Move loading Bundler without platform warnings to a method

Author: deivid-rodriguez

Manifest.txt

@@ -366,7 +366,6 @@ hide_lib_for_update/note.txt
 lib/rubygems.rb
 lib/rubygems/available_set.rb
 lib/rubygems/basic_specification.rb
-lib/rubygems/bundler_integration.rb
 lib/rubygems/bundler_version_finder.rb
 lib/rubygems/ci_detector.rb
 lib/rubygems/command.rb

lib/rubygems.rb

@@ -636,6 +636,34 @@ def self.load_safe_marshal
     @safe_marshal_loaded = true
   end
 
+  ##
+  # Load Bundler, making sure to avoid redefinition warnings in platform
+  # constants
+
+  def self.load_bundler
+    require "bundler/version"
+
+    if Bundler::VERSION > "2.6.9"
+      require "bundler"
+    else
+      previous_platforms = {}
+
+      platform_const_list = ["JAVA", "MSWIN", "MSWIN64", "MINGW", "X64_MINGW_LEGACY", "X64_MINGW", "UNIVERSAL_MINGW", "WINDOWS", "X64_LINUX", "X64_LINUX_MUSL"]
+
+      platform_const_list.each do |platform|
+        previous_platforms[platform] = Gem::Platform.const_get(platform)
+        Gem::Platform.send(:remove_const, platform)
+      end
+
+      require "bundler"
+
+      platform_const_list.each do |platform|
+        Gem::Platform.send(:remove_const, platform) if Gem::Platform.const_defined?(platform)
+        Gem::Platform.const_set(platform, previous_platforms[platform])
+      end
+    end
+  end
+
   ##
   # The file name and line number of the caller of the caller of this method.
   #
@@ -1144,7 +1172,7 @@ def self.use_gemdeps(path = nil)
 
     ENV["BUNDLE_GEMFILE"] ||= File.expand_path(path)
     require_relative "rubygems/user_interaction"
-    require_relative "rubygems/bundler_integration"
+    Gem.load_bundler
     begin
       Gem::DefaultUserInteraction.use_ui(ui) do
         Bundler.ui.silence do