Compiling with CMAKE_CXX_STANDARD=17 results in CUDA/Thrust "C++17 is not enabled" compiler warnings #27095
Description
System Information
OpenCV 4.x from a couple days ago (6eaaaa4), Windows 11, cmake 3.31.5, CUDA 12.8
Detailed description
Compiling with CMAKE_CXX_STANDARD=17 still results in CUDA/Thrust "C++17 is not enabled" compiler warnings" See below.
This is probably not an issue now as it still builds, and mixing C++14 and 17 shouldn't be a problem. But, as the warning says, it probably won't work for a lot longer, if CMAKE_CXX_STANDARD is not handled correctly throughout the OpenCV build.
Steps to reproduce
Building OpenCV with:
cmake -S ../../ -B . -G Ninja \
-DCMAKE_BUILD_TYPE=Release \
-DCMAKE_CXX_STANDARD=17 \
-DCMAKE_CXX_STANDARD_REQUIRED:BOOL=ON \
-DCMAKE_CXX_EXTENSIONS:BOOL=OFF \
-DCMAKE_INSTALL_PREFIX:PATH="C:/Users/User/opencv/install/" \
-DBUILD_SHARED_LIBS=ON \
-DBUILD_WITH_STATIC_CRT:BOOL=OFF \
-DBUILD_opencv_world:BOOL=0 \
-DWITH_CUDA:BOOL=1 \
-DOPENCV_EXTRA_MODULES_PATH:PATH="C:/Users/User/opencv_contrib/modules" \
-DCUDNN_LIBRARY:FILEPATH="C:/Program Files/NVIDIA/CUDNN/v9.8/lib/12.8/x64/cudnn.lib" \
-DCUDNN_INCLUDE_DIR:PATH="C:/Program Files/NVIDIA/CUDNN/v9.8/include/12.8" \
-DCMAKE_CUDA_ARCHITECTURES:STRING="86;89;90;100;120" \
-DCUDA_ARCH_BIN="8.6;8.9;9.0;10.0;12.0" \
-DCUDA_ARCH_PTX="12.0" \
The critical part being -DCMAKE_CXX_STANDARD=17. OpenCV's CMake configure output confirms this by showing:
-- C++ standard: 17
However during building, I get a tons of warnings where Thrust indicates that C++17 is not enabled:
[560/3092] Building NVCC (Device) object modules/core/CMakeFiles/cuda_compile_1.dir/src/cuda/cuda_compile_1_generated_gpu_mat_nd.cu.obj
gpu_mat_nd.cu
C:/Program Files/NVIDIA GPU Computing Toolkit/CUDA/v12.8/include\thrust/detail/config/cpp_dialect.h:117: warning: Thrust requires at least C++ 17.C++ 14 is deprecated but still supported.C++ 14 support will be removed in a future release.Define THRUST_IGNORE_DEPRECATED_CPP_DIALECT to suppress this message
Looks like CMAKE_CXX_STANDARD=17 might not be correctly passed through somewhere?
Issue submission checklist
- I report the issue, it's not a question
- I checked the problem with documentation, FAQ, open issues, forum.opencv.org, Stack Overflow, etc and have not found any solution
- I updated to the latest OpenCV version and the issue is still there
- There is reproducer code and related data files (videos, images, onnx, etc)