clang  -rdynamic      -shared-libgcc -fexceptions -fgnu-runtime -o obj/autogsdoc \
        ./obj/autogsdoc.obj/autogsdoc.m.o ./obj/autogsdoc.obj/AGSParser.m.o ./obj/autogsdoc.obj/AGSOutput.m.o ./obj/autogsdoc.obj/AGSIndex.m.o ./obj/autogsdoc.obj/AGSHtml.m.o \
          -L../Source/./obj    -L/home/tatd2/GNUstep/Library/Libraries -L/usr/GNUstep/Local/Library/Libraries -L/usr/GNUstep/System/Library/Libraries   -L/usr/GNUstep/System/Library/Libraries -L/usr/GNUstep/Local/Library/Libraries -L/usr/GNUstep/Local/Library/Libraries -L/usr/GNUstep/Local/Library/Libraries/gnu-gnu-gnu -L/usr/GNUstep/Local/Library/Libraries -L/usr/lib/ -L/usr/lib    -lgnustep-base    -lobjc   -lgmp   -L/usr/lib -lgnutls -lgcrypt -lgcrypt -L/usr/lib -lgnutls -lgcrypt -lxslt -lxml2 -lffi -lnsl -lrt -ldl  -lpthread -lz -licui18n -licuuc -licudata  -lm
clang: warning: argument unused during compilation: '-shared-libgcc'
../Source/./obj/libgnustep-base.so: undefined reference to `Block_copy'
../Source/./obj/libgnustep-base.so: undefined reference to `Block_release'


$ nm /usr/GNUstep/Local/Library/Libraries/libobjc.so | grep Block
00000000000104f0 T _Block_copy
0000000000010360 T _Block_object_assign
0000000000010560 T _Block_object_dispose
0000000000010690 T _Block_release