[OpenMP][libomptarget] Suppress C++ 11 related warnings when building libomptarget-nvptx bitcode library

[gtbercea]

Summary

Pass -std=c++11 flag to compiler to suppress C++ 11 related warnings when building NVPTX bitcode library.

[ABataev]

LG

[Hahnfeld]

Hi Doru, I think this patch is not yet in trunk? Additionally I'm seeing the same warnings when compiling with nvcc which doesn't seem addressed here. Should we pass -std=c++11 when compiling the CUDA code as well?

[ABataev]

Doru, do you plan to commit this?

[Hahnfeld]

@gtbercea Could you please commit this patch? The warnings are incredibly annoying.

libomptarget/cmake/Modules/LibomptargetNVPTXBitcodeLibrary.cmake

if (${discard_cached} OR NOT DEFINED ${output})
     else()
       message(STATUS "Performing Test ${output} - Failed")
     endif()
   endif()
 endfunction()
 
 # These flags are required to emit LLVM Bitcode. We check them together because
 # if any of them are not supported, there is no point in finding out which are.
-set(compiler_flags_required -emit-llvm -O1 --cuda-device-only --cuda-path=${CUDA_TOOLKIT_ROOT_DIR})
+set(compiler_flags_required -emit-llvm -O1 --cuda-device-only -std=c++11 --cuda-path=${CUDA_TOOLKIT_ROOT_DIR})
 set(compiler_flags_required_src "extern \"C\" __device__ int thread() { return threadIdx.x; }")
 check_bitcode_compilation(LIBOMPTARGET_NVPTX_CUDA_COMPILER_SUPPORTS_FLAGS_REQUIRED "${compiler_flags_required_src}" ${compiler_flags_required})
 
 # It makes no sense to continue given that the compiler doesn't support
 # emitting basic LLVM Bitcode
 if (NOT LIBOMPTARGET_NVPTX_CUDA_COMPILER_SUPPORTS_FLAGS_REQUIRED)
   return()
 endif()