alt Hacker NewsLegally that's been established as acceptable.
Google LLC v Oracle America assumed (though didn't establish) that API's are copyrightable... BUT that developing against them falls under fair use, as long as the function implementations are independent.
Test suites are again generally considered copyrightable... but the behavior being tested is not.
So no, it's not considered to be a work based on the library. This seems pretty clear-cut in US law by now.
Also, the LGPL text doesn't say "work based on the library". It says "If you modify a copy of the Library", and this is not a "combined work" either. And the whole point is that this is not a modified copy -- it's a reimplementation.
In theory, a license could be written to prevent running its tests from being run against software not derived from the original, i.e. clean-room reimplementations. In practice, it remains dubious whether any court would uphold that. And it would also be trivial to then get around it, by taking advantage of fair use to re-implement the tests in e.g. plain English (or any specification language), and then re-implementing those back into new test code. Because again, test behaviors are not copyrightable.
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> Also, the LGPL text doesn't say "work based on the library".
It does, about a dozen times.
Are you perhaps referring to LGPL3? I think the license under discussion here is LGPL2.1.
https://github.com/chardet/chardet/blob/6.0.0/LICENSE
I'm not well versed in copyright case law, so I won't argue with the rest of what you wrote. Thanks for elaborating on your thoughts.
> Google LLC v Oracle America assumed (though didn't establish) that API's are copyrightable... BUT that developing against them falls under fair use, as long as the function implementations are independent.
That was only one prong of the four fair use considerations in that case. Look at Breyer's opinion, it does not say that copying APIs is fair use if implementations are independent, just that Google's specific usage in that instance met the four fair use considerations.
There are likely situations in which copying APIs is not fair use even if function implementations are independent, Breyer looked at substantiality of the code copied from Java, market effects and purpose and character of use.
If your goal is to copy APIs, and those APIs make up a substantial amount of code, and reimplement functions in order to skirt licenses and compete directly against the source work, or replace it, those three considerations might not be met and it might not be fair use. Breyer said Google copied a tiny fraction of code (<1%), its purpose was not to compete directly with Oracle but to build a mobile OS platform, and Google's reimplementation was not considered a replacement for Java.