Andreas,
We don't have to tell developers who develop applications that because GNUstep currently works with clang. Most of the issues mentioned (i.e. "new" features) are compiler-specific. It is a common misconception that GNUstep has anything to do with GCC's feature set or that we are, somehow, in control of features added to GCC due to the fact that we are the major ObjC free software project.
GNUstep's core code tries to remain as compatible as possible with both tool-chains. This is done very much on purpose. When using clang, you can use many of the ObjC2.0 features. The main one missing is ARC, and that is the main one I am concerned about.
Apple isn't concerned with remaining compatible with any other compiler, so they were free to move completely to LLVM/Clang and use its features in their implementation of the frameworks. According to discussions, this saved Apple a lot of code and time debugging memory issues. We don't have that option since our priority is freedom.
My point during this discussion is and has been that GCC's objc support is non-existent, so at some point, we will need to make a decision. What I am hoping to do is to figure out what work needs to be done to make this happen on both sides (clang and GCC).
Yours, GC