swift/concurrency-checking-opt-out
Concurrency checking switched off to silence the compiler — `@unchecked Sendable`, `nonisolated(unsafe)`, `@preconcurrency import`, `MainActor.assumeIsolated`. Each removes data-race checking, so `final class Cache: @unchecked Sendable { var items = [Key: Value]() }` corrupts its dictionary under concurrent writes and crashes intermittently. Name the lock, queue or invariant that makes it safe, inline, with a ticket. Not when every mutable member really is guarded — say by what.
**/*.swiftmobile-iosstandards/stacks/swift.md:21Read it in the terminal
The same facts, from the checkout you are already in — no browser, and no network.
$ npx redlinegate explain swift/concurrency-checking-opt-out
Where this came from
You are most likely here from a review comment. A finding names its rule and, when your repository has told Redline where the standard is published, its address:
Redline/HIGH [swift/concurrency-checking-opt-out]: … → …/r/swift/concurrency-checking-opt-out
That second line is written by redline init --docs-url and is empty until an organisation sets one — there is no default, because a link to somebody else's copy of the standard is worse than no link. See Onboard a repository.
In context
The Swift (iOS) standard lists this rule with the rest of its stack, in the file a reviewer and an AI assistant both read.
Other HIGH rules in this stack
swift/unconfined-singleton-stateSingletons with mutable state and no actor/queue confinement — convert to `actor` or confine.swift/completion-handler-in-new-codeCompletion-handler APIs in new code where async/await is available.swift/missing-mainactorMissing `@MainActor` on ObservableObject/ViewModel classes driving UI.swift/unremoved-observer`NotificationCenter` observers without removal (pre-iOS 9-style APIs) or Combine subscriptions without `cancellables` storage.swift/oversized-viewMassive view controllers / SwiftUI views over ~300 lines — extract subviews and view models.swift/stringly-typed-identifiersStringly-typed identifiers (segues, notification names, userInfo keys) — use enums/constants.