originate_on_cancel(false) fails on the second co_await due to missed call, and does not work for IAsyncActions.

[antmor]

Bug: #1617

1. Remove throwing/originating errors in expected scenarios (Lookup/TryLookup and Cancel) #1512 introduced the setter originate_on_cancel and getter should_originate_on_cancel. The await_resume task would call originate_on_cancel (the setter) to check whether to RoOriginate the call. This is a bug, because the setter has a side effect. Its parameter defaults to true, so each call does std::exchange(m_originate_on_cancel, true): it returns the previous value, so the first check behaved correctly, and then wrote the flag back to true. Every later cancellation on that same promise originated again. A test that cancels only once passes even with the bug present.

IAsyncAction DoWork(HANDLE ready)
{
    auto cancel = co_await get_cancellation_token();
    cancel.originate_on_cancel(false);   // "don't debug spew when I'm cancelled"

    co_await resume_on_signal(ready);    // If cancelled before `ready`, doesn't originate.
                                         // The first Cancel() consumes the opt-out, re-arms the flag
    co_await CleanupAsync();             // If cancelled after, then the next co_await will 
                                         // call Cancel() again, and since should_originate is true now
                                         // it will Originate, thus causing the debug spew.
}

2. There was a missing scenario in the previous PR, it did not account for winrt::resume_after, winrt::resume_on_signal, and
   These three awaiter resume paths also threw hresult_canceled unconditionally, so originate_on_cancel(false) had no effect on them at all: impl::check_status_canceled (reached from await_adapter::await_resume for any coroutine awaiting a WinRT async that completes Canceled), timespan_awaiter::await_resume (resume_after) and signal_awaiter::await_resume (resume_on_signal).

Fix:

1. On callers that erroneously called the setter originate_on_cancel, call the getter instead.
2. cancellable_awaiter now captures the promise's preference in await_suspend, where the promise is known to be alive, and consults it on resume. Capturing at suspend time rather than reaching for the promise at resume time keeps await_adapter::await_resume const. check_status_canceled takes an originate parameter defaulting to true, so wait_get and any external callers keep originating exactly as before.

Test:
Adds async_originate_count_on_cancel, covering zero, single and repeated cancellation checks plus each of the three awaiter paths. It counts winrt_throw_hresult_handler invocations as a proxy for RoOriginateLanguageException, since observing the latter requires an out-of-process debugger.

[Copilot]

Pull request overview

Fixes cancellation origination behavior in C++/WinRT coroutines so cancellation_token::originate_on_cancel(false) reliably suppresses RoOriginate... across repeated cancellation checks and across additional awaiter paths (await_adapter, resume_after, resume_on_signal), including for IAsyncAction scenarios called out in #1617.

Changes:

• Stop consulting the stateful setter originate_on_cancel(...) for checks; instead consult should_originate_on_cancel() and thread that preference into cancellation-throw sites.
• Capture the “originate on cancel” preference at suspend time in cancellable_awaiter so resume paths can honor it without reaching back to the promise.
• Add a new regression test that counts winrt_throw_hresult_handler invocations as a proxy for origination across multiple cancellation paths and repeated checks.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 1 comment.

File	Description
test/test/test.vcxproj	Adds the new cancellation-origination regression test to the test project build.
test/test/async_originate_count_on_cancel.cpp	New test coverage for origination suppression across repeated cancellation checks and multiple awaiter resume paths.
strings/base_coroutine_threadpool.h	Captures per-promise origination preference at suspend time and applies it in timespan_awaiter / signal_awaiter cancellation throws.
strings/base_coroutine_foundation.h	Threads an originate choice into check_status_canceled and uses should_originate_on_cancel() in cancellation sites instead of the setter.

---

💡 Add a code-review agent skill or configure MCP servers for context-aware, tailored reviews. Learn more in the docs.