We recently added the EUPL-1.2 to our list of Various Licenses and Comments About Them. This list helps users to understand whether a particular license is a free software license, and whether it is compatible with the GNU General Public License (GNU GPL). Like the previous version of the EUPL (EUPL-1.1), the EUPL-1.2 is included in the section for free licenses that are GNU GPL-incompatible, but with an important caveat. While the EUPL-1.2's copyleft by itself is incompatible with the GNU GPL, the license provides a few mechanisms for re-licensing which enable combination with GNU GPL-licensed works. We explain the situation more fully in the entry itself:

This is a free software license. By itself, it has a copyleft comparable to the GPL's, and incompatible with it. However, it gives recipients ways to relicense the work under the terms of other selected licenses, and some of those—the Eclipse Public License in particular—only provide a weaker copyleft. Thus, developers can't rely on this license to provide a strong copyleft. The EUPL allows relicensing to GPLv2 only and GPLv3 only, because those licenses are listed as two of the alternative licenses that users may convert to. It also, indirectly, allows relicensing to GPL version 3 or any later version, because there is a way to relicense to the CeCILL v2, and the CeCILL v2 gives a way to relicense to any version of the GNU GPL. To do this two-step relicensing, you need to first write a piece of code which you can license under the CeCILL v2, or find a suitable module already available that way, and add it to the program. Adding that code to the EUPL-covered program provides grounds to relicense it to the CeCILL v2. Then you need to write a piece of code which you can license under the GPLv3+, or find a suitable module already available that way, and add it to the program. Adding that code to the CeCILL-covered program provides grounds to relicense it to GPLv3+.

These comments are very similar to the ones we made for the EUPL-1.1, as the EUPL-1.2 is an update that is very much in line with its predecessor. The biggest change was adding the GNU GPLv3 only as an alternative license, simplifying the process of incorporating EUPL-1.2 code into a GNU GPLv3 only project. Note, however, that the two-step re-licensing process previously described is still needed in order to incorporate EUPL-1.2 code into a GNU GPLv3+ project.

With all that said, the EUPL-1.2 is the newest addition to our list of free licenses, but more will be added in the future. To keep up to date, here's what you can do: