Windows: (soft) Require CUDA >= 12.4 on windows for pyflamegpu support due to c++20 errors

Author: ptheywood

README.md

@@ -63,7 +63,8 @@ Building FLAME GPU has the following requirements. There are also optional depen
 
 + [CMake](https://cmake.org/download/) `>= 3.25.2`
 + [CUDA](https://developer.nvidia.com/cuda-downloads) `>= 12.0` and a [Compute Capability](https://developer.nvidia.com/cuda-gpus) `>= 5.0` NVIDIA GPU.
-  + FLAME GPU aims to support the 2 most recent major CUDA versions, currently 12.x and 13.x
+  + FLAME GPU aims to support the 2 most recent major CUDA versions, currently `12` and `13`
+    + On Windows, CUDA >= 12.4 is required for some optional features (python support)
 + C++20 capable C++ compiler (host), compatible with the installed CUDA version
   + [Microsoft Visual Studio 2022](https://visualstudio.microsoft.com/) (Windows)
     + *Note:* Visual Studio must be installed before the CUDA toolkit is installed. See the [CUDA installation guide for Windows](https://docs.nvidia.com/cuda/cuda-installation-guide-microsoft-windows/index.html) for more information.
@@ -76,6 +77,7 @@ Optionally:
 + [Doxygen](http://www.doxygen.nl/) to build the documentation
 + [Python](https://www.python.org/) `>= 3.8` for python integration
   + With `setuptools`, `wheel`, `build` and optionally `venv` python packages installed
+  + On Windows, CUDA >= 12.4 is required for python integration
 + [swig](http://www.swig.org/) `>= 4.1.0` for python integration (with c++20 support)
   + Swig >= `4.1.0` will be automatically downloaded by CMake if not provided (if possible).
   + Swig `4.2.0` is problematic

swig/python/CMakeLists.txt

@@ -23,6 +23,17 @@ get_filename_component(FLAMEGPU_ROOT ${CMAKE_CURRENT_SOURCE_DIR}/../../ REALPATH
 # Ensure that the cuda toolkit package is available
 find_package(CUDAToolkit REQUIRED)
 
+# If using MSVC and CUDA < 12.4, pyflamegpu may fail to build in c++20 mode. Please use a newer CUDA for pyflamegpu support.
+if (MSVC AND CMAKE_CUDA_COMPILER_VERSION VERSION_LESS 12.4)
+    message(WARNING
+        " pyflamegpu may fail to build with MSVC and CUDA < 12.4 due to compilation errors under c++20.\n"
+        " \n"
+        " Please upgrade to CUDA >= 12.4 for pyflamegpu on Windows.\n"
+        " \n"
+        " Alternatively, WSL can be used for pyflamegpu with CUDA < 12.4 on Windows (excluding interactive visualisation)"
+    )
+endif()
+
 # include CMake function to enable setting of warning suppressions
 include(${FLAMEGPU_ROOT}/cmake/warnings.cmake)
 # Get FLAMEGPU Version information