e" => "exec"
     def exec(*args)
-      require "bundler/cli/exec"
+      require_relative "cli/exec"
       Exec.new(options, args).run
     end
 
@@ -479,19 +478,19 @@ module Bundler
       will show the current value, as well as any superceded values and
       where they were specified.
     D
-    require "bundler/cli/config"
+    require_relative "cli/config"
     subcommand "config", Config
 
     desc "open GEM", "Opens the source directory of the given bundled gem"
     def open(name)
-      require "bundler/cli/open"
+      require_relative "cli/open"
       Open.new(options, name).run
     end
 
     unless Bundler.feature_flag.bundler_3_mode?
       desc "console [GROUP]", "Opens an IRB session with the bundle pre-loaded"
       def console(group = nil)
-        require "bundler/cli/console"
+        require_relative "cli/console"
         Console.new(options, group).run
       end
     end
@@ -539,7 +538,7 @@ module Bundler
       method_option :without, :type => :array, :default => [], :aliases => "-W", :banner => "GROUP[ GROUP...]", :desc => "Exclude gems that are part of the specified named group."
       def viz
         SharedHelpers.major_deprecation 2, "The `viz` command has been moved to the `bundle-viz` gem, see https://github.com/bundler/bundler-viz"
-        require "bundler/cli/viz"
+        require_relative "cli/viz"
         Viz.new(options.dup).run
       end
     end
@@ -563,7 +562,7 @@ module Bundler
       def gem_command.run(instance, args = [])
         arity = 1 # name
 
-        require "bundler/cli/gem"
+        require_relative "cli/gem"
         cmd_args = args + [instance]
         cmd_args.unshift(instance.options)
 
@@ -591,7 +590,7 @@ module Bundler
     method_option "force", :type => :boolean, :default => false, :banner =>
       "Forces clean even if --path is not set"
     def clean
-      require "bundler/cli/clean"
+      require_relative "cli/clean"
       Clean.new(options.dup).run
     end
 
@@ -599,7 +598,7 @@ module Bundler
     method_option "ruby", :type => :boolean, :default => false, :banner =>
       "only display ruby related platform information"
     def platform
-      require "bundler/cli/platform"
+      require_relative "cli/platform"
       Platform.new(options).run
     end
 
@@ -610,7 +609,7 @@ module Bundler
      "Install gem into a bundler group"
     def inject(name, version)
       SharedHelpers.major_deprecation 2, "The `inject` command has been replaced by the `add` command"
-      require "bundler/cli/inject"
+      require_relative "cli/inject"
       Inject.new(options.dup, name, version).run
     end
 
@@ -642,7 +641,7 @@ module Bundler
     method_option "conservative", :type => :boolean, :banner =>
       "If updating, use bundle install conservative update behavior and do not allow shared dependencies to be updated"
     def lock
-      require "bundler/cli/lock"
+      require_relative "cli/lock"
       Lock.new(options).run
     end
 
@@ -662,13 +661,13 @@ module Bundler
     method_option "quiet", :type => :boolean, :banner =>
         "Only output warnings and errors."
     def doctor
-      require "bundler/cli/doctor"
+      require_relative "cli/doctor"
       Doctor.new(options).run
     end
 
     desc "issue", "Learn how to report an issue in Bundler"
     def issue
-      require "bundler/cli/issue"
+      require_relative "cli/issue"
       Issue.new.run
     end
 
@@ -679,12 +678,12 @@ module Bundler
       checkout --force`.
     D
     def pristine(*gems)
-      require "bundler/cli/pristine"
+      require_relative "cli/pristine"
       Pristine.new(gems).run
     end
 
     if Bundler.feature_flag.plugins?
-      require "bundler/cli/plugin"
+      require_relative "cli/plugin"
       desc "plugin", "Manage the bundler plugins"
       subcommand "plugin", Plugin
     end
diff --git a/lib/bundler/cli/common.rb b/lib/bundler/cli/common.rb
index 9ea52baa6b..5ec541f722 100644
--- a/lib/bundler/cli/common.rb
+++ b/lib/bundler/cli/common.rb
@@ -59,7 +59,7 @@ module Bundler
     end
 
     def self.gem_not_found_message(missing_gem_name, alternatives)
-      require "bundler/similarity_detector"
+      require_relative "../similarity_detector"
       message = "Could not find gem '#{missing_gem_name}'."
       alternate_names = alternatives.map {|a| a.respond_to?(:name) ? a.name : a }
       suggestions = SimilarityDetector.new(alternate_names).similar_word_list(missing_gem_name)
diff --git a/lib/bundler/cli/doctor.rb b/lib/bundler/cli/doctor.rb
index 6d038937c0..1b3913a300 100644
--- a/lib/bundler/cli/doctor.rb
+++ b/lib/bundler/cli/doctor.rb
@@ -56,7 +56,7 @@ module Bundler
     end
 
     def check!
-      require "bundler/cli/check"
+      require_relative "check"
       Bundler::CLI::Check.new({}).run
     end
 
diff --git a/lib/bundler/cli/exec.rb b/lib/bundler/cli/exec.rb
index c29d632307..6fdd55d106 100644
--- a/lib/bundler/cli/exec.rb
+++ b/lib/bundler/cli/exec.rb
@@ -1,6 +1,6 @@
 # frozen_string_literal: true
 
-require "bundler/current_ruby"
+require_relative "../current_ruby"
 
 module Bundler
   class CLI::Exec
@@ -69,7 +69,7 @@ module Bundler
       Process.setproctitle(process_title(file, args)) if Process.respond_to?(:setproctitle)
       ui = Bundler.ui
       Bundler.ui = nil
-      require "bundler/setup"
+      require_relative "../setup"
       TRAPPED_SIGNALS.each {|s| trap(s, "DEFAULT") }
       Kernel.load(file)
     rescue SystemExit, SignalException
diff --git a/lib/bundler/cli/install.rb b/lib/bundler/cli/install.rb
index 03edc7fbd2..cf0c71d766 100644
--- a/lib/bundler/cli/install.rb
+++ b/lib/bundler/cli/install.rb
@@ -80,7 +80,7 @@ module Bundler
       warn_ambiguous_gems
 
       if CLI::Common.clean_after_install?
-        require "bundler/cli/clean"
+        require_relative "clean"
         Bundler::CLI::Clean.new(options).run
       end
     rescue GemNotFound, VersionConflict => e
diff --git a/lib/bundler/cli/issue.rb b/lib/bundler/cli/issue.rb
index bba1619340..054ce76315 100644
--- a/lib/bundler/cli/issue.rb
+++ b/lib/bundler/cli/issue.rb
@@ -33,7 +33,7 @@ module Bundler
     end
 
     def doctor
-      require "bundler/cli/doctor"
+      require_relative "doctor"
       Bundler::CLI::Doctor.new({}).run
     end
   end
diff --git a/lib/bundler/cli/package.rb b/lib/bundler/cli/package.rb
index cd01ce422e..120a3fdcf3 100644
--- a/lib/bundler/cli/package.rb
+++ b/lib/bundler/cli/package.rb
@@ -25,7 +25,7 @@ module Bundler
   private
 
     def install
-      require "bundler/cli/install"
+      require_relative "install"
       options = self.options.dup
       if Bundler.settings[:cache_all_platforms]
         options["local"] = false
diff --git a/lib/bundler/cli/plugin.rb b/lib/bundler/cli/plugin.rb
index b5dd5b6d4b..1155c4ec9b 100644
--- a/lib/bundler/cli/plugin.rb
+++ b/lib/bundler/cli/plugin.rb
@@ -1,6 +1,6 @@
 # frozen_string_literal: true
 
-require "bundler/vendored_thor"
+require_relative "../vendored_thor"
 module Bundler
   class CLI::Plugin < Thor
     desc "install PLUGINS", "Install the plugin from the source"
diff --git a/lib/bundler/cli/update.rb b/lib/bundler/cli/update.rb
index b088853768..13d71bb50e 100644
--- a/lib/bundler/cli/update.rb
+++ b/lib/bundler/cli/update.rb
@@ -62,7 +62,7 @@ module Bundler
       Bundler.load.cache if Bundler.app_cache.exist?
 
       if CLI::Common.clean_after_install?
-        require "bundler/cli/clean"
+        require_relative "clean"
         Bundler::CLI::Clean.new(options).run
       end
 
diff --git a/lib/bundler/compact_index_client.rb b/lib/bundler/compact_index_client.rb
index 2f713041c8..a5120dbba4 100644
--- a/lib/bundler/compact_index_client.rb
+++ b/lib/bundler/compact_index_client.rb
@@ -13,8 +13,8 @@ module Bundler
 
     class Error < StandardError; end
 
-    require "bundler/compact_index_client/cache"
-    require "bundler/compact_index_client/updater"
+    require_relative "compact_index_client/cache"
+    require_relative "compact_index_client/updater"
 
     attr_reader :directory
 
diff --git a/lib/bundler/compact_index_client/updater.rb b/lib/bundler/compact_index_client/updater.rb
index d77285072c..40232019bc 100644
--- a/lib/bundler/compact_index_client/updater.rb
+++ b/lib/bundler/compact_index_client/updater.rb
@@ -1,6 +1,6 @@
 # frozen_string_literal: true
 
-require "bundler/vendored_fileutils"
+require_relative "../vendored_fileutils"
 require "stringio"
 require "zlib"
 
diff --git a/lib/bundler/compatibility_guard.rb b/lib/bundler/compatibility_guard.rb
index 958116ce55..eaff1a10d4 100644
--- a/lib/bundler/compatibility_guard.rb
+++ b/lib/bundler/compatibility_guard.rb
@@ -1,6 +1,6 @@
 # frozen_string_literal: false
 
-require "bundler/version"
+require_relative "version"
 
 if Bundler::VERSION.split(".").first.to_i >= 2
   if Gem::Version.new(Object::RUBY_VERSION.dup) < Gem::Version.new("2.3")
diff --git a/lib/bundler/definition.rb b/lib/bundler/definition.rb
index f9daae067c..506b0620d2 100644
--- a/lib/bundler/definition.rb
+++ b/lib/bundler/definition.rb
@@ -1,6 +1,6 @@
 # frozen_string_literal: true
 
-require "bundler/lockfile_parser"
+require_relative "lockfile_parser"
 require "set"
 
 module Bundler
@@ -385,7 +385,7 @@ module Bundler
     end
 
     def to_lock
-      require "bundler/lockfile_generator"
+      require_relative "lockfile_generator"
       LockfileGenerator.generate(self)
     end
 
diff --git a/lib/bundler/dependency.rb b/lib/bundler/dependency.rb
index 8840ad6a9c..e76c2bc08e 100644
--- a/lib/bundler/dependency.rb
+++ b/lib/bundler/dependency.rb
@@ -1,8 +1,8 @@
 # frozen_string_literal: true
 
 require "rubygems/dependency"
-require "bundler/shared_helpers"
-require "bundler/rubygems_ext"
+require_relative "shared_helpers"
+require_relative "rubygems_ext"
 
 module Bundler
   class Dependency < Gem::Dependency
diff --git a/lib/bundler/deployment.rb b/lib/bundler/deployment.rb
index 291e158ca0..b432ae6ae1 100644
--- a/lib/bundler/deployment.rb
+++ b/lib/bundler/deployment.rb
@@ -1,6 +1,6 @@
 # frozen_string_literal: true
 
-require "bundler/shared_helpers"
+require_relative "shared_helpers"
 Bundler::SharedHelpers.major_deprecation 2, "Bundler no longer integrates with " \
   "Capistrano, but Capistrano provides its own integration with " \
   "Bundler via the capistrano-bundler gem. Use it instead."
diff --git a/lib/bundler/dsl.rb b/lib/bundler/dsl.rb
index 7424a5c8a4..d3ead2a1ff 100644
--- a/lib/bundler/dsl.rb
+++ b/lib/bundler/dsl.rb
@@ -1,7 +1,7 @@
 # frozen_string_literal: true
 
-require "bundler/dependency"
-require "bundler/ruby_dsl"
+require_relative "dependency"
+require_relative "ruby_dsl"
 
 module Bundler
   class Dsl
diff --git a/lib/bundler/env.rb b/lib/bundler/env.rb
index 9cd9b8baca..8be4746e59 100644
--- a/lib/bundler/env.rb
+++ b/lib/bundler/env.rb
@@ -1,7 +1,7 @@
 # frozen_string_literal: true
 
-require "bundler/rubygems_integration"
-require "bundler/source/git/git_proxy"
+require_relative "rubygems_integration"
+require_relative "source/git/git_proxy"
 
 module Bundler
   class Env
diff --git a/lib/bundler/fetcher.rb b/lib/bundler/fetcher.rb
index 8397f7b72b..7ec41d62c0 100644
--- a/lib/bundler/fetcher.rb
+++ b/lib/bundler/fetcher.rb
@@ -1,6 +1,6 @@
 # frozen_string_literal: true
 
-require "bundler/vendored_persistent"
+require_relative "vendored_persistent"
 require "cgi"
 require "securerandom"
 require "zlib"
diff --git a/lib/bundler/fetcher/compact_index.rb b/lib/bundler/fetcher/compact_index.rb
index a117af72fa..1efd3e03af 100644
--- a/lib/bundler/fetcher/compact_index.rb
+++ b/lib/bundler/fetcher/compact_index.rb
@@ -1,7 +1,7 @@
 # frozen_string_literal: true
 
-require "bundler/fetcher/base"
-require "bundler/worker"
+require_relative "base"
+require_relative "../worker"
 
 module Bundler
   autoload :CompactIndexClient, "bundler/compact_index_client"
diff --git a/lib/bundler/fetcher/dependency.rb b/lib/bundler/fetcher/dependency.rb
index 1430d1ebeb..c52c32fb5b 100644
--- a/lib/bundler/fetcher/dependency.rb
+++ b/lib/bundler/fetcher/dependency.rb
@@ -1,6 +1,6 @@
 # frozen_string_literal: true
 
-require "bundler/fetcher/base"
+require_relative "base"
 require "cgi"
 
 module Bundler
diff --git a/lib/bundler/fetcher/index.rb b/lib/bundler/fetcher/index.rb
index 1a8064624d..e7baf63873 100644
--- a/lib/bundler/fetcher/index.rb
+++ b/lib/bundler/fetcher/index.rb
@@ -1,6 +1,6 @@
 # frozen_string_literal: true
 
-require "bundler/fetcher/base"
+require_relative "base"
 require "rubygems/remote_fetcher"
 
 module Bundler
diff --git a/lib/bundler/friendly_errors.rb b/lib/bundler/friendly_errors.rb
index dd9b847f10..45faf02020 100644
--- a/lib/bundler/friendly_errors.rb
+++ b/lib/bundler/friendly_errors.rb
@@ -1,7 +1,7 @@
 # frozen_string_literal: true
 
 require "cgi"
-require "bundler/vendored_thor"
+require_relative "vendored_thor"
 
 module Bundler
   module FriendlyErrors
diff --git a/lib/bundler/gem_helper.rb b/lib/bundler/gem_helper.rb
index e9ee03b8a2..33f1d51592 100644
--- a/lib/bundler/gem_helper.rb
+++ b/lib/bundler/gem_helper.rb
@@ -1,7 +1,7 @@
 # frozen_string_literal: true
 
-require "bundler/vendored_thor" unless defined?(Thor)
-require "bundler"
+require_relative "vendored_thor" unless defined?(Thor)
+require_relative "../bundler"
 require "shellwords"
 
 module Bundler
diff --git a/lib/bundler/gem_tasks.rb b/lib/bundler/gem_tasks.rb
index f736517bd7..bc725d3602 100644
--- a/lib/bundler/gem_tasks.rb
+++ b/lib/bundler/gem_tasks.rb
@@ -3,5 +3,5 @@
 require "rake/clean"
 CLOBBER.include "pkg"
 
-require "bundler/gem_helper"
+require_relative "gem_helper"
 Bundler::GemHelper.install_tasks
diff --git a/lib/bundler/inline.rb b/lib/bundler/inline.rb
index 93355c9460..034838b4b4 100644
--- a/lib/bundler/inline.rb
+++ b/lib/bundler/inline.rb
@@ -1,6 +1,6 @@
 # frozen_string_literal: true
 
-require "bundler/compatibility_guard"
+require_relative "compatibility_guard"
 
 # Allows for declaring a Gemfile inline in a ruby script, optionally installing
 # any gems that aren't already installed on the user's system.
@@ -32,7 +32,7 @@ require "bundler/compatibility_guard"
 #          puts Pod::VERSION # => "0.34.4"
 #
 def gemfile(install = false, options = {}, &gemfile)
-  require "bundler"
+  require_relative "../bundler"
 
   opts = options.dup
   ui = opts.delete(:ui) { Bundler::UI::Shell.new }
diff --git a/lib/bundler/installer.rb b/lib/bundler/installer.rb
index 49143b38f9..5bc53a8b61 100644
--- a/lib/bundler/installer.rb
+++ b/lib/bundler/installer.rb
@@ -2,10 +2,10 @@
 
 require "erb"
 require "rubygems/dependency_installer"
-require "bundler/worker"
-require "bundler/installer/parallel_installer"
-require "bundler/installer/standalone"
-require "bundler/installer/gem_installer"
+require_relative "worker"
+require_relative "installer/parallel_installer"
+require_relative "installer/standalone"
+require_relative "installer/gem_installer"
 
 module Bundler
   class Installer
diff --git a/lib/bundler/installer/parallel_installer.rb b/lib/bundler/installer/parallel_installer.rb
index 469b15b96c..391540af0b 100644
--- a/lib/bundler/installer/parallel_installer.rb
+++ b/lib/bundler/installer/parallel_installer.rb
@@ -1,7 +1,7 @@
 # frozen_string_literal: true
 
-require "bundler/worker"
-require "bundler/installer/gem_installer"
+require_relative "../worker"
+require_relative "gem_installer"
 
 module Bundler
   class ParallelInstaller
diff --git a/lib/bundler/lazy_specification.rb b/lib/bundler/lazy_specification.rb
index 69a721c120..cbd04b2c90 100644
--- a/lib/bundler/lazy_specification.rb
+++ b/lib/bundler/lazy_specification.rb
@@ -1,7 +1,7 @@
 # frozen_string_literal: true
 
 require "uri"
-require "bundler/match_platform"
+require_relative "match_platform"
 
 module Bundler
   class LazySpecification
diff --git a/lib/bundler/match_platform.rb b/lib/bundler/match_platform.rb
index 56cbbfb95d..69074925a6 100644
--- a/lib/bundler/match_platform.rb
+++ b/lib/bundler/match_platform.rb
@@ -1,6 +1,6 @@
 # frozen_string_literal: true
 
-require "bundler/gem_helpers"
+require_relative "gem_helpers"
 
 module Bundler
   module MatchPlatform
diff --git a/lib/bundler/plugin.rb b/lib/bundler/plugin.rb
index 996d29aafb..02985fa9b0 100644
--- a/lib/bundler/plugin.rb
+++ b/lib/bundler/plugin.rb
@@ -1,6 +1,6 @@
 # frozen_string_literal: true
 
-require "bundler/plugin/api"
+require_relative "plugin/api"
 
 module Bundler
   module Plugin
diff --git a/lib/bundler/plugin/index.rb b/lib/bundler/plugin/index.rb
index faabf3a8d1..2d70a046bb 100644
--- a/lib/bundler/plugin/index.rb
+++ b/lib/bundler/plugin/index.rb
@@ -139,7 +139,7 @@ module Bundler
 
           data = index_f.read
 
-          require "bundler/yaml_serializer"
+          require_relative "../yaml_serializer"
           index = YAMLSerializer.load(data)
 
           @commands.merge!(index["commands"])
@@ -162,7 +162,7 @@ module Bundler
           "sources"      => @sources,
         }
 
-        require "bundler/yaml_serializer"
+        require_relative "../yaml_serializer"
         SharedHelpers.filesystem_access(index_file) do |index_f|
           FileUtils.mkdir_p(index_f.dirname)
           File.open(index_f, "w") {|f| f.puts YAMLSerializer.dump(index) }
diff --git a/lib/bundler/psyched_yaml.rb b/lib/bundler/psyched_yaml.rb
index e654416a5a..c086b7651c 100644
--- a/lib/bundler/psyched_yaml.rb
+++ b/lib/bundler/psyched_yaml.rb
@@ -27,7 +27,7 @@ module Bundler
   end
 end
 
-require "bundler/deprecate"
+require_relative "deprecate"
 begin
   Bundler::Deprecate.skip_during do
     require "rubygems/safe_yaml"
diff --git a/lib/bundler/resolver.rb b/lib/bundler/resolver.rb
index 90f833bef1..d3e5f268cf 100644
--- a/lib/bundler/resolver.rb
+++ b/lib/bundler/resolver.rb
@@ -2,8 +2,8 @@
 
 module Bundler
   class Resolver
-    require "bundler/vendored_molinillo"
-    require "bundler/resolver/spec_group"
+    require_relative "vendored_molinillo"
+    require_relative "resolver/spec_group"
 
     # Figures out the best possible configuration of gems that satisfies
     # the list of passed dependencies and any child dependencies without
diff --git a/lib/bundler/rubygems_ext.rb b/lib/bundler/rubygems_ext.rb
index beed6372a3..df8646a2bb 100644
--- a/lib/bundler/rubygems_ext.rb
+++ b/lib/bundler/rubygems_ext.rb
@@ -8,7 +8,7 @@ require "rubygems/specification"
 # shouldn't be deferred.
 require "rubygems/source"
 
-require "bundler/match_platform"
+require_relative "match_platform"
 
 module Gem
   class Specification
diff --git a/lib/bundler/rubygems_integration.rb b/lib/bundler/rubygems_integration.rb
index ca7dd32611..32ddf185a0 100644
--- a/lib/bundler/rubygems_integration.rb
+++ b/lib/bundler/rubygems_integration.rb
@@ -111,7 +111,7 @@ module Bundler
     end
 
     def configuration
-      require "bundler/psyched_yaml"
+      require_relative "psyched_yaml"
       Gem.configuration
     rescue Gem::SystemExitException, LoadError => e
       Bundler.ui.error "#{e.class}: #{e.message}"
@@ -261,7 +261,7 @@ module Bundler
 
     def spec_from_gem(path, policy = nil)
       require "rubygems/security"
-      require "bundler/psyched_yaml"
+      require_relative "psyched_yaml"
       gem_from_path(path, security_policies[policy]).spec
     rescue Gem::Package::FormatError
       raise GemspecError, "Could not read gem at #{path}. It may be corrupted."
@@ -637,7 +637,7 @@ module Bundler
     end
 
     def all_specs
-      require "bundler/remote_specification"
+      require_relative "remote_specification"
       Gem::Specification.stubs.map do |stub|
         StubSpecification.from_stub(stub)
       end
@@ -686,7 +686,7 @@ module Bundler
 
     def use_gemdeps(gemfile)
       ENV["BUNDLE_GEMFILE"] ||= File.expand_path(gemfile)
-      require "bundler/gemdeps"
+      require_relative "gemdeps"
       runtime = Bundler.setup
       Bundler.ui = nil
       activated_spec_names = runtime.requested_specs.map(&:to_spec).sort_by(&:name)
diff --git a/lib/bundler/settings.rb b/lib/bundler/settings.rb
index d21789dba1..2d0c4174ae 100644
--- a/lib/bundler/settings.rb
+++ b/lib/bundler/settings.rb
@@ -357,7 +357,7 @@ module Bundler
       return unless file
       SharedHelpers.filesystem_access(file) do |p|
         FileUtils.mkdir_p(p.dirname)
-        require "bundler/yaml_serializer"
+        require_relative "yaml_serializer"
         p.open("w") {|f| f.write(YAMLSerializer.dump(hash)) }
       end
     end
@@ -397,7 +397,7 @@ module Bundler
       SharedHelpers.filesystem_access(config_file, :read) do |file|
         valid_file = file.exist? && !file.size.zero?
         return {} unless valid_file
-        require "bundler/yaml_serializer"
+        require_relative "yaml_serializer"
         YAMLSerializer.load file.read
       end
     end
diff --git a/lib/bundler/setup.rb b/lib/bundler/setup.rb
index 52a5b8889a..d156f494a8 100644
--- a/lib/bundler/setup.rb
+++ b/lib/bundler/setup.rb
@@ -1,9 +1,9 @@
 # frozen_string_literal: true
 
-require "bundler/shared_helpers"
+require_relative "shared_helpers"
 
 if Bundler::SharedHelpers.in_bundle?
-  require "bundler"
+  require_relative "../bundler"
 
   if STDOUT.tty? || ENV["BUNDLER_FORCE_TTY"]
     Bundler.ui = Bundler::UI::Shell.new
diff --git a/lib/bundler/shared_helpers.rb b/lib/bundler/shared_helpers.rb
index 1b703c5cbc..73c6dc3097 100644
--- a/lib/bundler/shared_helpers.rb
+++ b/lib/bundler/shared_helpers.rb
@@ -1,15 +1,15 @@
 # frozen_string_literal: true
 
-require "bundler/compatibility_guard"
+require_relative "compatibility_guard"
 
 require "pathname"
 require "rbconfig"
 require "rubygems"
 
-require "bundler/version"
-require "bundler/constants"
-require "bundler/rubygems_integration"
-require "bundler/current_ruby"
+require_relative "version"
+require_relative "constants"
+require_relative "rubygems_integration"
+require_relative "current_ruby"
 
 module Bundler
   module SharedHelpers
@@ -132,7 +132,7 @@ module Bundler
     def major_deprecation(major_version, message)
       bundler_major_version = Bundler.bundler_major_version
       if bundler_major_version > major_version
-        require "bundler/errors"
+        require_relative "errors"
         raise DeprecatedError, "[REMOVED] #{message}"
       end
 
@@ -289,20 +289,10 @@ module Bundler
     public :set_env
 
     def set_bundle_variables
-      begin
-        exe_file = Bundler.rubygems.bin_path("bundler", "bundle", VERSION)
-        unless File.exist?(exe_file)
-          exe_file = File.expand_path("../../../exe/bundle", __FILE__)
-        end
-        Bundler::SharedHelpers.set_env "BUNDLE_BIN_PATH", exe_file
-      rescue Gem::GemNotFoundException
-        exe_file = File.expand_path("../../../exe/bundle", __FILE__)
-        # for Ruby core repository
-        exe_file = File.expand_path("../../../../bin/bundle", __FILE__) unless File.exist?(exe_file)
-        Bundler::SharedHelpers.set_env "BUNDLE_BIN_PATH", exe_file
-      end
-
-      # Set BUNDLE_GEMFILE
+      exe_file = File.expand_path("../../../exe/bundle", __FILE__)
+      # for Ruby core repository
+      exe_file = File.expand_path("../../../../bin/bundle", __FILE__) unless File.exist?(exe_file)
+      Bundler::SharedHelpers.set_env "BUNDLE_BIN_PATH", exe_file
       Bundler::SharedHelpers.set_env "BUNDLE_GEMFILE", find_gemfile(:order_matters).to_s
       Bundler::SharedHelpers.set_env "BUNDLER_VERSION", Bundler::VERSION
     end
@@ -351,9 +341,9 @@ module Bundler
     end
 
     def prints_major_deprecations?
-      require "bundler"
+      require_relative "../bundler"
       return false if Bundler.settings[:silence_deprecations]
-      require "bundler/deprecate"
+      require_relative "deprecate"
       return false if Bundler::Deprecate.skip
       true
     end
diff --git a/lib/bundler/source/git.rb b/lib/bundler/source/git.rb
index a8afb341d8..aa24a87ed7 100644
--- a/lib/bundler/source/git.rb
+++ b/lib/bundler/source/git.rb
@@ -1,6 +1,6 @@
 # frozen_string_literal: true
 
-require "bundler/vendored_fileutils"
+require_relative "../vendored_fileutils"
 require "uri"
 
 module Bundler
diff --git a/lib/bundler/stub_specification.rb b/lib/bundler/stub_specification.rb
index bef94b505e..64b6d1b724 100644
--- a/lib/bundler/stub_specification.rb
+++ b/lib/bundler/stub_specification.rb
@@ -1,6 +1,6 @@
 # frozen_string_literal: true
 
-require "bundler/remote_specification"
+require_relative "remote_specification"
 
 module Bundler
   class StubSpecification < RemoteSpecification
diff --git a/lib/bundler/ui/rg_proxy.rb b/lib/bundler/ui/rg_proxy.rb
index e2f98481db..ef6def225b 100644
--- a/lib/bundler/ui/rg_proxy.rb
+++ b/lib/bundler/ui/rg_proxy.rb
@@ -1,6 +1,6 @@
 # frozen_string_literal: true
 
-require "bundler/ui"
+require_relative "../ui"
 require "rubygems/user_interaction"
 
 module Bundler
diff --git a/lib/bundler/ui/shell.rb b/lib/bundler/ui/shell.rb
index 7136fdfbf9..8e49fa5885 100644
--- a/lib/bundler/ui/shell.rb
+++ b/lib/bundler/ui/shell.rb
@@ -1,6 +1,6 @@
 # frozen_string_literal: true
 
-require "bundler/vendored_thor"
+require_relative "../vendored_thor"
 
 module Bundler
   module UI
diff --git a/lib/bundler/vendored_fileutils.rb b/lib/bundler/vendored_fileutils.rb
index d14e98baf7..4b71759224 100644
--- a/lib/bundler/vendored_fileutils.rb
+++ b/lib/bundler/vendored_fileutils.rb
@@ -2,7 +2,7 @@
 
 module Bundler; end
 if RUBY_VERSION >= "2.4"
-  require "bundler/vendor/fileutils/lib/fileutils"
+  require_relative "vendor/fileutils/lib/fileutils"
 else
   # the version we vendor is 2.4+
   require "fileutils"
diff --git a/lib/bundler/vendored_molinillo.rb b/lib/bundler/vendored_molinillo.rb
index 061b634f72..d1976f5cb4 100644
--- a/lib/bundler/vendored_molinillo.rb
+++ b/lib/bundler/vendored_molinillo.rb
@@ -1,4 +1,4 @@
 # frozen_string_literal: true
 
 module Bundler; end
-require "bundler/vendor/molinillo/lib/molinillo"
+require_relative "vendor/molinillo/lib/molinillo"
diff --git a/lib/bundler/vendored_persistent.rb b/lib/bundler/vendored_persistent.rb
index de9c42fcc1..7670b83992 100644
--- a/lib/bundler/vendored_persistent.rb
+++ b/lib/bundler/vendored_persistent.rb
@@ -15,7 +15,7 @@ module Bundler
     end
   end
 end
-require "bundler/vendor/net-http-persistent/lib/net/http/persistent"
+require_relative "vendor/net-http-persistent/lib/net/http/persistent"
 
 module Bundler
   class PersistentHTTP < Persistent::Net::HTTP::Persistent
diff --git a/lib/bundler/vendored_thor.rb b/lib/bundler/vendored_thor.rb
index 8cca090f55..b0b7e7be84 100644
--- a/lib/bundler/vendored_thor.rb
+++ b/lib/bundler/vendored_thor.rb
@@ -5,4 +5,4 @@ module Bundler
     Kernel.send(:require, "bundler/vendor/thor/lib/thor/actions")
   end
 end
-require "bundler/vendor/thor/lib/thor"
+require_relative "vendor/thor/lib/thor"
diff --git a/lib/bundler/vlad.rb b/lib/bundler/vlad.rb
index 68181e7db8..538e8c3e74 100644
--- a/lib/bundler/vlad.rb
+++ b/lib/bundler/vlad.rb
@@ -1,6 +1,6 @@
 # frozen_string_literal: true
 
-require "bundler/shared_helpers"
+require_relative "shared_helpers"
 Bundler::SharedHelpers.major_deprecation 2,
   "The Bundler task for Vlad"
 
@@ -8,7 +8,7 @@ Bundler::SharedHelpers.major_deprecation 2,
 #
 # Add "require 'bundler/vlad'" in your Vlad deploy.rb, and
 # include the vlad:bundle:install task in your vlad:deploy task.
-require "bundler/deployment"
+require_relative "deployment"
 
 include Rake::DSL if defined? Rake::DSL
 
diff --git a/spec/quality_spec.rb b/spec/quality_spec.rb
index e303b691b0..87279ebb74 100644
--- a/spec/quality_spec.rb
+++ b/spec/quality_spec.rb
@@ -1,5 +1,7 @@
 # frozen_string_literal: true
 
+require "set"
+
 if defined?(Encoding) && Encoding.default_external.name != "UTF-8"
   # An approximation of ruby -E UTF-8, since it works on 1.8.7
   Encoding.default_external = Encoding.find("UTF-8")
@@ -273,4 +275,20 @@ RSpec.describe "The library itself" do
       expect(warnings).to be_well_formed
     end
   end
+
+  it "does not use require internally, but require_relative" do
+    Dir.chdir(root) do
+      exempt = %r{templates/|vendor/}
+      all_bad_requires = []
+      lib_files = ruby_core? ? `git ls-files -z -- lib/bundler lib/bundler.rb` : `git ls-files -z -- lib`
+      lib_files.split("\x0").each do |filename|
+        next if filename =~ exempt
+        File.readlines(filename).each_with_index do |line, number|
+          line.scan(/^ *require "bundler/).each { all_bad_requires << "#{filename}:#{number.succ}" }
+        end
+      end
+
+      expect(all_bad_requires).to be_empty, "#{all_bad_requires.size} internal requires that should use `require_relative`: #{all_bad_requires}"
+    end
+  end
 end