alpaka CI: set CMAKE_CXX_COMPILER instead using update-alternatives

- Instead changing the default host compiler, set the compiler via CMAKE_CXX_COMPILER argument at CMake configure.
- Rename environment variable CXX to ALPAKA_CI_CXX, because CXX can cause unexpected side effects.
- The environment variable CMAKE_CXX_COMPILER is created in the scripts depending on the variable ALPAKA_CI_CXX.
- Remove the environment variable CC completely because we do not compile C code.
- Set also CMAKE_CUDA_COMPILER as CMake configure argument manually.

example/complex/CMakeLists.txt

@@ -15,7 +15,7 @@ set_property(GLOBAL PROPERTY USE_FOLDERS ON)
 
 set(_TARGET_NAME complexNumbers)
 
-project(${_TARGET_NAME})
+project(${_TARGET_NAME} LANGUAGES CXX)
 
 #-------------------------------------------------------------------------------
 # Find alpaka.

script/before_install.sh

@@ -95,10 +95,15 @@ if [ "$ALPAKA_CI_OS_NAME" = "Linux" ]
 then
     if [ "${ALPAKA_CI_STDLIB}" == "libc++" ]
     then
-        if [[ "${CXX}" == "g++"* ]]
+        if [[ "${ALPAKA_CI_CXX}" == "g++"* ]]
         then
             echo "using libc++ with g++ not yet supported."
             exit 1
         fi
     fi
 fi
+
+if [ "$ALPAKA_CI_OS_NAME" = "Windows" ] || [ "$ALPAKA_CI_OS_NAME" = "macOS" ]
+then
+    export CMAKE_CXX_COMPILER=$ALPAKA_CI_CXX
+fi

script/gitlabci/job_base.yml

@@ -18,13 +18,12 @@
   image: ubuntu:${ALPAKA_CI_UBUNTU_VER}
   variables:
     ALPAKA_CI_UBUNTU_VER: "20.04"
-    CC: gcc
-    CXX: g++
+    ALPAKA_CI_CXX: g++
     alpaka_ACC_CPU_B_SEQ_T_THREADS_ENABLE: "ON"
     alpaka_ACC_CPU_B_OMP2_T_SEQ_ENABLE: "ON"
     alpaka_ACC_CPU_B_SEQ_T_OMP2_ENABLE: "OFF"
     alpaka_ACC_GPU_CUDA_ENABLE: "ON"
-    CMAKE_CUDA_COMPILER: nvcc
+    ALPAKA_CI_CUDA_COMPILER: nvcc
     ALPAKA_CI_STDLIB: libstdc++
     # CI contains a Quadro P5000 (sm_61)
     CMAKE_CUDA_ARCHITECTURES: "61"
@@ -51,13 +50,12 @@
   image: ubuntu:${ALPAKA_CI_UBUNTU_VER}
   variables:
     ALPAKA_CI_UBUNTU_VER: "20.04"
-    CC: clang
-    CXX: clang++
+    ALPAKA_CI_CXX: clang++
     alpaka_ACC_CPU_B_SEQ_T_THREADS_ENABLE: "ON"
     alpaka_ACC_CPU_B_OMP2_T_SEQ_ENABLE: "ON"
     alpaka_ACC_CPU_B_SEQ_T_OMP2_ENABLE: "OFF"
     alpaka_ACC_GPU_CUDA_ENABLE: "ON"
-    CMAKE_CUDA_COMPILER: clang++
+    ALPAKA_CI_CUDA_COMPILER: clang++
     ALPAKA_CI_STDLIB: libstdc++
     # CI contains a Quadro P5000 (sm_61)
     CMAKE_CUDA_ARCHITECTURES: "61"
@@ -87,8 +85,7 @@
   image: ubuntu:${ALPAKA_CI_UBUNTU_VER}
   variables:
     ALPAKA_CI_UBUNTU_VER: "22.04"
-    CC: clang
-    CXX: clang++
+    ALPAKA_CI_CXX: clang++
     ALPAKA_CI_SANITIZERS: ""
     ALPAKA_CI_ANALYSIS: "OFF"
     ALPAKA_CI_TBB_VERSION: 2021.4.0

script/gitlabci/print_env.sh

@@ -39,7 +39,7 @@ fi
 echo -e "2. Run the following export commands in the container to setup enviroment\n"
 
 # take all env variables, filter it and display it with a `export` prefix
-printenv | grep -E 'alpaka_*|ALPAKA_*|CMAKE_*|BOOST_|CC|CXX|CUDA_' | while read -r line ; do
+printenv | grep -E 'alpaka_*|ALPAKA_*|CMAKE_*|BOOST_|CUDA_' | while read -r line ; do
     echo "export $line \\"
 done
 

script/install.sh

@@ -38,15 +38,13 @@ fi
 
 if [ "${ALPAKA_CI_ANALYSIS}" == "ON" ] ;then source ./script/install_analysis.sh ;fi
 
-# Install CUDA before installing gcc as it installs gcc-4.8 and overwrites our selected compiler
-if [ "${ALPAKA_CI_INSTALL_CUDA}" == "ON" ] ;then source ./script/install_cuda.sh ;fi
 
 if [ "$ALPAKA_CI_OS_NAME" = "Linux" ]
 then
-    if [[ "${CXX}" == "g++"* ]] ;then source ./script/install_gcc.sh ;fi
+    if [[ "${ALPAKA_CI_CXX}" == "g++"* ]] ;then source ./script/install_gcc.sh ;fi
     # do not install clang if we use HIP, HIP/ROCm is shipping an own clang version
-    if [[ "${CXX}" == "clang++" ]] && [ "${ALPAKA_CI_INSTALL_HIP}" != "ON" ] ;then source ./script/install_clang.sh ;fi
-    if [[ "${CXX}" == "icpx" ]] ;then source ./script/install_oneapi.sh ;fi
+    if [[ "${ALPAKA_CI_CXX}" == "clang++" ]] && [ "${ALPAKA_CI_INSTALL_HIP}" != "ON" ] ;then source ./script/install_clang.sh ;fi
+    if [[ "${ALPAKA_CI_CXX}" == "icpx" ]] ;then source ./script/install_oneapi.sh ;fi
 elif [ "$ALPAKA_CI_OS_NAME" = "macOS" ]
 then
     echo "### list all applications ###"
@@ -55,8 +53,10 @@ then
     sudo xcode-select -s "/Applications/Xcode_${ALPAKA_CI_XCODE_VER}.app/Contents/Developer"
 fi
 
+if [ "${ALPAKA_CI_INSTALL_CUDA}" == "ON" ] ;then source ./script/install_cuda.sh ;fi
+
 # Don't install TBB for oneAPI runners - it will be installed as part of oneAPI
-if [ "${ALPAKA_CI_INSTALL_TBB}" = "ON" ] && [ "${CXX}" != "icpx" ]
+if [ "${ALPAKA_CI_INSTALL_TBB}" = "ON" ] && [ "${ALPAKA_CI_CXX}" != "icpx" ]
 then
     source ./script/install_tbb.sh
 fi

script/install_boost.sh

@@ -18,8 +18,7 @@ then
     : "${ALPAKA_CI_STDLIB?'ALPAKA_CI_STDLIB must be specified'}"
 fi
 : "${CMAKE_BUILD_TYPE?'CMAKE_BUILD_TYPE must be specified'}"
-: "${CXX?'CXX must be specified'}"
-: "${CC?'CC must be specified'}"
+: "${ALPAKA_CI_CXX?'ALPAKA_CI_CXX must be specified'}"
 : "${ALPAKA_CI_INSTALL_ATOMIC?'ALPAKA_CI_INSTALL_ATOMIC must be specified'}"
 if [ "$ALPAKA_CI_OS_NAME" = "Windows" ]
 then
@@ -31,7 +30,7 @@ then
     ALPAKA_CI_STDLIB=""
 fi
 
-if [ "${CXX}" != "icpc" ] && [ "${ALPAKA_CI_STDLIB}" != "libc++" ]
+if [ "${ALPAKA_CI_CXX}" != "icpc" ] && [ "${ALPAKA_CI_STDLIB}" != "libc++" ]
 then
     if agc-manager -e boost@${ALPAKA_BOOST_VERSION} ; then
         echo_green "<USE: preinstalled BOOST ${ALPAKA_BOOST_VERSION}>"
@@ -71,15 +70,22 @@ then
         TOOLSET="msvc-14.3"
     fi
     # Add new versions as needed
-elif [ "${CXX}" == "icpc" ]
+elif [ "${ALPAKA_CI_CXX}" == "icpc" ]
 then
     TOOLSET="intel-linux"
-elif [ "${CXX}" == "icpx" ]
+elif [ "${ALPAKA_CI_CXX}" == "g++" ]
+then
+    TOOLSET="gcc"
+elif [ "${ALPAKA_CI_CXX}" == "clang++" ]
+then
+    TOOLSET="clang"
+elif [ "${ALPAKA_CI_CXX}" == "icpx" ]
 then
     # icpx is binary compatibly with g++ and ipcx is not supported by b2
     TOOLSET="gcc"
 else
-    TOOLSET="${CC}"
+    echo_red "unknown ALPAKA_CI_CXX: ${ALPAKA_CI_CXX}"
+    exit 1
 fi
 
 # Bootstrap boost.
@@ -151,7 +157,7 @@ then
 
     # Clang is not supported by the FindBoost script.
     # boost (especially old versions) produces too much warnings when using clang (newer versions) so that the 4 MiB log is too short.
-    if [[ "${CXX}" == "clang++"* ]]
+    if [[ "${ALPAKA_CI_CXX}" == "clang++"* ]]
     then
         ALPAKA_BOOST_B2_CXXFLAGS+=" -Wunused-private-field -Wno-unused-local-typedef -Wno-c99-extensions -Wno-variadic-macros"
     fi

script/install_clang.sh

@@ -12,7 +12,6 @@ echo_green "<SCRIPT: install_clang>"
 
 : "${ALPAKA_CI_CLANG_VER?'ALPAKA_CI_CLANG_VER must be specified'}"
 : "${ALPAKA_CI_STDLIB?'ALPAKA_CI_STDLIB must be specified'}"
-: "${CXX?'CXX must be specified'}"
 
 #TODO(SimeonEhrig): remove this statement, if ppa's are fixed in alpaka-group-container
 if [[ -f "/etc/apt/sources.list.d/llvm.list" ]];
@@ -69,11 +68,14 @@ else
         travis_retry sudo apt-get -y --quiet --allow-unauthenticated --no-install-recommends install "${LIBOMP_PACKAGE}"
     fi
 
-    sudo update-alternatives --install /usr/bin/clang clang /usr/bin/clang-"${ALPAKA_CI_CLANG_VER}" 50
-    sudo update-alternatives --install /usr/bin/clang++ clang++ /usr/bin/clang++-"${ALPAKA_CI_CLANG_VER}" 50
-    sudo update-alternatives --install /usr/bin/cc cc /usr/bin/clang-"${ALPAKA_CI_CLANG_VER}" 50
-    sudo update-alternatives --install /usr/bin/c++ c++ /usr/bin/clang++-"${ALPAKA_CI_CLANG_VER}" 50
+    which clang++-${ALPAKA_CI_CLANG_VER}
+    export CMAKE_CXX_COMPILER=$(which clang++-${ALPAKA_CI_CLANG_VER})
+
+    # create soft link clang and clang++ to the actual executable
+    # the boost build script requires that the executable clang++ exist
+    ln -s $(which clang-${ALPAKA_CI_CLANG_VER}) $(dirname $(which clang-${ALPAKA_CI_CLANG_VER}))/clang
+    ln -s $(which clang++-${ALPAKA_CI_CLANG_VER}) $(dirname $(which clang++-${ALPAKA_CI_CLANG_VER}))/clang++
 fi
 
-which "${CXX}"
-${CXX} --version
+which "${CMAKE_CXX_COMPILER}"
+${CMAKE_CXX_COMPILER} --version

script/install_cuda.sh

@@ -33,7 +33,7 @@ else
     if [ "$ALPAKA_CI_OS_NAME" = "Linux" ]
     then
         : "${ALPAKA_CI_CUDA_DIR?'ALPAKA_CI_CUDA_DIR must be specified'}"
-        : "${CMAKE_CUDA_COMPILER?'CMAKE_CUDA_COMPILER must be specified'}"
+        : "${ALPAKA_CI_CUDA_COMPILER?'ALPAKA_CI_CUDA_COMPILER must be specified'}"
 
         if [[ "$(cat /etc/os-release)" == *"20.04"* ]]
         then
@@ -157,7 +157,7 @@ else
         export PATH=/usr/local/nvidia/bin:/usr/local/cuda/bin:${PATH}
         export LD_LIBRARY_PATH=/usr/local/nvidia/lib:/usr/local/nvidia/lib64:$LD_LIBRARY_PATH
 
-        if [ "${CMAKE_CUDA_COMPILER}" == "clang++" ]
+        if [ "${ALPAKA_CI_CUDA_COMPILER}" == "clang++" ]
         then
             travis_retry sudo apt-get -y --quiet --allow-unauthenticated --no-install-recommends install g++-multilib
         fi
@@ -180,3 +180,14 @@ else
         ./cuda_installer.exe -s "nvcc_${ALPAKA_CI_CUDA_VERSION}" "curand_dev_${ALPAKA_CI_CUDA_VERSION}" "cudart_${ALPAKA_CI_CUDA_VERSION}" "thrust_${ALPAKA_CI_CUDA_VERSION}" "visual_studio_integration_${ALPAKA_CI_CUDA_VERSION}"
     fi
 fi
+
+if [ "${ALPAKA_CI_CUDA_COMPILER}" == "nvcc" ]
+then
+    export CMAKE_CUDA_COMPILER=$(which nvcc)
+elif [ "${ALPAKA_CI_CUDA_COMPILER}" == "clang++" ]
+then
+    export CMAKE_CUDA_COMPILER=$(which clang++-${ALPAKA_CI_CLANG_VER})
+else
+    echo_red "unknown ALPAKA_CI_CUDA_COMPILER: ${ALPAKA_CI_CUDA_COMPILER}"
+    exit 1
+fi

script/install_gcc.sh

@@ -12,7 +12,6 @@ echo_green "<SCRIPT: install_gcc>"
 
 : "${ALPAKA_CI_GCC_VER?'ALPAKA_CI_GCC_VER must be specified'}"
 : "${ALPAKA_CI_SANITIZERS?'ALPAKA_CI_SANITIZERS must be specified'}"
-: "${CXX?'CXX must be specified'}"
 
 if agc-manager -e gcc@${ALPAKA_CI_GCC_VER}
 then
@@ -26,12 +25,20 @@ else
     travis_retry sudo apt-get -y --quiet --allow-unauthenticated --no-install-recommends install g++-"${ALPAKA_CI_GCC_VER}"
 fi
 
-sudo update-alternatives --install /usr/bin/gcc gcc /usr/bin/gcc-"${ALPAKA_CI_GCC_VER}" 50
-sudo update-alternatives --install /usr/bin/g++ g++ /usr/bin/g++-"${ALPAKA_CI_GCC_VER}" 50
+which g++-${ALPAKA_CI_GCC_VER}
+export CMAKE_CXX_COMPILER=$(which g++-${ALPAKA_CI_GCC_VER})
+
+# the g++ executalbe is required for compiling boost
+# if it does not exist, create symbolic link to the install g++-${ALPAKA_CI_GCC_VER}
+if ! command -v g++ >/dev/null; then
+    echo_yellow "No g++ executable found."
+    ln -s $(which g++-${ALPAKA_CI_GCC_VER}) $(dirname $(which g++-${ALPAKA_CI_GCC_VER}))/g++
+fi
+
 if [[ "${ALPAKA_CI_SANITIZERS}" == *"TSan"* ]]
 then
     travis_retry sudo apt-get -y --quiet --allow-unauthenticated --no-install-recommends install libtsan0
 fi
 
-which "${CXX}"
-${CXX} -v
+which "${CMAKE_CXX_COMPILER}"
+${CMAKE_CXX_COMPILER} -v

script/install_hip.sh

@@ -101,3 +101,6 @@ hipconfig
 rocm-smi
 # print newline as previous command does not do this
 echo
+
+# use the clang++ of the HIP SDK as C++ compiler
+export CMAKE_CXX_COMPILER=$(which clang++)

script/install_oneapi.sh

@@ -9,9 +9,6 @@ source ./script/setup_utilities.sh
 
 echo_green "<SCRIPT: install_oneapi>"
 
-: "${CXX?'CXX must be specified'}"
-
-
 if agc-manager -e oneapi
 then
     echo_green "<USE: preinstalled OneAPI ${ALPAKA_CI_ONEAPI_VERSION}>"
@@ -55,10 +52,11 @@ else
         travis_retry sudo apt update
         travis_retry sudo apt install -y --no-install-recommends g++-11
     fi
+
+    # path depends on the SDK version
+    export CMAKE_CXX_COMPILER=$(which icpx)
 fi
 
-which "${CXX}"
-${CXX} --version
-which "${CC}"
-${CC} --version
+which "${CMAKE_CXX_COMPILER}"
+${CMAKE_CXX_COMPILER} --version
 sycl-ls

script/job_generator/generate_job_yaml.py

@@ -296,22 +296,19 @@ def job_variables(job: Dict[str, Tuple[str, str]]) -> Dict[str, str]:
     append_backend_variables(variables, job)
 
     if job[DEVICE_COMPILER][NAME] == GCC:
-        variables["CC"] = "gcc"
-        variables["CXX"] = "g++"
+        variables["ALPAKA_CI_CXX"] = "g++"
         variables["ALPAKA_CI_GCC_VER"] = job[DEVICE_COMPILER][VERSION]
         if ALPAKA_ACC_CPU_B_TBB_T_SEQ_ENABLE in job and job[ALPAKA_ACC_CPU_B_TBB_T_SEQ_ENABLE][VERSION] == ON_VER:
             variables["ALPAKA_CI_TBB_VERSION"] = "2021.10.0"
 
     if job[DEVICE_COMPILER][NAME] == CLANG:
-        variables["CC"] = "clang"
-        variables["CXX"] = "clang++"
+        variables["ALPAKA_CI_CXX"] = "clang++"
         variables["ALPAKA_CI_CLANG_VER"] = job[DEVICE_COMPILER][VERSION]
         if ALPAKA_ACC_CPU_B_TBB_T_SEQ_ENABLE in job and job[ALPAKA_ACC_CPU_B_TBB_T_SEQ_ENABLE][VERSION] == ON_VER:
             variables["ALPAKA_CI_TBB_VERSION"] = "2021.10.0"
 
     if job[DEVICE_COMPILER][NAME] == HIPCC:
-        variables["CC"] = "clang"
-        variables["CXX"] = "clang++"
+        variables["ALPAKA_CI_CXX"] = "clang++"
         variables["CMAKE_HIP_COMPILER"] = "clang++"
         variables["CMAKE_HIP_ARCHITECTURES"] = "${CI_GPU_ARCH}"
         # TODO(SimeonEhrig) check, if we can remove this variable:
@@ -347,33 +344,29 @@ def job_variables(job: Dict[str, Tuple[str, str]]) -> Dict[str, str]:
 
     if job[DEVICE_COMPILER][NAME] == NVCC:
         # general configuration, if nvcc is the CUDA compiler
-        variables["CMAKE_CUDA_COMPILER"] = "nvcc"
+        variables["ALPAKA_CI_CUDA_COMPILER"] = "nvcc"
 
         # configuration, if GCC is the CUDA host compiler
         if job[HOST_COMPILER][NAME] == GCC:
-            variables["CC"] = "gcc"
-            variables["CXX"] = "g++"
+            variables["ALPAKA_CI_CXX"] = "g++"
             variables["ALPAKA_CI_GCC_VER"] = job[HOST_COMPILER][VERSION]
         # configuration, if Clang is the CUDA host compiler
         elif job[HOST_COMPILER][NAME] == CLANG:
-            variables["CC"] = "clang"
-            variables["CXX"] = "clang++"
+            variables["ALPAKA_CI_CXX"] = "clang++"
             variables["ALPAKA_CI_CLANG_VER"] = job[HOST_COMPILER][VERSION]
         else:
             raise RuntimeError(
                 "generate_job_yaml.job_variables(): unknown CUDA host compiler: " f"{job[HOST_COMPILER][NAME]}"
             )
 
     if job[DEVICE_COMPILER][NAME] == CLANG_CUDA:
-        variables["CC"] = "clang"
-        variables["CXX"] = "clang++"
+        variables["ALPAKA_CI_CXX"] = "clang++"
         variables["ALPAKA_CI_CLANG_VER"] = job[DEVICE_COMPILER][VERSION]
-        variables["CMAKE_CUDA_COMPILER"] = "clang++"
+        variables["ALPAKA_CI_CUDA_COMPILER"] = "clang++"
 
     # oneAPI configuration
     if job[DEVICE_COMPILER][NAME] == ICPX:
-        variables["CC"] = "icx"
-        variables["CXX"] = "icpx"
+        variables["ALPAKA_CI_CXX"] = "icpx"
         if job[DEVICE_COMPILER][VERSION] == "2024.0":
             variables["ALPAKA_CI_CLANG_VER"] = "17"
         variables["ALPAKA_CI_STDLIB"] = "libstdc++"