In his post about EPL, GPL and Eclipse plugins (“EPL/GPL Commentary“), Mike Milinkovich says:
What is clear, however, is that it is not possible to link a GPL-licensed plug-in to an EPL-licensed code and distribute the result. Any GPL-licensed plug-in would have to be distributed independently and combined with the Eclipse platform by an end user.
Which is probably true because of the incompatible goals of the two licenses: The EPL was designed by companies, which make a lot of money with software, to protect the investments in the source code they contribute to an OSS project. Notice “a lot of money.”
The GPL was designed to make sure companies can’t steal from poor OSS developers and sell a product as their own or take some source code, add a few lines of code and then sell it as their own, etc. The GPL, unlike the EPL, is made as a sword to keep people away who don’t want to share their word under the GPL.
As such, both licenses work as designed and they are incompatible because their goals are incompatible. We as OSS developers can whine and complain that there is no legal way to build an Eclipse plugin for Subversion without first creating an Subversion client which is EPL licensed but that doesn’t change the fact that it is illegal. It’s the price we pay for the freedom we have. If the licenses were different, there would be legal loopholes.
Yes, it sucks.