Better printing of `T & U` where this is equivalent to `Extract<T, U>`

Suggestion

🔍 Search Terms

Extract intersection union ide editor printing

✅ Viability 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, new syntax sugar for JS, etc.)
• This feature would agree with the rest of TypeScript's Design Goals.

⭐ Suggestion

There are many cases where T & U is equivalent to Extract<T, U>. However, the former has much worse type printing in these cases than the latter, leading to a much worse developer experience for this case.

I initially raised this as an eslint rule, but it would be very difficult to do do from that side (as explained in the comments of https://github.com/typescript-eslint/typescript-eslint/issues/2983

📃 Motivating Example

type A = Action & { type: 'action1' | 'action2' } 
// ({
//     type: 'action1';
//     a: number;
// } & {
//     type: 'action1' | 'action2';
// }) | ({
//     type: 'action2';
//     b: string;
// } & {
//     type: 'action1' | 'action2';
// })

type B = Extract<Action, { type: 'action1' | 'action2' }>
// {
//     type: 'action1';
//     a: number;
// } | {
//     type: 'action2';
//     b: string;
// }

https://www.typescriptlang.org/play?#code/C4TwDgpgBAggxsAlgewHZQLwCgoB8oDeUokAXFAOQCGCKqAjBQDRRXmoCuAtgEYQBOUAL458REhHLVaaAEzMoPcgGdg-RKgDmw0YWLhJlGkjQBmBXBVqN2kViwTYmWDPQAyPRKnG6jPEdd5YSgHAygAIWcAUQAPNWMAHngTVBZxA29XP3xpFKChAD4gA

💻 Use Cases

Improve developer experience, error messages, and IDE support.

動機となる TypeScript の例と、リンクされている TypeScript Playground の再現から始めてください。型の出力と IDE サポートに関わる挙動を調査してください。完了条件は、実行時の挙動を変更せずに、同値な交差型がより明確な Extract-like 形式で提示されることです。