https://github.com/simonnickel/fb14108914-swift6bindingisolatedcrash

https://github.com/simonnickel/fb14108914-swift6bindingisolatedcrash

Last synced: about 1 month ago
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• Host: GitHub
• URL: https://github.com/simonnickel/fb14108914-swift6bindingisolatedcrash
• Owner: simonnickel
• Created: 2024-06-28T09:09:02.000Z (7 months ago)
• Default Branch: main
• Last Pushed: 2024-06-28T12:14:14.000Z (7 months ago)
• Last Synced: 2024-12-16T16:06:20.365Z (about 1 month ago)
• Language: Swift
• Size: 17.6 KB
• Stars: 0
• Watchers: 1
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md

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README

        
#  FB14108914 - Swift 6: Binding with isolated closures failes to compile / crashes

## Scenario

A SwiftUI app has a class that provides a custom Binding where the closures capture self to store the value.

## Issue

To be compliant with Swift 6 strict concurrency checking, the class and the closures are isolated to @MainActor.

When compiling with Swift 5.10 and strict concurrency checking = complete, there are no warnings and the binding is working fine.

When compiling with Swift 6, the code fails to compile without proper error message (see file: Build Swift6BindingIsolatedCrash_2024-06-28T10-51-08.txt).

~~In the actual project I encountered this issue, it was able to build, but the app crashed on initialisation of the binding. In this case, the binding is defined in a package with swiftLanguageVersions: [.version("6")] set and the consuming project set to compile with Swift 6.~~

Update: When the class is defined using Generics, the code compiles but crashes when the Binding is created.

	

## Example code

The example shows a Toggle, which uses a binding setup as described above. 

There are 2 implementations of the BindingProvider:

1. Without Generics: When compiled with Swift 5, it works fine. When compiled with Swift 6 it fails.

2. With Generics: Compiles with Swift 5 and 6, but crashes with Swift 6. 

## Tested on

	- Xcode Version 16.0 beta (16A5171c)