Use RMM's pached CCCL

Make sure to search for RMM if it will be used. This should pick up the
patched CCCL from RMM.

If RMM is not being used and this is a CUDA build, search for CCCL
explicitly.

Author: jakirkham

CMakeLists.txt

@@ -224,24 +224,6 @@ if(USE_CUDA)
   add_subdirectory(${PROJECT_SOURCE_DIR}/gputreeshap)
 
   find_package(CUDAToolkit REQUIRED)
-  find_package(CCCL CONFIG)
-  if(NOT CCCL_FOUND)
-    message(STATUS "Standalone CCCL not found. Attempting to use CCCL from CUDA Toolkit...")
-    find_package(CCCL CONFIG
-      HINTS ${CUDAToolkit_LIBRARY_DIR}/cmake)
-    if(NOT CCCL_FOUND)
-      message(STATUS "Could not locate CCCL from CUDA Toolkit. Using Thrust and CUB from CUDA Toolkit...")
-      find_package(libcudacxx CONFIG REQUIRED
-        HINTS ${CUDAToolkit_LIBRARY_DIR}/cmake)
-      find_package(CUB CONFIG REQUIRED
-        HINTS ${CUDAToolkit_LIBRARY_DIR}/cmake)
-      find_package(Thrust CONFIG REQUIRED
-        HINTS ${CUDAToolkit_LIBRARY_DIR}/cmake)
-      thrust_create_target(Thrust HOST CPP DEVICE CUDA)
-      add_library(CCCL::CCCL INTERFACE IMPORTED GLOBAL)
-      target_link_libraries(CCCL::CCCL INTERFACE libcudacxx::libcudacxx CUB::CUB Thrust)
-    endif()
-  endif()
 endif()
 
 if(FORCE_COLORED_OUTPUT AND (CMAKE_GENERATOR STREQUAL "Ninja") AND
@@ -327,6 +309,28 @@ if(PLUGIN_RMM)
   list(REMOVE_ITEM rmm_link_libs CUDA::cudart)
   list(APPEND rmm_link_libs CUDA::cudart_static)
   set_target_properties(rmm::rmm PROPERTIES INTERFACE_LINK_LIBRARIES "${rmm_link_libs}")
+
+  # Pick up patched CCCL from RMM
+elseif(USE_CUDA)
+  # If using CUDA and not RMM, search for CCCL.
+  find_package(CCCL CONFIG)
+  if(NOT CCCL_FOUND)
+    message(STATUS "Standalone CCCL not found. Attempting to use CCCL from CUDA Toolkit...")
+    find_package(CCCL CONFIG
+      HINTS ${CUDAToolkit_LIBRARY_DIR}/cmake)
+    if(NOT CCCL_FOUND)
+      message(STATUS "Could not locate CCCL from CUDA Toolkit. Using Thrust and CUB from CUDA Toolkit...")
+      find_package(libcudacxx CONFIG REQUIRED
+        HINTS ${CUDAToolkit_LIBRARY_DIR}/cmake)
+      find_package(CUB CONFIG REQUIRED
+        HINTS ${CUDAToolkit_LIBRARY_DIR}/cmake)
+      find_package(Thrust CONFIG REQUIRED
+        HINTS ${CUDAToolkit_LIBRARY_DIR}/cmake)
+      thrust_create_target(Thrust HOST CPP DEVICE CUDA)
+      add_library(CCCL::CCCL INTERFACE IMPORTED GLOBAL)
+      target_link_libraries(CCCL::CCCL INTERFACE libcudacxx::libcudacxx CUB::CUB Thrust)
+    endif()
+  endif()
 endif()
 
 if(PLUGIN_SYCL)