Crash occurs while attempting to use _printChanges() on a reducer that utilizes @Shared

[kevinanderson7]

Description

After upgrading our project that utilizes TCA and swift-sharing to use version 2.3.1 of swift-sharing, we are noticing a crash that occurs whenever the _printChanges() is used while debugging reducer state that leverages the @shared property wrapper. I have created a minimal project that reproduces the issue. We did not seem to see a crash while using swift-sharing 1.1.3, but from what I can tell, the issue seems to begin starting with version 2.0.0.

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

I would expect the _printChanges() function to print out changes without crashing for reducer state that utilizes the @shared property wrapper.

Actual behavior

A crash is observed as soon as _printChanges() is applied to the reducer.

Reproducing project

sharing-regression.zip

Sharing version information

2.3.1

Destination operating system

iOS 18.3.1

Xcode version information

Xcode 16.2

Swift Compiler version information

swift-driver version: 1.115.1 Apple Swift version 6.0.3 (swiftlang-6.0.3.1.10 clang-1600.0.30.1)

[jshier]

Looks like an infinite loop in isMirrorEqual.

[jshier]

It seems to be looping through the Combine subscriptions and PassthroughRelay.

[stephencelis]

The easiest fix here is to make sure SomeCustomStruct is equatable, bypassing our mirror equality check, but I'll look into a potential fix.