[NFC] Add utility function ur_unreachable to simplify code

[wenju-he]

No description provided.

[wenju-he]

@kbenzie could you please take a look if this PR makes sense?
std::unreachable is only available in c++ 23.

[PietroGhg]

Native CPU LGTM, thank you

[kbenzie]

I think there's a missing include in the CUDA file that's attempting to use ur::unreachable.

[wenju-he]

I think there's a missing include in the CUDA file that's attempting to use ur::unreachable.

added to both cuda/usm.cpp and hip/usm.cpp. I don't have access to cuda/hip machines to verify. After searching the headers used in hip/usm.cpp, it looks like ur_util.hpp is needed.

[kbenzie]

I think there's a missing include in the CUDA file that's attempting to use ur::unreachable.

added to both cuda/usm.cpp and hip/usm.cpp. I don't have access to cuda/hip machines to verify. After searching the headers used in hip/usm.cpp, it looks like ur_util.hpp is needed.

If you could add those includes we can let the CI check if the fix works.

Edit: I missed the commit. Seems there still an issue, I can look into this to see what's gone wrong.

[fabiomestre]

I have updated the target branch of this PR from the adapters branch to the main branch.
Development in UR is moving back to main. The adapters branch will soon be deleted.