Adding a compilerOption to disable error on property override accessor in 4.0.beta

Search Terms

property override accessor

Suggestion

Previously in 3.9, property can override an accessor with no emit errors. And in 4.0 beta, a break change was introduced by #33509.

It's reasonable to report an error on property override accessor in most case, but I'm using experimentalDecorators to inject a property accessor in prototype.

Currently I cannot find a solution for this use case, so I'm suggesting to add a new compilerOption to disable this check(strictOnly?) for compatibility.

Use Cases

class Animal {
    private _age: number
    get age(){ return this._age }
    set age(value){ this._age = value }
}

class Dog extends Animal {
    @defaultValue(100) age: number;     // Unexpected error here
}

function defaultValue(value) {
    return (obj, name) => {
        Object.defineProperty(obj, name, {
            get() { return value }
        })
    }
}

Checklist

My suggestion meets these guidelines:

• This wouldn't be a breaking change in existing TypeScript/JavaScript code
• This wouldn't change the runtime behavior of existing JavaScript code
• This could be implemented without emitting different JS based on the types of the expressions
• This isn't a runtime feature (e.g. library functionality, non-ECMAScript syntax with JavaScript output, etc.)
• This feature would agree with the rest of TypeScript's Design Goals.

まず、この issue を #33509 で参照されている breaking change と併せて読み、compiler options と property/accessor override diagnostics がどのように処理されているかを確認してください。この issue にはファイルやテストの指定がありません。完了には、出力される JavaScript を変更せずにこの diagnostic を抑制する、合意済みの互換性オプションと、decorator の例に対するカバレッジが必要です。