I'd agree in that case, mostly because the code does not have a restrictive license. Also, to me if you disclose that you are using yacc then you are being totally up front and have side stepped any issues. But in the case of like byacc the license specifically states you can use it in commercial or public code without restriction, so it is fair to use in my opinion.
Me personally, even in like this case where it isn't required or requested, I'd likely attribute the author or repository in my license file, credits or readme.
Comments
Sure, as long as you are not utilizing any of the code from the open source project.
Crossing the line is using other people's work and calling it your own, regardless of open/closed source.
What if you're creating a proprietary version of yacc, and you're using yacc to parse domain specific language for your clone?
I think that's fair enough?
I'd agree in that case, mostly because the code does not have a restrictive license. Also, to me if you disclose that you are using yacc then you are being totally up front and have side stepped any issues. But in the case of like byacc the license specifically states you can use it in commercial or public code without restriction, so it is fair to use in my opinion.
Me personally, even in like this case where it isn't required or requested, I'd likely attribute the author or repository in my license file, credits or readme.