Gem::RequestSet::GemDependencyAPI#ruby

# File tmp/rubies/ruby-4.0.0/lib/rubygems/request_set/gem_dependency_api.rb, line 783
def ruby(version, options = {})
  engine         = options[:engine]
  engine_version = options[:engine_version]

  raise ArgumentError,
        "You must specify engine_version along with the Ruby engine" if
          engine && !engine_version

  return true if @installing

  unless version == RUBY_VERSION
    message = "Your Ruby version is #{RUBY_VERSION}, " \
              "but your #{gem_deps_file} requires #{version}"

    raise Gem::RubyVersionMismatch, message
  end

  if engine && engine != Gem.ruby_engine
    message = "Your Ruby engine is #{Gem.ruby_engine}, " \
              "but your #{gem_deps_file} requires #{engine}"

    raise Gem::RubyVersionMismatch, message
  end

  if engine_version
    if engine_version != RUBY_ENGINE_VERSION
      message =
        "Your Ruby engine version is #{Gem.ruby_engine} #{RUBY_ENGINE_VERSION}, " \
        "but your #{gem_deps_file} requires #{engine} #{engine_version}"

      raise Gem::RubyVersionMismatch, message
    end
  end

  true
end