install

# File lib/rubygems/installer.rb, line 280
  def install
    pre_install_checks

    FileUtils.rm_f File.join gem_home, 'specifications', spec.spec_name

    run_pre_install_hooks

    # Set loaded_from to ensure extension_dir is correct
    if @options[:install_as_default] then
      spec.loaded_from = default_spec_file
    else
      spec.loaded_from = spec_file
    end

    # Completely remove any previous gem files
    FileUtils.rm_rf gem_dir
    FileUtils.rm_rf spec.extension_dir

    FileUtils.mkdir_p gem_dir

    if @options[:install_as_default] then
      extract_bin
      write_default_spec
    else
      extract_files

      build_extensions
      write_build_info_file
      run_post_build_hooks

      generate_bin
      write_spec
      write_cache_file
    end

    say spec.post_install_message if options[:post_install_message] && !spec.post_install_message.nil?

    Gem::Installer.install_lock.synchronize { Gem::Specification.reset }

    run_post_install_hooks

    spec

  # TODO This rescue is in the wrong place. What is raising this exception?
  # move this rescue to around the code that actually might raise it.
  rescue Zlib::GzipFile::Error
    raise Gem::InstallError, "gzip error installing #{gem}"
  end