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kotlinlang

What about adding a contract to delegated properties, which allows smartcast with the provided value by ensuring to always provide the same value?
Use case: kotlinx-cli parser or Compose State. Both libraries ensure the provided value is stable and does not change.
```val parser = ArgParser("ejwrapper")
val jobID by parser.option(ArgType.String)
parser.parse(args) // No changes to jobID after parsing

if (jobID != null) {
    val status = getJobStatus(jobID) // smart cast is not possible because jobID has a open or custom getter```
Current workaround is `!!`, another variable or `let`

I haven't seen proposals like that before, but perhaps it could tie into Roman's last comment in <https://youtrack.jetbrains.com/issue/KT-28413>

Regarding synchronization? I created the ticket <https://youtrack.jetbrains.com/issue/KT-53894>