WIP: Add curand's repackaged location when using nvhpc, but this then…

… exposes an issue with thrust.

src/CMakeLists.txt

@@ -656,6 +656,76 @@ target_link_libraries(${PROJECT_NAME} PUBLIC CUDA::nvrtc)
 
 target_link_libraries(${PROJECT_NAME} PUBLIC CUDA::cuda_driver)
 
+# If using cuda installed with older nvhpc, the location of curand won't implicitly be on the include directory path, so we must explicitly specify it.
+
+# do a find path for curand.h at the expected nvcc location. If it does not exist there, then try again where nvhpc places it, and if found add that to the include directories. Potentially this is not required for new enough nvhpc with gcc as the host compiler. 
+# Could also detect if this is neccesary via try compile, set a cache var, and if the cache var exists use that?
+message("CUDAToolkit_INCLUDE_DIRS ${CUDAToolkit_INCLUDE_DIRS}")
+find_path(curand_INCLUDE_DIRS
+    NAMES
+        curand.h
+    PATHS
+        ${CUDAToolkit_INCLUDE_DIRS}
+    NO_CACHE
+)
+# if not found, probably an nvhpc install (or curand is not installed)
+if(NOT curand_INCLUDE_DIRS)
+    # search for the (expected) split math library location
+    message(WARNING "curand not found at expected location, must be an nvhpc install.")
+    # if using nvhpc as the host compiler 
+    if(CMAKE_VERSION VERSION_GREATER_EQUAL "3.19")
+        file(REAL_PATH "${CUDAToolkit_LIBRARY_DIR}/../../../math_libs/${CUDAToolkit_VERSION_MAJOR}.${CUDAToolkit_VERSION_MINOR}" curand_split_search_dir)
+    else()
+        message(FATAL_ERROR "@todo - use get filename component isntead.")
+        get_filename_component(curand_split_search_dir "@todo" REALPATH)
+    endif()
+    message("curand_split_search_dir ${curand_split_search_dir}")
+    find_file(curand_header_abspath
+        NAMES
+            curand.h
+            include/curand.h
+        PATHS
+            ${curand_split_search_dir}
+        NO_CACHE
+    )
+    # if we still don't have curand, we probably can't continue so error.
+    if(NOT curand_header_abspath)
+        message(FATAL_ERROR "${curand_header_abspath} not found @todo")
+    else()
+        # if we found curand at the exepcted nvhpc installation location, we might have to resolve symlinks again, and return the parent directory
+        if(CMAKE_VERSION VERSION_GREATER_EQUAL "3.19")
+        message("curand_header_abspath ${curand_header_abspath}")
+            file(REAL_PATH "${curand_header_abspath}" curand_header_abspath)
+            cmake_path(GET curand_header_abspath PARENT_PATH curand_INCLUDE_DIRS)
+        else()
+            message(FATAL_ERROR "@todo - use get filename component isntead.")
+            get_filename_component(curand_split_search_dir "@todo" REALPATH)
+        endif()
+
+        # message(FATAL_ERROR "curand_INCLUDE_DIRS ${curand_INCLUDE_DIRS}")
+
+        target_include_directories(${PROJECT_NAME} PUBLIC ${curand_INCLUDE_DIRS})
+        unset(curand_header_abspath)
+    endif()
+endif()
+unset(curand_INCLUDE_DIRS)
+
+# @todo - correctly detect where nvcc came from, but when nvhpc is not the host compiler.
+# @todo - if using nvhpc and version is older, or using an nvcc install from within nvhpc?
+# if(CMAKE_CXX_COMPILER_ID STREQUAL "NVHPC" AND CMAKE_CXX_COMPILER_VERSION VERSION_LESS "22.3")
+#     target_link_libraries(${PROJECT_NAME} PUBLIC CUDA::curand)
+#     message(FATAL_ERROR "older nvhpc, doi curand manually")
+# # else()
+#     # message(FATAL_ERROR "${CMAKE_CXX_COMPILER_ID} ${CMAKE_CXX_COMPILER_VERSION}")
+# endif()
+
+# If using cuda installed with older nvhpc, and nvhpc as the host compiler, need to ensure that curands repackaged include directory is on the include path. the CUDA::curand target does not do this.
+# if(CMAKE_CXX_COMPILER_ID STREQUAL "NVHPC")
+#     target_link_libraries(${PROJECT_NAME} PUBLIC CUDA::curand)
+#     message(FATAL_ERROR "CUDAToolkit_INCLUDE_DIRS ${CUDAToolkit_INCLUDE_DIRS}")
+#     target_include_directories(${PROJECT_NAME} PUBLIC ${})
+# endif()
+
 if(FLAMEGPU_ENABLE_NVTX AND TARGET NVTX::nvtx)
     target_link_libraries(${PROJECT_NAME} PUBLIC NVTX::nvtx)
     # Get the version to set a definition value