This is key gap in GPL. Instead of being a single standard (like BSD-Sockets or POSIX), most programmers are forced to write a new solution from scratch every time. Year after year. Because a lot of opensource stuff can be only "GPL opensource stuff". Religion fanatic wars for "freedom", where not freedom. Not public domain license.
I ask once again to think each programmer over licensing wars and stop writing the GPL. And start write Public Domain stuff for each human. Otherwise, we will continue to write shit code for decades (Just for fan!) without achieving a good result, while having hundreds of weak solutions.
I don't see what's wrong with "I publish my work with sources for free and want others, who build upon it, do the same".
Otherwise, people would just sell open work with little or no modifications.
If everybody publishes the sources, there is no violation and everybody is free to do what they want.