anchor.diff:        out.write('|');
         out.write(error.errorCode.name);
         out.write('|');
  -      out.write(escapePipe(source.fullName));
  +      out.write(escapeForMachineMode(source.fullName));
         out.write('|');
         out.write(location.lineNumber);
         out.write('|');
  
positive.code: class ErrorFormatter {
    static final int _pipeCodeUnit = '|'.codeUnitAt(0);
    static final int _slashCodeUnit = '\\'.codeUnitAt(0);
  
    final StringSink out;
    final CommandLineOptions options;
  
negative.code:     }
    }
  
    static String escapeForMachineMode(String input) {
      StringBuffer result = new StringBuffer();
      for (int c in input.codeUnits) {
        if (c == _newline) {
          result.write(r'\n');
        } else if (c == _return) {
          result.write(r'\r');
        } else {
          if (c == _slashCodeUnit || c == _pipeCodeUnit) {
            result.write('\\');
          }
          result.writeCharCode(c);
        }
      }
      return result.toString();
    }
  