最近の変更で @Observable が struct にはつけられなくなってしまいましたね… [5.9] Observable protocol non-marker, @Observable class only by natecook1000 · Pull Request #67196 · apple/swift https://github.com/apple/swift/pull/67196

[5.9] Observable protocol non-marker, @Observable class only by nat...

Explanation: Three top-level changes: Converts Observable to be a non-marker protocol, which in turns requires a change in the @Observable macro to emit a conformance extension only when the targe...