[CMake] Problem when linking a library on a target with CUDA sources

[Robert Maynard]

This is caused by a combination of two things:

1. nvcc does not accept standard flags such as fpic or pthread
2. Packages such as Qt or your call to set_target_properties not
handling CUDA/C++ compilers having different flags.

For your pthread example you can use the following ( which is what
FindThreads.cmake does )

    set_target_property((mytarget PROPERTIES COMPILE_OPTIONS

"$<$<COMPILE_LANGUAGE:CUDA>:SHELL:-Xcompiler -pthread>
$<$<NOT:$<COMPILE_LANGUAGE:CUDA>>:-pthread>")

On Thu, Jan 3, 2019 at 1:31 PM <victornement at free.fr> wrote:
>
> Hello,
>
> I have a project with a few dependencies (Qt, opencv, aravis, etc) and I would like to add some sources in CUDA.
>
> Here is a minimal example:
>
> cmake_minimum_required(VERSION 3.0)
> project(myproject CXX CUDA)
> find_package(Qt5 REQUIRED COMPONENTS Core)
> add_executable(mytarget main.cpp gpu.cu)
> target_link_libraries(mytarget PUBLIC Qt5::Core)
>
> The previous example gives the following output
>
> [ 25%] Building CUDA object CMakeFiles/mytarget.dir/gpu.cu.o
> nvcc fatal   : Unknown option 'fPIC'
> make[2]: *** [CMakeFiles/mytarget.dir/build.make:76: CMakeFiles/mytarget.dir/gpu.cu.o] Error 1
> make[1]: *** [CMakeFiles/Makefile2:73: CMakeFiles/mytarget.dir/all] Error 2
> make: *** [Makefile:84: all] Error 2
>
> I would get the same problem if I replace target_link_libraries with
>
> set_target_properties(mytarget PROPERTIES COMPILE_OPTIONS -pthread)
>
> Does anyone know why I get this error? Am I doing it rightly? Is it a bug?
>
> Sincerely,
>
> Victor ML
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