anchor.diff:      OptionHandler('${Flags.codegenShards}=.+', setCodegenShards),
       OptionHandler(Flags.cfeOnly, setCfeOnly),
       OptionHandler(Flags.debugGlobalInference, passThrough),
  -    OptionHandler('--out=.+|-o.*', setOutput, multipleArguments: true),
  +    OptionHandler('--output(?:=.+)?|--out(?:=.+)?|-o.*', setOutput,
  +        multipleArguments: true),
       OptionHandler('-O.*', setOptimizationLevel),
       OptionHandler(Flags.allowMockCompilation, ignoreOption),
       OptionHandler(Flags.fastStartup, ignoreOption),
  
positive.code:       passThrough(argument);
        return;
      }
      helpAndFail("Error: Unsupported dump-info format '$argument', "
          "supported formats are: json or binary");
    }
  
    String nullSafetyMode = null;
    void setNullSafetyMode(String argument) {
      if (nullSafetyMode != null && nullSafetyMode != argument) {
        helpAndFail("Error: cannot specify both $nullSafetyMode and $argument.");
      }
      nullSafetyMode = argument;
      passThrough(argument);
  
negative.code:   void setOptimizationLevel(String argument) {
      int value = int.tryParse(extractParameter(argument));
      if (value == null || value < 0 || value > 4) {
        helpAndFail("Unsupported optimization level '$argument', "
            "supported levels are: 0, 1, 2, 3, 4");
        return;
      }
  