Future workに出ているUnsafeTransfer みたいな感じですかね？これはUnsafeですが... // The caller *promises* that it won't use the transferred object. https://github.com/apple/swift-evolution/blob/main/proposals/0302-concurrent-value-and-concurrent-closures.md#adaptor-types-for-legacy-codebases (edited)

swift-evolution/0302-concurrent-value-and-concurrent-closures.md at...

This maintains proposals for changes and user-visible enhancements to the Swift Programming Language. - swift-evolution/0302-concurrent-value-and-concurrent-closures.md at main · apple/swift-evolution