RMM error is unclear when LIBCUDACXX_ENABLE_EXPERIMENTAL_MEMORY_RESOURCE is not provided

[bdice]

Currently, RMM uses experimental features from libcudacxx. We define this in CMake (

rmm/CMakeLists.txt

Line 104 in c1ccdad

target_compile_definitions(rmm INTERFACE LIBCUDACXX_ENABLE_EXPERIMENTAL_MEMORY_RESOURCE)

) but not all users of RMM are consuming it via CMake (some people use Makefiles, etc.).

The error that users see looks like this:

/home/myuser/include/rmm/mr/device/device_memory_resource.hpp:312:65: error: 'cuda::mr' has not been declared
  312 |   friend void get_property(device_memory_resource const&, cuda::mr::device_accessible) noexcept {}

RMM should detect this case at compile time and explicitly issue a message about requiring LIBCUDACXX_ENABLE_EXPERIMENTAL_MEMORY_RESOURCE to be defined.

Maybe something like:

#ifndef LIBCUDACXX_ENABLE_EXPERIMENTAL_MEMORY_RESOURCE
#error "LIBCUDACXX_ENABLE_EXPERIMENTAL_MEMORY_RESOURCE must be defined to use RMM memory resources."
#endif

would suffice.

Alternatively we could explore enabling this definition in the RMM C++ code (if it's not defined).

[bdice]

This issue came from a Slack conversation with @ZiqiFrancisFan.