https://www.khronos.org/registry/cl/specs/
# get it
git clone --recursive https://github.com/KhronosGroup/OpenCL-CLHPP.git && \
cd OpenCL-CLHPP && \
mkdir build && \
cd build
# test it
git clean -dfx ; cmake .. \
-DCMAKE_C_COMPILER=gcc-9 -DCMAKE_CXX_COMPILER=g++-9 \
-DCMAKE_CXX_FLAGS="-fmax-errors=1" \
-DOPENCL_INCLUDE_DIR=/opt/intel/oneapi/compiler/2021.1-beta08/linux/include/sycl/ \
-DOPENCL_LIB_DIR=/opt/intel/oneapi/compiler/2021.1-beta08/linux/lib/ && make