Gem::Commands::PristineCommand#execute

# File tmp/rubies/ruby-3.1.3/lib/rubygems/commands/pristine_command.rb, line 99
def execute
  specs = if options[:all]
    Gem::Specification.map

  # `--extensions` must be explicitly given to pristine only gems
  # with extensions.
  elsif options[:extensions_set] &&
        options[:extensions] && options[:args].empty?
    Gem::Specification.select do |spec|
      spec.extensions && !spec.extensions.empty?
    end
  else
    get_all_gem_names.sort.map do |gem_name|
      Gem::Specification.find_all_by_name(gem_name, options[:version]).reverse
    end.flatten
  end

  specs = specs.select {|spec| RUBY_ENGINE == spec.platform || Gem::Platform.local === spec.platform || spec.platform == Gem::Platform::RUBY }

  if specs.to_a.empty?
    raise Gem::Exception,
          "Failed to find gems #{options[:args]} #{options[:version]}"
  end

  say "Restoring gems to pristine condition..."

  specs.each do |spec|
    if spec.default_gem?
      say "Skipped #{spec.full_name}, it is a default gem"
      next
    end

    if options.has_key? :skip
      if options[:skip].include? spec.name
        say "Skipped #{spec.full_name}, it was given through options"
        next
      end
    end

    unless spec.extensions.empty? || options[:extensions] || options[:only_executables] || options[:only_plugins]
      say "Skipped #{spec.full_name}, it needs to compile an extension"
      next
    end

    gem = spec.cache_file

    unless File.exist?(gem) || options[:only_executables] || options[:only_plugins]
      require_relative "../remote_fetcher"

      say "Cached gem for #{spec.full_name} not found, attempting to fetch..."

      dep = Gem::Dependency.new spec.name, spec.version
      found, _ = Gem::SpecFetcher.fetcher.spec_for_dependency dep

      if found.empty?
        say "Skipped #{spec.full_name}, it was not found from cache and remote sources"
        next
      end

      spec_candidate, source = found.first
      Gem::RemoteFetcher.fetcher.download spec_candidate, source.uri.to_s, spec.base_dir
    end

    env_shebang =
      if options.include? :env_shebang
        options[:env_shebang]
      else
        install_defaults = Gem::ConfigFile::PLATFORM_DEFAULTS["install"]
        install_defaults.to_s["--env-shebang"]
      end

    bin_dir = options[:bin_dir] if options[:bin_dir]
    install_dir = options[:install_dir] if options[:install_dir]

    installer_options = {
      :wrappers => true,
      :force => true,
      :install_dir => install_dir || spec.base_dir,
      :env_shebang => env_shebang,
      :build_args => spec.build_args,
      :bin_dir => bin_dir,
    }

    if options[:only_executables]
      installer = Gem::Installer.for_spec(spec, installer_options)
      installer.generate_bin
    elsif options[:only_plugins]
      installer = Gem::Installer.for_spec(spec, installer_options)
      installer.generate_plugins
    else
      installer = Gem::Installer.at(gem, installer_options)
      installer.install
    end

    say "Restored #{spec.full_name}"
  end
end