I'm sending this to maintainers who maintain involved pkgs. People that might be also interested are in Cc, please let me know should you find this mail too spammy/annoying :)
Next time please send this to the appropriate mailing list (arch-general or aur-general in most cases) and if you feel it's necessary you can still CC the maintainers.
The problem in question is a conflicting file, namely /usr/lib/libOpenCL.so (and possibly so version symlinks too). This file is currently provided by these packages (that I know of): nvidia-utils [extra], lib32-nvidia-utils [multilib],
multilib/lib32-nvidia-utils (275.09.07-1) : /usr/lib32/libOpenCL.so extra/nvidia-utils (275.09.07-1) : /usr/lib/libOpenCL.so There is no conflict.
Therefore, a sollution might be to simply pick one of available ICD loaders (a thin one preferably) and make it a dependency for other pkgs.
We only have one in our repos so there's nothing to do as far as I can tell. In case I misunderstood something, please clarify. -- Florian Pritz