Alpaka: CMake Option: Alpaka CXX Standard

[ivandrodri]

I have a problem to compile a module in c++14 with ALPAKA.

I have an ALPAKA class that is compiled into a library, "AlpakaLibrary".

Now I would like to have my executable, "MAIN", compiled in c++14 and link AlpakaLibrary and another c++14 host-library, "c++14HostLibrary", to it. Something like this :

SET(_TARGET_NAME "MAIN")

ALPAKA_ADD_EXECUTABLE(
${_TARGET_NAME}
${_FILES_SOURCE})
TARGET_LINK_LIBRARIES(
${_TARGET_NAME}
PUBLIC "AlpakaLibrary" "c++14HostLibrary")

I have two questions:

1) When I replace ALPAKA_ADD_EXECUTABLE --> ADD_EXECUTABLE I have many ALPAKA compilation errors and I don't understand why. Should I use always ALPAKA_ADD_EXECUTABLE ?

2) I want to compile MAIN in c++14 but If I set the CMAKE flags manually, i.e.:

set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++14)

I have plenty of compilation errors for ALPAKA.

So what is that right way to link an ALPAKA library with a c++14 module?

[ax3l]

Hi,

Should I use always ALPAKA_ADD_EXECUTABLE

yes, that's the current wrapper we deploy since CMake's CUDA language does not yet support clang -x cuda as a CUDA compiler: https://gitlab.kitware.com/cmake/cmake/issues/16586

For that reason, we manually add -std=c++11 instead of using a "C++11 or newer" target_compile_feature(s).

compile MAIN in c++14

We probably have to expose a CMake control variable to allow setting another C++ standard for the time being, which can be set from apps.

These are the locations you could change already to C++14:

• https://github.com/ComputationalRadiationPhysics/alpaka/blob/0.3.5/alpakaConfig.cmake#L456
• https://github.com/ComputationalRadiationPhysics/alpaka/blob/0.3.5/alpakaConfig.cmake#L516

[ivandrodri]

Thanks a lot!

[ax3l]

@ivandrodri allow me to keep this issue open so we implement a control var in CMake and document how to use it :)

[kloppstock]

Hi, sorry to open up an old issue, but setting the C++ version to 14 still doesn't work for me.

I tried setting the CMAKE_CXX_STANDARD variable and the ALPAKA_CXX_STANDARD, both before and after find_alpaka(), but make VERBOSE=1 still showed the -std=c++11 flag.

A current snapshot of the software can be found here.

[sbastrakov]

I've just tried to reproduce with the latest alpaka develop on hemera. It does not have cmake 3.11.4 that alpaka now requires, changed the requirements to 3.11.3. Adding -DALPAKA_CXX_STANDARD=14 to the command line seems to work for me.

[kloppstock]

Thanks, this solved the issue for me. Additionally, it seemed that somehow my alpaka version was not updated correctly after a git pull, but I could fix this by removing and redownloading the repository.