Use Gem::BUNDLED_GEMS.warning? at Bundler.setup

lib/bundler/rubygems_integration.rb

@@ -246,17 +246,13 @@ module Bundler
         kernel_class.send(:define_method, :require) do |file|
           file = File.path(file)
           name = file.tr("/", "-")
-          if (::Gem::BUNDLED_GEMS::SINCE.keys - specs.to_a.map(&:name)).include?(name)
-            unless $LOADED_FEATURES.any? {|f| f.end_with?("#{name}.rb", "#{name}.#{RbConfig::CONFIG["DLEXT"]}") }
+          if message = ::Gem::BUNDLED_GEMS.warning?(name)
             target_file = begin
               Bundler.default_gemfile.basename
             rescue GemfileNotFound
               "inline Gemfile"
             end
-              if ::Gem::BUNDLED_GEMS::SINCE[name]
-                be = ::Gem::BUNDLED_GEMS::SINCE[name] > RUBY_VERSION ? "will be" : "is"
-                message = "#{name} #{be} not part of the default gems since Ruby #{::Gem::BUNDLED_GEMS::SINCE[name]}." \
-                " Add #{name} to your #{target_file}."
+            message += " Add #{name} to your #{target_file}."
             location = caller_locations(1,1)[0]&.path
             if File.file?(location) && !location.start_with?(Gem::BUNDLED_GEMS::LIBDIR)
               caller_gem = nil
@@ -270,8 +266,6 @@ module Bundler
             end
             warn message, :uplevel => 1
           end
-            end
-          end
           kernel_class.send(:no_warning_require, file)
         end
         if kernel_class == ::Kernel