Gem::Specification._load

# File tmp/rubies/ruby-3.1.3/lib/rubygems/specification.rb, line 1294
def self._load(str)
  Gem.load_yaml

  array = begin
    Marshal.load str
  rescue ArgumentError => e
    #
    # Some very old marshaled specs included references to `YAML::PrivateType`
    # and `YAML::Syck::DefaultKey` constants due to bugs in the old emitter
    # that generated them. Workaround the issue by defining the necessary
    # constants and retrying.
    #
    message = e.message
    raise unless message.include?("YAML::")

    Object.const_set "YAML", Psych unless Object.const_defined?(:YAML)

    if message.include?("YAML::Syck::")
      YAML.const_set "Syck", YAML unless YAML.const_defined?(:Syck)

      YAML::Syck.const_set "DefaultKey", Class.new if message.include?("YAML::Syck::DefaultKey")
    elsif message.include?("YAML::PrivateType")
      YAML.const_set "PrivateType", Class.new
    end

    retry
  end

  spec = Gem::Specification.new
  spec.instance_variable_set :@specification_version, array[1]

  current_version = CURRENT_SPECIFICATION_VERSION

  field_count = if spec.specification_version > current_version
    spec.instance_variable_set :@specification_version,
                               current_version
    MARSHAL_FIELDS[current_version]
  else
    MARSHAL_FIELDS[spec.specification_version]
  end

  if array.size < field_count
    raise TypeError, "invalid Gem::Specification format #{array.inspect}"
  end

  spec.instance_variable_set :@rubygems_version,          array[0]
  # spec version
  spec.instance_variable_set :@name,                      array[2]
  spec.instance_variable_set :@version,                   array[3]
  spec.date =                                             array[4]
  spec.instance_variable_set :@summary,                   array[5]
  spec.instance_variable_set :@required_ruby_version,     array[6]
  spec.instance_variable_set :@required_rubygems_version, array[7]
  spec.instance_variable_set :@original_platform,         array[8]
  spec.instance_variable_set :@dependencies,              array[9]
  # offset due to rubyforge_project removal
  spec.instance_variable_set :@email,                     array[11]
  spec.instance_variable_set :@authors,                   array[12]
  spec.instance_variable_set :@description,               array[13]
  spec.instance_variable_set :@homepage,                  array[14]
  spec.instance_variable_set :@has_rdoc,                  array[15]
  spec.instance_variable_set :@new_platform,              array[16]
  spec.instance_variable_set :@platform,                  array[16].to_s
  spec.instance_variable_set :@license,                   array[17]
  spec.instance_variable_set :@metadata,                  array[18]
  spec.instance_variable_set :@loaded,                    false
  spec.instance_variable_set :@activated,                 false

  spec
end