Mutable Dispatch interaction with zero sized enqueue is unspecified

[EwanC]

This issue is split of from original issue #1437

From @AhmedAmraniAkdi

1- Are zero sized enqueue kernels allowed to be modified in the command buffer?

Starting from OpenCL 2.1 and newer devices, zero sized enqueue is supported. What is the expected behaviour when changing the global size in this case?

I understand a zero sized clCommandNDRangeKernelKHR can be used for synchronisation, is it still correct to change the global size in such case?

Reply from @EwanC

I don't think we have any wording that forbids either a) updating from zero global size to a non-zero global size, or b) updating for a non-zero global size to a zero global size. So if a device with OpenCL 2.1 or newer implements the extension, then as the extension is currently specified then they should work. Saying that, I don't think we have any CTS tests for these cases, if we confirm the group does indeed want this behavior, we should add those to the CTS.

We discussed this on the 19/08/2025 OpenCL WG call, and it was variable how much implementation effort would be required to support this for all vendors and some prototyping research may be required before making a decision.