Two way assignability condition with generic params is not working as expected

Bug Report

🔎 Search Terms

assignability, ternary, conditions, generics

🕗 Version & Regression Information

• This is the behavior in every version I tried

⏯ Playground Link

Playground link with relevant code

💻 Code

type NumberIfExtends<T, U> = T extends U ? U extends T ? number : string : string;
function f<G>() {
  const x: NumberIfExtends<G, G> = 1;
}

🙁 Actual behavior

The value 1 is not assignable to variable x, with the following error: Type 'number' is not assignable to type 'NumberIfExtends<G, G>'.

🙂 Expected behavior

This should be assignable, since the the value passed to both T and U generic params is the same.

Please note the following very similar examples, that works without errors.
This is to show this is a minimal reproduction, and that the different do not justify the error:

type NumberIfExtends<T, U> = T extends U ? U extends T ? number : string : string;
const x: NumberIfExtends<'some type', 'some type'> = 1; // if I pass an explicit type (Not a generic)

type NumberIfExtends<T, U> = T extends U ? number : string; // if I use the condition in only one way. 
function f<G>() {
  const x: NumberIfExtends<G, G> = 1;
}

function f<G>(): void {
  const x: G extends G ? G extends G ? number : string : string = 1; // if I define the type without an alias. This is not always possible if instead of defining a variable I would be passing the value to a function who defines its own type
}

リンクされている TypeScript Playground と最小限の NumberIfExtends<G, G> の再現コードから始めてください。ジェネリックパラメーターを持つ条件型の代入可能性がどのようにチェックされるかを追跡し、エイリアス形式とインラインおよび一方向の例を比較してください。報告されているエラーなしで、ジェネリック条件型に 1 を代入できれば完了です。