There are cases when the long options are of the format abc-def. In current implementation FLAG_xxx macros are generated for long options too. with __-__ sign in the macro, it will generate errors.

I am of the opinion that __-__ be converted to '_' for generating the FLAG_xxx macros and be used in the command.

This will enable the user to 'abc-def', but be handled like 'abc_def' in code.