Linking error with vrpn and libusb in Mac OS X

Question

I'm getting the following error when I try to compile vrpn 7.33 on a Mac. It says that libusb was compiled for a different architecture than vrpn is being compiled:

Linking CXX executable client_and_server
ld: warning: ignoring file /usr/local/lib/libusb-1.0.dylib, file was built for i386 which is not the architecture being linked (x86_64): /usr/local/lib/libusb-1.0.dylib
Undefined symbols for architecture x86_64:
  "_libusb_claim_interface", referenced from:
      vrpn_Tracker_USB::vrpn_Tracker_USB(char const*, vrpn_Connection*, unsigned short, unsigned short, long) in libvrpnserver.a(vrpn_Tracker.C.o)
      vrpn_Tracker_USB::mainloop() in libvrpnserver.a(vrpn_Tracker.C.o)
  "_libusb_close", referenced from:
      vrpn_Tracker_USB::vrpn_Tracker_USB(char const*, vrpn_Connection*, unsigned short, unsigned short, long) in libvrpnserver.a(vrpn_Tracker.C.o)
      vrpn_Tracker_USB::~vrpn_Tracker_USB() in libvrpnserver.a(vrpn_Tracker.C.o)
      vrpn_Tracker_USB::mainloop() in libvrpnserver.a(vrpn_Tracker.C.o)
  "_libusb_exit", referenced from:
      vrpn_Tracker_USB::vrpn_Tracker_USB(char const*, vrpn_Connection*, unsigned short, unsigned short, long) in libvrpnserver.a(vrpn_Tracker.C.o)
      vrpn_Tracker_USB::~vrpn_Tracker_USB() in libvrpnserver.a(vrpn_Tracker.C.o)
  "_libusb_init", referenced from:
      vrpn_Tracker_USB::vrpn_Tracker_USB(char const*, vrpn_Connection*, unsigned short, unsigned short, long) in libvrpnserver.a(vrpn_Tracker.C.o)
  "_libusb_open_device_with_vid_pid", referenced from:
      vrpn_Tracker_USB::vrpn_Tracker_USB(char const*, vrpn_Connection*, unsigned short, unsigned short, long) in libvrpnserver.a(vrpn_Tracker.C.o)
      vrpn_Tracker_USB::mainloop() in libvrpnserver.a(vrpn_Tracker.C.o)
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
make[2]: *** [server_src/client_and_server] Error 1
make[1]: *** [server_src/CMakeFiles/client_and_server.dir/all] Error 2
make: *** [all] Error 2

But when I recompile libusb changing the architecture to x86_64 I start getting the following error:

Linking CXX executable client_and_server
ld: warning: ignoring file /usr/local/lib/libusb-1.0.dylib, file was built for x86_64 which is not the architecture being linked (i386): /usr/local/lib/libusb-1.0.dylib
Undefined symbols for architecture i386:
  "_libusb_claim_interface", referenced from:
      vrpn_Tracker_USB::vrpn_Tracker_USB(char const*, vrpn_Connection*, unsigned short, unsigned short, long) in libvrpnserver.a(vrpn_Tracker.C.o)
      vrpn_Tracker_USB::mainloop() in libvrpnserver.a(vrpn_Tracker.C.o)
  "_libusb_close", referenced from:
      vrpn_Tracker_USB::vrpn_Tracker_USB(char const*, vrpn_Connection*, unsigned short, unsigned short, long) in libvrpnserver.a(vrpn_Tracker.C.o)
      vrpn_Tracker_USB::~vrpn_Tracker_USB() in libvrpnserver.a(vrpn_Tracker.C.o)
      vrpn_Tracker_USB::mainloop() in libvrpnserver.a(vrpn_Tracker.C.o)
  "_libusb_exit", referenced from:
      vrpn_Tracker_USB::vrpn_Tracker_USB(char const*, vrpn_Connection*, unsigned short, unsigned short, long) in libvrpnserver.a(vrpn_Tracker.C.o)
      vrpn_Tracker_USB::~vrpn_Tracker_USB() in libvrpnserver.a(vrpn_Tracker.C.o)
  "_libusb_init", referenced from:
      vrpn_Tracker_USB::vrpn_Tracker_USB(char const*, vrpn_Connection*, unsigned short, unsigned short, long) in libvrpnserver.a(vrpn_Tracker.C.o)
  "_libusb_open_device_with_vid_pid", referenced from:
      vrpn_Tracker_USB::vrpn_Tracker_USB(char const*, vrpn_Connection*, unsigned short, unsigned short, long) in libvrpnserver.a(vrpn_Tracker.C.o)
      vrpn_Tracker_USB::mainloop() in libvrpnserver.a(vrpn_Tracker.C.o)
ld: symbol(s) not found for architecture i386
clang: error: linker command failed with exit code 1 (use -v to see invocation)
make[2]: *** [server_src/client_and_server] Error 1
make[1]: *** [server_src/CMakeFiles/client_and_server.dir/all] Error 2
make: *** [all] Error 2

Notice how now the linker is searching for the original i386 architecture.

Why does vrpn complain in both cases?

Answer 1

vrpn is being compiled for multiple architectures at the same time. That is why a compiling libusb for a single architecture doesn't work.

The solution is to compile libusbfor the two architecutres at the same time using the following sequence of commands:

./configure
make CFLAGS="-arch x86_64 -arch i386" LDFLAGS="-arch x86_64 -arch i386"
sudo make install

If you want more information about compiling Universal binaries in Mac OS X check this link:

• Compiling Your Code in OS X (Compiling for Multiple CPU Architectures)