Thanks for helping out!
I looked through the compile commands, but they all look like this one:
+ clang-8 FSNodeRep.m -c -MMD -MP -DGNUSTEP -DGNUSTEP_BASE_LIBRARY=1
-DGNU_GUI_LIBRARY=1 -DGNUSTEP_RUNTIME=1 -D_NONFRAGILE_ABI=1
-DGNUSTEP_BASE_LIBRARY=1 -fno-strict-aliasing -fexceptions
-fobjc-exceptions -D_NATIVE_OBJC_EXCEPTIONS -pthread -fPIC -Wall
-DGSWARN -DGSDIAGNOSE -Wno-import -g -O2 -fblocks
-fobjc-runtime=gnustep-2.0 -fblocks -Wall
-fconstant-string-class=NSConstantString -IExtendedInfo -I..
-I./derived_src -I. -I/home/joey/GNUstep/Library/Headers
-I/usr/GNUstep/Local/Library/Headers
-I/usr/GNUstep/System/Library/Headers -o obj/FSNode.obj/FSNodeRep.m.o
So you will always find clang-8 and -fobjc-runtime=gnustep-2.0. It's
just sometimes you will find some flags twice for compiling or linking,
but I assume that does not do any harm.