FindCUDAToolkit: Search all of nvcc implicit includes and library dirs

Improves the handling of CUDA layouts where we have multiple include
and library directories listed in the output of `nvcc -v`. This
updates both when the CUDA language is enabled or not.

Fixes: #24915

Tests/Cuda/Toolkit/CMakeLists.txt

@@ -26,9 +26,11 @@ set(should_exist
   CUDAToolkit_LIBRARY_ROOT
   )
 foreach (cuda_loc_var IN LISTS should_exist)
-  if(NOT EXISTS "${${cuda_loc_var}}")
-    message(FATAL_ERROR "${cuda_loc_var} variable is expected to be set to valid path")
-  endif()
+  foreach (entry IN LISTS ${cuda_loc_var})
+    if(NOT EXISTS "${entry}")
+      message(FATAL_ERROR "${cuda_loc_var} variable is expected to be set to valid path")
+    endif()
+  endforeach()
 endforeach()
 
 

Tests/CudaOnly/Toolkit/CMakeLists.txt

@@ -1,5 +1,5 @@
 cmake_minimum_required(VERSION 3.15)
-project(CudaOnlyToolkit CUDA)
+project(CudaOnlyToolkit LANGUAGES CUDA)
 find_package(CUDAToolkit REQUIRED)
 
 if(NOT DEFINED CUDAToolkit_VERSION)
@@ -13,8 +13,22 @@ message(STATUS "CUDAToolkit_VERSION_PATCH: ${CUDAToolkit_VERSION_PATCH}")
 message(STATUS "CUDAToolkit_BIN_DIR: ${CUDAToolkit_BIN_DIR}")
 message(STATUS "CUDAToolkit_INCLUDE_DIRS: ${CUDAToolkit_INCLUDE_DIRS}")
 message(STATUS "CUDAToolkit_LIBRARY_DIR: ${CUDAToolkit_LIBRARY_DIR}")
+message(STATUS "CUDAToolkit_LIBRARY_ROOT: ${CUDAToolkit_LIBRARY_ROOT}")
 message(STATUS "CUDAToolkit_NVCC_EXECUTABLE ${CUDAToolkit_NVCC_EXECUTABLE}")
 
+set(should_exist
+  CUDAToolkit_BIN_DIR
+  CUDAToolkit_INCLUDE_DIRS
+  CUDAToolkit_LIBRARY_DIR
+  CUDAToolkit_LIBRARY_ROOT
+  )
+foreach (cuda_loc_var IN LISTS should_exist)
+  foreach (entry IN LISTS ${cuda_loc_var})
+    if(NOT EXISTS "${entry}")
+      message(FATAL_ERROR "${cuda_loc_var}[${entry}] variable is expected to be set to valid path")
+    endif()
+  endforeach()
+endforeach()
 
 set(cuda_libs cudart cuda_driver cublas cufft cufftw curand cusolver cusparse)
 if(CUDAToolkit_VERSION VERSION_GREATER_EQUAL 10.1)