how can I migrate to swift 6 without modifiying my code base

To migrate to Swift 6 without modifying your code base, you can take advantage of Swift's source compatibility guarantee. This means that, aside from very minor changes, your app should build with the new Swift 6 compiler without requiring modifications. However, to fully benefit from Swift 6's new features, such as data race safety, you will need to enable the Swift 6 language mode.

Here's a step-by-step approach to migrate incrementally:

1. Enable Complete Concurrency Checking: This is a per-module setting that allows you to remain in Swift 5 mode while receiving warnings for code that would fail under Swift 6's enforced data isolation. This helps identify areas that need attention.

2. Resolve Warnings: Address the warnings generated by the concurrency checking to ensure your code is ready for Swift 6.

3. Enable Swift 6 Mode: Once the warnings are resolved for a module, enable Swift 6 mode to lock in changes and prevent regressions.

4. Repeat for Each Module: Continue this process for each module in your project.

5. Consider Whole App Refactoring: After migrating all modules, you might want to refactor the entire app to optimize for Swift 6's features.

This incremental approach allows you to migrate at your own pace and ensures that your codebase remains stable throughout the transition.

For more detailed guidance, you can refer to the session Migrate your app to Swift 6 (07:26) which covers the strategy for migration.