Add CMake logic to support HIP test build

CMakeLists.txt

@@ -18,6 +18,7 @@ option(MDSPAN_ENABLE_EXAMPLES "Build examples." Off)
 option(MDSPAN_ENABLE_BENCHMARKS "Enable benchmarks." Off)
 option(MDSPAN_ENABLE_COMP_BENCH "Enable compilation benchmarks." Off)
 option(MDSPAN_ENABLE_CUDA "Enable Cuda tests/benchmarks/examples if tests/benchmarks/examples are enabled." Off)
+option(MDSPAN_ENABLE_HIP "Enable HIP tests/benchmarks/examples if tests/benchmarks/examples are enabled." Off)
 option(MDSPAN_ENABLE_OPENMP "Enable OpenMP benchmarks if benchmarks are enabled." On)
 option(MDSPAN_USE_SYSTEM_GTEST "Use system-installed GoogleTest library for tests." Off)
 
@@ -115,6 +116,22 @@ if(MDSPAN_ENABLE_CUDA)
   endif()
 endif()
 
+if(MDSPAN_ENABLE_HIP)
+  include(CheckLanguage)
+  check_language(HIP)
+  if(CMAKE_HIP_COMPILER)
+    message(STATUS "Using ${CMAKE_CXX_STANDARD} as CMAKE_HIP_STANDARD")
+    set(CMAKE_HIP_STANDARD ${CMAKE_CXX_STANDARD})
+    set(CMAKE_HIP_STANDARD_REQUIRED ON)
+    enable_language(HIP)
+  else()
+    message(FATAL_ERROR "Requested HIP support, but no CMAKE_HIP_COMPILER available")
+  endif()
+  if(MDSPAN_ENABLE_TESTS)
+    set(MDSPAN_TEST_LANGUAGE HIP)
+  endif()
+endif()
+
 ################################################################################
 
 add_library(mdspan INTERFACE)