No backward compatibility for types conforming to both RawRepresentable and Codable

[junpluse]

Description

Since version 2.7.0, the handling of types in AppStorageKey that conform to both RawRepresentable and Codable has changed. These types are now processed as Codable, which prevents access to values saved in previous versions. This affects types such as the Tagged struct from swift-tagged.

import Sharing
import Tagged

enum Tag {}
typealias TaggedValue = Tagged<Tag, Int>

extension SharedKey where Self == AppStorageKey<TaggedValue>.Default {
    static var value: Self {
        // In swift-sharing 2.6.0, access is done through CastableLookup, 
        // whereas in 2.7.0 it is done through CodableLookup, 
        // resulting in a different data format in UserDefaults.
        Self[.appStorage("value"), default: 0]
    }
}

I understand this change is due to the addition of Codable support in #182, but if this change in behavior is intentional, it may be a good idea to warn library users about it.

Checklist

• I have determined whether this bug is also reproducible in a vanilla SwiftUI project.
• If possible, I've reproduced the issue using the main branch of this package.
• This issue hasn't been addressed in an existing GitHub issue or discussion.

Expected behavior

If the Value of an AppStorageKey conforms to both RawRepresentable and Codable, it can continue to access values saved up to version 2.6.0 even in version 2.7.0 and later.

Actual behavior

If the Value of an AppStorageKey conforms to both RawRepresentable and Codable, it cannot access values saved up to version 2.6.0 in version 2.7.0 or later.

Reproducing project

SharingRawRepresentableCodableDemo.zip

Sharing version information

2.7.0

Destination operating system

iOS 18, macOS 15.6

Xcode version information

16.4

Swift Compiler version information

swift-driver version: 1.120.5 Apple Swift version 6.1.2 (swiftlang-6.1.2.1.2 clang-1700.0.13.5)

[pyrtsa]

This feedback aligns well with my criticism in the PR that got merged and included in the release yesterday, FWIW: #182 (comment)

Precisely the reason we shouldn't overload .appStorage(...) with so many types and protocols at the same time.

[stephencelis]

@junpluse Thanks for the report! We've addressed the regression and added a test with #185. Wanna confirm that this fixes things for you?

@pyrtsa While this regression is unfortunate, support for codable was a constant request that almost every other third party wrapper around user defaults supports. We do think it's possible to add support in a reasonable way and address your concerns. If there's a show-stopping reason to remove support in the future, we are always open to it

[junpluse]

@stephencelis Thanks for the quick fix! It now works as expected in 2.7.1.