I ask this because I think of the recent switch of Ubuntu to the Rust recode of the GNU core utils, which use an MIT license. There are many Rust recodes of GPL software that re-license it as a pushover MIT or Apache licenses. I worry these relicensing efforts this will significantly harm the FOSS ecosystem. Is this reason to start worrying or is it not that bad?
IMO, if the FOSS world makes something public, with extensive liberties, then the only thing that should be asked in return is that people preserve these liberties, like the GPL successfully enforces. These pushover licenses preserve nothing.
GPL requires this, since linking with a library is considered a derivative work even if the library is dynamically loaded.
This is why the LGPL exists, which makes the library copyleft but does not extend the derivative work classification to programs linking with the library.
The FSF says this is the case but the actual legal situation is less clear, especially in the EU. Linking does not necessarily constitute a derivative work. Even decompilation of a (proprietary) library in order to link to it might be acceptable depending on the circumstance.
This isn’t something that can be fixed with a license, it’s a direct result of EU copyright law. Historically companies have tended to err on the side of the FSF interpretation, but it is on somewhat shaky grounds.
That’s the orthodoxy but noone ever bothers to actually back it up. If I write an encyclopedia and refer extensively to external sources it’s not a derivative work, and that seems to be the closest obvious example.