anchor.diff:        defaultsTo: '8080')
     ..addFlag('force-compile',
         help: 'Compile code with static errors', defaultsTo: false)
  -  ..addOption('log', abbr: 'l', help: 'Logging level', defaultsTo: 'severe')
  +  ..addOption('log', abbr: 'l', help: 'Logging level (defaults to severe)')
     ..addFlag('dump-info',
  -      abbr: 'i', help: 'Dump summary information', defaultsTo: false)
  +      abbr: 'i', help: 'Dump summary information', defaultsTo: null)
     ..addOption('dump-info-file',
         abbr: 'f',
         help: 'Dump info json file (requires dump-info)',
  
positive.code: /// Parses options from the command-line
  CompilerOptions parseOptions(List<String> argv) {
    ArgResults args = argParser.parse(argv);
    var levelName = args['log'].toUpperCase();
    var useColors = stdioType(stdout) == StdioType.TERMINAL;
    var sdkPath = args['dart-sdk'];
    if (sdkPath == null && !args['mock-sdk']) {
  
negative.code:   if (runtimeDir == null) {
      runtimeDir = _computeRuntimeDir();
    }
    var outputDir = args['out'];
    if (outputDir == null && serverMode) {
      outputDir = Directory.systemTemp.createTempSync("dev_compiler_out_").path;
    }
    var dumpInfo = args['dump-info'];
    if (dumpInfo == null) dumpInfo = serverMode;
  
    return new CompilerOptions(
        allowConstCasts: args['allow-const-casts'],
        checkSdk: args['sdk-check'],
        dumpInfo: dumpInfo,
        dumpInfoFile: args['dump-info-file'],
        dumpSrcDir: args['dump-src-to'],
        forceCompile: args['force-compile'] || serverMode,
        formatOutput: args['dart-gen-fmt'],
        ignoreTypes: args['ignore-types'],
        outputDart: args['dart-gen'],
        outputDir: outputDir,
        covariantGenerics: args['covariant-generics'],
        relaxedCasts: args['relaxed-casts'],
        useColors: useColors,
  