message: Use C++14 if building with Ginkgo (required by headers)
diff: @@ -16,6 +16,9 @@ set(USER_CONFIG "${CMAKE_CURRENT_SOURCE_DIR}/config/user.cmake" CACHE PATH
  # Require C++11 and disable compiler-specific extensions
  set(CMAKE_CXX_STANDARD 11)
  +if (MFEM_USE_GINKGO)
  + set(CMAKE_CXX_STANDARD 14)
  +endif()
  set(CMAKE_CXX_STANDARD_REQUIRED ON)
  set(CMAKE_CXX_EXTENSIONS OFF)
  @@ -99,6 +102,9 @@ if (MFEM_USE_CUDA)
  endif()
  enable_language(CUDA)
  set(CMAKE_CUDA_STANDARD 11)
  + if (MFEM_USE_GINKGO)
  + set(CMAKE_CUDA_STANDARD 14)
  + endif()
  set(CMAKE_CUDA_STANDARD_REQUIRED ON)
  set(CMAKE_CUDA_EXTENSIONS OFF)
  set(CUDA_FLAGS "--expt-extended-lambda")
  @@ -366,6 +372,9 @@ if (MFEM_USE_HIP)
  if (HIP_ARCH)
  message(STATUS "Using HIP architecture: ${HIP_ARCH}")
  list(APPEND HIP_HIPCC_FLAGS "--amdgpu-target=${HIP_ARCH}")
  + if (MFEM_USE_GINKGO)
  + list(APPEND HIP_HIPCC_FLAGS "-std=c++14")
  + endif()
  endif()
  endif()
  