Gem::PackageTask#define

# File tmp/rubies/ruby-3.4.1/lib/rubygems/package_task.rb, line 93
def define
  super

  gem_file = File.basename gem_spec.cache_file
  gem_path = File.join package_dir, gem_file
  gem_dir  = File.join package_dir, gem_spec.full_name

  task package: [:gem]

  directory package_dir
  directory gem_dir

  desc "Build the gem file #{gem_file}"
  task gem: [gem_path]

  trace = Rake.application.options.trace
  Gem.configuration.verbose = trace

  file gem_path => [package_dir, gem_dir] + @gem_spec.files do
    chdir(gem_dir) do
      when_writing "Creating #{gem_spec.file_name}" do
        Gem::Package.build gem_spec

        verbose trace do
          mv gem_file, ".."
        end
      end
    end
  end
end