Correctly propagate C++17 standard flags to NVCC compilation with older CMake versions.#93
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… source compilation. Signed-off-by: Josh Romero <joshr@nvidia.com>
…logic to handle C++ std for .cu files. Signed-off-by: Josh Romero <joshr@nvidia.com>
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A user reported compilation issues for cuDecomp using the most recent NVHPC release (25.9) against CUDA 13.0. The root cause of their issue was a combination of an older GCC (earlier than GCC-10) and older CMake version (earlier than 3.18).
#72 bumped the required C++ standard to 17 to address deprecation warnings from
libcu++about C++14, which became a true compilation error in thelibcu++version packaged with CUDA 13. It turns out that CMake versions older than 3.18 do not propagate the C++17 flags (viaCMAKE_CXX_STANDARD=17) to.cufile compilation, likely becauseCMAKE_CUDA_STANDARDdoes not support C++17 until CMake 3.18 (ref). This doesn't matter if the GCC compiler is 10 or newer, as C++17 is the default standard applied and works in lieu of CMake providing the C++17 flags tonvcc, but breaks when the GCC is older and the default standard is pre-C++17.To address this, I am manually adding
-std=c++17toCMAKE_CUDA_FLAGSfor CMake versions prior to 3.18. While I could make the CMake minimum version 3.18, this would break builds on Ubuntu 20.04 which defaults to CMake 3.16.