YouCompleteMe and CUDA source files - vim

Question

I am trying to make YCM plugin of vim to work for CUDA source files.
Since CUDA is basically C++ syntax with some extensions, I thought that editing the standard '.ycm_extra_conf.py' file would be sufficient. I changed the line
SOURCE_EXTENSIONS = [ '.cpp', '.cxx', '.cc', '.c', '.m', '.mm']
to
SOURCE_EXTENSIONS = [ '.cpp', '.cxx', '.cc', '.c', '.m', '.mm', '.cu' ]
and the line
return extension in [ '.h', '.hxx', '.hpp', '.hh']
to
return extension in [ '.h', '.hxx', '.hpp', '.hh', '.cuh' ]
But YCM does not work, it does not even ask me to use the config file as it should in the beginning. In normal C/C++ source files YCM works correct.
Any ideas what is missing?

Answer 1

I got this working by the following steps:
First remap .cu files to cpp in your .vimrc
" Map cuda files to c++ so that Ycm can parse
autocmd BufNewFile,BufRead *.cu set filetype=cpp
Next update .ycm_extra_conf.py with flags for Clang CUDA support.
import os
import ycm_core
includes = ['-I/opt/cudatoolkit/6.5/include', '-I/your/includes/here']
common = ['-std=c++11',
'-DUSE_CLANG_COMPLETER',
'-I/usr/local/include',
'-I/usr/include/clang/3.5/include',
'-I/usr/include/x86_64-linux-gnu',
'-I/usr/bin/../lib/gcc/x86_64-linux-gnu/4.9/include',
'-I/usr/include',
'-I/usr/include/c++/4.9']
cpp_flags = ['-x', 'c++',]
# http://llvm.org/docs/CompileCudaWithLLVM.html
cuda_flags = ['-x', 'cuda', '--cuda-gpu-arch=sm_35']
def FlagsForFile( filename ):
compile_flags = cpp_flags
if filename.endswith('.cu'):
compile_flags = cuda_flags
compile_flags.extend(common)
compile_flags.extend(includes)
return {
'flags': compile_flags,
'do_cache': True
}
Finally you need to add in a header file to your .cu file so Ycm can parse the CUDA builtins. This file, cuda_builtin_vars.h was in my local Clang build.
#ifdef __clang__
#include <cuda_builtin_vars.h>
#endif
Even with all this, the Clang parser still doesn't seem to accept that my __global__ functions are actually __global__ (even though it can handle the kernel call syntax with any problems), so I usually wrap them with #ifndef __clang__
Sources:
https://github.com/Valloric/YouCompleteMe/issues/1766
http://llvm.org/docs/CompileCudaWithLLVM.html
https://github.com/Microsoft/clang-1/blob/master/test/SemaCUDA/kernel-call.cu