Cancellation is lost between registration and start

Rule ID: concurrency.cancel-register-start-race@1.0.0. Availability below refers to source-scan at product 524fa07e.

V-ASYNC-08 — Cancellation is lost between registration and start#

Cancellation is lost between registration and start. It examines task ordering, suspension, cancellation, progress, and async obligations.

Availability#

Not available in source-scan. There is no source-scan flag to activate this condition.

Example and action#

Illustrative design scenario, not a runnable Swift example or a reproduced analyzer result. The stated availability and evidence boundaries still apply.

Before: Cancellation arrives before an operation handle is stored, so the cancellation callback has nothing to cancel and start proceeds afterward.

Review the following change against the contract and build variants described above.

After: Keep cancelled, starting and started states under one synchronization protocol. A start that observes prior cancellation must not escape it; registering a handle after cancellation must immediately follow the defined cancellation path.

Intended analysis#

Intended reasoning: Follow the relevant state, task or synchronization events across control-flow and suspension boundaries. The intended decision needs the complete event ordering and the operation contract; opaque events can leave the result unknown. Required evidence: task, suspension, cancellation, ordering, and progress facts

Assumptions and unknown#

The relevant facts must be admitted for the selected immutable build world. Unknown aliases, external effects, unsupported source forms or incomplete consumers can prevent a conclusion. Availability in this workflow is stated above; the illustration does not expand that availability.

Evidence and interpretation#

The target catalog describes the intended condition. It is not evidence of an active source-scan diagnostic.

Historical evidence at 4558458d: recovery-required (historical qualification is incomplete and needs further evidence). That evidence has not been requalified for this product revision.

How we validate checks explains the evidence boundary. Foundations separates method assumptions from implementation claims.