sealed classes and interfaces can't permit classes or records from sub packages

[david Grajales]

Hello Amber Team,

I’ve observed a counter intuitive behavior, and I’m unsure whether it’s
intentional or a potential issue.

Here’s the scenario:

   1. I have a package named vehicles containing a *sealed interface*
   called Vehicle.
   2. Inside this vehicles package, I’ve created two sub-packages:
      - land-vehicles
      - water-vehicles
   3. Each sub-package contains two records implementing the Vehicle
   interface.

However, the compiler raises an error when I attempt this setup:

"A class is not allowed to extend or implement a sealed class from another
package."

This seems counterintuitive because all components are conceptually part of
the same package with the records merely placed in sub-packages for better
organization.

Here’s a textual representation of the package layout for reference:


vehicles/

├── Vehicle.java            // Sealed interface

├── land-vehicles/

│   ├── Car.java            // Record implementing Vehicle

│   ├── Motorcycle.java     // Record implementing Vehicle

├── water-vehicles/

    ├── Boat.java           // Record implementing Vehicle

    ├── Submarine.java      // Record implementing Vehicle


Could you clarify whether this behavior is intended or a bug? If not, could
this be an area for potential improvement?

I am using openjdk 23.0.1

Thank you for your time and assistance!

Best regards and I hope you all have a nice new year.
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