---
title: Migrating to upcoming language features
framework: swift-migration-guide
path: swift-migration-guide/documentation/swift-6-concurrency-migration-guide/featuremigration
---

# Migrating to upcoming language features

Migrate your project to upcoming language features.

## SwiftPM

Upcoming language features can be enabled in the Swift compiler via a -enable-upcoming-feature <FeatureName> flag. Some of these features also support a migration mode. This mode does not actually enable the desired feature. Instead, it produces compiler warnings with the necessary fix-its to make the existing code both source- and binary-compatible with the feature. The exact semantics of such a migration is dependent on the feature, see their corresponding documentation for more details. SwiftPM note: This feature is in active development. Test with a nightly snapshot for best results. swift package migrate builds and applies migration fix-its to allow for semi-automated migration. Make sure to start with a clean working tree (no current changes staged or otherwise) and a working build - applying the fix-its requires there to be no build errors and will modify files in the package in place. To eg. migrate all targets in your package to NonisolatedNonsendingByDefault: swift package migrate --to-feature NonisolatedNonsendingByDefault Or a target at a time with --targets: swift package migrate --targets TargetA --to-feature NonisolatedNonsendingByDefault This will start a build, apply any migration fix-its, and then update the manifest: > Starting the build. ... regular build output with migration diagnostics ... > Applying fix-its. > Updating manifest. Check out the changes with your usual version control tooling, e.g., git diff: diff --git a/Package.swift b/Package.swift index a1e587c..11097be 100644 --- a/Package.swift +++ b/Package.swift @@ -14,10 +14,16 @@ let package = Package(      targets: [          .target(              name: "TargetA", +            swiftSettings: [ +                .enableUpcomingFeature("NonisolatedNonsendingByDefault"), +            ]          ),      ]

diff --git a/Sources/packtest/packtest.swift b/Sources/packtest/packtest.swift index 85253f5..8498bb5 100644 --- a/Sources/TargetA/TargetA.swift +++ b/Sources/TargetA/TargetA.swift @@ -1,5 +1,5 @@  struct S: Sendable { -  func alwaysSwitch() async {} +  @concurrent func alwaysSwitch() async {}  } In some cases, the automated application of upcoming features to a target in the package manifest can fail for more complicated packages, e.g., if settings have been factored out into a variable that’s then applied to multiple targets: error: Could not update manifest for 'TargetA' (unable to find array literal for 'swiftSettings' argument). Please enable 'NonisolatedNonsendingByDefault' features manually. If this happens, manually add a .enableUpcomingFeature("SomeFeature") Swift setting to complete the migration: // swift-tools-version: 6.2

let targetSettings: [SwiftSetting] = [     // ...     .enableUpcomingFeature("NonisolatedNonsendingByDefault") ]

let targetSettings: let package = Package(     name: "MyPackage",     products: [         // ...     ],     targets: [         .target(             name: "TargetA",             swiftSettings: targetSettings         ),     ] )