class Gem::Ext::ExtConfBuilder

# File lib/rubygems/ext/ext_conf_builder.rb, line 13
def self.build(extension, directory, dest_path, results, args=[], lib_dir=nil)
  tmp_dest = Dir.mktmpdir(".gem.", ".")

  t = nil
  Tempfile.open %w"siteconf .rb", "." do |siteconf|
    t = siteconf
    siteconf.puts "require 'rbconfig'"
    siteconf.puts "dest_path = #{(tmp_dest || dest_path).dump}"
    %w[sitearchdir sitelibdir].each do |dir|
      siteconf.puts "RbConfig::MAKEFILE_CONFIG['#{dir}'] = dest_path"
      siteconf.puts "RbConfig::CONFIG['#{dir}'] = dest_path"
    end

    siteconf.flush

    siteconf_path = File.expand_path siteconf.path

    rubyopt = ENV["RUBYOPT"]
    destdir = ENV["DESTDIR"]

    begin
      ENV["RUBYOPT"] = ["-r#{siteconf_path}", rubyopt].compact.join(' ')
      cmd = [Gem.ruby, File.basename(extension), *args].join ' '

      begin
        run cmd, results
      ensure
        FileUtils.mv 'mkmf.log', dest_path if File.exist? 'mkmf.log'
      end

      ENV["DESTDIR"] = nil
      ENV["RUBYOPT"] = rubyopt
      siteconf.unlink

      make dest_path, results

      if tmp_dest
        # TODO remove in RubyGems 3
        if Gem.install_extension_in_lib and lib_dir then
          FileUtils.mkdir_p lib_dir
          entries = Dir.entries(tmp_dest) - %w[. ..]
          entries = entries.map { |entry| File.join tmp_dest, entry }
          FileUtils.cp_r entries, lib_dir
        end

        FileEntry.new(tmp_dest).traverse do |ent|
          destent = ent.class.new(dest_path, ent.rel)
          destent.exist? or File.rename(ent.path, destent.path)
        end
      end
    ensure
      ENV["RUBYOPT"] = rubyopt
      ENV["DESTDIR"] = destdir
    end
  end
  t.unlink if t and t.path

  results
ensure
  FileUtils.rm_rf tmp_dest if tmp_dest
end