Disallow argument mismatch between interface and implementation

Currently, the compiler will allow the following program:

export interface IAdder {
  add(a: number, b: number): number;
}

export class Adder implements IAdder {
  public add(a1: number, b1: number): number {
    return a1 + b1;
  }
}

Notice the argument names in Adder.add are different from IAdder.add.

This results in an incompatibility between the IAdder interface and the Adder class in python. See:

We should have the compiler enforce that functions in implementations (or subclasses) use the same argument names as the parent.

Notes

Unless we roll out a new major version, we cannot start enforcing this on existing projects because the fix would have to be argument renaming, and this would be a breaking change. In order to maintain backwards compatibility and stop the proliferation of this mistake, we need to provide an allow list mechanism to ignore existing violations, as well as a feature toggle to activate this validation. In the next major version of the compiler, we can remove these provisions and start enforcing it.
It would be nice to resurrect and merge https://github.com/aws/jsii/pull/2937 as well, as this would protect us against accidental renaming, either in an attempt to fix the inconsistency, or just an ad-hoc decision to rename some arguments.

aws / jsii-compiler

Disallow argument mismatch between interface and implementation #1320

Notes