Clarify license for generated code about jacc

[zipwith]

Under normal circumstances, I wouldn't even think about a license for the code that is generated by jacc; it is just an artifact of the compilation process, much like the .class files that might be produced when you run a Java compiler. The issues that you've mentioned in relation to Bison do not apply here because there are no substantial parser templates, GPL-ed or otherwise, in the jacc distribution.

In some situations, it may be useful to include jacc-generated Java code in a source distribution so that users can compile and run a program without having to install jacc. So long as both the source and generated code are included in the distribution, I would expect the generated code to have the same license as the source, with no requirement for them to use the same license as jacc itself.

The statement above does not address situations where jacc-generated code is distributed without the original .jacc source code. Such uses should be discouraged because they will substantially limit the opportunities for understanding and modifying the generated parsers.

[travisdowns]

Thanks for the comments! In my scenario (MIT-licensed project), I am including the .jacc grammar file and the resulting generated parser .java file in the source, so that the usual end-user build process doens't need invoke jacc and I do not include jacc itself as part of the project.

I don't think it is that obvious that the output jacc produces wouldn't be covered under the GPL. The parser doesn't include large portions of GPLed code, but it does include some boilerplate code like the yyexpand function whose code presumably falls under the GPL. Whether it is substantial enough to cause the whole work to be considered a "derived work" and hence fall under the GPL is certainly not clear to me. I have been told that even a single line can be enough, depending on your circumstances.

You mention compilation with javac - I'm not sure on the licensing situation there, but I do now that gcc includes specifically includes an exception from the GPL for the binaries produced by gcc compilation since otherwise it might be unclear whether such binaries would fall under the GPL since various bits of GPL'd code get embedded in as part of the compilation process.

I'll continue using jacc in my MIT-licensed project based on your comments here since after all it is only a small personal project for research purposes, but if you had a few minutes you might want to consider making this explicit with an exception note in the license. I would rest easier :).