Remove name assignment when renaming a renamed destructured property to its original name

Search Terms

rename, destructuring

Suggestion

When renaming a variable, which comes from an object destructuring and is assigned with another name, back to its original name, the name assignment is not removed, and becomes a little extra and useless code. It would make the code cleaner if the assignment can be removed when rename is done.

Use Cases

To have cleaner code.

Examples

const obj = { a: 1 };
const { a: b } = obj;
console.log(b);

Renaming b to a:

Now (at least up to 3.6.3):

const { a: a } = obj;
console.log(a);

Better:

const { a } = obj;
console.log(a);

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.

分割代入宣言で b を a に名前変更して TypeScript の例を再現します。issue では実装ファイル、テスト、エントリポイントは指定されていません。名前変更の動作を追跡し、{ a: a } が { a } になる一方で、その他の名前変更ケースでは代入が維持されることを示すカバレッジを追加します。