[SYCL] Reusable Events limitation for cross-context dependencies.

[slawekptak]

Currently, cross-context dependencies are not supported for the Reusable Events APIs.

Cross-context dependencies use host tasks internally, so the event wait might be queued behind the host task in the runtime, which is currently not supported by the extension APIs.

[Copilot]

Pull request overview

This PR updates the SYCL Reusable Events extension to explicitly reject cross-context dependencies for enqueue_wait_event(s), aligning behavior with the current runtime limitation that cross-context waits may be queued behind host-task machinery.

Changes:

• Add context-matching validation to enqueue_wait_event / enqueue_wait_events, throwing sycl::errc::invalid for cross-context waits.
• Update unit tests to expect the new exception behavior for cross-context waits (single and multiple events).
• Extend the scheduler-bypass limitation enforcement in queue_impl::submit_barrier_direct_impl to cover wait-only reusable-events calls (CallerNeedsEvent == false).

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 5 comments.

File	Description
sycl/unittests/Extensions/ReusableEvents.cpp	Adjusts tests to validate that cross-context waits are rejected, and adds a multi-event variant.
sycl/source/reusable_events.cpp	Adds explicit runtime checks to reject cross-context waits in the reusable-events API surface.
sycl/source/detail/queue_impl.cpp	Updates barrier submission control flow to enforce the scheduler-bypass limitation for wait-only reusable-events calls.

[Copilot]

Pull request overview

Copilot reviewed 11 out of 11 changed files in this pull request and generated 2 comments.

Comments suppressed due to low confidence (1)

sycl/unittests/Extensions/ReusableEvents.cpp:531

• Typo in comment: "limiation" should be "limitation".

  // Current limiation is that an event from different context