Fix a issue that libclang.dylib won't be loaded when it is linked with libLLVM-3.5.dylib

[ghost]

When I try to use ycmd with homebrewed libclang where libclang.dylib is linked to libLLVM-3.5.dylib, the ycm_core.so won't load (error message: dyld: no suitable image found).

For macs, we can have multiple RPATHs. To my surprise, appending the dependent library's path to the ycm_core.so's rpath list just solves this issue.

BTW passing the argument -Wl,rpath,EXTRA_LIB_PATH to the compiler should produce the same effect as the command install_name_tool -add_rpath does.

[Valloric]

Sorry, but this is extra complexity only to support a homebrewed setup that others are unlikely to have. This isn't worth maintaining long-term.

[ghost]

Well, if the clang+llvm is built from source with shared libraries enabled, libclang is linked with libLLVM(or a series of libLLVMXXX libraries if you are using cmake). We don't set correct rpath for ycm_core.so or don't set global environment variable DYLD_FALLBACK_LIBRARY_PATH for this situation, so the vim will fail to load YCM.

To be clear, I use several copies of clang+llvm (both prebuilt ones and self-built ones, homebrewed one is only one of them), and YCM won't work with any of them that are built with shared-libraries option on.

It is sad to see this fix not getting merged while it is a quite common situation for devs. I think the similar issue exists for the linux platform as well if we are using self-built clang+llvm or versions of clangs.

Thanks!

BTW: If you want to come back to deal with this issue, set up your environment variable DYLD_PRINT_RPATHS and this will save you a lot of debug time.

[Valloric]

You've convinced me to give this another chance. I'll need to test it out on my Mac at home when I have the time, but I'm now open to this merging.

[Valloric]

BTW you've deleted the branch; you'll probably need to re-send the PR.

[ghost]

Yeah, I opened a new PR in #66