Fix no-cuda build (#484)

Closes #482

Authors:
  - Mads R. B. Kristensen (https://github.com/madsbk)

Approvers:
  - Lawrence Mitchell (https://github.com/wence-)
  - Bradley Dice (https://github.com/bdice)

URL: #484

cpp/CMakeLists.txt

@@ -145,7 +145,10 @@ if(KvikIO_BUILD_EXAMPLES)
   add_subdirectory(examples)
 endif()
 
-if(KvikIO_BUILD_TESTS AND CMAKE_PROJECT_NAME STREQUAL PROJECT_NAME)
+if(CUDAToolkit_FOUND
+   AND KvikIO_BUILD_TESTS
+   AND CMAKE_PROJECT_NAME STREQUAL PROJECT_NAME
+)
   include(cmake/thirdparty/get_gtest.cmake)
 
   # include CTest module -- automatically calls enable_testing()

cpp/include/kvikio/utils.hpp

@@ -25,7 +25,9 @@
 #include <tuple>
 #include <type_traits>
 
+#ifdef KVIKIO_CUDA_FOUND
 #include <nvtx3/nvtx3.hpp>
+#endif
 
 #include <kvikio/error.hpp>
 #include <kvikio/shim/cuda.hpp>
@@ -291,6 +293,7 @@ inline bool is_future_done(const T& future)
   return future.wait_for(std::chrono::seconds(0)) != std::future_status::timeout;
 }
 
+#ifdef KVIKIO_CUDA_FOUND
 /**
  * @brief Tag type for libkvikio's NVTX domain.
  */
@@ -309,6 +312,7 @@ struct libkvikio_domain {
     }                                                         \
   }
 #define GET_KVIKIO_NVTX_FUNC_RANGE_MACRO(_1, _2, NAME, ...) NAME
+#endif
 
 /**
  * @brief Convenience macro for generating an NVTX range in the `libkvikio` domain
@@ -329,9 +333,15 @@ struct libkvikio_domain {
  * }
  * ```
  */
+#ifdef KVIKIO_CUDA_FOUND
 #define KVIKIO_NVTX_FUNC_RANGE(...)                                  \
   GET_KVIKIO_NVTX_FUNC_RANGE_MACRO(                                  \
     __VA_ARGS__, KVIKIO_NVTX_FUNC_RANGE_2, KVIKIO_NVTX_FUNC_RANGE_1) \
   (__VA_ARGS__)
+#else
+#define KVIKIO_NVTX_FUNC_RANGE(...) \
+  do {                              \
+  } while (0)
+#endif
 
 }  // namespace kvikio