returning CL_INVALID_OPERATION from clSetProgramSpecializationConstant

When we made IL programs optional in OpenCL 3.0, we added the error condition for clSetProgramSpecializationConstant:

CL_INVALID_OPERATION if no devices associated with program support intermediate language programs.

Note that clSetProgramSpecializationConstant also has the error condition:

CL_INVALID_PROGRAM if program is not a valid program object created from an intermediate language (e.g. SPIR-V), or if the intermediate language does not support specialization constants.

In the description of clCreateProgramWithIL, though, we also have the error condition:

CL_INVALID_OPERATION if no devices in context support intermediate language programs.

This means:

• If no devices in the context support intermediate language programs, it is impossible to create a valid program object created from an intermediate language, because clCreateProgramWithIL will return an error.
• Therefore, the CL_INVALID_OPERATION error condition for clSetProgramSpecializationConstant is debatably redundant and unnecessary, because in all of the conditions when it could be returned it will also be a CL_INVALID_PROGRAM.

We have a "consistency check" CTS test for this scenario, but note that the error could just as correctly be CL_INVALID_PROGRAM (since the program is created from source) as it could be CL_INVALID_OPERATION (since no devices associated with the program support IL programs).

https://github.com/KhronosGroup/OpenCL-CTS/blob/b8f8906c251926b1b3679323bfbf3df730b40fb8/test_conformance/api/test_api_consistency.cpp#L955

Should we remove this error condition (and update the CTS)? Or, is there a different way we should phrase the error condition, instead?

Start by comparing the clSetProgramSpecializationConstant and clCreateProgramWithIL error conditions in the linked OpenCL specification sections. Then inspect test_conformance/api/test_api_consistency.cpp around line 955. Done means the error wording has an agreed resolution and the consistency test is updated to match it.