Obtaining the CUDA include dir in C++ targets with native-CUDA-support CMake?

Question

In CMake version 3.8, native support for CUDA as a language was introduced. When a project has CUDA as one of its languages, CMake will proceed to locate CUDA (e.g. it locates the nvcc binary).

As long as you only compile CUDA code - this is enough. But what if you want to compile a C++ target in that project? The CUDA includes are not -I'ed automatically, and CMakeCache.txt does not seem to contain the CUDA include path anywhere.

Do I actually have to run something find_package(CUDA 9.0 REQUIRED) even when CMake itself has already located CUDA? Or - can I obtain the include directory some other way?

Answer 1

The include directories, which are used by the compiler set by CMAKE_CUDA_COMPILER, can be retrieved from the CMake variable CMAKE_CUDA_TOOLKIT_INCLUDE_DIRECTORIES.

For getting the libraries, the best way is probably to use find_library() in combination with CMAKE_CUDA_IMPLICIT_LINK_DIRECTORIES.

Example:

cmake_minimum_required(VERSION 3.9)
project(MyProject VERSION 1.0)
enable_language(CUDA)

find_library(CUDART_LIBRARY cudart ${CMAKE_CUDA_IMPLICIT_LINK_DIRECTORIES})

add_executable(
    binary_linking_to_cudart 
    my_cpp_file_using_cudart.cpp
)
target_include_directories(
    binary_linking_to_cudart 
    PRIVATE 
    ${CMAKE_CUDA_TOOLKIT_INCLUDE_DIRECTORIES}
)
target_link_libraries(
    binary_linking_to_cudart 
    ${CUDART_LIBRARY}
)

This issue is also discussed on the CMake bug tracker: Provide target libraries for cuda libraries.

---

Update: CMake 3.17.0 adds FindCUDAToolkit

Instead of doing find_library() manually, the best way as of CMake 3.17.0 would be to use the CUDAToolkit module.

find_package(CUDAToolkit)
add_executable(
    binary_linking_to_cudart 
    my_cpp_file_using_cudart.cpp
)
target_link_libraries(binary_linking_to_cudart PRIVATE CUDA::cudart)

For support with earlier CMake versions, you can ship the CUDATookit module file with minimal changes in your repository.