• Install the latest deoplete.nvim
• Make sure you already have clang(clang command)

" Change clang binary path
call deoplete#custom#var('clangx', 'clang_binary', '/usr/local/bin/clang')

" Change clang options
call deoplete#custom#var('clangx', 'default_c_options', '')
call deoplete#custom#var('clangx', 'default_cpp_options', '')

deoplete-clangx supports neoinclude plugin

https://github.com/Shougo/neoinclude.vim/

neoinclude adds include directory options(-I) automatically for clang.

You can configure compiler options using the file.

https://github.com/Rip-Rip/clang_complete#minimum-configuration

• compile_commands.json file support