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.

首先阅读此 issue 以及 #33509 中引用的 breaking change，并检查 compiler options 和 property/accessor override diagnostics 的处理方式。该 issue 未指定文件或测试；要完成此工作，需要一个达成共识的兼容性选项，在不改变生成的 JavaScript 的情况下抑制此 diagnostic，并为 decorator 示例添加覆盖。