[dded]

I'm not part of the Ada world, so I don't actually know, but I thought the important Ada compiler(s) were also proprietary.

[jordigh]

Ada is one of the poster children for early GPL success:

https://en.wikipedia.org/wiki/GNAT#History

They also sell GPL exceptions, which I think is a good thing:

https://news.ycombinator.com/item?id=7027926