> I'm also not sure fair use trumps licensing, since one is a copyright issue, and the other is the terms of use.
Licenses and copyright are strictly related - the 'terms of use' in the form of a license simply is a grant for someone to reuse something in full granted they uphold their end of the bargain which might mean (for the GPL) relicensing code that touches said licensed code; but, if someone doesn't agree to the license or they don't uphold their end (such as by releasing their own code under the same license), the license states that the use is now invalid and they're not allowed to copy it in the permissive form provided unless the use passes the fair use doctrine.
Now 'fair use' is actually a pretty high bar, and most especially for code - feel free to read 17 USC 107 [0] which lays out how this is determined. What's tough for code is that, in terms of for copying code or using a library, it usually doesn't qualify for the initial requirement "for purposes such as criticism, comment, news reporting, teaching, scholarship, or research, is not an infringement of copyright". Unless you're taking GPL code and writing up how bad it is, or how efficient is is, chances are the use doesn't fit into fair use.
So while I think I was indeed a bit obtuse in saying that code could be used in a fair use way (since that's not what happens in these contexts) it's technically possible.
Licenses and copyright are strictly related - the 'terms of use' in the form of a license simply is a grant for someone to reuse something in full granted they uphold their end of the bargain which might mean (for the GPL) relicensing code that touches said licensed code; but, if someone doesn't agree to the license or they don't uphold their end (such as by releasing their own code under the same license), the license states that the use is now invalid and they're not allowed to copy it in the permissive form provided unless the use passes the fair use doctrine.
Now 'fair use' is actually a pretty high bar, and most especially for code - feel free to read 17 USC 107 [0] which lays out how this is determined. What's tough for code is that, in terms of for copying code or using a library, it usually doesn't qualify for the initial requirement "for purposes such as criticism, comment, news reporting, teaching, scholarship, or research, is not an infringement of copyright". Unless you're taking GPL code and writing up how bad it is, or how efficient is is, chances are the use doesn't fit into fair use.
So while I think I was indeed a bit obtuse in saying that code could be used in a fair use way (since that's not what happens in these contexts) it's technically possible.
0: https://www.law.cornell.edu/uscode/text/17/107