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Track the adoption of Swift 6 strict concurrency checks for data race safety. How many packages are Ready for Swift 6?

Build Information

Successful build of Future, reference 1.4.0 (ff9634), with Swift 6.1 for Linux on 25 Apr 2025 20:46:57 UTC.

Swift 6 data race errors: 3

Build Command

bash -c docker run --pull=always --rm -v "checkouts-4609320-0":/host -w "$PWD" registry.gitlab.com/finestructure/spi-images:basic-6.1-latest swift build --triple x86_64-unknown-linux-gnu -Xswiftc -Xfrontend -Xswiftc -stats-output-dir -Xswiftc -Xfrontend -Xswiftc .stats -Xswiftc -strict-concurrency=complete -Xswiftc -enable-upcoming-feature -Xswiftc StrictConcurrency -Xswiftc -enable-upcoming-feature -Xswiftc DisableOutwardActorInference -Xswiftc -enable-upcoming-feature -Xswiftc GlobalActorIsolatedTypesUsability -Xswiftc -enable-upcoming-feature -Xswiftc InferSendableFromCaptures 2>&1

Build Log

========================================
RunAll
========================================
Builder version: 4.61.0
Interrupt handler set up.
========================================
Checkout
========================================
Clone URL: https://github.com/kean/Future.git
Reference: 1.4.0
Initialized empty Git repository in /host/spi-builder-workspace/.git/
hint: Using 'master' as the name for the initial branch. This default branch name
hint: is subject to change. To configure the initial branch name to use in all
hint: of your new repositories, which will suppress this warning, call:
hint:
hint: 	git config --global init.defaultBranch <name>
hint:
hint: Names commonly chosen instead of 'master' are 'main', 'trunk' and
hint: 'development'. The just-created branch can be renamed via this command:
hint:
hint: 	git branch -m <name>
From https://github.com/kean/Future
 * tag               1.4.0      -> FETCH_HEAD
HEAD is now at ff9634c Version 1.4.0
Cloned https://github.com/kean/Future.git
Revision (git rev-parse @):
ff9634c819962aa78f7bb360fdae7299d62f1cdc
SUCCESS checkout https://github.com/kean/Future.git at 1.4.0
========================================
Build
========================================
Selected platform:         linux
Swift version:             6.1
Building package at path:  $PWD
https://github.com/kean/Future.git
https://github.com/kean/Future.git
WARNING: environment variable SUPPRESS_SWIFT_6_FLAGS is not set
{
  "dependencies" : [
  ],
  "manifest_display_name" : "Future",
  "name" : "Future",
  "path" : "/host/spi-builder-workspace",
  "platforms" : [
    {
      "name" : "macos",
      "version" : "10.13"
    },
    {
      "name" : "ios",
      "version" : "11.0"
    },
    {
      "name" : "tvos",
      "version" : "11.0"
    },
    {
      "name" : "watchos",
      "version" : "4.0"
    }
  ],
  "products" : [
    {
      "name" : "Future",
      "targets" : [
        "Future"
      ],
      "type" : {
        "library" : [
          "automatic"
        ]
      }
    }
  ],
  "targets" : [
    {
      "c99name" : "FutureTests",
      "module_type" : "SwiftTarget",
      "name" : "FutureTests",
      "path" : "Tests/FutureTests",
      "sources" : [
        "A+Tests.swift",
        "CancellationTokenTests.swift",
        "Extensions.swift",
        "FutureExtensionsTests.swift",
        "FutureTests.swift",
        "StressTests.swift"
      ],
      "target_dependencies" : [
        "Future"
      ],
      "type" : "test"
    },
    {
      "c99name" : "Future",
      "module_type" : "SwiftTarget",
      "name" : "Future",
      "path" : "Sources",
      "product_memberships" : [
        "Future"
      ],
      "sources" : [
        "CancellationToken.swift",
        "Future.swift",
        "FutureExtensions.swift",
        "FutureOperators.swift"
      ],
      "type" : "library"
    }
  ],
  "tools_version" : "5.1"
}
Running build ...
bash -c docker run --pull=always --rm -v "checkouts-4609320-0":/host -w "$PWD" registry.gitlab.com/finestructure/spi-images:basic-6.1-latest swift build --triple x86_64-unknown-linux-gnu -Xswiftc -Xfrontend -Xswiftc -stats-output-dir -Xswiftc -Xfrontend -Xswiftc .stats -Xswiftc -strict-concurrency=complete -Xswiftc -enable-upcoming-feature -Xswiftc StrictConcurrency -Xswiftc -enable-upcoming-feature -Xswiftc DisableOutwardActorInference -Xswiftc -enable-upcoming-feature -Xswiftc GlobalActorIsolatedTypesUsability -Xswiftc -enable-upcoming-feature -Xswiftc InferSendableFromCaptures 2>&1
basic-6.1-latest: Pulling from finestructure/spi-images
Digest: sha256:3bdcac04179f4ed3e5b8e9dbd6e74bbf5ebc0f4fde48bbaad7d1e5c757e65bcb
Status: Image is up to date for registry.gitlab.com/finestructure/spi-images:basic-6.1-latest
Building for debugging...
[0/2] Write sources
[1/2] Write swift-version-24593BA9C3E375BF.txt
[3/7] Compiling Future CancellationToken.swift
[4/7] Emitting module Future
/host/spi-builder-workspace/Sources/Future.swift:292:23: warning: static property 'default' is not concurrency-safe because it is nonisolated global shared mutable state; this is an error in the Swift 6 language mode
290 |     /// behavior where callbacks attached via `on` method are always called on
291 |     /// the main thread.
292 |     public static var `default` = Scheduler.main
    |                       |- warning: static property 'default' is not concurrency-safe because it is nonisolated global shared mutable state; this is an error in the Swift 6 language mode
    |                       |- note: convert 'default' to a 'let' constant to make 'Sendable' shared state immutable
    |                       |- note: add '@MainActor' to make static property 'default' part of global actor 'MainActor'
    |                       `- note: disable concurrency-safety checks if accesses are protected by an external synchronization mechanism
293 |
294 |     /// If the task finishes on the main thread, the callbacks are executed
<unknown>:0: note: a function type must be marked '@Sendable' to conform to 'Sendable'
/host/spi-builder-workspace/Sources/Future.swift:297:23: warning: static property 'main' is not concurrency-safe because non-'Sendable' type 'ScheduleWork' (aka '(@escaping () -> ()) -> ()') may have shared mutable state; this is an error in the Swift 6 language mode
295 |     /// immediately. Otherwise, they are dispatched to be executed
296 |     /// asynchronously on the main thread.
297 |     public static let main: ScheduleWork = { work in
    |                       |- warning: static property 'main' is not concurrency-safe because non-'Sendable' type 'ScheduleWork' (aka '(@escaping () -> ()) -> ()') may have shared mutable state; this is an error in the Swift 6 language mode
    |                       |- note: add '@MainActor' to make static property 'main' part of global actor 'MainActor'
    |                       `- note: disable concurrency-safety checks if accesses are protected by an external synchronization mechanism
298 |         Thread.isMainThread ? work() : DispatchQueue.main.async(execute: work)
299 |     }
/host/spi-builder-workspace/Sources/Future.swift:298:74: warning: passing non-sendable parameter 'work' to function expecting a @Sendable closure
295 |     /// immediately. Otherwise, they are dispatched to be executed
296 |     /// asynchronously on the main thread.
297 |     public static let main: ScheduleWork = { work in
    |                                              `- note: parameter 'work' is implicitly non-sendable
298 |         Thread.isMainThread ? work() : DispatchQueue.main.async(execute: work)
    |                                                                          `- warning: passing non-sendable parameter 'work' to function expecting a @Sendable closure
299 |     }
300 |
<unknown>:0: note: a function type must be marked '@Sendable' to conform to 'Sendable'
/host/spi-builder-workspace/Sources/Future.swift:302:23: warning: static property 'immediate' is not concurrency-safe because non-'Sendable' type 'ScheduleWork' (aka '(@escaping () -> ()) -> ()') may have shared mutable state; this is an error in the Swift 6 language mode
300 |
301 |     /// Immediately executes the given closure.
302 |     public static let immediate: ScheduleWork = { work in
    |                       |- warning: static property 'immediate' is not concurrency-safe because non-'Sendable' type 'ScheduleWork' (aka '(@escaping () -> ()) -> ()') may have shared mutable state; this is an error in the Swift 6 language mode
    |                       |- note: add '@MainActor' to make static property 'immediate' part of global actor 'MainActor'
    |                       `- note: disable concurrency-safety checks if accesses are protected by an external synchronization mechanism
303 |         work()
304 |     }
[5/7] Compiling Future Future.swift
/host/spi-builder-workspace/Sources/Future.swift:292:23: warning: static property 'default' is not concurrency-safe because it is nonisolated global shared mutable state; this is an error in the Swift 6 language mode
290 |     /// behavior where callbacks attached via `on` method are always called on
291 |     /// the main thread.
292 |     public static var `default` = Scheduler.main
    |                       |- warning: static property 'default' is not concurrency-safe because it is nonisolated global shared mutable state; this is an error in the Swift 6 language mode
    |                       |- note: convert 'default' to a 'let' constant to make 'Sendable' shared state immutable
    |                       |- note: add '@MainActor' to make static property 'default' part of global actor 'MainActor'
    |                       `- note: disable concurrency-safety checks if accesses are protected by an external synchronization mechanism
293 |
294 |     /// If the task finishes on the main thread, the callbacks are executed
<unknown>:0: note: a function type must be marked '@Sendable' to conform to 'Sendable'
/host/spi-builder-workspace/Sources/Future.swift:297:23: warning: static property 'main' is not concurrency-safe because non-'Sendable' type 'ScheduleWork' (aka '(@escaping () -> ()) -> ()') may have shared mutable state; this is an error in the Swift 6 language mode
295 |     /// immediately. Otherwise, they are dispatched to be executed
296 |     /// asynchronously on the main thread.
297 |     public static let main: ScheduleWork = { work in
    |                       |- warning: static property 'main' is not concurrency-safe because non-'Sendable' type 'ScheduleWork' (aka '(@escaping () -> ()) -> ()') may have shared mutable state; this is an error in the Swift 6 language mode
    |                       |- note: add '@MainActor' to make static property 'main' part of global actor 'MainActor'
    |                       `- note: disable concurrency-safety checks if accesses are protected by an external synchronization mechanism
298 |         Thread.isMainThread ? work() : DispatchQueue.main.async(execute: work)
299 |     }
/host/spi-builder-workspace/Sources/Future.swift:298:74: warning: passing non-sendable parameter 'work' to function expecting a @Sendable closure
295 |     /// immediately. Otherwise, they are dispatched to be executed
296 |     /// asynchronously on the main thread.
297 |     public static let main: ScheduleWork = { work in
    |                                              `- note: parameter 'work' is implicitly non-sendable
298 |         Thread.isMainThread ? work() : DispatchQueue.main.async(execute: work)
    |                                                                          `- warning: passing non-sendable parameter 'work' to function expecting a @Sendable closure
299 |     }
300 |
<unknown>:0: note: a function type must be marked '@Sendable' to conform to 'Sendable'
/host/spi-builder-workspace/Sources/Future.swift:302:23: warning: static property 'immediate' is not concurrency-safe because non-'Sendable' type 'ScheduleWork' (aka '(@escaping () -> ()) -> ()') may have shared mutable state; this is an error in the Swift 6 language mode
300 |
301 |     /// Immediately executes the given closure.
302 |     public static let immediate: ScheduleWork = { work in
    |                       |- warning: static property 'immediate' is not concurrency-safe because non-'Sendable' type 'ScheduleWork' (aka '(@escaping () -> ()) -> ()') may have shared mutable state; this is an error in the Swift 6 language mode
    |                       |- note: add '@MainActor' to make static property 'immediate' part of global actor 'MainActor'
    |                       `- note: disable concurrency-safety checks if accesses are protected by an external synchronization mechanism
303 |         work()
304 |     }
/host/spi-builder-workspace/Sources/Future.swift:309:48: warning: passing non-sendable parameter 'work' to function expecting a @Sendable closure
306 |     /// Runs asynchronously on the given queue.
307 |     public static func async(on queue: DispatchQueue, flags: DispatchWorkItemFlags = []) -> ScheduleWork {
308 |         return { work in
    |                  `- note: parameter 'work' is implicitly non-sendable
309 |             queue.async(flags: flags, execute: work)
    |                                                `- warning: passing non-sendable parameter 'work' to function expecting a @Sendable closure
310 |         }
311 |     }
[6/7] Compiling Future FutureOperators.swift
[7/7] Compiling Future FutureExtensions.swift
/host/spi-builder-workspace/Sources/FutureExtensions.swift:53:13: warning: capture of 'promise' with non-sendable type 'Future<(), Never>.Promise' in a '@Sendable' closure; this is an error in the Swift 6 language mode
 51 |         let promise = Promise()
 52 |         queue.asyncAfter(deadline: deadline) {
 53 |             promise.succeed(value: ()) // Never produces an error
    |             `- warning: capture of 'promise' with non-sendable type 'Future<(), Never>.Promise' in a '@Sendable' closure; this is an error in the Swift 6 language mode
 54 |         }
 55 |         return promise.future
/host/spi-builder-workspace/Sources/Future.swift:202:24: note: class 'Promise' does not conform to the 'Sendable' protocol
200 |
201 |     /// A promise to provide a result later.
202 |     public final class Promise: CustomDebugStringConvertible {
    |                        `- note: class 'Promise' does not conform to the 'Sendable' protocol
203 |         private var memoizedResult: Result? // nil when pending
204 |         private var inlinedHandler: ((Result) -> Void)?
Build complete! (6.13s)
Build complete.
{
  "dependencies" : [
  ],
  "manifest_display_name" : "Future",
  "name" : "Future",
  "path" : "/host/spi-builder-workspace",
  "platforms" : [
    {
      "name" : "macos",
      "version" : "10.13"
    },
    {
      "name" : "ios",
      "version" : "11.0"
    },
    {
      "name" : "tvos",
      "version" : "11.0"
    },
    {
      "name" : "watchos",
      "version" : "4.0"
    }
  ],
  "products" : [
    {
      "name" : "Future",
      "targets" : [
        "Future"
      ],
      "type" : {
        "library" : [
          "automatic"
        ]
      }
    }
  ],
  "targets" : [
    {
      "c99name" : "FutureTests",
      "module_type" : "SwiftTarget",
      "name" : "FutureTests",
      "path" : "Tests/FutureTests",
      "sources" : [
        "A+Tests.swift",
        "CancellationTokenTests.swift",
        "Extensions.swift",
        "FutureExtensionsTests.swift",
        "FutureTests.swift",
        "StressTests.swift"
      ],
      "target_dependencies" : [
        "Future"
      ],
      "type" : "test"
    },
    {
      "c99name" : "Future",
      "module_type" : "SwiftTarget",
      "name" : "Future",
      "path" : "Sources",
      "product_memberships" : [
        "Future"
      ],
      "sources" : [
        "CancellationToken.swift",
        "Future.swift",
        "FutureExtensions.swift",
        "FutureOperators.swift"
      ],
      "type" : "library"
    }
  ],
  "tools_version" : "5.1"
}
basic-6.1-latest: Pulling from finestructure/spi-images
Digest: sha256:3bdcac04179f4ed3e5b8e9dbd6e74bbf5ebc0f4fde48bbaad7d1e5c757e65bcb
Status: Image is up to date for registry.gitlab.com/finestructure/spi-images:basic-6.1-latest
Done.