instance method check_for_unbuilt_gems

# File railties/lib/initializer.rb, line 311
    def check_for_unbuilt_gems
      unbuilt_gems = @configuration.gems.select(&:frozen?).reject(&:built?)
      if unbuilt_gems.size > 0
        # don't print if the gems:build rake tasks are being run
        unless $gems_build_rake_task
          abort <<-end_error
The following gems have native components that need to be built
  #{unbuilt_gems.map { |gem| "#{gem.name}  #{gem.requirement}" } * "\n  "}

You're running:
  ruby #{Gem.ruby_version} at #{Gem.ruby}
  rubygems #{Gem::RubyGemsVersion} at #{Gem.path * ', '}

Run `rake gems:build` to build the unbuilt gems.
          end_error
        end
      end
    end