> The CDDL was intentionally written to be incompatible with the GPL. Which other copyleft licenses do you have in mind, and what advantages do they have over GPL-compatible licenses?

What strong copyleft licence do you know that is compatible with any GPL?

The F.S.F. indeed alleges that it was intentional, and perhaps it was, but every single strong copyleft licence is pretty much incompatible with every other — one must go out of one's way to make them compatible and even it's typically an asymmetric compatibility.

Advantages? They obviously do things differently and there's probably a reason why big companies tend to craft their own licence rather than relying upon a template.

Examples:

- Eclipse Public Licence - Mozilla Public Licence 0.1 and 0.2 - Apple Public Licence - Common Development and Distribution Licence - GPLv2 — yes, it should be mentioned as an example

> If you release your code under a permissive license, it's basically guaranteed to be compatible with the future GPLv4, so you're in that situation anyway.

You assume that the only option one have is GPLv2+ or a permissive licence.

Linux is simply released under GPLv2, exactly because Linus Torvalds and many others in it disagree with some of the GPLv3 provisions; ZFS is simply released under the CDDL, and FixFox simply under the MPL.

They have their reasons to choose other licences than GPLv3, because they disagree with some of the provisions thereof.