[SYCL][PI][OpenCL] unhelpful piProgramCreate error code if extension not supported

[bjoernknafla]

The piProgramCreate function in pi_opencl.cpp checks late in its execution if a device supports the OpenCL cl_khr_il_program extension. If the check fails it returns a CL_INVALID_CONTEXT equivalent PI error code.
This error code seems to indicate that the context is bad and does not convey that a device in the context is missing an extension or is not an OpenCL 2.x device.

[bjoernknafla]

One idea could be to check devices during platform discovery if they support the required functionality for SYCL, e.g., to create a program, and otherwise filter them out as unsupported.
Another idea could be to return a more specific PI error code for the problem and update the documentation of piProgramCreate.

[AlexeySachkov]

@smaslov-intel: FYI

One idea could be to check devices during platform discovery if they support the required functionality for SYCL, e.g., to create a program, and otherwise filter them out as unsupported.

I think this might be pretty surprising for end-users: clinfo or something similar shows the device, but SYCL RT cannot see it. This needs to be well documented and described to end-users if we want to go this way

Another idea could be to return a more specific PI error code for the problem and update the documentation of piProgramCreate.

This sounds better to me. What about CL_INVALID_DEVICE or CL_INVALID_OPERATION? I originally thought about CL_COMPILER_NOT_AVAILABLE, but at "create" stage we don't need a compiler since we are not trying to build anything

[bjoernknafla]

This sounds better to me. What about CL_INVALID_DEVICE or CL_INVALID_OPERATION? I originally thought about CL_COMPILER_NOT_AVAILABLE, but at "create" stage we don't need a compiler since we are not trying to build anything

A PI_INVALID_DEVICE error code makes a lot of sense to me.