Compile error with conditionalAssignment and Swift version 5.9

[honkmaster]

With swift-version 5.9 the following code

let hotspotConfiguration: NEHotspotConfiguration
if let passphrase {
  hotspotConfiguration = NEHotspotConfiguration(ssid: ssid, passphrase: passphrase, isWEP: isWEP)
 } else {
  hotspotConfiguration = NEHotspotConfiguration(ssid: ssid)
}

becomes:

let hotspotConfiguration: NEHotspotConfiguration = if let passphrase {
  .init(ssid: ssid, passphrase: passphrase, isWEP: isWEP)
} else {
  .init(ssid: ssid)
}

Subsequently the compilation fails.

Command SwiftCompile failed with a nonzero exit code

Currently, the compiler does not give more information, the current workaround, besides the possibility to revert to 5.8, is to disable conditionalAssignment. The code itself looks fine...

[nicklockwood]

@calda possible Swift bug?

[calda]

Which rule is converting NEHotspotConfiguration( to just .init(? Does the code compile without that change?

[nicklockwood]

@calda good point. Presumably it's https://github.com/nicklockwood/SwiftFormat/blob/main/Rules.md#redundanttype

[honkmaster]

When removing the code above, I get the same error in files where the subsequent shown code snippets were changed (each before / after). Before, the code compiles fine.

(1)

var text: String
if entry.yValues.contains(where: { $0.key == .foo }) {
  text = startFormatted
} else {
  text = startFormatted + "\u{00a0}–\u{00a0}" + endFormatted
}

var text: String = if entry.yValues.contains(where: { $0.key == .foo }) {
  startFormatted
} else {
  startFormatted + "\u{00a0}–\u{00a0}" + endFormatted
}

(2)

let data: Data?
if case let .jpeg(compressionQuality) = imageType {
  data = newValue.jpegData(compressionQuality: compressionQuality)
} else {
  data = newValue.pngData()
 }

let data: Data? = if case let .jpeg(compressionQuality) = imageType {
  newValue.jpegData(compressionQuality: compressionQuality)
} else {
  newValue.pngData()
}

(3) (code changed not due to conditionalAssignment but redundantReturn)

extension MSALManagerError: CustomDebugStringConvertible {
    var debugDescription: String {
        switch self {
        case .invalidURL:
            return "Invalid authority URL provided."
        case .noRootViewController:
            return "App has no root view controller."
        case let .authorityCreation(error):
            return "Can't create authority (\(error.localizedDescription))."
        case let .publicClientApplicationCreation(error):
            return "Can't create application (\(error.localizedDescription))."
        case let .accessAccounts(error):
            return "Error accessing accounts (\(error.localizedDescription))."
        case .noAccountInCache:
            return "No account in cache."
        case .multipleAccountsInCache:
            return "Multiple accounts in cache."
        case .userNotSignedIn:
            return "User not signed in."
        case .unknownTokenError:
            return "Unknown token error."
        case .unknownMSALResultError:
            return "Unknown MSALResult error."
        }
    }
}

extension MSALManagerError: CustomDebugStringConvertible {
    var debugDescription: String {
        switch self {
        case .invalidURL:
            "Invalid authority URL provided."
        case .noRootViewController:
            "App has no root view controller."
        case let .authorityCreation(error):
            "Can't create authority (\(error.localizedDescription))."
        case let .publicClientApplicationCreation(error):
            "Can't create application (\(error.localizedDescription))."
        case let .accessAccounts(error):
            "Error accessing accounts (\(error.localizedDescription))."
        case .noAccountInCache:
            "No account in cache."
        case .multipleAccountsInCache:
            "Multiple accounts in cache."
        case .userNotSignedIn:
            "User not signed in."
        case .unknownTokenError:
            "Unknown token error."
        case .unknownMSALResultError:
            "Unknown MSALResult error."
        }
    }
}

Just to be sure: swiftformat --version <-> 0.52.7; Xcode Version 15.0 (15A240d)

[nicklockwood]

@honkmaster all of the output examples you've given seem to be valid Swift code, and compile OK when I run them in isolation. I suspect you've stumbled across a bug in Swift itself.

In principle I'm OK with adding version-specific fixes to SwiftFormat to work around known Swift bugs, but in this case I think the circumstance that produce the bug probably depend on project-specific context that SwiftFormat wouldn't be able to determine.

My suggestion would be to report this bug to Apple, and to make use of SwiftFormat's // swiftformat:disable:next directives to conditionally exclude these particular cases from being formatted until Apple fixes the issue.