Python: return a subclass of a known class implementing an interface

[eladb]

🐛 Bug Report

Affected Languages

• TypeScript or Javascript
• Python
• Java
• .NET (C#, F#, ...)

General Information

• JSII Version: 0.20.4

What is the problem?

export interface IReturn {
  readonly foo: number;
}

export class Base {
}

export class SomeType {
  static returnReturn(): IReturn {
    class Derived extends Base implements IReturn {
      foo: 333
    }
  }
}

When calling SomeTime.return_return() from Python, the returned object will be Base instead of IReturn.

See aws/aws-cdk#4966