Support safe index access for noImplicitAny

It is hard to use noImplicitAny without enabling suppressImplicitAnyIndexErrors on the current TypeScript.

Search Terms

noImplicitAny suppressImplicitAnyIndexErrors

Suggestion

Provide safe indexes without explicit type declarations to avoid unsafe index access errors.

Use Cases

• for-in
• Object.keys

Examples

const o = {};
for (const key in o) {
    o[key]; // Should be no error.
}
for (const key of Object.keys(o)) {
    o[key]; // Should be no error.
}

Checklist

My suggestion meets these guidelines:

• This wouldn't be a breaking change in existing TypeScript/JavaScript code (for-in only)
• 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、issue に記載されている noImplicitAny と suppressImplicitAnyIndexErrors の動作、および for-in と Object.keys の例を確認してください。示されているインデックスアクセスが、明示的な型宣言なしで安全に受け入れられ、提示されているランタイムおよび JavaScript 互換性の制約が維持されれば完了です。