iOSDC 2026

https://fortee.jp/iosdc-japan-2026/proposal/c6c83b6f-3f12-49bd-8557-e192f605817f

Transcript

1. プログラムは思った通りには動かない、 書いた通りに動く 作者不詳
2. const a = '1'; const b = 2; const c = a + b; console.log(c); // 3? ❌ 🤔
3. const a = '1'; const b = 2; const c = a + b; console.log(c); // '12' 🤮
4. const a = 1; const b = 2; const c = a + b; console.log(c); // 3 😇
5. import Foundation import SamplePackage @main struct Runner { static func main() { SamplePackage.run { print("Hello, world!") } let result = SamplePackage.greeting { "c" } print(result == "C: c") } } import Testing @testable import SamplePackage @Test func run() async throws { SamplePackage.run { print("Hello, world!") } } @Test func greeting() async throws { let result = SamplePackage.greeting { "c" } #expect(result == "C: c") } ※サンプルコードです。実際のコードとは関係ありません。
6. import Foundation import SamplePackage @main struct Runner { static func main() { SamplePackage.run { print("Hello, world!") } let result = SamplePackage.greeting { "c" } print(result == "C: c") } } import Testing @testable import SamplePackage @Test func run() async throws { SamplePackage.run { print("Hello, world!") } } @Test func greeting() async throws { let result = SamplePackage.greeting { "c" } #expect(result == "C: c") } ※サンプルコードです。実際のコードとは関係ありません。
9. 書いた通りに動いていない… だと…？
10. OSのバージョン差異 ライブラリ Xcode/Swift のバージョン差異 のバージョン差異
11. ＿人人人人人人人人＿ ＞ 全て同じ条件 ＜ ￣Y^Y^Y^Y^YY^Y^￣
12. 🤔
13. // swift-tools-version: 6.3 import PackageDescription let package = Package( name: "iOSDC2026_SampleRunner", products: [], dependencies: [ .package(name: "iOSDC2026_Sample", path: "../"), ], targets: [ .executableTarget( name: "SampleRunner", dependencies: [ .product( name: "SamplePackage", package: "iOSDC2026_Sample" ), ], swiftSettings: [ .enableUpcomingFeature("ForwardTrailingClosures"), ], ), ], swiftLanguageModes: [.v5] ) // swift-tools-version: 6.3 import PackageDescription let package = Package( name: "iOSDC2026_Sample", products: [ .library( name: "SamplePackage", targets: ["SamplePackage"] ), ], targets: [ .target( name: "SamplePackage", ), .testTarget( name: "SamplePackageTests", dependencies: ["SamplePackage"] ), ], swiftLanguageModes: [.v5] )
14. お分かりいただけただろうか
15. // swift-tools-version: 6.3 import PackageDescription let package = Package( name: "iOSDC2026_SampleRunner", products: [], dependencies: [ .package(name: "iOSDC2026_Sample", path: "../"), ], targets: [ .executableTarget( name: "SampleRunner", dependencies: [ .product( name: "SamplePackage", package: "iOSDC2026_Sample" ), ], swiftSettings: [ .enableUpcomingFeature("ForwardTrailingClosures"), ], ), ], swiftLanguageModes: [.v5] ) // swift-tools-version: 6.3 import PackageDescription let package = Package( name: "iOSDC2026_Sample", products: [ .library( name: "SamplePackage", targets: ["SamplePackage"] ), ], targets: [ .target( name: "SamplePackage", ), .testTarget( name: "SamplePackageTests", dependencies: ["SamplePackage"] ), ], swiftLanguageModes: [.v5] )
16. フラグが…ない…
17. 完
18. 解説
19. 解説 ForwardTrailingClosures(SE-0286、Swift 5.8+) public func run( _ a: (() -> Void)? = nil, _ b: (() -> Void)? = nil, _ c: (() -> Void)? = nil, ) { if let a { print("\u{001B}[31mRunning A\u{001B}[0m") a() } if let b { print("\u{001B}[32mRunning B\u{001B}[0m") b() } if let c { print("\u{001B}[33mRunning C\u{001B}[0m") c() } } run { print("Hello, world!") } ForwardTrailingClosures = NO ForwardTrailingClosures = YES
20. 解説 Upcoming Feature Flagsはコンパイルに渡すフラグ • 各モジュールはUpcoming Feature Flagsの情報を持たない • モジュール間で分割可能 ForwardTrailingClosures YES ForwardTrailingClosures NO A B
21. 対策(同じ挙動にしたい場合) 全モジュールに適用する-Package内の全targetに適用 let package = Package( name: "SamplePackage", products: [], dependencies: [~], targets: [ .target( name: "FeatureA", dependencies: [~], swiftSettings: [ .enableUpcomingFeature("ForwardTrailingClosures"), ], ), .target( name: "FeatureB", dependencies: [~], swiftSettings: [ .enableUpcomingFeature("ForwardTrailingClosures"), ], ), .target( name: "FeatureC", dependencies: [~], swiftSettings: [ .enableUpcomingFeature("ForwardTrailingClosures"), ], ), … ], )
22. 対策(同じ挙動にしたい場合) 全モジュールに適用する-Package内の全targetに適用 let package = Package( name: "SamplePackage", products: [], dependencies: [~], targets: [ .target( name: "FeatureA", dependencies: [~], ), .target( name: "FeatureB", dependencies: [~], ), .target( name: "FeatureC", dependencies: [~], ), … ], ) package.targets.forEach { $0.swiftSettings = [ .enableUpcomingFeature("ForwardTrailingClosures"), ] }
23. 対策(同じ挙動にしたい場合) 全モジュールに適用する-複数Packageを跨ぐ場合 • 仕組みで検知するのは難しい🥺
24. そこでAIの出番🤖
26. まとめ • 書いたとおりに動いていないと思っていたけど結局書いた通りに動いていた • Package.swiftやxcodeprojのBuild Settingsも疑おう • そもそもそんな変な実装するな
27. もう対応終わってるし！ なんならSwift 6対応できてるし！ 😤
28. NonisolatedNonsendingByDefault ImmutableWeakCaptures MemberImportVisibility Swift 7対応が待ってます😇 InferIsolatedConformances InternalImportsByDefault ExistentialAny
29. Self Introduction • 417.72KI • Twitter: @417̲72ki • GitHub: 417-72KI • Icon by: @fredii • Working at: (REDACTED)
30. おまけ
31. コンパイル時に評価される過程 SILで差分確認 $ swiftc -emit-silgen -swift-version 5 sample.swift > sample-5.sil $ swiftc -emit-silgen -swift-version 6 sample.swift > sample-6.sil import Foundation public func run( _ a: (() -> Void)? = nil, _ b: (() -> Void)? = nil, _ c: (() -> Void)? = nil, ) {} run { print("Hello world!") }
33. プログラムは思った通りには動かない。 書いた通りに動k... 動かない...だと...？ 2026/09/13 iOSDC 2026 Day 2