# File lib/phusion_passenger/platform_info/binary_compatibility.rb, line 59
        def self.ruby_extension_binary_compatibility_id
                ruby_engine = defined?(RUBY_ENGINE) ? RUBY_ENGINE : "ruby"
                ruby_ext_version = RUBY_VERSION
                if RUBY_PLATFORM =~ /darwin/
                        if RUBY_PLATFORM =~ /universal/
                                ruby_arch = "universal"
                        else
                                # OS X <  10.8: something like:
                                #   "/opt/ruby-enterprise/bin/ruby: Mach-O 64-bit executable x86_64"
                                output = `file -L "#{ruby_executable}"`.strip
                                ruby_arch = output.sub(/.* /, '')
                                if ruby_arch == "executable"
                                        # OS X >= 10.8: something like:
                                        #   "/opt/ruby-enterprise/bin/ruby: Mach-O 64-bit executable"
                                        if output =~ /Mach-O 64-bit/
                                                ruby_arch = "x86_64"
                                        else
                                                raise "Cannot autodetect the Ruby interpreter's architecture"
                                        end
                                end
                        end
                elsif RUBY_PLATFORM == "java"
                        ruby_arch = "java"
                else
                        ruby_arch = cpu_architectures[0]
                end
                return "#{ruby_engine}-#{ruby_ext_version}-#{ruby_arch}-#{os_name}"
        end