AMD only supports OpenCL 2.0 today.

So practically speaking, OpenCL 2.0 is the best you can get, unless you want to run on Intel's iGPUs or Intel's AVX 512 on their CPUs.

AMD does have support of C++ in OpenCL 1.2 as an optional extension, but their support of C++ in OpenCL 1.2 doesn't work when you enable OpenCL 2.0 for some reason. Also, the CodeXL debugger only works on OpenCL 1.2 at the moment...

As far as I can tell, AMD's implementation of OpenCL 2.0 is still early stage. Its fine if you're cool with debugging with "printf" statements.

I know, most of the drivers still don't support it properly after two years, and there are no good debuggers available.

Meanwhile on the CUDA C++ side,

"Designing (New) C++ Hardware” - https://www.youtube.com/watch?v=86seb-iZCnI

That was an interesting talk.