install:

1. load: git clone https://github.com/Valloric/YouCompleteMe.git
2. integrity checking: git submodule update --init --recursive
3. install:(cmake is needed)
   1. fast install: pacman -S clang python ./install.py --clang-completer --system-libclang
   2. complete install: ...
4. config: cp ~/.vim/bundle/YouCompleteMe/third_party/ycmd/cpp/ycm/.ycm_extra_conf.py ~/ -try:
   • final_flags.remove( '-stdlib=libc++' ) -except ValueError:
   • pass +'-isystem', +'/usr/include', +'-isystem', +'/usr/include/c++/7.1.1',