Created attachment 528204 [details]
USE="libobjc2" emerge gnustep-make
I have =gnustep-base/libobjc2-1.8.1 and =sys-devel/clang-5.0.1 installed to build gnustep-make with clang, however libobjc2 blocks it and adding USE="libobjc2" to gnustep-make doesn't have effect.
Created attachment 528206 [details]
I think this is intentional. You need to unmerge gnustep-make before merging libobjc2 (which then will pull in gnustep-make again).