libide is a GPL-3.0 shared library
Typically I use LGPL-2.1+ for shared libraries. However, due to the nature of libide being the "guts" of Builder, I do intend for this to be GPL-3.0. Additionally, it simplifies what we can include in the library without worrying about staying LGPL safe. Exceptions will of course be made for upstreaming into libraries such as GtkSourceView. Just ask if you want something in particular.