irony-server-install fail on OS X 10.11 /w XCode 8

[weijiangan]

-*- mode: compilation; default-directory: "/var/folders/8y/zxw3vpdd5ml7y04qhdjlb_7m0000gn/T/build-irony-server-0.2.0/" -*-
Compilation started at Tue Oct 25 15:49:20

cmake -DCMAKE_INSTALL_PREFIX\=/Users/weijiangan/.emacs.d/irony/ /Users/weijiangan/.emacs.d/elpa/irony-20160925.1030/server && cmake --build . --use-stderr --config Release --target install
-- The C compiler identification is AppleClang 8.0.0.8000038
-- The CXX compiler identification is AppleClang 8.0.0.8000038
-- Check for working C compiler: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/cc
-- Check for working C compiler: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/cc -- works
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Detecting C compile features
-- Detecting C compile features - done
-- Check for working CXX compiler: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/c++
-- Check for working CXX compiler: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/c++ -- works
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Detecting CXX compile features
-- Detecting CXX compile features - done
-- Setting build type to 'Release' as none was specified
-- Performing Test HAS_STDCXX11
-- Performing Test HAS_STDCXX11 - Success
-- Performing Test HAS_CXX11_STDLIB
-- Performing Test HAS_CXX11_STDLIB - Success
-- C++11 compiler option(s): -std=c++11
CMake Error at /opt/local/share/cmake-3.6/Modules/FindPackageHandleStandardArgs.cmake:148 (message):
  Could NOT find LibClang (missing: LIBCLANG_LIBRARY LIBCLANG_INCLUDE_DIR)
Call Stack (most recent call first):
  /opt/local/share/cmake-3.6/Modules/FindPackageHandleStandardArgs.cmake:388 (_FPHSA_FAILURE_MESSAGE)
  cmake/modules/FindLibClang.cmake:90 (find_package_handle_standard_args)
  src/CMakeLists.txt:3 (find_package)


-- Configuring incomplete, errors occurred!
See also "/var/folders/8y/zxw3vpdd5ml7y04qhdjlb_7m0000gn/T/build-irony-server-0.2.0/CMakeFiles/CMakeOutput.log".

Compilation exited abnormally with code 1 at Tue Oct 25 15:49:24

I understand that most people install llvm with brew on macOS with the --with-clang flag, but I checked Xcode and it already comes with libclang. Can I make use of that? It's stored in
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/lib/libclang.dylib

[ANDRON94]

Maybe it helps You:
"
When libclang is installed in a non-standard location (one that is missing from the path list of the dynamic loader, see ld.so.conf) you can tell CMake to use the rpath when installing the target irony-server. To enable rpath in CMake use the following command:

cmake -DCMAKE_INSTALL_RPATH_USE_LINK_PATH=ON <args...>

If you're running OS X, you can also use install_name_tool to explicitly tell irony-server where an appropriate version of libclang.dylib lives. For example, Homebrew (with brew install llvm --with-clang) will install a libclang.dylib library at /usr/local/opt/llvm/lib/libclang.dylib; you can instruct irony-server to use this with something like:

install_name_tool -change @rpath/libclang.dylib /usr/local/opt/llvm/lib/libclang.dylib irony-server"

From README.md

[Sarcasm]

I understand that most people install llvm with brew on macOS with the --with-clang flag, but I checked Xcode and it already comes with libclang. Can I make use of that?

I think XCode provides libclang.dylib but does provide clang-c/Index.h?

This was discussed from here: #138 (comment) to here #138 (comment)

It's possible things have changed, in this case let me know.

[weijiangan]

@Sarcasm Thanks for the link I followed the instructions in this comment and it solved my problems #138 (comment)

Perhaps you want to add this to the readme for macOS users? I mean not everybody wants to install a full copy of llvm-clang when it already comes with Xcode, especially when the space llvm-clang requires is not negligible. Thanks!

[Sarcasm]

I added this to the wiki:

• https://github.com/Sarcasm/irony-mode/wiki/Mac-OS-X-issues-and-workaround

Feel free to improve.

Thank you