Out of curiosity, how does the GPL promise that versus the other common open source licenses? E.g MIT, BSD or Apache?
MIT code can be freely taken into proprietary fork, with software modified and sold and no patches contributed.
Not sure how often it happens? Has it actually happened and is it a plausible attack? Nowadays at least AGPL is needed to defang "and we will sell it as service rather than selling software" workaround for GPL.
These are things some projects like to do, and GPL blocks that. So all thing considered, it may be easiest to just not use GPL code.
And you can statically link GPL code, assuming you release the source to all app users. You might be confusing it with LGPL, which says you can link to proprietary apps dynamically, but have to release source in all other cases.
You have only obligations when you distribute the results. Whatever you do in your private basement is completely unaffected by that. The GPL gives you freedom to do whatever you please. That's the whole point of it!
When you distribute binaries resulting form work based on GPL code than the people receiving those binaries (and only them) are eligible to get alongside the source code which allows them to rebuild the binaries you distributed to them. That makes sure that those other people also have the same freedom as you to do whatever they please with the programs and code. So the GPL preserves freedom among users of GPL code.
The GPL is the prototypical copyleft licence, designed to encourage the liberation of software, in part via its dependencies.
https://web.archive.org/web/20091118172944/http://www.pureda...
That can't be said about software under the above mentioned licenses.
You can always relicense GPL content as long as everyone agrees. You can also change it to source on request versus always accessible.
I didn't mean "code quality", or the like, as a license can not enforce that obviously.